Sensibilité à l'atracurium des muscles abdominaux latéraux

Objective: To study the effect of atracurium on the electromyographic activity of the lateral abdominal muscles and adductor pollicis in anaesthetized subjects. Study design: Prospective, comparative, open study. Patients and methods: Sixteen patients, ASA physical status 1 or 2, undergoing elective orthopaedic surgery under general anaesthesia were studied. Anaesthesia was induced with propofol/fentanyl and orotracheal intubation performed after glottic local anaesthesia without using muscle relaxant. Anaesthesia was maintained with isoflurane/nitrous oxide/oxygen and fentanyl reinjections. Supramaximal percutaneous stimulations in a simple twitch mode (0.1 Hz) were applied at the 9th-10th intercostal nerve on the posterior axillary line and at the ulnar nerve at the wrist. The electromyographic responses were enregistered using skin surface electrodes, placed on the D9-D10 dermatome in regard of the lateral abdominal muscles and of the thenar muscles. After a single bolus dose of atracurium 0.5 mg·kg^-1, the following parameters were studied: the maximum effect (Emax), the time for obtaining Emax (Delay) and the recovery time of 5, 10, 25, 50, 75 and 100% of the control neuromuscular response (T5, T10, T25, T50, T75, T100). Results: The dose of 0.5 mg·kg^-1 of atracurium induced 100% block in both lateral abdominal muscles and adductor pollicis. Lateral abdominal muscles blockade had faster onset (136 ± 4 s versus 205 ± 29 s) and shorter recovery, T5, T10, T25, T50, T75 and T100 were significantly (p < 0.05) shorter than at the adductor pollicis. Conclusion: Lateral abdominal muscles blockade have faster onset and recovery than adductor pollicis.