Introduction: The administration of succinylcholine in children with DMD is associated with specific, sometimes life-threatening complications like rhabdomyolysis, hyperkalemia, or cardiac arrest. However, there are conflicting results by case reports or reports with small numbers about the sensitivity of these patients to non-depolarizing neuromuscular blocking agents (NMBA)^1,2. The aim of this study was to determine the response of children with DMD to rocuronium, a known fast onset non-depolarizing NMBA.
Methods: After approval of the local Ethics Committee and signed consent, 12 children undergoing orthopedic surgery of the spine were included. Following preoxygenation anesthesia was induced with propofol (2-3mg/kg) and fentanyl 5-10 mcg/kg. Awaiting sufficient depth of anesthesia tracheal intubation was performed without NMBA. Anesthesia was maintained with weight-adapted propofol infusion, supplemented with remifentanil infusion to effect. The children`s lungs were mechanically ventilated with a mixture of oxygen in air, minute volume was adapted to an arterial CO<sub>2</sub> of 35-40mmHg. After moving patients in prone position, right arm was prepared for acceleromyographical monitoring of neuromuscular blockade by stimulation of the ulnar nerve and monitoring the adductor pollicis muscle, using TOF-watch SX monitoring system (Organon, Germany). After calibration and signal stabilization rocuronium 0.6 mg/kg was administered. Onset time (95% reeduction of twich response, T0), time of recovery of first twitch response to 10% (T10%), 25% (T25%) and 90% (T90%), recovery index (time between 25% and 75% recovery of first twitch, T25%-T75%), and recovery time (time between 25% recovery of first twitch and recovery of TOF ratio to 90%, T25%-TOF90%) were measured. All procedures were done with reference to the Copenhagen Consensus Conference. Data are shown as mean ± SD.
Results: Children`s mean age was 13.3 ± 2.05 yrs, weight 49,8 ± 13.63 kg; height 157 ± 11 cm, and body mass index (BMI) 20.0 ± 3.73. Time course data of response to rocuronium are presented in the table. In all children a maximum effect of 100 % was achieved. Pharmakodynamic data showed high interindividual differences, expressed by the high SD. Conclusions: We present first pharmakodynamic data of rocuronium administered in children with DMD. While recovery time was partially very long in these children indicating increased sensitivity against rocuronium, the surprisingly found delayed onset time apparently contradicts such an interpretation. Our data suggest that children with DMD response different to rocuronium compared to children without muscle disease.
References: ¹Anesthesiology 1998;88::351-4, ²Anesth Analg 1999;89:340-1.
Anesthesiology 2003; 99: A1141