Ian Barker

5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: summary of main findings and risk factors

We present the main findings of the 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia (AAGA). Incidences were estimated using reports of accidental awareness as the numerator, and a parallel national anaesthetic activity survey to provide denominator data. The incidence of certain/probable and possible accidental awareness cases was ~1:19,600 anaesthetics (95% confidence interval 1:16,700-23,450). However, there was considerable variation across subtypes of techniques or subspecialities. The incidence with neuromuscular block (NMB) was ~1:8200 (1:7030-9700), and without, it was ~1:135,900 (1:78,600-299,000). The cases of AAGA reported to NAP5 were overwhelmingly cases of unintended awareness during NMB. The incidence of accidental awareness during Caesarean section was ~1:670 (1:380-1300). Two-thirds (82, 66%) of cases of accidental awareness experiences arose in the dynamic phases of anaesthesia, namely induction of and emergence from anaesthesia. During induction of anaesthesia, contributory factors included: use of thiopental, rapid sequence induction, obesity, difficult airway management, NMB, and interruptions of anaesthetic delivery during movement from anaesthetic room to theatre. During emergence from anaesthesia, residual paralysis was perceived by patients as accidental awareness, and commonly related to a failure to ensure full return of motor capacity. One-third (43, 33%) of accidental awareness events arose during the maintenance phase of anaesthesia, mostly due to problems at induction or towards the end of anaesthesia. Factors increasing the risk of accidental awareness included: female sex, age (younger adults, but not children), obesity, anaesthetist seniority (junior trainees), previous awareness, out-of-hours operating, emergencies, type of surgery (obstetric, cardiac, thoracic), and use of NMB. The following factors were not risk factors for accidental awareness: ASA physical status, race, and use or omission of nitrous oxide. We recommend that an anaesthetic checklist, to be an integral part of the World Health Organization Safer Surgery checklist, is introduced as an aid to preventing accidental awareness. This paper is a shortened version describing the main findings from NAP5--the full report can be found at http://www.nationalauditprojects.org.uk/NAP5_home.

Awareness and memory function during paediatric anaesthesia

BACKGROUND Previous research indicates a much higher incidence of awareness during anaesthesia in children than in adults. The present study is the first large-scale, intraoperative assessment of awareness during paediatric anaesthesia using the isolated forearm technique, and the first large-scale study of memory function during paediatric anaesthesia. METHODS One hundred and eighty-four children, 5-18 yr, underwent the isolated forearm technique during the first 17 min of surgery while receiving volatile anaesthesia. The isolated forearm technique was modified to accommodate brief or no paralysis. Bispectral index was monitored in a subset of 54 patients. Sixteen neutral words were played 20 times during surgery and, on recovery, implicit memory for these words was tested with a word identification task. Explicit memory for the surgical period was tested with a structured interview. Behavioural changes were assessed with age-appropriate questionnaires. RESULTS No child had explicit recall of intraoperative events on recovery, and there was no evidence of implicit memory for words presented during anaesthesia. Two of 184 children made unambiguous and verified responses on the modified isolated forearm technique, an incidence of intraoperative awareness of 1.1%. One of these children reported that he was uncomfortable and not completely unconscious during surgery. Neither child had implicit memory for the neutral words, or adverse behaviour change. CONCLUSIONS The incidence of awareness during surgery in children is approximately eight times that measured in adults by postoperative recall. In contrast to adults, there is no evidence for preserved memory priming during anaesthesia.

Propofol infusion vs thiopentone/isoflurane anaesthesia for prominent ear correction in children

Postoperative nausea and vomiting (PONV) frequently follows prominent ear correction under general anaesthesia in children. In a prospective, single‐blind study, we compared the incidence of PONV after propofol infusion anaesthesia with that following thiopentone induction and isoflurane maintenance in 30 children aged from four to 14 years randomly allocated to one of two groups. All the children were mechanically ventilated. Anaesthesia was supplemented in both groups with nitrous oxide and infiltration of the ears using a mixture of bupivacaine, adrenaline, and hyaluronidase. One child receiving propofol (group P) complained of nausea, compared with eight receiving thiopentone/isoflurane, (group T) (P=0.005), while three children in group P and ten in group T vomited before hospital discharge, (P=0.01). Eight children in group P were considered to be fit for discharge on the day of surgery as against four in group T, (not significant). Only four out of twelve children receiving opioid analgesia vomited.

A comparison of thiopentone/isoflurane anaesthesia vs propofol infusion in children having repeat minor haematological procedures

We have performed a randomized, cross over study in 22 children suffering from acute leukaemia, who underwent repeated anaesthesia for bone marrow aspiration and lumbar puncture. For their first anaesthetic, the children (aged 3–10 years old) received, either a thiopentone/isoflurane anaesthetic or intravenous propofol, both supplemented with nitrous oxide. On a second occasion they received the alternative technique. Of those children receiving thiopentone/isoflurane, 32% had significant coughing during anaesthesia, two progressing to laryngospasm requiring 100% oxygen. None of the patients receiving propofol had a respiratory disturbance (P=0.016). 68% of the children preferred the propofol anaesthetic. Only one child in the thiopentone/isoflurane group preferred this technique. Twenty‐seven per cent had no preference. There was no significant difference in length of anaesthetic time (P=0.07) or the time taken for recovery (P=0.17) between the two groups. There was a large individual variation in propofol requirements and movement was common during stimulation of patients in this group, though this did not adversely affect the surgical procedure.

Anaesthetic management of a child with Burkitt's lymphoma of the larynx

An eight‐year‐old boy with a Burkitts lymphoma of the upper airway is described. The use of sevoflurane for induction of anaesthesia in patients with airway obstruction is discussed. The logistical problems of upper airway surgery and anaesthesia in this type of patient are considered.

The finding of an undiagnosed long segment tracheal stenosis in a cyanotic child undergoing an arterial switch operation and VSD closure

This report details the case of a 2-month-old baby boy with known cyanotic congenital heart disease (double outlet right ventricle with subpulmonary ventricular septal defect, VSD) in whom tracheal stenosis was undetected, being found later on failed intubation while undergoing anaesthesia for an arterial switch operation and VSD closure. As a result, the cardiac surgery was postponed. Such an association between congenital heart disease and tracheal stenosis has been reported but remains exceptionally rare. The baby subsequently underwent a slide tracheoplasty the next day and had major cardiac surgery a few days later. He was discharged approximately 3 weeks later after spending 8 days on the cardiac intensive care unit.