RESUMO
Objective To investigate the 50% effective dose(ED)and 95% effective dose(ED)of dexmedetomidine(DEX)combined with 0.032 μg/(kg·h)sufentanil as well as its analgesic effect for patient-controlled intravenous analgesia(PCIA)after video-assisted thoracoscopic surgery(VATS).Methods Totally 25 patients undergoing elective VATS were enrolled. DEX and 0.032 μg/(kg·h)sufentanil were used for postoperative PCIA. The loading dose of DEX was 0.048 μg/(kg·h),and the dose difference between two adjacent patients was 0.008 μg/(kg·h). The DEX dose of a current patient was determined by whether the previous patient was satisfied with postoperative analgesic effect. If the previous patient was satisfied with postoperative analgesic effect,the DEX dose of the current patient was decreased by 0.008 μg/(kg·h);and if the previous analgestic effect was not satisfactory,DEX dose of the current patient was increased by 0.008 μg/(kg·h). The study endpoint was dexmedetomidine dose was<0.008 μg/(kg· h) within 7 upper and lower cycles in 7 consecutive cases. Finally,the probability unit regression was used to estimate the ED and ED of DEX and their 95% .Results When DEX combined with 0.032 μg/(kg·h) sufentanil was used for postoperative PCIA in young patients undergoing VATS,the ED and EDof DEX were 0.0346 μg/(kg· h)[95%:0.0283-0.0408 μg/(kg·h)] and 0.0459 μg/(kg·h)[95%:0.0400-0.0880 μg/(kg·h)],respectively. No adverse reaction such as vomiting,respiratory depression,or bradycardia occurred. The average Visual Analogue Scale(VAS)scores at rest(=-5.128,=0.000)and cough(Z=-6.642,=0.000)and the Ramsay sedation score(Z=-2.335,=0.020)within 6 hours after surgery were higher than those after 6 hour.Conclusion DEX combined with 0.032 μg/(kg·h) sufentanil are effective for postoperative PCIA in patients undergoing VATS when the ED and ED are 0.0346 μg/(kg·h)and 0.0459 μg/(kg·h),respectively.