Effects of ultrasound-guided lateral quadratus lumborum block on ED50 of butorphanol by patient controlled intravenous analgesia after cesarean section under general anesthesia
AIM To investigate the effect of ultrasound-guided lateral quadratus lumborum block(QLB-1)on the median effective dosage(ED50)of butorphanol by patient controlled intravenous analgesia(PCIA)performed after cesarean section under general anesthesia.METHODS Parturients were scheduled for cesarean section under general anesthesia,gestation 37-42 weeks,ASA physical status Ⅱ were assigned into two groups,group Q(QLB-1 combined with butorphanol PCIA)and group C(butorphanol PCIA).Each group was expected to have 35 cases.Both groups were administered general anesthesia with endotracheal intubation.The group Q:0.3％ropivacaine with 25 mL were injected in the QLB-1 in each side respectively under ultrasound guidance before extubation at the end of the surgery.The group C:no nerve block.The two groups underwent PCIA after extubation.The scores of resting visual analogue scale(VAS)≤3 points or VAS of motion state≤4 points within 48 hours after operation were used as the criteria of analgesia satisfaction.The initial dose of butorphanol with PCIA was 4 pg·kg-1·h-1,adjusted by the modified Dixon's up-and-down method with a dose gradient of 0.25 pg·kg-1·h-1.Probit analysis was used for calculating ED50 and 95％confidence interval(CI)of butorphanol PCIA for satisfactory analgesia.RESULTS The sample size included in group Q and group C were 31 and 28 cases,respectively.The ED50 of butorphanol PCIA for satisfactory analgesia was 3.81 pg·kg-1·h-1 for the group C(95％CI:2.87 to 4.25 pg·kg-1·h-1)and 2.45 pg·kg-1·h-1 for the group Q(95％CI:2.16 to 2.70 pg·kg-1·h-1).In the parturients with satisfactory analgesia of the two groups,the incidence of drowsiness,dizziness and nausea was higher in the group C than that in the group Q(P＜0.05).CONCLUSION The ED50 of butorphanol PCIA combined with QLB-1 for satisfactory relieve postoperative analgesia after cesarean section under general anesthesia reduce butorphanol PCIA alone by 36％and reduce the incidence of adverse reactions.
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