BIS Monitoring in Paralyzed Patients

Critical Limitation: NMBAs Confound BIS Readings

Neuromuscular blocking agents (NMBAs) directly reduce BIS scores even in awake, unsedated patients, making BIS values unreliable indicators of true sedation depth 1, 2
Studies demonstrate that awake patients who received NMBAs without sedatives showed significant BIS reductions, and the monitor failed to detect awareness in completely paralyzed subjects 1, 2

All paralyzed patients must receive adequate analgesia and sedation targeting deep sedation levels before and throughout neuromuscular blockade 1, 2
NMBAs have zero analgesic or sedating properties, making inadequate sedation during paralysis a high-risk scenario for awareness and recall 1, 2
The Society of Critical Care Medicine suggests using objective measures like BIS as adjuncts (not primary monitors) when subjective sedation assessments are impossible due to paralysis 5

Do not rely on BIS alone—incorporate vital signs (heart rate, blood pressure), diaphoresis, and lacrimation, though these signs lack specificity 1, 2
Implement scheduled interruptions of NMBA infusions or use bolus dosing to permit periodic assessment of actual sedation adequacy and ongoing paralysis necessity 1, 2, 3

Never discontinue analgesics or sedatives while NMBAs are running—this is a critical safety error 1, 2
Avoid using BIS as the sole determinant of sedation adequacy in paralyzed patients, as studies show extensive overlap and poor discrimination between sedation levels 1, 2, 3

Train-of-four (TOF) monitoring via peripheral nerve stimulation should be incorporated into overall assessment but not used alone for monitoring neuromuscular blockade depth 1, 3
Consider continuous EEG monitoring (not just processed BIS) for detecting nonconvulsive seizures in patients with known seizures or unexplained depressed consciousness 5, 6