Abstract
We investigated the relationship between anti-acetylcholine receptor (AchR) antibodies titers and sensitivity to vecuronium in eleven patients with myasthenia gravis (MG). Blood samples were collected just before induction of anesthesia and serum anti-AchR binding antibodies and blocking antibodies were measured (Mitsubishi-Kagaku Bio-Chemical Laboratories Inc.). Anesthesia was induced with propofol and maintained with sevoflurane, nitrous oxide and oxygen, together with epidural lidocaine. Vecuroniun was carefully administrated under neuromuscular transmission monitor (Datex). The initial dose (μg•kg-1) and maintenance dose (μg•kg-1•h-1) of vecuronium were calculated in each patient. AchR binding antibody was positive in six patients, and AchR blocking antibody was positive in ten patients. The maintenance dose was significantly inversely correlated to the serum AchR blocking antibody titer. Initial dose of vecuronium was significantly lower in patients positive for AchR binding antibody (group A) than in six non-MG control patients (group C). Maintenance dose of group A was significantly fewer than in patients negative for AchR binding antibody and positive for AchR blocking antibody (group B), and that in group B was significantly fewer than that in group C. We found marked sensitivity to veccuronium even in MG patients negative for AchR binding antibody (seronegative MG). We suspect anti-AchR blocking antibodies may play some part in the sensitivity to vecuronium in patients with MG.
