Effects of different body temperatures on neuromuscular block induced by different doses of cisatracurinm in rabbits / 中华麻醉学杂志

ABSTRACT

Objective To investigate the effects of different body temperatures on the neuromuscular block induced by different doses of cisatracurium in rabbits. Methods Seventy-two healthy New Zealand white rabbits of both sexes weighing 2.0-2.2 kg were randomly divided into 3 groups (n=24 each): hypothermia group (L), normothermia group (N) and hyperthermia group (H). The rectal temperature was set at 34.5℃, 38.5℃ and 41.8℃ in group L, N and H respectively. Each group was further divided into 4 subgroups (n=6 each) receiving intravenous cisatracurinm 0.33, 0.66, 0.99 and 1.32 mg/kg respectively after rectal temperature was stabilized for 20 min. The animals were anesthetized with iv 20% methane 1 g/kg, tracheostomized and mechanically ventilated (VT 12 ml/kg, RR 60 bpm, I:E = 1:2;FiO2 100% ). TOF was monitored. The onset time, the duration of action (from the end of cisatracurium injection to the recovery of T1 to 5%, 25% and 95% of control height) and recovery index (recovery of T1 from 25% to 75% of control height) were recorded. MAP, HR and rectal temperature were recorded at 5 min before alteration of the body temperature, at 2 min before and 5, 10, 30, 60 and 90 min after administration of cisatracurium. Results (1) With the same dose of cisatracurium the onset time and duration of action were significantly shorter in group H, longer in group L and recovery from N-M block faster in group H, slower in group L as compared with group N. (2) At the same body temperature the onset time was significantly shortened and the duration of action and recovery were significantly prolonged as the dose of cisatracurium increased. (3) There was significant difference in the effect of interaction between different doses of cisatracurium and different temperatures on the onset time. (4) With the same dose of cisatracurium MAP was significantly decreased in group H, increased in group L, while HR was significantly increased in group H, decreased in group L. Conclusion The neuromuscular blocking effect of cisatracurium is decreased when the body temperature is increased and vice versa. The neuromuscular blocking effect of cisatracurium (0.33-1.32 mg/kg) is dose-dependent at the same body temperature. There is interaction between the two factors.