The influence of body mass index on neuromuscular blocking agent of rocuronium in patients undergoing general anesthesia

Objective To investigate the influence of body mass index(BMI)on neuromuscular blocking agent of rocuronium in patients undergoing general anesthesia.Methods Eighty ASA Ⅰ or Ⅱ patients,aged 20 y～60 y,undergoing elective surgery under general anesthesia,were divided into 3 groups:overweight (group Ⅰ) group,nomad body weight (group Ⅱ) group and underweight (group Ⅲ) group.Rocuronium 0.9 mg/kg was given in 5 s.Onset time (period from drug injection to the point when T1 became 0％),nonresponsive time (period when T1 was 0％) and recovery index (period when T1 was above 25％ and below 75％)was recorded.Results Onset time in group Ⅰ 、Ⅱ and Ⅲ was (75±15)、(91±23) s and (135±27) s respectively.Onset time in group Ⅰ was shorter than in group Ⅱ and group Ⅲ (P＜0.01),and it was shorter in group Ⅱ than in group Ⅲ (P＜0.01).The nonresponse period in group Ⅰ 、Ⅱ and Ⅲ was (49t14)、(37±8)、(28±7) min respectively.Nonresponse period in group Ⅰ was longer than in group Ⅱ and group Ⅲ (P＜0.01),and it was longer in group Ⅱ than in group Ⅲ (P＜0.01).There was no significant difference in recovery index between three groups (P＞0.05).Conclusions BMI is a significant factor for the administration of rocuronium by affecting onset time and nonresoonse oeriod. Key words: Androstanols;  Body mass index;  Neuromuscular blockade