ACCIDENTAL AWARENESS DURING GENERAL ANESTHESIA
Accidental awareness
is one of the most feared complications of general anaesthesia for both
patients and anaesthetists. Patients report this failure of general anaesthesia
in approximately 1 in every 19,000 cases, according to a report published in Anaesthesia. Known asaccidental
awareness during general anaesthesia (AAGA), it occurs when general anaesthesia is intended but the
patient remains conscious. This incidence of patient reports of awareness is
much lower than previous estimates of awareness, which were as high as 1 in 600
The findings come from
the largest ever study of awareness, the 5th National Audit
Project (NAP5), which has been conducted over the last three years by the Royal
College of Anaesthetists (RCoA) and the Association of Anaesthetists of Great
Britain and Ireland (AAGBI). The researchers studied 3 million general
anaesthetics from every public hospital in UK and Ireland, and studied more
than 300 new reports of awareness.
The extensive study
showed that the majority of episodes of awareness are short-lived, occur before
surgery starts or after it finishes, and do not always cause concern to
patients. Despite this, 51% of episodes led to distress and 41% to longer-term
psychological harm. Sensations experienced included tugging, stitching, pain,
paralysis and choking. Patients described feelings of dissociation, panic,
extreme fear, suffocation and even dying. Longer-term psychological harm often
included features of post-traumatic stress disorder.
Sandra described her
feelings when, as a 12-year-old, she suffered an episode of AAGA during a
routine orthodontic operation:
"Suddenly, I knew
something had gone wrong," said Sandra, "I could hear voices around
me, and I realised with horror that I had woken up in the middle of the
operation, but couldn't move a muscle... while they fiddled, I frantically
tried to decide whether I was about to die."
For many years after
the operation Sandra described experiencing nightmares in which, "a Dr Who
style monster leapt on me and paralysed me." Sandra experienced the
nightmares for more than 15 years until she realised the link: "I suddenly
made the connection with feeling paralysed during the operation; after that I
was freed of the nightmare and finally liberated from the more stressful
aspects of the event."
Sandra's account is
borne out by the research findings that longer-term adverse effects are closely
linked with patients experiencing a sensation of paralysis during their
awareness. The use of drugs to stop muscles working (muscle relaxants), often
needed for safe surgery, is responsible. Distress at the time of the experience
appears to be key in the development of later psychological symptoms.
Professor Jaideep
Pandit, Consultant Anaesthetist in Oxford and Project Lead, explained:
"NAP5 is patient focussed, dealing as it does entirely with patient
reports of AAGA. Risk factors were complex and varied, and included those
related to drug type, patient characteristics and organisational variables. We
found that patients are at higher risk of experiencing AAGA during caesarean
section and cardiothoracic surgery, if they are obese or when there is
difficulty managing the airway at the start of anaesthesia. The use of some
emergency drugs heightens risk, as does the use of certain anaesthetic
techniques. However, the most compelling risk factor is the use of muscle
relaxants, which prevent the patient moving. Significantly, the study data also
suggest that although brain monitors designed to reduce the risk of awareness
have a role with certain types of anaesthetic, the study provides little
support for their widespread use."
Professor Tim Cook,
Consultant Anaesthetist in Bath and co-author of the report, commented:
"NAP5 has studied outcomes from all anaesthetics in five countries for a
full year, making it a uniquely large and broad project. It is reassuring that
the reports of awareness (1 in 19,000) in NAP5 are a lot rarer than incidents
in previous studies. The project dramatically increases our understanding of
anaesthetic awareness and highlights the range and complexity of patient
experiences. NAP5, as the biggest ever study of this complication, has been
able to define the nature of the problem and those factors that contribute to
it more clearly than ever before. As well as adding to the understanding of the
condition, we have also recommended changes in practice to minimise the
incidence of awareness and, when it occurs, to ensure that it is recognised and
managed in such a way as to mitigate longer-term effects on patients."
The project report
includes clear recommendations for changes in clinical practice. Two main
recommendations are the introduction of a simple anaesthesia checklist to be
performed at the start of every operation, and the introduction of an Awareness
Support Pathway -- a structured approach to the management of patients
reporting awareness. These two interventions are designed to decrease errors
causing awareness and to minimise the psychological consequences when it
occurs.
It is anticipated that
NAP5 will lead to changes in the practice of individual anaesthetists, their
training and hospital support systems both nationally and internationally.
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