When the bispectral index (bis) can give false results

Area of Science:

• Anesthesiology
• Neurophysiology
• Medical Monitoring

Background:

• The bispectral index (BIS) is a key electroencephalogram (EEG)-derived parameter for monitoring anesthesia's hypnotic state.
• Its algorithm, developed from extensive EEG data, aids in reducing intraoperative awareness and recall.
• However, the BIS can be influenced by various clinical factors not initially accounted for.

Purpose of the Study:

• To review clinical situations leading to false-positive or false-negative bispectral index (BIS) readings.
• To identify patient-specific conditions and anesthetic-related factors that can skew BIS values.
• To enhance anesthesiologists' awareness of BIS limitations.

Main Methods:

• Literature review of clinical scenarios impacting BIS accuracy.
• Analysis of factors causing abnormal electroencephalogram (EEG) patterns.
• Examination of drug effects and equipment interference on BIS monitoring.

Main Results:

• False BIS readings can occur due to abnormal EEG patterns, unconsidered drug effects, electrical interference, and monitor-specific issues.
• Patient conditions and unforeseen anesthetic actions can lead to inaccurate BIS values.
• Awareness of these factors is critical for correct interpretation.

Conclusions:

• Anesthesiologists must recognize situations causing erroneous BIS readings to prevent anesthetic overdose or underdosing.
• Understanding BIS limitations is vital for avoiding intraoperative awakening and recall.
• Despite algorithm updates, vigilance regarding false BIS values remains essential.