Estimation of the success rate of anesthetic management for thymectomy in patients with myasthenia gravis treated without muscle relaxants: a retrospective observational cohort study.

Although maintaining anesthesia for myasthenia gravis (MG) with minimal muscle relaxants (MR) is common, the success rate of anesthetic management for MG without MR is not clear. We therefore retrospectively examined the success rate of anesthetic management for MG without MR among 66 consecutive cases of thymectomy for MG performed at our hospital between January 2004 and April 2010, before approval of using sugammadex. A total of 60 patients (90.9 %) were treated without MR (N group). Among the 60 cases, 17 (28.3 %) patients were not extubated in the operating room due to postoperative respiratory depression or other reasons. Therefore, the success rate of anesthetic management for thymectomy in patients with MG without treating MR was 71.7 % (43/60) [95 % confident interval (CI): 65.9-77.5 %]. The reasons for using MR included coughing at intubation in one case, bucking during surgery in two cases, and MR was considered to be safer by the attending anesthesiologist in three cases. The number of cases of impossible extubation requiring ventilation on that day was three in the N group and none in the R group. Finally, the success rate of anesthetic management for MG without MR was estimated to be 71.1 % (95 % CI: 65.9-77.5 %).