Effects Of Different Adjuvant Methods Of Dexmedetomidine On Thoracic Paravertebral Block Analgesia

Objective: Video-assisted thoracoscopic surgery(VATS)is more and more widely used in thoracic surgery because of its less trauma and faster recovery than conventional thoracotomy,but the management of postoperative pain is still very important.Thoracic paravertebral block has similar analgesic effect as thoracic epidural analgesia(long considered as the gold standard),with less side effects and lower rate of hemodynamic instability.Dexmedetomidine can be used as an adjuvant of local anesthetics,which helps to prolong the time of nerve block and improve the blocking effect.The aim of this study was to investigate the effects of dexmedetomidine on single thoracic paravertebral block analgesia.Methods: A total of 105 patients undergoing video-assisted thoracoscopic surgery from May 2018 to January 2019 in the Second Affiliated Hospital of Dalian Medical University were selected.Non-invasive blood pressure,electrocardiogram,pulse oxygen saturation,bispectral index of EEG were monitored after patients entered the operating room.Intravenous infusion pathway was established and invasive arterial monitoring was performed under local anesthesia.Ultrasound-guided paravertebral block of thoracic spine was performed by an experienced anesthesiologist with the same manipulation under sterile conditions.The study participants were assigned to three study groups according to the random number table 1:1:1,and received thoracic paravertebral block and intravenous drug infusion according to the grouping.Thefollowing were: Dex(iv)group,right metomidine vein group,0.5% ropivacaine 20 ml single thoracic paravertebral block,right metomidine vein infusion immediately after block;Dex(p)group,right metomidine paravertebral group,0.5% ropivacaine + 0.5ug/kg.Dexmedetomidine was used as a single thoracic paravertebral block for 20 ml,and saline was pumped immediately after the block.In control group,0.5% ropivacaine was used as a single thoracic paravertebral block for 20 ml,and saline was pumped immediately after the block.Three groups of intravenous drug infusion mode is the same,that is,1 ug/kg of drug infusion(10-15 minutes)immediately after blockade,and 0.5ug/kg/h continuous infusion during operation.Standardized induction of anesthesia,double-lumen intubation,maintenance of anesthesia and mechanical ventilation were followed.All patients received patient-controlled intravenous analgesia(PCIA)and intravenous injection of non-steroidal anti-inflammatory drugs.At the end of the operation,all patients were transferred to the post anesthesia care unit(PACU).Bipectral index(BIS),intraoperative anesthetic dosage,adverse hemodynamic events,duration of postoperative analgesia,total dosage of analgesics,rating scale(NRS)score at rest and cough at 2,6,12,24,48 hours after thoracic paravertebral block were recorded.Results: There was no significant difference in general data among the three groups(P > 0.05).Compared with group C,the total amount of propofol in group Dex(iv)decreased significantly(P < 0.05);compared with group C,the incidence of intraoperative bradycardia in group Dex(iv)increased significantly(P < 0.05);compared with group C,the incidence of intraoperative bradycardia in group Dex(iv)was significantly higher(P < 0.05);compared with group C and group Dex(iv),Dex(p(p < 0.05).)Compared with group C,the dosage of analgesics in group Dex(iv)and group Dex(p)decreased significantly(P < 0.05),but there was no significant difference between group Dex(iv)and group Dex(p)(P = 0.268).At 2,6 and 12 hours after operation,the NRS scores of resting and coughing pain in group Dex(p)were significantly lower than those in group C(P < 0.05).Compared with group C,the NRS scores of resting pain and cough pain in Dex(iv)group were significantly lower thanthose in group C at 6 and 12 hours after operation(P < 0.05).At 12 hours,the NRS scores of resting pain and cough pain in Dex(p)group were significantly lower than those in Dex(iv)group,with significant difference(P < 0.05).At 12 hours,the NRS scores of resting pain and cough pain in Dex(p)group were significantly lower than those in Dex(iv)group,with significant difference(P < 0.05).5).Dex(p)group had the highest overall satisfaction with the analgesic effect(P < 0.05);there was no significant difference in the incidence of intraoperative hypotension and the dosage of remifentanil among the three groups.Conclusion: For patients undergoing video-assisted thoracoscopic surgery,dexmedetomidine combined with ropivacaine for thoracic paravertebral block can prolong the time of postoperative analgesia,reduce the degree of pain and improve patient satisfaction.