Objective: To observe the effects of dexmedetomidine given by different methods of administration combined with transversus abdominis plane block(TAPB) on postoperative analgesia and early recovery in patients undergoing radical colorectal resection. Methods: A total of 100 patients scheduled for elective radical colorectal resection were randomly divided into four groups(n=25 in each group): dexmedetomidine intravenous plus TAPB group(group DV-T), dexmedetomidine mixed with ropivacaine TAPB group(group DR-T), ropivacaine TAPB group(group R-T) and control group(group C). In group DV-T, dexmedetomidine was given intravenously at 0.5 μg/kg over 10 minutes before anesthesia induction, followed by intravenous infusion at the rate of 0.5 μg/kg.h. Ultrasound guided bilateral TAPB was performed in all patients after anesthesia induction, group DR-T with dexmedetomidine 1μg/kg plus 0.375% ropivacaine of 40 ml and group DV-T, group R-T with 0.375% ropivacaine of 40 ml, and equal volume of saline was used in group C. Systolic blood pressure(SBP), diastolic blood pressure(DBP), and heart rate (HR) were recorded before induction(T0), 10 minutes after TAPB(T1), at the beginning of operation(T2), 30 min(T3), 60 min(T4) after the beginning of operation, at the end of operation (T5). VAS score at rest and on movement at 2, 6, 12, 24and 48 h after operation were assessed. The requirements of sufentanil and the total times of pressing the analgesia pump on the first day after operation, the frequency of severe hypotension, bradycardia, nausea and vomiting, the first off-bed time, the first flatus time and the length of postoperative hospital stay were also recorded. Results: Compared with group C, SBP, DBP in group DR-T and group DV-T were significantly decreased at T2-T5 (P<0.05). Compared with group C and group R-T, HR in group DR-T and group DV-T were obviously decreased at T1-T5 (P<0.05). Compared with group C, VAS scores on movement at 6 h, 12 h after operation in group R-T and group DV-T, at 6, 12 and 24 h after operation in group DR-T were decreased (P<0.05). VAS scores on movement at 12 h after operation in group DR-T were significantly lower than those in group R-T(P<0.05).Compared with group C, the requirements of sufentanil and the total times of pressing the analgesia pump in the first day after operation in group R-T, group DR-T and group DV-T were significantly decreased(P<0.05), and the requirements of sufentanil and the total times of pressing the analgesia pump in the first day after operation in group DR-Twere obviously less than those of in group R-T and group DV-T(P<0.05). In group R-T, group DR-T and group DV-T, the first time ofgetting down from bed was significantly shorter than that in group C(P<0.05). The first flatus time in group DR-T and group DV-T was also earlier than that in group C. Compared with group C, the frequency of severe bradycardia in group DV-T was obviously increased(P<0.05). Conclusion: Both of dexmedetomidine intravenous plus TAPB and dexmedetomidine mixed with ropivacaine for TAPB can significantly reduce the increase of blood pressure and heart rate caused by surgical stress, and promote earlier recovery. But dexmedetomidine mixed with ropivacaine can prolong the time of postoperative analgesia with a lower incidence of severe bradycardia.
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