The Terror of Being Awake

Photo by Pfree2014 via Wikimedia Commons (CC BY-SA 2.0)

When you’re under general anaesthesia, a good anaesthesiologist uses a combo of consciousness-dulling agents and neuromuscular blockers — one to put you to sleep and block pain sensations, one to paralyze you. What if the latter works but the former doesn’t? The stuff of horror movies. At Mosaic, David Robson explores research suggesting that up to 5 percent of surgical patients could experience pain during their procedures but be unable to communicate that to hospital staff, or even to remember the experience afterward.

This all makes anaesthesia as much art as science, and in the vast majority of cases, it works astonishingly well. More than 170 years after Morton’s public demonstration, anaesthetists across the world plunge millions of people each year into comas and then bring them out safely. This doesn’t just reduce patients’ immediate suffering; many of the most invasive lifesaving procedures would simply not be possible without good general anaesthesia.

But as with any medical procedure, there can be complicating factors. Some people may have a naturally higher threshold for anaesthesia, meaning that the drugs don’t reduce the brain’s activity enough to dim the light of consciousness.

In some cases, such as injuries involving heavy bleeding, an anaesthetist may be forced to use a lower dose of the anaesthetic for the patient’s own safety.

It may also be difficult to time the effects of the different drugs, to ensure that the so-called induction dose – which gets you to sleep – doesn’t fade before the maintenance dose – to keep you unconscious – kicks in.

In some situations, you might be able to raise or lower your limb, or even speak, to show the anaesthetic is not working before the surgeon picks up their scalpel. But if you have also been given neuromuscular blockers, that won’t be possible. The unfortunate result is that a small proportion of people may lie awake for part or all of their surgery without any ability to signal their distress.

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