BIS is unnecessary and inaccurate

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Kate Leslie
Department of Anaesthesia and Pain Management, Royal Melbourne Hospital

The Bispectral Index (BIS; Aspect Medical Systems Inc.) is reported to aid in the titration of anaesthesia [1] and reduce the incidence of awareness [2]. However, significant concerns remain within the anaesthetic community about the necessity for and accuracy of BIS monitoring (or any other type of depth of anaesthesia monitoring) [3]. These concerns include:

1. Unusually low baseline values in awake patients [4]
2. Agent-dependent effects (ketamine [5]; nitrous oxide [6]; halothane [7])
3. Interference from electrical equipment in the operating theatre [8]
4. EMG interference and controversial effects of muscle relaxants [9] [10]
5. The interpretation of burst suppression by the algorithm [11] [12]
6. Reports of awareness in BIS-monitored patients [2]
7. The real benefits of improved recovery times [13] [14]
8. The effects of anaesthetic depth and BIS monitoring on long-term outcome [15]
9. Whether other monitors are worse, better or the same [16] [17]

Time of Presentation
Sunday 8 May 2005 - 1330-1500

References

1. Gan TJ et al: Bispectral Index monitoring allows faster emergence and improved recovery from propofol, alfentanil, and nitrous oxide anesthesia. Anesthesiology 1997, 87:808-815.