MIDAZOLAM PRETREATMENT DOES NOT AMELIORATE MYOGLOBINEMIA OR THE CLINICAL SIDE-EFFECTS OF SUCCINYLCHOLINE

Study Objective: To determine whether the levels of serum myoglobin an d the occurrence of fasciculations and postoperative symptoms followin g a single dose of succinylcholine are modified by the prior administr ation of midazolam. Design: Randomized, double-blind, placebo-controll ed study. Setting: Outpatient surgical service of a university hospita l. Patients: 69 ASA physical status I and II healthy, adult female out patients undergoing laparoscopy (for diagnosis or tubal ligation) with general anesthesia that included succinylcholine. Interventions: Pati ents 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 s uccinylcholine. Measurements and Main Results: Serum myoglobin prior t o pretreatment and at 5 (t5) and 30 (t30) minutes after succinylcholin e was determined by radioimmunoassay. Pain was assessed by telephone i nterview 24 to 36 hours postoperatively. Baseline myoglobin levels ran ged from 14 to 69 ng/ml; the 5- and 30-minute samples varied widely (r ange, 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 betwe en groups were not significant. The frequency of fasciculations (77% i n 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 w as not significantly different between groups. Conclusions: Midazolam had no effect on myoglobin level or postoperative symptoms following s uccinylcholine.