Andreas Ekman and Maj-Lis Lindholm contributed equally to this study.
Reduction in the incidence of awareness using BIS monitoring
Article first published online: 12 DEC 2003
Acta Anaesthesiologica Scandinavica
Volume 48, Issue 1, pages 20–26, January 2004
How to Cite
Ekman, A., Lindholm, M.-L., Lennmarken, C. and Sandin, R. (2004), Reduction in the incidence of awareness using BIS monitoring. Acta Anaesthesiologica Scandinavica, 48: 20–26. doi: 10.1111/j.1399-6576.2004.00260.x
- Issue published online: 12 DEC 2003
- Article first published online: 12 DEC 2003
- Accepted for publication 29 August 2003
- general anaesthesia;
Background: Explicit recall (ER) is evident in approximately 0.2% of patients given general anaesthesia including muscle relaxants. This prospective study was performed to evaluate if cerebral monitoring using BIS to guide the conduction of anaesthesia could reduce this incidence significantly.
Patients and methods: A prospective cohort of 4945 consecutive surgical patients requiring muscle relaxants and/or intubation were monitored with BIS and subsequently interviewed for ER on three occasions. BIS values between 40 and 60 were recommended. The results from the BIS-monitored group of patients was compared with a historical group of 7826 similar cases in a previous study when no cerebral monitoring was used.
Results: Two patients in the BIS-monitored group, 0.04%, had ER as compared with 0.18% in the control group (P < 0.038). Both BIS-monitored patients with ER were aware during intubation when they had high BIS values (>60) for 4 min and more than 10 min, respectively. However, periods with high BIS = 4 min were also evident in other patients with no ER. Episodes with high BIS, 4 min or more, were found in 19% of the monitored patients during induction, and in 8% of cases during maintenance.
Conclusions: The use of BIS monitoring during general anaesthesia requiring endotracheal intubation and/or muscle relaxants was associated with a significantly reduced incidence of awareness as compared with a historical control population.