Rocuronium 0.3 mg·kg−1 (ED95) induces a normal peak effect but an altered time course of neuromuscular block in patients with Duchenne's muscular dystrophy

Summary Background:  In patients with Duchenne's muscular dystrophy (DMD) recovery from neuromuscular block is delayed. It has been assumed that this is because of a higher potency of muscle relaxants in this patient cohort. We determined the peak effect, and the time course of action of rocuronium 0.3 mg·kg−1 (ED95) in DMD patients. Methods:  Twenty-four patients (12 with DMD and 12 controls; aged 10–18 years) were studied. All patients were anesthetized with propofol and fentanyl/remifentanil. Neuromuscular transmission was monitored by acceleromyography. After induction all patients received a single dose of rocuronium 0.3 mg·kg−1. The complete time course of action as onset, peak effect and spontaneous recovery was recorded. Results:  The onset time (s) to maximum block was significantly (P < 0.01) prolonged in DMD patients (median: 315; range: 120–465) compared with controls (195, 75–270). The peak effect (% twitch depression relative to baseline) was not different between the groups (DMD: 59–100; controls: 28–100). In the DMD group, recovery was significantly (P < 0.01) delayed compared with controls at all recorded time points. The clinical duration (min) was 40.3 (22–89) in the DMD group vs 9.8 (6–17) in the control group (P <  0.01). Conclusions:  The similar peak effect in both groups does not confirm the thesis of rocuronium having a higher potency in DMD patients. The documented very long recovery after the ED95 of rocuronium emphasizes the need for careful assessment of neuromuscular function in DMD patients.