Monitoring of neuromuscular blockade during general anaesthesia

Abstract

Accidental awareness under general anaesthesia (AAGA) is an uncommon but particularly distressing complication, with potentially long-lasting psychological consequences. Over 400 reported cases of AAGA were reported during the fifth National Audit Project, with a projected incidence of 1:136000 general anaesthetics. 1 However, 97% of reported cases of AAGA were associated with the use of neuromuscular blocking drugs (NMBDs), an incidence of 1:80001. Around one-fifth of these reported cases were at emergence with all patients experiencing residual neuromuscular blockade. Failure to use a peripheral nerve stimulator was seen as causal or at least contributory in half of these cases. The 2015 updated guidance from the Association of Anaesthetists of Great Britain and Ireland (AAGBI) 2 stated that a peripheral nerve stimulator must be used when a NMBD is given, as part of the minimum standards of monitoring during general anaesthesia.2 We aimed to explore the current use of NMBDs, nerve stimulators and reversal agents during general anaesthesia in a UK teaching hospital. A retrospective anaesthetic chart review of patients receiving surgery under general anaesthesia was undertaken at Leicester Royal Infirmary. Information collected included patient characteristics, NMBD used and timings, use of a nerve stimulator and reversal agent. Twenty nine patient anaesthetic charts post general anaesthetic and neuromuscular blockade drug have been reviewed to date. 11 male, mean age 50.8, 4 emergency procedures (14%) 25 elective procedures (86%), ASA 1-3. Atracurium was used in 62% of procedures and 87% of patients had a documented reversal agent administered. 14 charts (48%) had documented use of a peripheral nerve stimulator or neuromuscular monitoring peri-operatively. A Consultant Anaesthetist was present in all cases and trainees were also present in approximately half of the procedures. The documented use of neuromuscular monitoring showed no relationship with level of anaesthetist present. Neuromuscular blockade drugs are commonly used during general anaesthetic and increase the risk of accidental awareness under general anaesthesia. Although monitoring can reduce this risk, use has only been documented in 50% of cases by anaesthetists of varying experience. Data collection is ongoing and we plan to investigate any potential barriers or difficulties in our local hospital to using neuromuscular monitoring. 1.The Royal College of Anaesthetists and the Association of Anaesthetists of Great Britain and Ireland. Report and findings of the 5th National Audit Project, Accidental Awareness during General Anaesthesia in the United Kingdom and Ireland. 2014; Available from: http://www.nationalauditprojects.org.uk/NAP5home.2.The Association of Anaesthetists of Great Britain & Ireland. Recommendations for standards of monitoring during anaesthesia and recovery. 2015; Available from: http://www.aagbi.org/sites/default/files/Standards_of_monitoring_2015_0.pdf.