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Depth of block after divided doses of mivacurium spaced 60 seconds apart
1Department of Anesthesiology, Yale University School of Medicine, New Haven, CT 06510.
Abstract:
We compared the depth of block attained after divided- and single-dose administration of mivacurium to evaluate our clinical impression that the former regimen resulted in a lesser depth of block. In 30 patients anesthetized with midazolam, fentanyl, thiopental, and nitrous oxide, adductor pollicis contraction was measured in response to train-of-four stimulation at 12-s intervals. Patients then received (by random assignment) mivacurium as a single 0.15 mg/kg bolus (Group I) or two 0.075 mg/kg (Group II) boluses separated by 60 s. All 15 Group I patients developed > or = 95% twitch (T1) depression, and 10/15 attained 100% depression; the maximum depression (mean +/- SD) was 99.1% +/- 1.4%. Only 8/15 Group II patients achieved > or = 95% T1 depression (P < 0.05 for the interregimen comparison with chi 2 analysis), and only 4/15 achieved 100% depression (P = 0.07); the maximum depression was 92.2% +/- 12.9% (P < 0.05 by unpaired t-test). Thus, administration of mivacurium in divided doses spaced 60 s apart does not provide the depth of neuromuscular block that is attained when a single bolus of the same total dose is administered.
Insights
Divided-dose mivacurium administration results in a shallower neuromuscular block compared to a single dose. This study found single-dose regimens provide a deeper block for anesthesia.
Area of Science:
- Anesthesiology and Pharmacology
- Neuromuscular Blockade
Background:
- Mivacurium is a neuromuscular blocking agent used in anesthesia.
- The method of drug administration can influence the depth and duration of its effects.
Purpose of the Study:
- To compare the depth of neuromuscular block achieved with single-dose versus divided-dose mivacurium administration.
- To clinically evaluate the hypothesis that divided doses yield a lesser block depth.
Main Methods:
- Thirty patients undergoing anesthesia received either a single bolus or two divided boluses of mivacurium.
- Neuromuscular blockade was assessed by measuring adductor pollicis muscle response to train-of-four stimulation.
- Patients were randomized into Group I (single dose) or Group II (divided doses).
Main Results:
- All patients receiving a single mivacurium dose achieved at least 95% twitch depression, with 10/15 reaching 100%.
- Fewer patients (8/15) in the divided-dose group achieved 95% twitch depression (P < 0.05).
- The maximum mean depression was significantly lower in the divided-dose group (92.2%) compared to the single-dose group (99.1%) (P < 0.05).
Conclusions:
- Administering mivacurium in divided doses 60 seconds apart does not achieve the same depth of neuromuscular block as a single bolus.
- Single-dose administration of mivacurium is more effective in achieving profound neuromuscular blockade.