Awareness during emergence from anaesthesia: significance of neuromuscular monitoring in patients with butyrylcholinesterase deficiency

BACKGROUND

Butyrylcholinesterase deficiency can result in prolonged paralysis after administration of succinylcholine or mivacurium. We conducted an interview study to assess whether patients with butyrylcholinesterase deficiency were more likely to have experienced awareness during emergence from anaesthesia if neuromuscular monitoring had not been applied.

METHODS

Patients referred during 2004-2012 were included. Data on the use of neuromuscular monitoring were available from a previous study. Interviews, conducted by telephone, included questions about awareness and screening for post-traumatic stress disorder. Reports of panic, hopelessness, suffocation, or a feeling of being dead or dying resulted in the experience being classified further as distressful. Patients were categorized as aware or unaware by investigators blinded to use of neuromuscular monitoring.

RESULTS

Ninety-five patients were eligible to be interviewed. Of the 70 patients interviewed, 35 (50%) were aware while paralysed during emergence. Of these, 28 (80%) were not monitored with a nerve stimulator when awakened, compared with 17 (49%) of the 35 unaware patients (P=0.012, Fisher's exact test). Thirty (86%) aware patients reported distress compared with seven (20%) unaware patients (P<0.001). The aware patients scored higher in screening for post-traumatic stress disorder (P=0.006, Mann-Whitney U-test).

CONCLUSIONS

Butyrylcholinesterase deficiency is a major risk factor for distressing awareness during emergence. Lack of neuromuscular monitoring increases the risk significantly. Neuromuscular monitoring should be applied even when using short-acting neuromuscular blocking agents.

[Danish Cholinesterase Research Unit diagnoses patients with prolonged paralysis after succinylcholine and mivacurium]

The Danish Cholinesterase Research Unit (DCRU) is a nationwide unit for patients carrying mutations in the butyrylcholinesterase enzyme (BChE). BChE hydrolyzes the neuromuscular blocking drugs succinylcholine and mivacurium. Patients with mutations in the butyrylcholinesterase gene are at risk of experiencing a prolonged effect of the drugs, such as weakness or paralysis for hours. In order to diagnose the referred patients correctly, DCRU combines results such as BChE activity, genotyping, pedigree and clinical reactions to succinylcholine or mivacurium.

[Danish Cholinesterase Research Unit diagnoses patients with prolonged paralysis after succinylcholine and mivacurium]

The Danish Cholinesterase Research Unit (DCRU) is a nationwide unit for patients carrying mutations in the butyrylcholinesterase enzyme (BChE). BChE hydrolyzes the neuromuscular blocking drugs succinylcholine and mivacurium. Patients with mutations in the butyrylcholinesterase gene are at risk of experiencing a prolonged effect of the drugs, such as weakness or paralysis for hours. In order to diagnose the referred patients correctly, DCRU combines results such as BChE activity, genotyping, pedigree and clinical reactions to succinylcholine or mivacurium.