不同剂量右美托咪定对宫腔镜手术患者扩宫刺激时七氟烷最低肺泡有效浓度的影响

Effects of Different Doses of Dexmedetomidine on the MAC of Sevoflurane in Gynecological Patients with Hysteroscopy Stimulus

目的比较不同剂量右美托咪定对宫腔镜手术患者扩宫刺激时七氟烷最低肺泡有效浓度(MAC)的影响,探讨宫腔镜手术中右美托咪定与七氟烷联合用药的适宜剂量。方法选择择期拟行宫腔镜手术患者150例,ASA分级Ⅰ~Ⅱ级,年龄20~45岁,采用随机数字表法,将患者随机分为1个对照组(C)和5个右美托咪定组(D_(1-5)),每组25例。D_(1-5)组麻醉诱导前10 min分别静脉输注右美托咪定0.2、0.4、0.6、0.8、1.0μg/kg,C组输注等容量生理盐水。各组吸入七氟烷诱导,待适宜麻醉深度时完成喉罩置入,保留自主呼吸调节呼末七氟烷浓度至预设值并维持稳定15 min以上,观察扩宫刺激时有无体动反应,采用序贯法测定各组七氟烷MAC值。记录扩宫刺激前后心率和血压变化、苏醒及拔除喉罩时间、术后Ramsay镇静评分及VAS疼痛评分。结果C组和D_(1-5)组的MAC值分别为(1.90±0.13)%、(1.70±0.13)%、(1.50±0.13)%、(1.23±0.16)%、(1.03±0.10)%和(0.93±0.08)%。与C组相比,D_(1-5)组的MAC值明显降低(P<0.05),但D_(4)与D_(5)组间七氟烷MAC值差异无统计学意义。D_(1-5)组患者术后10 min的Ramsay镇静评分明显高于C组(P<0.05)。D_(2-5)组术后10 min的VAS疼痛评分明显低于C组(P<0.05)。D_(4-5)组拔除喉罩时间较其余各组明显延长,心动过缓及呼吸抑制发生率亦明显增加。D_(5)组苏醒时间较其它各组明显延长(P<0.05)。结论妇科患者扩宫刺激时七氟烷MAC值随静脉输注右美托咪定剂量的增加而降低,当右美托咪定剂量超过0.8μg/kg时,其降低作用产生封顶效应。

Objective To compare the effects of different doses of dexmedetomidine on the minimum alveolar concentration(MAC)of sevoflurane in patients with cervical dilatation stimulus under hysteroscopy.Methods 150 patients undergoing hysteroscopy surgery,ASA physical statusⅠ~Ⅱ,aged 20~45 years,were enrolled in this study.All patients were randomly divided into 6 groups(C,D_(1),D_(2),D_(3),D_(4) and D_(5))with different doses of dexmedetomidine(0,0.2,0.4,0.6,0.8,1.0μg/kg).All doses of dexmedetomidine were diluted into 20 ml normal saline and finished infusion within 10 min before induction.Anesthesia induction with sevoflurane was initiated after infusion of dexmedetomidine had been finished.Laryngeal mask was placed when depth of anesthesia was appropriate.Patients' spontaneous breathing was retained,and end-tidal sevoflurane concentration was adjusted to its preset value and maintained stable more than 15 min.Patient's response to cervical dilatation stimulus was observed and MAC values of sevoflurane in 6 groups were measured by a sequential method.Heart rate,blood pressure,anesthesia recovery time,removing laryngeal mask time,postoperative Ramsay sedation score and visual analogue scale(VAS)pain score were recorded.Results Sevoflurane MAC in group C and groups D_(1-5 )were(1.90±0.13)%,(1.70±0.13)%,(1.50±0.13)%,(1.23±0.16)%,(1.03±0.10)%and(0.93±0.08)%,respectively.Compared with group C,MAC in groups D_(1-5 )were decreased significantly(P<0.05).There was no statistical difference in MAC value of sevoflurane between group D_(4) and D_(5).Compared with group C,Ramsay sedation 10 min after operation in groups D_(1-5 )were increased significantly,scores of VAS 10 min after operation in groups D_(2-5 )were significantly decreased,removal time of laryngeal mask was significantly prolonged in groups D_(4-5),incidences of respiratory depression and sinus bradycardia were increased during surgery in groups D_(4-5),and recovery time from anesthesia in group D_(5) was significantly prolonged(P<0.05).Conclusion Sevoflurane MAC was decreased with increase of infusion dose of dexmedetomidine during hysteroscopy surgery.A ceiling effect was found in the decrease of sevoflurane MAC when dose of dexmedetomidine exceeded 0.8μg/kg.