Midazolam pretreatment does not ameliorate myoglobinemia or the clinical side effects of succinylcholine.

STUDY

OBJECTIVE

To determine whether the levels of serum myoglobin and the occurrence of fasciculations and postoperative symptoms following a single dose of succinylcholine are modified by the prior administration of midazolam.

DESIGN

Randomized, double-blind, placebo-controlled study.

SETTING

Outpatient surgical service of a university hospital.

PATIENTS: 69 ASA physical status I and II healthy, adult female outpatients undergoing laparoscopy (for diagnosis or tubal ligation) with general anesthesia that included succinylcholine.

INTERVENTIONS: Patients received pretreatment of either a saline placebo (Group 1, n = 31) or intravenous midazolam 0.03 mg/kg (Group 2, n = 38) 5 minutes before succinylcholine.

MEASUREMENTS AND MAIN

RESULTS

Serum myoglobin prior to pretreatment and at 5 (t5) and 30 (t30) minutes after succinylcholine was determined by radioimmunoassay. Pain was assessed by telephone interview 24 to 36 hours postoperatively. Baseline myoglobin levels ranged from 14 to 69 ng/ml; the 5- and 30-minute samples varied widely (range, 16 to 900 ng/ml). The rise was 3 or more SDs above the baseline mean in 23% and 42% of Group 1 at t5 and t30, respectively, and in 21% and 35% of Group 2 at t5 and t30, respectively. The differences between groups were not significant. The frequency of fasciculations (77% in Group 1, 87% in Group 2), postoperative sore throat (64% in Group 1, 57% in Group 2), and myalgias (44% in Group 1, 51% in Group 2) also was not significantly different between groups.

CONCLUSIONS

Midazolam had no effect on myoglobin level or postoperative symptoms following succinylcholine.