Modified double burst stimulation of varying stimulating currents

Area of Science:

• Anesthesiology
• Neurophysiology
• Clinical Monitoring

Background:

• Modified double burst stimulation (DBS) aids in diagnosing neuromuscular blockade (NMB) recovery (train-of-four (TOF) ratio > 0.7).
• Modified DBS can be used in awake patients in the postanesthetic care unit.
• Reducing stimulating current decreases neurostimulation-induced discomfort in awake individuals.

Purpose of the Study:

• To investigate the utility of modified DBS at lower currents for assessing neuromuscular blockade recovery.
• To evaluate the trade-off between reduced patient discomfort and diagnostic accuracy at decreased stimulation intensities.

Main Methods:

• 121 adult patients undergoing anesthesia were randomized into groups receiving modified DBS at 50, 30, or 20 mA.
• Neuromuscular blockade was quantified mechanically in a fixed arm.
• Fade detection and discomfort (visual analog scale) were assessed in the contralateral arm and in awake volunteers.

Main Results:

• Higher probabilities of fade detection were observed at 30 and 20 mA compared to 50 mA, particularly at higher TOF ratios (e.g., 79% at 0.81-0.90 with 20 mA).
• Supramaximal responses were achieved at currents >= 30 mA.
• Mean visual analog scale scores for discomfort significantly decreased with lower currents (8.7 at 50 mA vs. 4.1 at 20 mA).

Conclusions:

• Decreasing modified DBS current reduces patient discomfort.
• Stimulation at 30 or 20 mA leads to increased detection of fade, even when adequate neuromuscular recovery is present, potentially compromising diagnostic accuracy.