Increased potency of nondepolarizing relaxants after poliomyelitis

The pathophysiology of poliomyelitis and the recognition of the "post-polio syndrome" suggest that susceptibility to muscle relaxants of patients previously affected by this disease, may be altered. We compared the effects of d-tubocurarine (dTc), pancuronium (P), and gallamine (G) on two pediatric surgical patient groups: one with a previous history of polio disease, occurring 6 to 12 years prior admission (N = 30, average age: 13 yrs, weight: 43 kg) and another without history of this disease (N = 51, average age: 11 yrs, weight: 39 kg). Following uniform premedication, thiopental, N2O/O2 + narcotic (fentanyl) anesthesia was given for reconstructive surgeries. For orotracheal intubation the patients were briefly paralyzed with 0.7 mg/kg suxamethonium. The thumb adductor responses to supramaximal 1/5 Hz impulses (continuous mode) and to 50 Hz tetanic stimuli (periodically) were recorded. After full recovery from the effect of suxamethonium (100% return of the neurally evoked muscle response) cumulative ED50 values and the recovery index (minutes elapsed from 90% to 50% block of the twitch response) of the three nondepolarizing muscle relaxants were determined. The ED50 of dTc and P were significantly lower with both neuromuscular responses in the post-polio groups (dTc, N = 12 and P, N = 10) as compared to the controls (N = 24 and 18). A tendency toward lower ED50 values in the polio group was also observed with G (N = 6). The differences, however, as compared to the control group (N = 9) were not significant (P less than .2). Recovery times were identical in the polio versus non-polio groups.(ABSTRACT TRUNCATED AT 250 WORDS)