New research presented at this year's Euroanaesthesia congress in Copenhagen, Denmark aims to raise awareness of a rare but extremely distressing phenomenon: patients being aware during resuscitation following a cardiac arrest. The study is by Dr Rune Lundsgaard, and colleagues at the Department of Anaestesiology, Herlev Hospital, Copenhagen, Denmark and Nykøbing Falster Hospital, Denmark.

Awareness during cardiopulmonary resuscitation (CPR) has been reported in medical literature but is an extremely rare event and it is still not clear whether these tragic cases have anything in common.

This study investigated the case of a 69-year-old male who was admitted to hospital after suffering symptoms of indigestion for 3 days. He reported feeling breathless a few hours before arrival but had no other complaints. During admission the patient experienced a short period of tachycardia (rapid heart rate) followed by a cardiac arrest, causing medical staff to immediately begin CPR in the form of chest compressions and the provision of ventilation with 100% oxygen via a mask. By the time the cardio-resuscitation-team arrived, the patient had a blood oxygen level of 100% and a high level of awareness with open eyes and movement of the head and limbs.

Regular checks were made to see if the patient's heart had begun to beat but these showed no rhythm, and no noticeable movement of the heart was observed during the multiple ultrasound echocardiograms that were conducted during the 90 minutes of CPR. The patient was intubated to ensure a clear airway and epinephrine (adrenaline) was given every 3-5 minutes in an attempt to restore a pulse and spontaneous blood circulation. After one hour of treatment, an ultrasound scan of the region around the heart was performed which raised suspicion of an aortic dissection.

Despite the best efforts of the medical staff, the patient did not survive and an autopsy later confirmed that he had suffered a complete aortic dissection; a serious and often fatal condition in which the inner and outer layers of the aorta separate as blood is forced between them.

The authors conclude that the high level of patient awareness plus oxygen saturation and arterial gas being almost within the normal range throughout the 90 minutes of treatment indicate that peripheral and cerebral blood flow was good and the chest compressions were highly effective. They note that that even though the patient had a poor prognosis, the termination of CPR after 90 minutes raised ethical questions in the team as the individual was still conscious at the time.

Dr Lundsgaard says that, despite its rarity: "Awareness during CPR also raises the question of proper sedation during resuscitation, which is not currently part of the guidelines."

A previous study from 2014 showed that survivors of cardiac arrest experience a range of cognitive issues, with 2% exhibiting full awareness, which can in turn lead to post-traumatic stress disorder. And of course, regardless of whether or not the person survives, awareness during CPR would be extremely traumatic up until the moment of death should the person go on to die.

Dr Lundsgaard concludes: "I believe that further attention and research should be directed to the area of sedation during CPR. At this time we the medical profession are not attending to the pain we cause nor are we aware about patients' levels of consciousness during CPR. This should be an area of future research."