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Sparks v Hobson; Gray v Hobson [2018] NSWCA 29 (1 March 2018)

Last Updated: 14 May 2018





Court of Appeal

Supreme Court New South Wales



[Note: The Uniform Civil Procedure Rules 2005 provide (Rule 36.11) that unless the Court otherwise orders, a judgment or order is taken to be entered when it is recorded in the Court's computerised court record system. Setting aside and variation of judgments or orders is dealt with by Rules 36.15, 36.16, 36.17 and 36.18. Parties should in particular note the time limit of fourteen days in Rule 36.16.]

HEADNOTE

[This headnote is not to be read as part of the judgment]

Mr Brendan Hobson, the respondent, suffers from Noonan Syndrome, a genetic disorder that prevents normal development in various parts of the body. As a result of that disorder, Mr Hobson’s ability to fill his lungs with air, and hence to breathe, was restricted. Without surgical intervention, his prognosis was grave. Surgery to correct this problem was designed to take place in two stages. The first operation was successful. The second, which occurred on 17 November 2009, had to be terminated before its intended conclusion. As a result of that operation, Mr Hobson became a paraplegic.

Mr Hobson initiated proceedings claiming damages for negligence. His claims ultimately proceeded against the principal surgeon, Dr Randolph Gray, and the principal anaesthetist, Dr Christopher Sparks. Dr Gray is an experienced specialist orthopaedic/spine surgeon and Dr Sparks is an experienced specialist anaesthesiologist.

After an 11 day hearing before Harrison J in the Common Law Division of the Supreme Court, his Honour found that Drs Gray and Sparks had breached the duties of care that they owed to Mr Hobson and were liable in negligence for damages in the amount of $3,828,075. The basis of the decision against both doctors was that, in light of adverse blood gas readings for carbon dioxide obtained in the course of the operation, they should have caused the operation to be terminated earlier than occurred. His Honour held that if the operation had been so terminated, Mr Hobson would not have suffered a significant cardio-vascular collapse during the operation at about 21:30, his spine would not have been damaged and he would not have become a paraplegic.

Drs Gray and Sparks each appealed against the primary judge’s decision on liability. As well as contending that the primary judge erred in finding that they acted negligently, the appellants relied, as they did at first instance, on sections 5 I and 5 O of the Civil Liability Act 2002 (NSW).

The appellants also appealed against his Honour’s decision on damages in three limited respects. They contended that his Honour erred in the allowances that he made for past and future domestic care, and for motor vehicle expenses.

By majority (Simpson JA dissenting), the Court dismissed Dr Sparks’ appeal with costs. The Court unanimously allowed Dr Gray’s appeal.

In relation to Dr Sparks’ appeal:

(1) Breach of duty was established.

Per Basten JA at [93]: “Dr Sparks was faced with a difficult intraoperative choice. However, it was not one which required an instantaneous decision, nor one which required further information or advice. The patient’s metabolic decline was continuing despite Dr Sparks having taken every available step to alleviate the condition whilst the operation proceeded. However, whilst the operation continued, the patient was heading for cardiovascular failure. The operation was expected to last for some four hours; at 9pm the operation was only half completed, on that timescale. (The orthopaedic experts stated that it had 2-4 hours to go.) The decision to allow it to continue for 30 minutes after Dr Sparks had sought help from two experienced anaesthetists, without success, involved more than an erroneous clinical judgment; the trial judge was correct to find a breach of duty of care” (citations omitted).

Per Macfarlan JA at [181] and [182]: “Dr Sparks made an unreasonable decision to ignore a serious and imminent intra-operative danger to Mr Hobson’s well-being when Dr Sparks knew that the other risk with which he was concerned (namely the risk to Mr Hobson if the operation were not completed) did not have the same immediacy...It was not for Dr Sparks to assess the urgency of the operation and decide that it justified a serious and immediate intra-operative risk to Mr Hobson being ignored, at least not without consulting Dr Gray who, as principal surgeon, was head of the surgical team.”

Per Simpson JA (dissenting) at [359]: “The medical evidence does not...support a finding that, in failing to direct the termination of the surgery before 21:28, Dr Sparks failed to exercise reasonable care and skill. The decision Dr Sparks had to make (on a continuing basis throughout the surgery) involved the exercise of clinical judgment...The respondent bore the onus of establishing that Dr Sparks’ decision not to direct the termination of the surgery before that time represented a departure from the standard of care and skill required of a specialist anaesthetist. That onus was not discharged. The medical evidence falls well short of permitting a conclusion to that effect.”

(2) Section 5 I of the Civil Liability Act 2002 (NSW) did not provide a defence to Dr Sparks (Simpson JA dissenting).

(3) Section 5 O of the Civil Liability Act 2002 (NSW) did not provide a defence to Dr Sparks. Discussion by the Court of the correct interpretation of s 5 O.

McKenna v Hunter & New England Local Health District [2013] NSWCA 476; (2013) Aust Torts Rep 82-158 considered. Hunter and New England Local Health District v McKenna (2014) 253 CLR 270; [2014] HCA 44 referred to.

In relation to Dr Gray’s appeal:

Per Macfarlan JA at [201]: “[T]he surgery that took place on 17 November was complex, protracted and difficult. It was Dr Sparks’ role to monitor indicators of Mr Hobson’s condition during the surgery, the two main ones being Mr Hobson’s blood oxygenation and blood pressure, although other indicators were relevant. At least in respect of the other relevant indicators, Dr Gray was entitled to rely on Dr Sparks to inform him of any matter of concern without Dr Gray making any inquiry. There is no evidence that Dr Sparks did so in the period 20:50 to 21:20, and the evidence did not indicate that any matter came to Dr Gray’s notice during that time that should have caused him to make an inquiry as to Mr Hobson’s carbon dioxide level. Without such information, Dr Gray was not negligent in failing to direct termination of the operation during that period. When Dr Sparks did advise termination of the operation at around 21:25, Dr Gray promptly did so. Dr Gray’s appeal on liability therefore succeeds.”

In relation to both appeals:

The challenges to the primary judge’s damages assessment were rejected.

JUDGMENT

BASTEN JA: The respondent, Brendan Hobson, was born with Noonan Syndrome, one feature of which was a serious curvature of the spine resulting in a reduced chest cavity, particularly on the left side. In the course of 2009, Mr Hobson suffered increasing breathlessness and a pattern of restrictive airways disease. Corrective surgery was undertaken which involved a two-stage operation intended to relieve the pressure on the chest cavity by straightening the spine. The first stage of the operation took place on 13 November 2009, which was completed uneventfully in a surgical sense. The second stage was planned for 10 days later. However, whilst Mr Hobson was in the intensive care unit his respiratory condition deteriorated as a result of the left main airway (bronchus) becoming obstructed, with the result that pneumonia developed in the left lung. The second stage of the operation was brought forward to the evening of 17 November 2009. The procedure was expected to take some four hours, commencing shortly after 7pm. However, the senior anaesthetist, Dr Christopher Sparks, requested the surgeons to terminate the procedure at about 9.25pm, when the patient’s blood pressure and oxygen levels had dropped dramatically. Once the wound had been closed the patient, who had been in a prone position on the operating table, was returned to a supine position, whereupon his condition improved. Nevertheless, there had been a severe ischaemic collapse in his spinal column resulting in paraplegia. The operation was later completed successfully, but Mr Hobson did not recover the use of his lower limbs. Mr Hobson commenced proceedings against the hospital and various members of the team who operated on him, alleging negligence in various respects. In November 2016 a trial was conducted before Harrison J in the Common Law Division. On 17 May 2017 judgment was delivered for the plaintiff against the principal surgeon, Dr Gray, and the principal anaesthetist, Dr Sparks. Mr Hobson was awarded damages.[1] The particular of negligence which was upheld with respect to both practitioners was the failure to terminate the operation no later than 9.15pm that evening. Both the medical background and the procedural background have been fully explained in other judgments. For the reasons given by Macfarlan JA, it is clear that, with respect to the single particular of negligence which was upheld, the primary responsibility lay with the anaesthetist, Dr Sparks. I agree that the finding of negligence on the part of Dr Gray was not justified and Dr Gray’s appeal should be allowed. The situation with respect to Dr Sparks has led to differing conclusions. The following reasons address the case against Dr Sparks and the basis on which he has challenged the decision below. Much of the relevant material was set out clearly and comprehensively by the trial judge in reasons the bulk of which are not the subject of challenge on this appeal. Despite the complexity of the medical evidence, the number of experts called and the somewhat variable course taken on behalf of the plaintiff during the trial, the issues raised on the appeal are circumscribed; the trial judge rejected some 13 particulars of negligence in respect of which there is no notice of contention.[2] It is convenient to commence by identifying the relevant grounds of appeal.

Dr Sparks: grounds of appeal

Dr Sparks pleaded seven grounds of appeal, six of which related to liability and the seventh to aspects of the assessment of damages. Grounds 1 and 2 alleged error in the application of s 5O of the Civil Liability Act 2002 (NSW), set out in the next part of these reasons. It is convenient to set the grounds out in full.

“1. The primary judge erred in failing to find, pursuant to section 5O of the Civil Liability Act 2002 (NSW), (“the Act”) that the appellant did not incur a liability in negligence, in circumstances where:

a. the appellant adduced expert evidence to the effect that he acted in a manner that (at the time the service was provided) was widely accepted in Australia by peer professional opinion as competent professional practice;

b. that evidence was not challenged; and

c. the primary judge did not find that the peer professional opinion is irrational and could not, for that reason, be relied on.

2. The primary judge erred in failing to determine the standard of care according to the evidence of what was, in 2009, widely accepted in Australia by peer professional opinion as competent professional practice.”

The syntax of ground 3 was obscure, but it appeared to be directed to s 5I of the Civil Liability Act. In short, it alleged that the respondent suffered harm as a result of the materialisation of an inherent risk which could not be avoided by the exercise of reasonable care. The risk was identified as “risk of suffering spinal cord ischemia”. Ground 4 alleged that the judge failed to identify “the risk of harm” against which the appellant ought to have taken precautions. Ground 5 alleged that the judge had wrongly held there was a breach of duty merely because the risk of harm could have been avoided by doing something in a different way. Ground 6 asserted in broad terms that the time for terminating the procedure was a matter of clinical judgment for the anaesthetist and that allowing the operation to proceed for some 15 minutes after the last moment at which it should reasonably have been terminated (as identified by the trial judge) did not constitute a breach of duty. Grounds 1 and 2 are central to the appeal and it is convenient to turn to the operation of s 5O of the Civil Liability Act.

Civil Liability Act, s 5O

Both appellants appealed from the rejection by the trial judge of their respective defences based on s 5O of the Civil Liability Act. There are a number of reasons for addressing the defence separately in each case. First, Dr Gray originally pleaded the section with five particulars, three of which appeared to be directed to s 5I. Neither of the other two potentially relevant particulars addressed the termination of the operation.[3] Dr Sparks, by contrast, originally pleaded the section, but without any particulars at all.[4] Secondly, although both appellants addressed the issue in written submissions at trial, they did so in somewhat disparate terms.[5] Thirdly, the nature of each defence case turned primarily upon the evidence of the expert witnesses practising in the field of the particular specialist. Before addressing these separate circumstances it is convenient to consider the scope and operation of s 5O. The section is located in Pt 1A of the Civil Liability Act dealing with “Negligence”. The Part does not constitute a comprehensive statement of the principles governing the tort of negligence, but identifies in separate divisions a number of specific principles. Section 5O appears in Div 6, entitled “Professional negligence”. The primary principle is stated in subs (1), but it is convenient to set out the whole of the section, including the subsidiary provisions:

5O Standard of care for professionals

(1) A person practising a profession (a professional) does not incur a liability in negligence arising from the provision of a professional service if it is established that the professional acted in a manner that (at the time the service was provided) was widely accepted in Australia by peer professional opinion as competent professional practice.

(2) However, peer professional opinion cannot be relied on for the purposes of this section if the court considers that the opinion is irrational.

(3) The fact that there are differing peer professional opinions widely accepted in Australia concerning a matter does not prevent any one or more (or all) of those opinions being relied on for the purposes of this section.

(4) Peer professional opinion does not have to be universally accepted to be considered widely accepted.

The section envisages a conflict in the evidence as to whether the defendant’s conduct was accepted by his or her peers as “competent professional practice.” In order to establish negligence, there will usually need to be expert evidence called by the plaintiff to the effect that the defendant failed to exercise reasonable care and skill in providing a relevant service. Under the general law, the defendant would seek to challenge that evidence by calling expert opinion to a contrary effect. For the plaintiff to succeed, the court would need to be satisfied on the probabilities that the appropriate standard was that for which the plaintiff’s experts contended. That position has been varied by s 5O(1); although expressed in the passive voice (“if it is established that ...”), it has been broadly accepted that the section provides a defence.[6] Despite the common acceptance of the provision as a “defence”, that characterisation gives rise to difficulty. To be a defence carries the implication that the plaintiff must establish breach according to the general requirements of s 5B of the Civil Liability Act, following which the practitioner bears the burden of establishing that his or her conduct amounted to “competent professional practice” in the terms of s 5O(1). The heading of the section (“Standard of care for professionals”) indicates its purpose. Although the heading is not part of the Act,[7] it may be taken into account as extrinsic material in construing the provision, in accordance with s 34(1) of the Interpretation Act. In any event, it is tolerably clear that the provision sets a standard. However, if the standard is met, it follows that the conduct was not negligent. Accordingly, once s 5O is invoked, arguably the general exercise required by s 5B becomes otiose. There can only be one standard against which to judge the conduct of a professional defendant, although that standard may depend upon the resolution of conflicting evidence called by the plaintiff and the defendant. It is only if one takes the plaintiff’s evidence in isolation that a two-stage process, involving the assessment of the plaintiff’s claim followed by assessment of an affirmative defence, will arise. However, in a practical sense, that is not how the dispute should be determined. Rather, a judgment will be given based on all of the evidence. Nor is the exercise helpfully clarified by speaking of shifting burdens of proof. The question for the trial judge is ultimately whether the plaintiff has established that the conduct of the defendant failed to comply with the relevant standard of care. This approach is consistent with Dobler and is not to say that a plaintiff must seek out and negative opinions inconsistent with those of the experts on whom he or she relies.[8] Beyond that proposition, Dobler did not turn upon the onus of proof.[9] This approach obtains support from an understanding of s 5O in its historical context. Prior to the enactment of s 5O, Australian courts identified the standard of care in medical negligence cases according to the principles set out in Rogers v Whitaker:[10]

“In Australia, it has been accepted that the standard of care to be observed by a person with some special skill or competence is that of the ordinary skilled person exercising and professing to have that special skill. But, that standard is not determined solely or even primarily by reference to the practice followed or supported by a responsible body of opinion in the relevant profession or trade.”

This statement rejected the approach then applied in the UK[11] by reference to a direction given to a jury by McNair J in Bolam v Friern Hospital Management Committee.[12] As Lord Scarman explained in Sidaway v Board of Governors of Bethlem Royal Hospital:[13]

“The Bolam principle may be formulated as a rule that a doctor is not negligent if he acts in accordance with a practice accepted at the time as proper by a responsible body of medical opinion even though other doctors adopt a different practice. In short, the law imposes the duty of care: but the standard of care is a matter of medical judgment.”

Lord Scarman himself preferred a different approach:[14]

“In my view the question whether or not the omission to warn constitutes a breach of the doctor's duty of care towards his patient is to be determined not exclusively by reference to the current state of responsible and competent professional opinion and practice at the time, though both are, of course, relevant considerations, but by the court's view as to whether the doctor in advising his patient gave the consideration which the law requires him to give to the right of the patient to make up her own mind in the light of the relevant information whether or not she will accept the treatment which he proposes.”

Australian authority, as explained by Gleeson CJ in Rosenberg v Percival,[15] adopted the dissenting view of Lord Scarman by which “the relevance of professional practice and opinion was not denied; what was denied was its conclusiveness.” The Australian approach was not confined to cases of warnings and medical advice; it extended to diagnosis and treatment.[16] However, the language of s 5O differs from Bolam, which referred to a practice accepted as “proper” by a “responsible body of medical men”. Lord Scarman also referred to “responsible and competent professional opinion”. The differences may not have practical significance. In Dobler, Giles JA stated :[17]

“Section 5O may end up operating so as to determine the defendant’s standard of care, but the standard of care will be that determined by the court with guidance from evidence of acceptable professional practice unless it is established (in practice, by the defendant) that the defendant acted according to professional practice widely accepted by (rational) peer professional opinion.”

Ipp JA and I agreed. On reflection, this passage may be open to misunderstanding. It is true that s 5O will not be engaged unless there is evidence of a widely accepted professional practice supporting the defendant’s conduct, but where there is such evidence, unless it can be rejected by the trial judge, it will fix the relevant standard; there cannot be two legally supportable standards operating in the one case.

There remains a question as to the extent to which the trial judge has a discretion to reject evidence of a widely accepted professional practice. The judge may dismiss “peer professional opinion” as “irrational”, in accordance with subs 5O(2). By contrast, the older cases, while tending to use transferred epithets, refer to opinions of responsible and competent practitioners in the field. It may be that the reference in s 5O to “peer professional opinion” is to be so understood. But then it is difficult to understand how an irrational opinion could qualify as a relevant peer opinion. More importantly, the provision raises the possibility of a negative inference, namely that the court may not reject an opinion even though satisfied that it is unreasonable (though not irrational), or otherwise not one the court would itself adopt. Such a general negative inference should not be inferred; there will be other questions which will arise. First, there will be a question as to whether the evidence of one or two experts can satisfactorily establish opinions which are “widely accepted” in circumstances where such a view is contradicted by other evidence. No doubt evidence of “general professional opinion”, in addition to the personal opinion of the expert, is admissible in such circumstances.[18] Secondly, it will be a matter for the court to assess the significance of particular evidence. Evidence may be at a greater or lesser level of generality. At a high level of generality it may readily be accepted that an opinion is widely held amongst peers of the practitioner. However, the standard so identified may not assist greatly in resolving the particular case. On the other hand, the more particular the opinion, based on the specific circumstances of the case, the more difficult it may be to establish an opinion which can be described as “widely accepted” among fellow practitioners. Accordingly, whether or not evidence of medical opinion is properly described as conclusive in a particular case will depend upon a range of factors and not merely the fact that it can properly be described as not irrational. Subsections (3) and (4) do little more than explain what might otherwise readily have been inferred, namely that for an opinion to be “widely accepted” it need not be “universally accepted” and, if not universally accepted, there must be more than one opinion and may be more than one which is widely accepted. If the court is satisfied that the defendant’s conduct is considered competent according to widely accepted peer professional opinion, that opinion provides a standard against which to assess the claim. At trial, both practitioners raised s 5O as a defence. Counsel for the plaintiff treated the reasoning of this Court in McKenna v Hunter & New England Local Health District[19] as an effective answer to the defence. In McKenna Macfarlan JA stated that:[20]

“To establish a defence under s 5O a medical practitioner needs to demonstrate, first, that what he or she did conformed with a practice that was in existence at the time the medical service was provided and, secondly, to establish that that practice was widely, although not necessarily universally, accepted by peer professional opinion as competent professional practice.”

On the appeal, counsel for Dr Sparks submitted that McKenna was wrong in holding that it was necessary to demonstrate the existence of “a practice” extant at the time of the conduct in question.

Although it is uncertain how this reasoning in McKenna will operate in particular cases, there is a risk in reformulating the statutory language. To speak of “a practice” adopted by a group of professional persons suggests a regular course of conduct adopted in particular circumstances. By contrast, the phrase “competent professional practice” is apt to cover the whole gamut of professional services provided by the practitioner, whether or not the particular circumstances have arisen sufficiently often to result in an established practice. For example, although opinions may differ as to the conclusion to be drawn, there is no grammatical or semantic difficulty in describing an argument run by counsel in a novel case as demonstrating competent or incompetent professional practice. The same judgment may be offered about the failure of counsel to call a defendant in a criminal trial, where no settled practice exists. Where an acquittal depends on establishing an affirmative defence and there is no other evidence to support the defence, it may be described as incompetent professional practice not to call the defendant who could have given such evidence. Where an opinion is given and challenged, it will be supported (or attacked) not by reference to some established practice, but by reference to how an assessment of the circumstances (which may be unique) would be undertaken by a knowledgeable and experienced practitioner. There are other reasons for thinking that the reference to “competent professional practice” does not require evidence of “a practice”. First, it is the “manner” in which the defendant acted which must be the focus of the opinion. Secondly, if it were necessary to establish a practice, one might expect subs (3) to refer to “opinions ... concerning that practice”, rather than “opinions ... concerning a matter”. To take an example closer to the present case (but still hypothetical) an anaesthetist might allow an operation to proceed on the basis that two indicators remained within acceptable limits but a third indicator did not. An expert might express an opinion that such conduct was not competent practice, not because he or she had experienced the same circumstance in the past, or had read about it in a textbook, but because basic principles of human physiology led to that conclusion. Accordingly, although the language used in McKenna may well sufficiently describe many circumstances in which s 5O is invoked, I would not understand it as a general proposition as to the constraints imposed by s 5O(1). If that understanding is too restrictive and it is necessary to go further, I would not follow McKenna. The decision in McKenna having been overturned in the High Court,[21] the reasoning of the majority in this Court is no longer binding. As Kirby J noted in Garcia v National Australia Bank:[22]

“It is fundamental to the ascertainment of the binding rule of a judicial decision that it should be derived from (1) the reasons of the judges agreeing in the order disposing of the proceedings; (2) upon a matter in issue in the proceedings; (3) upon which a decision is necessary to arrive at that order. Thus, the opinions of judges in dissent are disregarded for this purpose, however valuable they may otherwise be.”

When the decision of an intermediate court of appeal is overturned by the High Court, the reasoning of the majority is no longer dispositive, even if the High Court does not directly reject it, as it did not with respect to the interpretation of s 5O in McKenna, having determined the appeal on a different point. There is some irony in the fact that the primary support for this conclusion is often sourced to a brief statement by Aickin J in dissent in Federal Commissioner of Taxation v St Helens Farm (ACT) Pty Ltd[23] stating:

“I should add that there is no basis on which one point in the judgment of a primary court should be regarded as authoritative where the judgment is reversed on other grounds.”

Given that the reasons of the intermediate court in a case where the decision has been reversed are no longer dispositive, they are analogous to the reasoning of a dissenting judge. Allsop P explained in Holmes a Court v Papaconstuntinos[24] that dissenting judgments “may contain valuable discussions of legal principle”, but that is “a different thing to being taken as an exposition of the common law to be applied.” The same proposition applies with respect to discussion of statutes. The position would, of course, be quite different if the High Court, despite reversing the decision in this Court in McKenna, had approved the reasoning with respect to s 5O. The reasoning would not then form part of the ratio, but it would clearly obtain the authority of dicta of the High Court. However, that did not happen in the present case. The High Court held that the plaintiff must fail on the basis that there was no duty of care owed to relatives of the deceased. The Court continued:[25]

“Consideration of those other issues, about ss 5B, 5O, 43 and 43A of the [Civil Liability Act], should await a case in which it is necessary to examine them.”

While the reasoning of this Court in McKenna as to the scope and operation of s 5O is not to be disregarded, there is no obligation on this Court, as a matter of precedent, to follow it. For the reasons set out above, in my view it is too restrictive.[26]

Civil Liability Act, s 5I

Dr Sparks also called in aid the exclusion from liability for the materialisation of an inherent risk, as set out in s 5I of the Civil Liability Act. The section provides:

5I No liability for materialisation of inherent risk

(1) A person is not liable in negligence for harm suffered by another person as a result of the materialisation of an inherent risk.

(2) An inherent risk is a risk of something occurring that cannot be avoided by the exercise of reasonable care and skill.

(3) This section does not operate to exclude liability in connection with a duty to warn of a risk.

The scope and operation of the provision has been the subject of careful consideration in earlier decisions, including Paul v Cooke.[27] The apparently simple language of the provision is fraught with difficulties. On one reading of subs (2), that which “cannot be avoided” by the exercise of reasonable care is the “risk”; the alternative reading is that it is the materialisation of the risk which cannot be avoided by exercise of reasonable care. To speak of “avoiding” a risk is meaningful in some circumstances, but not in others. Ordinary usage would suggest that it is the occurrence (the materialisation of the risk) which may or may not be “avoided”. Context suggests that that is the intended meaning because the provision only operates where a person has suffered harm as a result of the “materialisation of an inherent risk.” The next problem stems from the use of the words “cannot be” avoided. A risk is less than a certainty; it may be quantified in a particular case at, say, 25%. In three out of four cases the harm will not materialise and in one sense “can” be avoided. However, the section should be understood as referring to the exercise of skill having no causal consequence in terms of the outcome. Thus, in a sense, the provision may be read as operating where the skill of the surgeon does not affect the risk of an adverse outcome. Of course, the application of s 5I will only arise in circumstances where (staying with the medical example) the patient has had an adverse outcome, in which case liability will depend upon establishing negligence and causation. Assuming negligence, the plaintiff will fail if she cannot demonstrate a causal connection between the negligence and the harm. In that case, s 5I is not required by the defendant; if causation is established, s 5I is not engaged. Rogers v Whitaker is often cited as a paradigm of an inherent risk. The patient had an operation on her right eye, which resulted in her losing her sight in her left eye as a result of a condition known as sympathetic ophthalmia. Evidence suggested that the risk materialised in fewer than one in 10,000 cases. The operation had been carried out with the required skill and care. Rogers itself involved a failure to warn and thus s 5I would not have applied.[28] There may be cases, of which Paul v Cooke was one, where negligence may be conceded and the case will turn on causation. However, as Leeming JA explained, where s 5I is raised, “it unquestionably remains for the plaintiff to establish s 5D legal causation, and the logical consequence of so doing may (and often will be) to negate s 5I.”[29] This is not a case where the risk of harm was less than 50%, so that, had the negligence not occurred, the operation would have been conducted on a different occasion when, on the probabilities, the harm that in fact occurred would not have occurred. Section 5I has no application in the present case. The risk which accompanied the surgery was the neurological collapse of the spinal column which in fact occurred. There is no doubt that if the operation had ceased at a point in time before the collapse occurred (which was probably shortly before the operation in fact ceased) the risk would not have materialised; the harm would not have occurred. That result would have been achieved in the exercise of reasonable care and skill. The question for the determination of the Court was whether the continuation of the operation involved a failure to exercise reasonable care and skill. Because the definition of “inherent risk” in s 5I assumes that the exercise of reasonable care and skill would not affect the outcome, it is not clear how the section was said to be engaged in the present case.

Evidence and findings at trial

There were five methods adopted for the monitoring of the patient’s condition during surgery. These were (a) blood pressure, (b) oxygen levels in blood, (c) CO2 levels in blood, (d) exhaled CO2 levels and (e) spinal cord monitoring. The last (spinal cord monitoring) was abandoned, but that proved to be only indirectly relevant to breach of duty; it may conveniently be addressed first. Dr Sparks based his decision-making on the first two parameters; a critical question was whether he should have paid greater attention to the CO2 levels.

(a) spinal cord monitoring

It is convenient to consider first the significance of the spinal cord monitoring. The importance of such monitoring arose from the fact that part of the arterial blood supply to the spinal cord had been diminished through the first procedure. An episode of low blood pressure (hypotension) was liable to place the spinal cord at risk through loss of blood supply. A number of criticisms were made of the monitoring procedure. First, it was important to obtain a baseline reading. The neurophysiologist responsible for the monitoring, Associate Professor Jim Lagopoulos gave evidence that he arrived at the theatre after the procedure was already underway. He said that a normal baseline reading was not able to be established. It was common ground that at or about 8.35pm Dr Sparks administered vecuronium to improve the patient’s ventilation. The drug, a muscle relaxant, led to the discontinuation of the spinal cord monitoring as it had become ineffective. There was inconsistent evidence given at the trial as to whether the readings from the monitoring were ever normal and as to whether Dr Gray or Dr Sparks was advised of the fact that they were abnormal, to the extent that they were. However, the expert evidence did not support the proposition that the surgery should have been terminated in light of the results of the monitoring. Rather, the concern focused on the fact that the monitoring ceased at about 8.35pm, when vecuronium was administered. At that stage, Dr Sparks believed that there was a problem with ventilation, and hoped that administration of vecuronium would correct the problem. The trial judge accepted that this was a reasonable step to take. He continued:[30]

“However, the significant compromise in those circumstances was that the spinal cord monitoring was immediately neutralised by its administration and any form of spinal insult that spinal cord monitoring might otherwise have been expected to highlight would remain dangerously undetected. In other words, Dr Gray and Dr Sparks were effectively trading off any concern they might have had that Mr Hobson may be neurologically compromised if the surgery proceeded in the absence of spinal cord monitoring against the possibility that he might die if the corrective surgery were discontinued.”

The judge then considered what warnings might have been available had the spinal cord monitoring continued after 8.30pm. Dr Westbrook had given evidence that “had spinal-cord monitoring been properly established in a timely manner that there would have been advanced warning to the clinicians that spinal cord perfusion was threatened particularly during the transient, earlier episodes of hypoxaemia.”[31] Dr Michael Johnson, an orthopaedic surgeon, gave evidence that he would have “insisted that spinal cord monitoring was available.”[32] Dr Peter Heath also gave evidence of the importance of effective monitoring. In effect there was a wealth of evidence from the plaintiff’s experts that spinal cord monitoring was an important safety mechanism in circumstances where blood supply to the spinal cord was reduced by the earlier surgery, and where even transient elements of hypotension suggested cardiovascular instability which needed to be monitored. On the other hand Dr Geoffrey Askin, who was called by Dr Gray, stated:[33]

“MEP monitoring in this case would not have allowed remedial action given that the only remedial action that allowed the patient to restore blood pressure and PCO2 was to turn the patient supine. Having MEPs running during the time of the physiological crisis would not have expedited the termination of the procedure and changing the patient’s position at all. Hence, the loss of MEPs would not have changed the outcome.”

The trial judge had extracted, at [66] and [67], lengthy extracts from the evidence of Dr Peter Silbert, a neurologist and expert in spinal cord monitoring. Dr Silbert’s conclusion was that, had spinal cord monitoring continued, it would not have detected abnormalities prior to 9.25pm, which was the time at which the collapse in other indicators led Dr Sparks to request that the surgery end. The trial judge placed weight on that evidence, and the evidence of other experts to similar effect. The consequence was that although the absence of spinal cord monitoring should have led to caution on the part of the anaesthetist and the surgeon, its presence would not have altered the outcome. This conclusion was expressed in two parts. First, at [223], the judge concluded that continuing the operation beyond 8.30pm was perfectly reasonable. Allowing that use of vecuronium was also a reasonable step, “there was ... at the time no useful place for spinal cord monitoring.”[34] The second stage in the argument was addressed at [243] in the following terms:

“Sixthly, there was a need to be particularly mindful of the consequences for Mr Hobson of his rapidly deteriorating ventilation by reason of the fact that spinal cord monitoring was absent or effectively neutralised. For present purposes it does not matter which it is. Indeed, I accept the opinion of Dr Silbert that he did not believe that SSEPs and MEPs would have detected significant spinal cord electrophysiological abnormalities prior to 21.25. In that sense I am not satisfied that the absence of spinal cord monitoring for whatever reason properly informs or supports a finding of negligence by either defendant. Its absence or ineffectiveness was a fact of life in the operating theatre at 20.30 and at the very point at which Dr Sparks telephoned Dr Barratt. It was however to my mind a critically significant factor that not only enlivened, but in fact heightened, the need to act conservatively and to proceed expeditiously. It told against the appropriateness of taking an expectant approach when the solution to Mr Hobson’s difficulties had not emerged or was not understood.”

(b) measuring other conditions

Putting monitoring to one side, there were four other measurable parameters taken into account. Dr Sparks relied primarily on arterial blood pressure and oxygen saturation in the blood, as supporting continuation of the surgery. Until those fell below acceptable limits, he allowed the surgery to continue. The challenge to his decision-making was based upon his failure to act upon the concerns raised by the other parameters demonstrating that carbon dioxide was not being removed from the blood stream. There is no doubt that the readings caused him serious concern and led to him telephoning from the operating theatre a senior colleague, Dr Stephen Barratt with whom Dr Sparks had performed a bronchoscopy at the intensive care unit during the day before the operation. It was agreed that the telephone call was at approximately 8.50pm. Dr Barratt gave the following evidence in an affidavit:[35]

“11. Dr Sparks told me that Mr Hobson was in the prone position on a Jackson table during the surgery. In my view, if the breast plate of the Jackson Table was pressing on Mr Hobson, the cardiac compression would generate potential for hypotension.

12. Dr Sparks expressed his concern about a high arterial carbon dioxide at the time, I think he said approximately 65 mmHg. This is about 50% more than normal. This usually means inadequate ventilation and this issue had been excluded with multiple bronchoscopies, checking for breath stacking and pneumothorax. However, at the time Mr Hobson’s end tidal carbon dioxide was only 30-25mmHg which means a significantly increased dead space ventilation. Inadequate ventilation on its own does not explain this. Therefore, I proposed to Dr Sparks that maybe a pulmonary artery was being compressed along with possible cardiac compression which would mean he would have a section of his lung which was being ventilated, but not perfused. The telephone call abruptly ended when Dr Sparks said ‘I gotta go’.”

The trial judge summarised the plaintiff’s case at trial in the following terms:

“[124] Mr Hobson submitted that a failure to consider factors beyond oxygen saturation and blood pressure was indicative of a standard of medical practice below the standard required in Australia in November 2009 of a reasonably competent anaesthetist or orthopaedic surgeon, performing spinal surgery in the particular method adopted to treat Mr Hobson. ...

[125] Mr Hobson was in respiratory difficulty from the commencement of the surgery and the surgical team had trouble ventilating him throughout. His metabolic state, especially as reflected in his blood gasses, was also poor from the start and continually deteriorated during the surgery.

[126] Blood gasses demonstrated a clear deterioration in Mr Hobson’s metabolic state as the surgery progressed. Samples taken at 20.08 and 20.21 had by then already demonstrated a very high carbon dioxide level despite various attempts at pulmonary ventilation with a double lumen tube. This was causing significant respiratory acidosis. From the early stages of the surgery, blood gasses disclosed evidence of an increasing lactate level suggesting inadequate organ perfusion. Blood gas samples at 20.37 and 20.51 demonstrated significant further deterioration of all parameters.

[127] A reasonably competent anaesthetist would have concluded that Mr Hobson was suffering a profound respiratory and metabolic acidosis. Both Dr Sparks and Dr Gray were aware of this dangerous downward spiral in Mr Hobson’s metabolic state.

[128] By 20.50 Dr Sparks had tried various means of reversing this deteriorating trend without success. In particular, maintenance of blood pressure and ventilation at reasonable levels after transient drops had failed to address Mr Hobson’s dire and deteriorating metabolic state.

[129] As noted above, Dr Sparks spoke to Dr Barratt over the telephone at 20.50 or thereabouts. Dr Barratt correctly suggested to Dr Sparks that the breastplate of the Jackson table may have been pressing on Mr Hobson, creating cardiac and pulmonary artery compression. This meant that a section of lung was being ventilated but not perfused. Dr Sparks agreed with this analysis. Mr Hobson submitted that a reasonably competent anaesthetist would have called a stop to the surgery by this time at the latest. Had the surgery been paused or halted at that, or any earlier time, and Mr Hobson turned supine, he would not have suffered spinal cord damage.”

The findings of the trial judge in relation to this aspect of the case appeared as the fifth element in a series:[36]

“Fifthly, even if there was arguably no single unambiguous indication for stopping the surgery before the decision to do so was made, there were several factors which together certainly gave that indication. As Mr Hobson emphasises, the evidence of Dr Barratt, who was after all the expert to whom Dr Sparks turned when his options appeared to be evaporating, emphasises the importance of heeding several factors in combination. It is reasonably clear that Dr Barratt’s telephone input inspired the events that followed it. The attending doctors undoubtedly had access to several significant indicators of Mr Hobson’s condition, even if none taken alone pointed only in one direction. The combination of these factors provided a different perspective. The earlier indications available from Mr Hobson’s vital signs appeared to be that any deteriorations that were observed, in particular, episodes of hypoxia and hypotension occurring at or about 18.50, 19.10 and up until about 20.35, some of which were severe, were transient and recoverable but not such as to indicate that continuing with the surgery could not be justified. Up until about 20.35, Dr Gray and Dr Sparks were, in effect, permissibly taking an expectant approach, in the absence of material that indicated only one possible course of action. That position changed very shortly thereafter.”

On the appeal, Dr Sparks challenged the sentence italicised above. However, that sentence could be omitted without interfering with the process of reasoning. The judge then set out in some detail Dr Westbrook’s evidence, together with the responses of Dr Forrest and Dr Manasiev. He referred to Dr Sparks’ own evidence and to the expert evidence of two orthopaedic surgeons in the following terms:[37]

“As I have earlier noted, the orthopaedic surgeons in their joint report indicated that the surgery should have ceased ‘when the anaesthetists reached the stage that they were unable to maintain satisfactory cardio respiratory parameters’. The orthopaedic surgeons made no precise reference to a time when the surgery should have ceased. Satisfactory cardio respiratory parameters were not being maintained by 20.30.”

Before turning to the evidence of Dr Barratt, on whom the trial judge placed some weight, it is convenient to return to the evidence given by Drs Westbrook and Forrest addressing their joint report. Dr Westbrook had set out in his affidavit and a chart annexed to the affidavit the evidence of steadily deteriorating metabolic conditions and their consequence. In responding to questioning from the plaintiff’s counsel he stated:[38]

“So – well, so the carbon dioxide level at 19.13 was, as I say, 64, well – well above the upper limit of normal of 48. Subsequently it went [to] 69, so it steadily increased until it really reached a peak at 20.51. But even at 20.37 and 20.21 it was up to 70 which was, as I say, well above the normal limits. Now, the consequence of that is that the patient had become increasingly [acidotic] and that was further aggravated by what’s referred to as a metabolic acidosis. That – so that was an accumulation of acids in the blood stream most likely due to inadequate perfusion of other organs. So by 20.37 the patient had a pH of 7.027 which really is a serious acidosis, a mixed metabolic and respiratory acidosis, the consequences of which are depressed myocardial function and other depressed cellular functions in the body.

MENZIES: Could that lead to some result adverse to the patient at that point?

WESTBROOK: Well, if – certainly were it to continue to deteriorate which it – of course it did at 20.51 and 21.01, the pH was even lower and at 21.13 lower still. That, coupled with the compression of the great vessels in the chest, you know, there was an inevitable deterioration towards to the eventual collapse at ... 21.20 or thereabouts. I think ... the problem for the anaesthetist is they didn’t have anything they could do to improve the situation. They were doing everything they possible could in terms of ventilation of the lungs, in terms of maintaining h[a]emodynamics. And despite these measures, the acidosis was deteriorating.

MENZIES: You’ve already expressed an opinion that, in the light of that deterioration ..., that the collapse that occurred [at] 21.33 or thereabouts was inevitable at some point. ... When did that inevitability arise? Or put another way, in as much as it was inevitable and you’ve already said the surgery should have been stopped, at what point then do you say the surgery should have been stopped?

WESTBROOK: I – I mean I think at 2021 things were looking pretty grim but certainly at 2037 with a pH of 7 and an increasing lactate I – it’s my view the surgery should have been abandoned at that point.”

Dr Forrest agreed that with “a benefit of hindsight I think you couldn’t argue that [it] would have been preferable to abandon the surgery earlier than ... the time that it was abandoned.”[39] He was challenged as to whether that conclusion could only be advanced with hindsight. He referred to the steps which were taken, the difficult choice the doctors were required to make given the possible effects of abandoning the surgery, and the attempts made to correct the underlying cases of metabolic acidosis. He continued:[40]

“Now, that in fact proved to be unsuccessful, because his carbon dioxide continued to climb, so as his carbon dioxide reached a level of over a hundred at – at – 2051. And I think really, the key to this is that – is that the difficulty in ventilation was already one of the key factors that was aggravating his metabolic acidosis because as carbon dioxide climbed, that led to an increase in his pulmonary-vascular resistance, which is the – basically the impedance against which the right ventricle has to eject. That in turn led to a reduction in right-ventricular function, right-ventricular performance, which decreases pulmonary blood flow. And of course, pulmonary blood flow is exactly the same as your cardiac output, so ultimately that right-ventricular dysfunction led to the cardio-vascular collapse that occurred around 2130.”

It is then necessary to return to the oral evidence of Dr Barratt, upon which the trial judge placed significant weight. Dr Barratt was cross-examined about the conversation he had with Dr Sparks over the telephone. His evidence was that the conversation took place at about 9.30pm, but it was accepted that the phone call occurred just prior to 9pm. He agreed that the discussion had included the possibility of cardiac compression generating the potential for hypotension with the consequence that critical organs might not be adequately perfused. The discussion had included Dr Sparks’ concern about high arterial carbon dioxide and the fact that he had checked that the patient was properly ventilated “but he still could not explain the problem.” The cross-examination continued:[41]

“Q. So your response was that probably, or maybe, a pulmonary artery was compressed along with possible cardiac compressions, it means his lung was being ventilated but not perfused?

A. That is exactly correct.

Q. What is ventilated but not perfused mean?

A. It means that there is inability to eliminate carbon dioxide from the lung because there’s no blood going through the alveolus and all this air is just coming into the lung and can’t take the carbon dioxide out so the carbon dioxide is going to build up.

Q. And the consequence of that is what?

A. A carbon dioxide level of 65 is not a problem physiologically but for that to happen, you have to be pressing on a pulmonary artery in such a significant way that it’s going to impede [cardiac] output and organ perfusion.

Q. And the consequence of that is what? ... If uncorrected?

A. Critical end–organ ischemia.

...

Q. And the consequence of that in a longer term sense if these organs are damaged was what?

A. Well, a low [cardiac] output state could damage the brain, the spinal cord, the kidneys, or the liver, for instance, potentially.

...

Q. Doctor Sparks told you that the various metabolic indicators were critical?

A. Yes, yes.

Q. Despite, apparently, adequate blood pressure and blood oxygen levels. That was one of his dilemmas, wasn’t it?

A. Yes, yep.

Q. Then in those circumstances, it really wasn’t appropriate, was it, to look at the blood pressure and oxygen levels alone when making a decision whether to persist or abandon surgery?

A. I agree with that statement.”

The trial judge’s conclusion, based on that evidence was expressed in the following terms:[42]

“It is important not to lose sight of the fact that Dr Sparks and Dr Gray were confronted with what was patently a distressing and fraught intraoperative emergency. It is difficult to over-emphasise just how awful it must have been at that time for all concerned. It is clear that Dr Sparks had attempted all of the anaesthetic manoeuvres in his armoury to correct the problem without apparent success. Criticism of these doctors in those circumstances may seem harsh. However, it is not in question that stopping the surgery when no obvious answer to the problems confronting the doctors was presenting itself would have avoided the damage. We know with hindsight that postural adjustment from prone to supine produced immediate resolution of these problems. That was something which in my opinion Dr Sparks and Dr Gray should have foreseen and acted upon. Failure to do so amounted to a want of reasonable care. It was in my view not appropriate to take the risk that something that could not be explained would or might somehow spontaneously resolve or improve. It is no answer to insist that the surgery was lifesaving in circumstances where Mr Hobson’s respiratory difficulties at or after 20.30 had deteriorated below his pre-operative condition in ICU.”

Finally, the judge considered that the absence of spinal cord monitoring “heightened the need to act conservatively and to proceed expeditiously. It told against the appropriateness of taking an expectant approach when the solution to Mr Hobson’s difficulties had not emerged or was not understood.” So far as Dr Sparks is concerned, and without reference to s 5O of the Civil Liability Act, in my view that conclusion was sound.

Application of s 5O

(a) approach adopted at trial

For reasons set out above, the proper course in a case where s 5O has been pleaded and has been the subject of evidence is to determine first the standard of care to be applied, before assessing the alleged negligence against that standard. The trial judge did not take that approach but rather, in accordance with what was understood to be the appropriate course at the time, considered s 5O as a defence to be addressed after findings had been made on the plaintiff’s case. That indeed was the manner in which counsel for Dr Sparks dealt with the matter in written submissions at trial. Counsel for Dr Sparks asserted that where there is evidence to demonstrate that the defendant acted in a manner which was widely accepted by peer professional opinion as competent professional practice, that opinion determined the standard of care and the expert evidence was conclusive.[43] Counsel further asserted that the approach adopted by this Court in McKenna should not be followed as it was inconsistent with the reasoning in Dobler. However, if McKenna were to be followed, it was submitted that the conduct of the defendant in exercising judgment as to the time for cessation of the operation constituted a “practice”. The submissions simply relied upon the evidence of Dr Forrest as establishing the defence. In oral submissions, there was reference to the reasoning in McKenna, but no further attempt to grapple with the evidential requirements of s 5O. In these circumstances, it is unsurprising that the trial judge dealt with the matter by way of a defence, noting the paucity of evidence in support of it. Having already rejected the views of the defendants’ doctors as to whether the conduct of the practitioners was negligent, the judge considered that the defence under s 5O had also effectively been rejected.[44] It is correct to say that the reasoning of the trial judge did not address the submission that Dr Forrest’s evidence could not be rejected unless it was shown to be irrational. Nor did it expressly address the proposition that Dr Forrest’s opinion was “conclusive” as to the relevant standard of care. Grounds 1 and 2 in Dr Sparks’ notice of appeal rely on these matters as demonstrating error. On the appeal, Dr Sparks’ written submissions identified the evidence relied on in support of the s 5O test as that of Dr Forrest (called in Dr Sparks’ case) and the evidence of Dr Manasiev, called for Dr Gray but who expressed opinions as to the conduct of both Dr Gray and Dr Sparks. It was submitted that the opinions were unchallenged. As Simpson JA explains, the trial did not proceed smoothly. The pleadings left much to be desired as to detail; parties were joined and then removed; the plaintiff’s case was recast on more than one occasion, and the evidence of the experts was, inevitably in these circumstances, not always clearly directed to the issues as they finally emerged. The task of the trial judge in these circumstances was fraught with difficulties. Nevertheless, it is apparent that s 5O was relied upon by Dr Sparks and was not correctly disposed of at trial. It is therefore necessary for this Court to address the evidence. Despite the conclusion reached above that the proper approach where s 5O is relied upon is to consider all the evidence in order to reach satisfaction as to the relevant standard of competent professional practice, to adopt such a course on this appeal would be impractical for two reasons, both of which operated at the trial. First, one cannot seek to identify a standard of competent professional practice in the abstract; the standard must relate to the specific ways in which negligence is alleged. Because the pleadings of the plaintiff bore limited resemblance to the case ultimately presented for determination, the plaintiff’s case provided a moving target for the defendant. (Although there were grumbles in Dr Sparks’ written submissions at trial, no issue of procedural unfairness was raised on appeal.) Secondly, the reasoning of the trial judge followed the structure presented by the parties. It would not be possible to recast that reasoning on appeal to comply with a structure not presented at trial.

(b) expert opinion evidence – anaesthetists

The primary evidence relied upon by Dr Sparks was that of Dr Forrest, an expert anaesthetist called by Dr Sparks. In his principal report (the only report which addressed this issue) the final question and answer were as follows:[45]

“5. Did Dr. Sparks, in his anaesthetic management of Mr Hobson, act in a manner that was widely accepted in Australia by peer professional opinion as competent profession practice, at the time the service was provided?

Yes.

Mr Hobson was a high-risk patient who required major emergency surgery on his spine, in the prone position.

From the preceding, Dr. Sparks identified the critical issue of the patient’s bronchial compression preoperatively. ...

However, it proved very difficult to effectively ventilate the patient in the prone position, despite the trial of a variety of different ventilation techniques. These difficulties were likely due to the patient’s pre-existing pneumonia and bronchial compression, which were significantly aggravated by the use of the prone position for surgery.

The patient was appropriately monitored intraoperatively, and the anaesthetic drugs, dosages and fluid administration were also appropriate.

The management of the patient’s critical deterioration at 21:30h was appropriate, as was the decision to abandon the procedure at that time.

The anaesthetic management of Mr. Hobson by Dr. Sparks would therefore have been widely accepted by peer professional opinion in 2009 as competent professional practice.”

In its terms, this answer constituted an opinion that the relevant steps taken by Dr Sparks involved competent professional practice. However, it did not squarely address what became the critical issue, namely whether the failure to terminate the operation at an earlier point satisfied that test. Of course, the answer to question 5 should not be read in isolation. Question 2 invited Dr Forrest to “review the blood gas readings, the blood pressure results and the tidal flow measurements” and express an opinion as to the most likely cause of the collapse at 9.35pm. Dr Forrest answered that question in the following manner:[46]

“In my opinion, the cause of Mr. Hobson’s intraoperative collapse was acute right ventricular failure (RVF).

This would account for the high central venous pressure, low oxygen saturation and low blood pressure that occurred at about 21:30h on 17 November. It would also account for the large difference in the carbon dioxide level measured in the patient’s blood and his expired breath (‘end-tidal carbon dioxide’) prior to that time, the congested (‘purple’) appearance of his head that was observed when he was turned from prone to supine and the echocardiography findings at that time (‘empty LV... RA full’).

Mr. Hobson’s probably developed acute RVF because of predisposing factors and because of the use of the prone position for his surgery.

The predisposing factors that would have contributed to acute RVF were his spinal deformity, which caused restrictive lung function and left lung collapse / infection due to bronchial compression. These factors would have caused the pulmonary arteries to constrict and thereby increased pulmonary vascular resistance (PVR). An increase in PVR causes the RV to dilate and may eventually decrease its capacity to pump blood (cardiac output).

When Mr. Hobson was turned prone, it proved very difficult to ventilate him effectively, despite confirmation of the DLT position and despite the use of a variety of different ventilation techniques. As soon as he was turned supine again, ventilation became much easier and his oxygenation, blood pressure and carbon dioxide levels rapidly normalized. The use of the prone position probably compromised his ventilation by increasing compression of the left main stem bronchus by his spine, due to the effects of gravity. His spine may also have been compressing pulmonary arteries and veins, which would also increase PVR and decrease cardiac output. Because of the difficulties in ventilation, the carbon dioxide level increased in his blood. This would also have significantly increased PVR, because raised carbon dioxide levels cause the pulmonary arteries to constrict.

The combination of increased PVR and decreased cardiac output cause the blood supply to the RV itself to fall. When the blood supply to the RV falls below a critical level, acute, severe RVF can occur. However, it is not possible to accurately predict in an individual patient if, or when this will occur.”

The next question asked whether it was appropriate and reasonable for Dr Sparks to direct that the surgery cease at about 9.30pm. He said that it was and continued:[47]

“Taken in isolation, a fall in blood pressure to 95mmHg (even from a high baseline value) would not be sufficient reason for abandoning a surgical procedure.

However at that time (about 21:30h), Mr. Hobson also had rapidly falling oxygen saturations (to less than 80%), a high CVP and severe respiratory and metabolic derangement. Hence this blood pressure signalled the onset of critical haemodynamic deterioration, which would likely have rapidly progressed to refractory cardiac arrest if surgery had not been abandoned at that time and he was not turned supine.

It was therefore appropriate and reasonable for Dr. Sparks to request that surgery be abandoned at that time.”

Finally, Dr Forrest was asked to express his own opinion as to the standard of anaesthetic management during surgery. In concluding that the standard was reasonable, he stated:

“Mr. Hobson was a high-risk patient who required major emergency surgery at that time. He posed a very unusual and difficult anaesthetic challenge due to the significant compression of his left main bronchus by his spine and due to the requirement for prone positioning during surgery.

...

The main clinical dilemma in this case was whether surgery should have been allowed to continue given the difficulties in ventilating the patient that were encountered before the severe deterioration that occurred at 21:30h. As noted above, he patient had been difficult to ventilate prior to this time due to compression of his left main bronchus, which was exacerbated in the prone position. However, given that the patient’s surgery was considered to be sufficiently urgent that it needed to be performed out-of-hours, and given also that his lung infection would not have been expected to resolve until the compression of his left main bronchus was relieved by surgery, it was reasonable to continue the anaesthetic at that time.”

As with the answer to question 5, in relation to widely accepted peer professional opinion, Dr Forrest’s statement as to his own view deals with the question of earlier termination only indirectly. The final conclusion “it was reasonable to continue the anaesthetic at that time” is not precise as to the time in question. Secondly, unlike Dr Sparks, Dr Forrest, in explaining Mr Hobson’s situation, placed weight upon the raised carbon dioxide levels and their effect in causing constriction of the pulmonary arteries and therefore pulmonary vascular resistance, leading to decreased cardiac output and ultimately right ventricular failure. It was clear at some point that the only answer to those problems was to cease surgery and return the patient to a supine position, as eventually happened. The submission that Dr Forrest’s views were not challenged was only partly true. In the course of his joint evidence with Dr Westbrook, senior counsel for the plaintiff obtained Dr Forrest’s agreement that there was continuous deterioration of the plaintiff’s metabolic state, and that acidosis was a harbinger of ongoing problems which could, unresolved, have proved fatal. The cross-examination ended with the following exchange:[48]

“MENZIES: ... What I’m suggesting to you, for example, that if at any of those times before 2051, a decision was made to stop the surgery at that time, it’s not as if the consequence was going to be the patient was going to die in front of you, is it?

WITNESS FORREST: What the consequence would have been – and the expectation of the doctors looking after the patient at that time would have been – that because they hadn’t corrected his underlying bronchial compression, that he would continue to have ongoing severe respiratory failure, which would ultimately be – would ultimately lead to his demise because the underlying cause had not been addressed.

MENZIES: So the proposition remains the same, doesn’t it? That the semi-emergen[cy] situation as you describe it – but I’m happy with that – continued unchanged. In other words, at any time before 2125 or 2130 when the surgery was stopped, it could have been stopped with no further harm to the patient than he was already suffering. That’s right isn’t it?

WITNESS FORREST: Yes, well, that’s right. But as I’ve already said, the reason why the surgery was done in the first place at that time was because it was felt that ... (not transcribable)...would not be improved if his surgery had not gone ahead. So expectation would have been that he would have died at some point post-operatively in intensive care from... (not transcribable)... respiratory failure.”

Neither the questions nor the answers given by the witness were entirely clear. The question to be answered by the Court is whether the evidence of Dr Forrest, taken as a whole, established the proposition that it was widely accepted peer professional opinion that it would be competent professional practice to continue the administration of anaesthetic for the purpose of surgery in all the circumstances. That required taking into account the need for the corrective surgery, and the deterioration in the patient’s condition as at about 9pm, given the expectation that it would be relieved by ceasing the operation and returning the patient to the supine position. To the extent that the evidence did address that proposition, it is by no means clear that Dr Forrest expressed a clear view about it. Dr Sparks sought to obtain further assistance as to the relevant standard of competent professional practice in the evidence of Dr Manasiev. Dr Manasiev is a consultant anaesthetist and was called on behalf of Dr Gray. The doctor was asked a number of questions; question 2 was whether Dr Gray should have halted or advised “the halting of the surgery following the earlier episodes of hypoxia and hypotension ... and related complications reported in the anaesthetic record between approximately 19:10 and 21:20.”[49] After dealing with two earlier events which are no longer significant, Dr Manasiev dealt with “a transient period of desaturation and relative hypotension” at 20.35. The event occurred at the time of placement of a pedicle screw in the patient’s spine. He identified three reasons for not halting the operation at that time. First, the cause was transient and, secondly, the blood pressure and saturation returned to normal values once the pressure was relieved. He continued:[50]

“Third, the decision was balanced against the apparent necessity of the operation as a potential lifesaving technique. As such, it was not warranted by Dr Sparks or Dr Gray to halt the surgery at this time and would be considered widely accepted in Australia by peer professional opinion as competent medical practice to continue the surgery.”

After dealing with the appropriateness of halting the surgery at 21.20, Dr Manasiev noted that “the management of the ventilatory and cardiovascular parameters are primarily the responsibility of the anaesthetist.”[51] He then repeated, in relation to Dr Sparks, his opinion as to competent medical practice as at the times identified in question 2. Dr Manasiev did not participate in the joint conclave of anaesthetists with Drs Westbrook and Forrest. However, he gave oral evidence at the trial. In the course of cross-examination he gave the following evidence:[52]

“Q. What are the factors, you say, that would inform competent professional practice, with respect to anaesthetists and the continuance or otherwise of a surgery?

A. Well, it’s the whole gambit of all the hemodynamic parameters that you’re looking at within a patient. Predominantly, the blood pressure and saturation, which are telling you how the organs are being perfused, but as well as that, all the attempts that are made, in this case, to improve ventilation: whether they are successful or non-successful, the response of all the blood gas analysis. It’s a complicated gambit of numbers and figures that you’re looking at.

Q. You certainly, do I understand it then, wouldn’t limit yourself to the – in a manner which excluded all the other parameters in the blood gases?

A. No, you wouldn’t exclude all the parameters, no --

Q. Because that would not be consistent with competent professional practice, in circumstances such as this in Australia, in 2009, would it?

A. You wouldn’t exclude, but you would give different parameters different weights upon the patient’s stability.”

In his original report, Dr Manasiev did not squarely address the effect on his opinion of the evidence accepted by Dr Westbrook and Dr Forrest of the plaintiff’s continuously deteriorating metabolic state which was likely to lead to a cardiovascular collapse, if not remedied. Further, the evidence in the course of the trial progressed beyond the parameters put to Dr Manasiev for the purposes of his report. The question was not whether the events around 8.30pm should have led to the termination of the operation but whether the events around 9pm should have led to termination. No evidence was led from Dr Manasiev in relation to these further considerations. In summary, the evidence relied upon by Dr Sparks fell short of establishing a standard, widely accepted in Australia, of competent professional practice. A bald statement by a practitioner, however well qualified, without reference to the specific factors giving rise to a claim of negligence may well not persuade the court that there is a relevant standard identified in the evidence. Further, a bald claim that the practice is “widely accepted” as falling within the scope of competent professional practice may not be accepted by the court as evidence of that fact. To persuade the court that the terms of the section have been satisfied one would generally expect evidence which stated the basis of the standard. Further, the evidence is more likely to be persuasive if it seeks to grapple with possible conflicting views in a reasoned manner. That is not to say that any of the evidence was “irrational”. Rather, the test of irrationality applies to the opinion as to competent professional practice. The Court must always be satisfied as to two antecedent questions, namely that the opinion addresses the conduct as found at the trial and that the evidence supports the view that the expressed opinion was, at the time of the conduct, “widely accepted in Australia”. In the result, the erroneous approach to the terms of s 5O was not material to the outcome. It follows that Dr Sparks’ appeal should be rejected.

Inherent risk – s 5I

Adopting the reasoning of Leeming JA in Paul v Cooke, the trial judge rejected the submission that Mr Hobson’s injury was the result of an inherent risk which could not have been avoided by the exercise of reasonable care and skill. He accepted that “Mr Hobson was always going to be vulnerable to ischemia during the second stage of the surgery due to the first stage surgery ligation of the segmental spinal arteries that necessarily reduced blood supply to the spinal cord.”[53] He repeated that aspect of his medical condition, amongst others, which exposed him to a “pre-surgical anatomical vulnerability to spinal cord stroke and the effects of hypotension.”[54] He reasoned that, because the risk could have been avoided by the exercise of reasonable care and skill, it was not an “inherent risk” within the meaning of s 5I(2). On the appeal, counsel for Dr Sparks repeated the submissions which had not found favour at the trial. The submissions ran into one of two difficulties; either they adopted a colloquial meaning of “inherent risk” which does not conform to the specific statutory definition, or they assumed a favourable answer with respect to negligence and causation, which would, of course, render reliance on s 5I otiose. As noted above, the circumstances in which s 5I will provide a valuable defence are likely to be few and far between. This case is not one of them. It is clear that the harm might not have occurred if the operation had terminated at an earlier point in time. It certainly cannot be said that the harm “could not” have materialised through exercise of reasonable care and skill. Furthermore, the issue in the case was whether the harm eventuated as a result of the failure to exercise reasonable care and skill. That question cannot be avoided by relying on s 5I.

Conclusion

As the trial judge fairly recognised, Dr Sparks was faced with a difficult intraoperative choice. However, it was not one which required an instantaneous decision, nor one which required further information or advice. The patient’s metabolic decline was continuing despite Dr Sparks having taken every available step to alleviate the condition whilst the operation proceeded. Whilst the operation continued, the patient was heading for cardiovascular failure. The operation was expected to last for some four hours; at 9pm the operation was only half completed, on that timescale. (The orthopaedic experts stated that it had 2-4 hours to go.[55]) The decision to allow it to continue for 30 minutes after Dr Sparks had sought help from two experienced anaesthetists, without success, involved more than an erroneous clinical judgment; the trial judge was correct to find a breach of duty of care.

Dr Gray

The responsibility of Dr Gray as the principal surgeon is to be determined on the expert evidence regarding medical practice in Australia. Although the Court was referred to authorities dealing with the role of the surgeon, the defence under s 5O is not established according to a legal standard as such, but rather by widely accepted peer professional opinion. Case-law will not assist in identifying the role of each of the medical practitioners in the operating theatre; that needed to be determined on the facts of the case as they appeared in the evidence; no question of legal principle was raised. In passages which have already been considered, the trial judge treated the liability of Dr Gray and Dr Sparks as necessarily to be assessed on the same basis. There were certainly reasons why that might have been thought appropriate. First, because Dr Gray was in charge of the operation, and would be the person primarily responsible for monitoring its progress, one might expect that he would be kept informed of any difficulties with anaesthesia including ventilation of the lungs and levels of blood gases. Secondly, he accepted in his evidence (and particularly his affidavit of 7 November 2016) that he was being informed by Dr Lagopoulos of the findings based on the spinal cord monitoring, up until the monitoring was terminated. His evidence treated the decision-making as jointly undertaken:[56]

“21. The deterioration in the plaintiff’s respiratory function in ICU prior to surgery had necessitated the surgery being brought forward. Respiratory failure could have resulted in death. The decision to bring forward the surgery was to avoid the risk of fatality.

22. In view of this risk, the lack of spinal cord monitoring became secondary and Dr Cree and I decided to continue with the surgery. We made a collective decision that it would be appropriate given the circumstances of it being a life-saving procedure to continue with the surgery.

23. The plaintiff, shortly before the surgery was stopped, underwent a rapid deterioration, one aspect of which related to a reduction in his level of oxygenation.

24. Dr Sparks informed those present of difficulties encountered by him including the ongoing reduction in oxygenation, hypotension, a decrease in end-tidal CO2 and an increase in PaCO2. He said words to the effect ‘I’m having problems with ventilating ...’.

...

25. Dr Cree said words to the effect ‘Should we stop’. Dr Sparks indicated that the surgery could continue. Dr Sparks said [words] to the effect of ‘no, keep going, I’ll let you know’. Dr Sparks then shortly afterwards indicated that it would be necessary to cease the surgery. Dr Sparks said words to the effect ‘I think we need to stop’. There was a collective discussion and decision to cease the surgery.”

In this evidence, and in his oral evidence, Dr Gray spoke in terms of a consultative team working together. There were countervailing considerations. First, as Macfarlan JA explains, the evidence did not demonstrate knowledge on Dr Gray’s part which would suggest that he had full understanding of the difficulties which Dr Sparks was facing. Secondly, Dr Sparks was cross-examined by counsel for Dr Lagopoulos (whilst he was still a defendant):[57]

“Q. The decision to stop the surgery at about 21.30 on 17 November 2009 was made by the process of discussion amongst the members of the surgical and the anaesthetic team. Isn’t that correct?

A. Yes, but I think it was really my decision.

Q. Thank you. However, there was consultation between the two?

A. There was no disagreement when I told them what I thought.”

It was not suggested to Dr Sparks that he had at particular times conveyed to Dr Gray his specific concerns, or entered into a consultation as to how long the operation was likely to take. Thirdly, there was the evidence of Dr Manasiev to which reference has been made in a different context:[58]

“It is important to note that the management of the ventilatory and cardiovascular parameters are primarily the responsibility of the anaesthetist. The anaesthetist would be the first to comment on difficulties in achieving adequate ventilation and perfusion of the vital organs and as such direct the surgeon if the surgery would need to be halted to effectively resuscitate the patient. It would not be the responsibility of the surgeon to halt the surgery on the basis of haemodynamic or respiratory difficulties unless there was a question of the management of those difficulties by the anaesthetist.”

That passage was raised with Dr Manasiev by counsel for the plaintiff in cross-examination:[59]

“Q. So that if the anaesthetist was reporting difficulties, then it would be incumbent upon the surgeon, wouldn’t it, obviously depending on what has been told, to make a decision to halt the surgery?

A. Yes, a communication process between the anaesthetist and the surgeon together.

Q. Of course, the ultimate decision to stop must be in the hands of the surgeon, because the anaesthetist is hardly in a position to say, ‘stop, I’m out of here,’ is he?

A. Yeah, can’t physically restrain the surgeon from operating, but, yeah ultimately, the surgeon would decide if and when he stops.”

According to Dr Gray, Dr Cree’s inquiry as to whether the surgery should stop, with the response from Dr Sparks saying they could proceed, came only minutes before Dr Sparks told them to stop. Dr Cree’s question, as Dr Gray recalled it, was in response to a remark by Dr Sparks, “I’m having problems with ventilating ...”. It can reasonably be inferred that no other information suggesting significant difficulties had been conveyed by Dr Sparks after the spinal cord monitoring terminated. Dr Gray also gave evidence that he was not aware of Dr Sparks leaving the operating table to make telephone calls. Based on this evidence, I agree with Macfarlan JA that the case in negligence against Dr Gray should have been dismissed. Given this conclusion, it is not necessary to address the other grounds of appeal raised by Dr Gray.

Damages

Dr Gray raised three specific challenges to the assessment of damages undertaken by the trial judge. The same challenges were raised in Dr Sparks’ appeal, but Dr Sparks made no specific submissions in relation to these issues, merely adopting the submissions made on behalf of Dr Gray. Although Dr Gray’s appeal has been upheld and the issues do not arise in his case, it is necessary to deal with the challenges thus adopted by Dr Sparks. I agree that each of the challenges should be rejected, for the reasons given by Macfarlan JA.

Conclusion

For these reasons I agree with the orders proposed by Macfarlan JA. MACFARLAN JA: Mr Brendan Hobson, the respondent, was born in 1985. He suffers from Noonan Syndrome, a genetic disorder that prevents normal development in various parts of the body. As a result of the disorder, Mr Hobson’s breast bone was too close to his spine. This restricted his ability to fill his lungs with air, and hence to breathe. Without surgical intervention to create more space in his chest cavity by straightening his spine, his prognosis was grave. Surgery to correct this problem was designed to take place in two stages. The first operation was successfully undertaken on 13 November 2009. The second, which occurred on 17 November 2009, had to be terminated before its intended conclusion. As a result of that operation, Mr Hobson became a paraplegic. In the proceedings now under appeal, Mr Hobson initially claimed damages from the hospital where the operation took place and from a number of members of the surgical team. Ultimately, his claim proceeded only against the principal surgeon, Dr Randolph Gray, and the principal anaesthetist, Dr Christopher Sparks. Dr Gray is an experienced specialist orthopaedic/spine surgeon and Dr Sparks is an experienced specialist anaesthesiologist. After an 11 day hearing before Harrison J in the Common Law Division of the Supreme Court, his Honour found that Drs Gray and Sparks had breached the duties of care that they owed to Mr Hobson and were liable in negligence for damages in the amount of $3,828,075. The basis of the decision against both doctors was that, in light of adverse blood gas readings for carbon dioxide obtained in the course of the operation, they should have caused the operation to be terminated earlier than occurred. If the operation had been so terminated, Mr Hobson would not have had a significant cardio-vascular collapse at about 21:30 on 17 November, his spine would not have been damaged and he would not have become a paraplegic. His Honour rejected a number of other particulars of negligence, including that the operation should not have proceeded at all on 17 November. Drs Gray and Sparks each appeal against the primary judge’s decision on liability and, in three limited respects, against his Honour’s assessment of damages. As to the latter, they contend that his Honour erred in the allowances that he made for past and future domestic care, and for motor vehicle expenses. Mr Hobson has not filed a cross appeal or notice of contention. As well as contending that the primary judge erred in finding that they acted negligently, the appellants rely, as they did at first instance, on sections 5 I and 5 O of the Civil Liability Act 2002 (NSW). These sections are in the following terms:

“5I NO LIABILITY FOR MATERIALISATION OF INHERENT RISK

(1) A person is not liable in negligence for harm suffered by another person as a result of the materialisation of an inherent risk.

(2) An inherent risk is a risk of something occurring that cannot be avoided by the exercise of reasonable care and skill.

(3) This section does not operate to exclude liability in connection with a duty to warn of a risk.

5O STANDARD OF CARE FOR PROFESSIONALS

(1) A person practising a profession ("a professional") does not incur a liability in negligence arising from the provision of a professional service if it is established that the professional acted in a manner that (at the time the service was provided) was widely accepted in Australia by peer professional opinion as competent professional practice.

(2) However, peer professional opinion cannot be relied on for the purposes of this section if the court considers that the opinion is irrational.

(3) The fact that there are differing peer professional opinions widely accepted in Australia concerning a matter does not prevent any one or more (or all) of those opinions being relied on for the purposes of this section.

(4) Peer professional opinion does not have to be universally accepted to be considered widely accepted.”

Before turning to the evidence adduced at first instance which is relevant to the issues on appeal, it is convenient to give a brief description of the doctors involved in the events in question and of the medical experts, and to summarise the issues that arose in relation to the second operation. Dr Gray was the principal surgeon. He was assisted by Dr Cree and Dr Lyons. Dr Sparks was the principal anaesthetist. He was assisted by Dr Wang. Dr Lagopoulos, a specialist neurophysiologist, was a part of the surgical team but was not present between 20:30 and 21:30 when the events of concern on the appeal occurred. Dr Stephen Barratt, a specialist anaesthetist, was not present at the operation but spoke to Dr Sparks at about 20:50 when Dr Sparks called him for advice. At about the same time, Dr Sparks also called Dr Marshman, a cardiothoracic surgeon. Dr Marshman did not give evidence. At the trial, Mr Hobson tendered expert reports by Dr John Westbrook (a specialist anaesthetist), Dr James Wilson-Macdonald and Dr Michael Johnson (the latter two being specialist orthopaedic surgeons). The appellants called expert anaesthetic evidence from Dr Paul Forrest and Dr Bojidar Manasiev, and expert orthopaedic evidence from Dr Geoff Askin. In their written submissions, Dr Sparks’ counsel described the physiological issues that arose in relation to the second operation as follows:

“24. The treating and medico legal expert evidence demonstrated these things:

a. The second stage surgery required Mr Hobson to be placed faced down (prone) on the operating table, allowing the surgeons to access the spine posteriorly and perform the spinal fusion.

b. The fusion required the placement of pedicle screws. The actions of the orthopaedic surgeon emplacing the pedicle screws can put downward pressure on the patient’s spine, and with it, the risk of cardiac compression.

c. With Mr Hobson being in the prone position, the effects of gravity may have unavoidably caused his spine to compress the left main bronchus and the pulmonary arteries and veins.

d. Compression of the pulmonary arteries and veins can increase pulmonary vascular resistance, which decreases cardiac output. As a result, carbon dioxide in the blood (PCO2) increases, which in turn causes the pulmonary arteries to constrict. The combination causes blood supply to the right ventricle to fall, leading to reduced cardiac output and if it falls to a critical level, right ventricular failure (cardiac collapse) occurs.

e. An elevated PCO2 causes the blood’s pH to drop, (known as respiratory acidosis) which, alone or together with a decreased base excess and an elevated lactate, are markers indicative of metabolic acidosis (a build-up of metabolic acids in the body)” (citations omitted).

To this should be added that the cardiac compression indicated by high carbon dioxide readings can result in inadequate supply of oxygenated blood to the body’s organs including, as occurred in Mr Hobson’s case, to the spinal cord.

THE EVIDENCE AT THE TRIAL

Dr Christopher Sparks

In his affidavit of 11 November 2015, Dr Sparks said that he understood that the close proximity of Mr Hobson’s vertebral column to his sternum was displacing his heart into his left thorax. Dr Sparks’ understanding was that without surgery this condition could be fatal, and that it followed that surgical intervention was required to save Mr Hobson’s life. Dr Sparks understood that prior to the operation on 17 November 2009 the intensive care unit (“ICU”) was having difficulty ventilating Mr Hobson because of compression of his left main bronchus, and that Mr Hobson was developing pneumonia. When Mr Hobson was turned to the prone (that is, face down) position at the commencement of the operation on 17 November, Dr Sparks asked the surgeons if they could “minimise downward force on Mr Hobson’s spine during the operation as it could cause cardiovascular compression”. Dr Sparks recognised the possibility of increased compression on Mr Hobson’s pulmonary artery whilst in the prone position. Dr Sparks continued:

“31 The medical records show the operation commenced at about 19:30 to 19:40 hours.

32 The blood gas readings at 19:13 hours were: P02243 (90 to 95 normal parameters) and PC02 65 (35 to 40 normal parameters). A PC02 reading of 65 was outside of normal parameters and in normal circumstances I would not anaesthetise such a patient but the emergency nature of the situation meant I needed to accommodate the PC02 level and did so by increasing ventilation in response. I assumed the PC02 at 65 was a result of low minute volume, which is the reason why the ventilation was increased. I assumed the high reading of a P02 at 243 was a result of Mr Hobson’s left lung being oxygenated effectively for the first time in 4 days.

33 By around 20:30 hours the arterial blood CO2 level had risen from 64.7 mmHg to 70.5mmHg. I could not detect any mechanical obstruction to ventilation but nevertheless I felt compelled to give muscle relaxant, Vecuronium. I informed the surgeons of this course of action.

34 Vecuronium was administered at around 20:30 hours in response to the rising carbon dioxide level. It was given to allow us to attempt to improve ventilation. The O2 partial pressure remained high and the trend systolic blood pressure was normal to high. Because it was emergency surgery I had resolved in my mind that while the oxygenation and blood pressure were normal to high it was appropriate for the surgery to continue.

35 The arterial carbon dioxide levels continued to be elevated and I tried everything I could think of to identify the cause of the problem. I checked for mechanical problems with the ventilation. I increased the tidal volume, I undertook hand ventilation and I checked the position of the tube with the bronchoscope several times, but there was no mechanical problem with the double lumen tube or the breathing circuit.

36 I considered a pneumothorax and breath stacking in the left thorax. I tried to disconnect the left lung from ventilation and leave it open to air, but the blood gas results stayed much the same. The partial pressure oxygen (PO2) remained high.

37 The arterial carbon dioxide continued to be elevated and the expired waveform diminished. I tried hand ventilation and I got down on my knees on numerous occasions to check the tube with the bronchoscope again, but it was always in the correct position. I was comfortable that the double lumen tube was working properly.

38 Having excluded these reasons for the problem, I formed the opinion that the likely cause was cardiac and not the ventilation. I formed this opinion even though the systolic blood pressure was stable at about 150 systolic for most of the time. Each arterial line in the left and right hands measured the blood pressure continuously and recorded the same result.

39 I was conscious of Mr Hobson’s history of previous ASD repair and pulmonary valvectomy in 1988; and a prior trans-thoracic echo showing raised pulmonary artery pressure. In addition there was the thoracic vertebral body compressing the Left Atrium all of which indicated that the patient’s right ventricle had a high workload. I considered the use of cardiac inotrope but rejected it. With a typical systolic pressure of 140 to 150 during most of the surgery and obstruction to the right ventricle caused by bone I felt that inotropes would only precipitate Right Ventricular Failure. In short I thought that inotropes were unlikely to assist or help the patient, rather they were more likely to harm him.

40 By about 20:50 hours, I telephoned Dr Barratt and Dr Marshmann (sic), cardiothoracic surgeon, to discuss the circumstances, specifically the patient’s low exhaled C02 even though the blood pressure was high to normal and normal ventilation. Neither specialist could recommend anything that I had not already considered. In my telephone conversation with Dr Barratt, he said words to the effect: ‘it must be due to ‘dead space’ and not a problem with ventilation’. Dr Marshman had nothing further to add.

41 By about 21:25 hours, 2 hours into the procedure, the exhaled carbon dioxide expired waveform had diminished, which most likely meant that not enough blood was reaching the lungs. The CVP was 37 and I was concerned that the right ventricle was failing. I raised my concern with Drs Gray and Cree with words to the effect: ‘hurry up as the patient’s condition is deteriorating’. They responded by agreeing to operate faster in order to complete the operation as quickly as possible.

42 However, over the following minutes I became very concerned that Mr Hobson was about to suffer a cardiac arrest as his blood pressure dropped from the previous level of 150. I administered Adrenaline and directed Dr Gray to stop the procedure immediately. Dr Gray closed up the wound as quickly as possible without completing the spine stabilisation, and Mr Hobson was turned to a supine position on the bed.

43 Once he was turned to a supine position, Mr Hobson’s head was noted to be a purple colour, although within a relatively short space of time his carbon dioxide, blood pressure and CVP levels all returned to normal as did his colour without any other intervention.”

In relation to the administration of vecuronium (a muscle relaxant) at 20:30, Dr Sparks gave the following answer to an interrogatory:

“I formed the opinion that the patient’s PaCO2 was very serious and believed that if a muscle relaxant was administered, it may bring the patient’s PaCO2 down. As it was an emergency procedure and the consequence of the surgery not proceeding was the likely death of the patient, I felt obliged to try administering the muscle relaxant to reduce the PaCO2.”

In relation to the termination of the operation, Dr Sparks stated:

“Dr Wang and I agreed that while the arterial blood gas oxygen was normal to high and the blood pressure was normal to high it was reasonable for the surgeons to try and complete the operation. By around 21:28hrs however, it was clear to us that it was not possible for the operation to complete by those two criteria so I immediately told the surgeons to stop operating. They agreed immediately.”

Dr Sparks gave the following further evidence in the course of his cross-examination. Dr Sparks said that at around 20:30, in response to Mr Hobson’s raised carbon dioxide levels, he decided that vecuronium would be administered. He gave evidence that there were two ways in which the vecuronium might have reduced Mr Hobson's carbon dioxide reading to a more acceptable level. First, “it decreases the oxygen consumption and carbon dioxide production on muscles, and secondly, [it was administered] in the hope that it would improve his ventilation which is the normal cause of a raised carbon dioxide impaired ventilation, total volume minute volume”. Dr Sparks said that during the operation Mr Hobson was being effectively ventilated, and therefore his carbon dioxide level should have been normal. Instead it was high, indicating that something was wrong. Dr Sparks gave evidence that there are three causes of an elevated carbon dioxide level. One is a problem in ventilation, another is increased carbon dioxide production (in this case, possibly as a result of a slight fever which Mr Hobson had), and the third is a cardiac problem. By a cardiac problem,