Intraoperative electrocardiogram monitoring induced bispectral index interference – A misleading heart–mind connection

Abstract

Bi-spectral index (BIS) is a common but an important tool in anaesthesiologist's armamentarium across the world which helps to assess the level of sedation and effect of hypnotic drugs. A value between 40-60 in BIS is considered as optimal level of sedation during general anaesthesia. However, numerous factors can interfere with accurate BIS value. Electrocardiogram (ECG), has been mentioned as a factor resulting into fallacious BIS values in the literature, which may have significant implications on appropriate dosage of hypnotic drugs. ECG inferences are usually filtered by proprietary algorithm of BIS, and few cases have been documented wherein ECG interference resulted in fallacious BIS readings. Our case reports a less frequently reported interference in BIS values by ECG, which resulted into lower BIS values.