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Accelographic train-of-four at near-threshold currents
D G Silverman1, N R Connelly, T Z O'Connor
1Department of Anesthesiology, Yale University School of Medicine, Yale-New Haven Hospital, Connecticut 06510.
Anesthesiology
|January 1, 1992
Summary
Train-of-four (TOF) fade measurements using accelography are consistent across a wide range of stimulating currents. Reliable neuromuscular monitoring is achieved at currents at least 10 mA above the fourth-twitch (T4) threshold.
Area of Science:
- Anesthesiology
- Neurophysiology
- Pharmacology
Background:
- Accurate neuromuscular blockade monitoring is crucial during anesthesia.
- Train-of-four (TOF) fade is a key indicator of neuromuscular function.
- Accelography provides quantitative measurement of TOF fade.
Purpose of the Study:
- To determine the range of stimulating currents for consistent TOF fade measurements using accelography.
- To assess the reliability of TOF ratio measurements at varying stimulation intensities.
Main Methods:
- Evaluated TOF fade via accelography in 31 patients under general anesthesia.
- Stimulated the ulnar nerve at currents from 10 to 60 mA after vecuronium administration.
- Quantified TOF responses at different blockade depths and stimulation currents.
Main Results:
- TOF ratios showed intercurrent consistency, except near the fourth-twitch (T4) threshold.
- Testing at ≥10 mA above T4 threshold eliminated inconsistency.
- TOF ratios at 10 mA above T4 threshold correlated highly with those at 60 mA (r=0.94).
Conclusions:
- The TOF ratio is consistent over a broad range of stimulating currents.
- Submaximal currents for TOF testing are reliable when applied ≥10 mA above the T4 threshold.
- Accelography offers a reliable method for quantitative neuromuscular monitoring.