RESUMO
Volatile anaesthetics have long been known to intensify the effect of muscle relaxants. In this study we investigated the effects of desflurane and isoflurane on the neuromuscular blockade of vecuronium in geriatric patients. Fifty-two patients requiring elective surgery, aged > or = 65 years, with ASA status II - III were randomly assigned to receive general anaesthesia using desflurane (Des, n = 26) or isoflurane (Iso, n = 26). The effects of both inhalation anaesthetics on the neuromuscular blockade of vecuronium were compared by means of the duration of the depression of the first twitch (T1) of a train-of-four stimulation pattern. Succinylcholine 1.5 mg/kg was used to facilitate intubation, vecuronium 0.05 mg/kg was given as the succinylcholine wore off; additional doses of 0.01 mg/kg were given when T1 exceeded 25% of baseline amplitude. There were no significant differences in the patients' biometric data or the duration of anaesthesia. The median duration of action of the first vecuronium dose (0.05 mg/kg) was: Des: 18.3 (9.4-42.9) min and Iso: 15.9 (3.1-46.0) min. The number of repetitive dosages (0.01 mg/kg) was: Des: 5; 0-13 and Iso: 5; 0-14 and their median duration was: Des: 10.2 (3.6-37.6) min and Iso: 8.9 (2.1-43.9) min. There were no differences between the two groups (p > 0.05). These results suggest that augmentation of neuromuscular blockade by older fluorinated anesthetics is also exhibited by desflurane. The magnitude of this effect in geriatric patients is similar to that of isoflurane.
