Sleep well, hopefully (Image: Tim Pannell/plainpicture)

If you’re facing surgery this may well be your worst nightmare: waking up while under the knife without medical staff realising.

The biggest-ever study of this phenomenon is shedding light on what such an experience feels like – and is causing debate about how best to prevent it.

For one year, starting in 2012, an anaesthetist at every hospital in the UK and Ireland recorded whenever a patient later told a staff member that they had been awake during surgery. They investigated 300 cases by interviewing the patient and doctors involved.


One of the most striking findings, says lead author Jaideep Pandit of Oxford University Hospitals, was that pain was not generally the worst part of the experience – it was paralysis. For some operations, paralysing drugs are given to relax muscles and stop unconscious reflex movements. “Pain was something they understood, but very few of us have experienced what it’s like to be paralysed,” says Pandit. “They thought they had been buried alive.”

“I thought I was about to die,” says Sandra, who regained consciousness but was unable to move during a dental operation when she was 12 years old. “It felt as though nothing would ever work again – as though the anaesthetist had removed everything apart from my soul.”

It felt as though the anaesthetist had removed everything apart from my soul

The audit, carried out by the Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland, found that most episodes of awareness were brief and happened before or after the surgery took place. But waking still caused distress in 51 per cent of cases. As well as paralysis, people reported sensations of pain and choking.

The audit found a much lower incidence of waking up than previous studies – 1 case per 19,000 general anaesthetics. Smaller studies had suggested the rate could be as high as 1 in 500.

The latest study only recorded volunteered reports, but older studies questioned everyone who underwent surgery. This proactive questioning could overestimate the problem by picking up moments of awareness that patients would not have reported unasked, says Pandit.

But John Andrzejowski, an anaesthetist at the Royal Hallamshire Hospital in Sheffield, thinks the latest audit probably missed many non-trivial cases. “The true figure is probably somewhere in the middle,” he says.

The audit confirmed that waking when paralysing agents were used, such as during abdominal, heart and brain surgery, was more likely to be reported, because they stop patients from alerting medical staff to their plight. The audit team are urging anaesthetists to use a low-tech device called a nerve stimulator to enable them to give the minimum dose. A lower dose should be enough to stop spontaneous movements yet still allow the patient to move if they became conscious enough to feel pain, says Pandit.

Sometimes complete paralysis is essential to avoid severing a nerve, points out Andrzejowski, who advocates using monitors that record brain activity through scalp electrodes. But Pandit argues that these give no clear signal of consciousness and are hard to interpret.

This article appeared in print under the headline “Paralysis, not pain, panics waking surgery patients”