When Anaesthesia Fails

Dr Martin Brookes

February 2005

There was a time when ignorance of anaesthesia made surgery only slightly more appealing than execution. In those dark and distressing days, operating theatres staged gruesome performances of extreme human suffering. Prostrate patients, delirious with fear, had to be restrained with straps, while surgeons cut, sawed and hacked against the clock. This was not so long ago. Indeed, it wasn't until the late 1840s that anaesthesia became a regular part of surgical procedure. Now we have sophisticated sedation systems, but the fear of an anaesthetized patient regaining consciousness during surgery remains, for those on both sides of the knife.

By the beginning of the 19th century, a number of drugs began trickling into public consciousness. Alcohol and opiates had been available for centuries and their intoxicating properties were occasionally exploited during surgery, but it was in 1799 that the English chemist Sir Humphrey Davy discovered the anaesthetic properties of nitrous oxide (laughing gas). It could do wonders for a toothache, he claimed. Two decades later, his protégé Michael Faraday found that ether had similar effects.

The first official public demonstration of ether anaesthesia took place on 16 October 1846 at Massachusetts General Hospital in Boston. It's difficult to overstate the importance of this medical milestone. For patients, the deep, ether-induced sleep offered escape from a terrifying trauma. For surgeons, it opened the door to a whole new world of operative inquiry. With the patient sedated, surgery could slow down, allowing a much-needed element of accuracy and control to come into the operation. The surgeon's scope of activity, once limited to speedy amputations and work at the surface, could now encompass more delicate areas like the inside of the chest, the abdomen and the skull. Suddenly, surgery was no longer seen as a last resort, but as an integral part of medical practice.

ABC of anaesthesia

First up is a thorough evaluation of the patient: in some ways, this is the most important aspect of the procedure. An assessment of the patient's weight, age, medical history and current medication enables the anaesthetist to make informed decisions on which drugs to use, when to use them, and in what dosages.

Before a patient enters the operating theatre, they are often given a sedative to help them relax and relieve any anxiety they may be feeling about the operation. This is followed by the general anaesthetic itself, usually administered via intravenous injection, which will cause loss of consciousness in the patient.

At this stage, it's also common to inject a muscle relaxant, so that the patient's body becomes more submissive to the surgeon's knife. Early forms of muscle relaxant were derivatives of the plant extract curare, a potent neurotoxin used by South American Indians to make poison arrows.

With the muscles paralysed, breathing is impossible, so the patient must be intubated and attached to a breathing machine throughout the operation. To sustain the anaesthesia, the patient typically breathes a sleepy blend of nitrous oxide, oxygen and halothane. This mix of gases is sometimes augmented by drugs fed intravenously through a canula in the patient's hand.

As soon as the operation is over, the patient is injected with a cholinesterase, a drug which reverses the effects of the muscle relaxant. Once normal breathing is re-established, the intubation tube can be removed and the breathing machine turned off. As the patient comes round, analgesic drugs are made available to control any post-operative pain.

A waking nightmare

In 1960 the medical community woke up to a startling revelation. A study had found that more than 1% of patients experienced some kind of awareness whilst under general anaesthetic, ranging from full-blown consciousness to recollection of fragments of surgical events. Pain and anguish during the operation were followed, in many cases, by mental problems afterwards. Some patients suffered from anxiety, depression and a pre-occupation with death. This was years before post-traumatic stress disorder was a recognised syndrome, but its symptoms were already on full display.

Anaesthesia has come a long way since this seminal study. More sophisticated drugs and improvements in technology mean that anaesthesia is safer than it's ever been. But the fear of consciousness regained during surgery still haunts the operating theatre. In a recent survey of over 10,000 patients who were due to undergo an operation, 54% said that they were anxious about anaesthetic awareness.

Are these fears justified? Latest estimates suggest that about 1 in 1000 patients will experience some level of awareness during surgery. What seems like a small percentage becomes far more significant when you realise that worldwide there are about 100 million operations annually. Which means that about 100,000 people will suffer from anaesthetic awareness every year. In 90% of cases, patients will suffer no pain, but the memory of the experience may lead to psychological trauma.

In a sense, anaesthetic awareness is a more terrifying prospect than the unsophisticated surgery of yesteryear, before the advent of anaesthesia. Back then, patients could at least register their discomfort with a scream. Today, there's no such luxury. The drugs for muscle paralysis that are often administered during surgery may leave patients utterly helpless. If the patient does wake up, there's no way to raise the alarm. They may hear and feel everything that's going on around them, but they are unable to communicate their pain.

The anatomy of failure

Mistakes are inevitable in any procedure involving a human operator. Some patients have woken up during operations simply because the anaesthetist failed to spot an empty gas bottle or a leak in the breathing system. But negligence alone cannot explain all cases of anaesthetic awareness.

Anaesthesia remains an inexact science. While things normally go according to plan, the whole procedure is dogged by elements of uncertainty. The anaesthetist's initial evaluation will direct him towards the most appropriate course of treatment, but the system isn't foolproof. Patients don't always tell the truth about themselves, especially when it comes to sensitive issues like drink and drugs. Even when patients are forthcoming, exact outcomes are impossible to predict. Individuals vary in their response to anaesthesia because of differences in health, history and genetics. And while the anaesthetist may be able to get a handle on the first two factors, tailoring an anaesthetic to an individual's unique genetic make-up is still something for the future.

Added complications arise in those operations where the anaesthetist is already walking a fine line. In caesarean sections, for instance, the anaesthetist must balance the needs of the mother with the needs of the unborn child. If he uses too much anaesthetic he runs the risk of damaging the child. But use too little and there is a real danger that the mother will wake up.

Of course, the modern operating theatre is equipped with all kinds of gadgets designed to help the anaesthetist monitor and control the anaesthesia. But the depth of anaesthesia remains a notoriously difficult quantity to measure. A monitor that provides a definitive guide to awareness is seen as the Holy Grail of anaesthesia. Currently, there is considerable excitement surrounding the bispectral index (BIS), a new device which turns the electrical activity of the brain into a simple measure of awareness.

The memory effect

General anaesthesia can be seen as a controlled coma, in which the anaesthetist steers the patient into unconsciousness and back again. Throughout the operation, the patient should remain oblivious to the surgeon's knife and unresponsive to instructions. When the patient wakes up, the surgery should be a blank to them. Of course, anaesthetic awareness represents a catastrophic failure of these principles. But the picture is far from black and white.

Evidence seems to suggest that even patients who have been adequately anaesthetized retain some sense of memory. In one experiment, for instance, patients under general anaesthetic were read a series of words during surgery. After the operation, they had no memory of the event. But when asked to pick out the suspect words from an identity parade, they were far more successful at doing so than the control subjects. In other words, explicit memory had been wiped clean, but implicit memory (involving the sub-conscious processing of information) was intact.

Interestingly, not all anaesthetic agents produce these kinds of effects. The physiological mechanisms underlying the action of anaesthetics are still poorly understood, but it seems clear that different anaesthetics act in varying ways, leading to correspondingly different effects on implicit memory.

There is concern among some physicians that any memory retained during operation, implicit or otherwise, represents a failure of general anaesthesia. Although implicit memory doesn't imply awareness, there are cases where patients have experienced classic post-operative symptoms of anaesthetic awareness, like depression, nightmares and anxiety, without any explicit recall of surgical events. Thankfully, anaesthesia has come a long way in 160 years, but with gaps like this in our knowledge it remains something of an enigma.

Find out more

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Websites

Anesthetic awareness fact sheet
http://aana.com/patients/aware/factsheet.asp
Useful page of information from the American Association of Nurse Anesthetists.

How to avoid waking up during surgery
www.abcclassics.com/science/news/stories
/s1118130.htm
Looks at new research that uses a machine to monitor the brain activity of patients during surgery, and how it could reduce the risk of waking up under the knife.

Learning and awareness during anaesthesia
www.shef.ac.uk/~pc1ja/anaesthesia.html
Recent Canadian research has suggested that almost one in five children become aware during surgery under general anaesthesia. Studies are now being carried out with a tourniquet applied to the patient's arm, so they can move their hand to alert the anaesthetist.

Utopian surgery
www.general-anaesthesia.com/
Excellent and comprehensive site that covers the history of anaesthesia and the consequences of the public demonstration of ether anaesthesia carried out in 1846.

Women and anaesthesia
www.annieappleseedproject.org/womandan.html
Interesting article looking at several studies that find women are more prone to waking up during surgery.

Organisations

Action for the Victims of Medical Accidents (AVMA)
44 High Street
Croydon
CR0 1YB
Helpline: 0845 123 23 52 (Mon-Fri 10-12pm and 2-4pm)
E-mail: admin@avma.org.uk
Website: www.avma.org.uk
Charity supporting people injured by medical accidents. Offers free practical help and advice to anyone who has suffered injury or harm as a result of inappropriate medical care, poor treatment, misdiagnosis and failure to diagnose.

Citizens Advice Bureau
www.adviceguide.org.uk
Provides advice on a range of subjects including health issues through hundreds of offices across the UK. The telephone directory will list your local CAB. The website has lots of useful information and contact details as well.

Health Service Ombudsman
13th Floor
Millbank Tower
London
SW1P 4QP
Tel: 0845 015 4033
E-mail: OHSC.Enquiries@ombudsman.gsi.gov.uk
Website: www.ombudsman.org.uk/hse
The Health Service Ombudsman investigates complaints about the National Health Service. The Ombudsman is completely independent of the NHS and the government. There is no charge for the service.

National Institute for Clinical Excellence (NICE)
MidCity Place
71 High Holborn
London
WC1V 6NA
Tel: 020 7067 5800
Fax: 020 7067 5801
E-mail: nice@nice.nhs.uk
Website: www.nice.org.uk
Part of the NHS, NICE provides patients, health professionals and the public with guidance on current best practice. Website contains a comprehensive range of health and patient links, including regional health authority websites.

Patients Association
PO Box 935
Harrow
HA1 3YJ
Tel: 020 8423 9111
Helpline: 0845 608 4455 (Mon-Fri 10am-4pm)
E-mail: mailbox@patients-association.com
Website: www.patients-association.com
Represents the consumer voice in UK healthcare. Website has news articles and campaigns.

Patient Concern
PO Box 23732
London
SW5 9FY
E-mail: patientconcern@hotmail.com
Website: www.patientconcern.org.uk
Organisation committed to promoting choice and empowerment for all health service users and campaigning on issues that matter to patients. Website has campaign information and news. Leaflets on a range of issues will be sent to you if you write to them with a SAE.

Patient Protect
Tel: 01227 713661
Fax: 01227 711426
E-mail: info@patientprotect.org
Website: www.patientprotect.org
Dedicated to the prevention of neglect and incompetence in the NHS, and to the elimination of the secrecy that allows problems to flourish. Website has a good section on what to do should you want to make a complaint.

Scottish Public Services Ombudsman
4 Melville Street
Edinburgh
EH3 7NS
Tel: 0870 011 5378
E-mail: enquiries@scottishombudsman.org.uk
Website: www.scottishombudsman.org.uk
Offers members of the public an independent, free and fair response to complaints about public services, including health services.

Sufferers of Iatrogenic Neglect (SIN)
Tel: 01924 407195 or 0115 9431 320
E-mail: sinfo@boltblue.com or mag@sinfo.freeserve.co.uk
Website: www.sin-medicalmistakes.org
Patient support and pressure group for sufferers of iatrogenic neglect – this relates to medical disorders or symptoms caused inappropriately by any clinician through diagnosis, manner or treatment.

Books

	How to Stop Your Doctor Killing You by Vernon Coleman (European Medical Journal, 2003) Coleman argues that the person most likely to kill you is not a relative, a mugger or a drunken driver but in fact, your doctor. One in six patients currently in hospital are there because they have been made ill by a doctor. Get this book
	Silenced Screams: Surviving anesthetic awareness during surgery: A true-life account Jeanette M Liska (American Association of Nurse Anesthetists, 2002) Harrowing story of Jeanette Liska who found herself awake during routine surgery in 1990. During the months and years that followed, Liska struggled to cope with the psychological and emotional aftermath of her experience. Get this book
	Trust Me I'm a Doctor: The guide to getting the best from your doctor by Phil Hammond and Michael Mosley (Metro Publishing, 2002) Examines health issues from a consumer's perspective, exposing the myths and reluctance of the medical profession to pass on findings to patients. Get this book
	How to Make a Complaint (Patients Association) This booklet guides you through the national complaints procedure across all areas of the NHS. Available free

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