How reliable is the Bispectral Index in critically ill patients? A prospective, comparative, single-blinded observer study*

Abstract

The correlation between SAS and BIS scores was suboptimal and inconsistent in a heterogeneous group of critically ill patients. The generation of BIS hardware and software, studied herein, is neither reliable nor valid for routinely monitoring the level of consciousness in the critically ill patient. Excessive muscle movement by the patient is an important and spurious influence on BIS values and seriously undermines BIS reliability.