Neuromuscular effects of succinylcholine following different pretreatments.

STUDY

OBJECTIVE

To study the neuromuscular effects (onset, intensity, and duration of block) of succinylcholine following different pretreatments.

DESIGN

Randomized open study.

SETTING

University-affiliated hospital.

PATIENTS: Fifty ASA physical status I and II adult inpatients undergoing elective ophthalmic surgery.

INTERVENTIONS: Succinylcholine 0.5 mg/kg was administered after no pretreatment or after pretreatment with d-tubocurarine 0.05 mg/kg intravenously (IV) 3 minutes before, chlorpromazine 0.1 mg/kg i.v. 3 minutes before, alpha-tocopherol (vitamin E) 600 mg in three divided doses orally at 6-hour intervals, or aspirin 600 mg orally 1 hour before in groups of ten patients each.

MEASUREMENTS AND MAIN

RESULTS

Neuromuscular block by stimulation of the ulnar nerve at the wrist by application of train-of-four stimuli at 2 Hz every 12 seconds and recording the force of contraction of the adductor pollicis muscle. There was no significant difference in the time to occurrence of maximum block (49 to 53 seconds), reappearance of the twitch response (254 to 307 seconds), or complete recovery of twitch response (532 to 607 seconds) between the groups receiving no pretreatment and those pretreated with chlorpromazine, alpha-tocopherol, or aspirin. However, the time to maximum block (71 seconds) was significantly longer and the time to reappearance of the response (172 seconds) was significantly shorter (both p < 0.05) in the d-tubocurarine pretreated group in comparison with the control group. The time to complete recovery (420 seconds) also was shorter but not significantly different.

CONCLUSIONS

Of the pretreatments used, only d-tubocurarine interferes with the neuromuscular blocking effects of succinylcholine. Chlorpromazine, which attenuates the muscle pains as well as the increase in creatine kinase and can be administered with the same convenience, may be a better pretreatment in the prevention of side effects of succinylcholine.