Abstract:

Objective To investigate the effects of dexmedetomidine （0.5， 1.0， 2.0 μg/kg） combined with ropivacaine ultrasound guided thoracic paravertebral nerve block （TPVB） in patients undergoing thoracoscopic surgery under general anesthesia on the vital signs， stress response and other indexes， and to provide reference for the optimization of anesthesia regimen in the clinic. Methods A total of 99 cases of patients undergoing thoracoscopic surgery under general anesthesia were selected， and the patients were divided into the low， medium， and high-dose groups of 33 cases each according to the method of randomized numerical table. At the end of anesthesia induction， dexmedetomidine 0.5， 1.0， and 2.0 μg/kg compounded with 0.375% ropivacaine ultrasound-guided TPVB was administered to the low， medium， and high-dose groups， respectively， and all three groups were observed until 3 d postoperatively. Perioperative indicators， quality of awakening， degree of pain at 2， 6， 12， and 24 h postoperatively， vital signs before anesthesia （T1）， at tracheal extubation （T2）， and at 5 min of tracheal extubation （T3）， and immune function， stress response， and adverse reactions during the observation time were compared between the groups. Results Compared with the low-dose group， remifentanil and propofol dosages were lower in the medium- and high-dose groups， and the number of postoperative self-controlled analgesia was lower （P < 0.05）. Awakening， tracheal extubation， and recovery room stay were prolonged between the low， medium， and high dose groups （P < 0.05）. Scores of visual analog scale （VAS） were progressively lower in the three groups at 2， 6， 12， and 24 h postoperatively （P < 0.05）， and compared with the low-dose group， scores of VAS were lower in the medium and high-dose groups at 2， 6， and 12 h postoperatively （P < 0.05）. Compared with T1， heart rate （HR）， mean arterial pressure （MAP） were higher in all three groups at T2， T3， and HR， MAP at T2， T3 were higher between the low， medium， and high dose groups （P < 0.05）； compared with T2， HR， MAP were lower in all three groups at T3 （P < 0.05）. Compared with the preoperative period， levels of whole blood CD8⁺， serum cortisol （Cor）， C-reactive protein （CRP）， norepinephrine （NE）， and epinephrine （E） were increased in the three groups at 3 d postoperatively， and the above indexes were elevated between the low， medium， and high dosage groups at 3 d postoperatively （P < 0.05）； levels of whole blood CD3⁺， CD4⁺， CD4⁺/CD8⁺ were decreased in the three groups at 3 d postoperatively， and the above indexes were elevated between the low， medium， and high dosage groups at 3 d postoperatively （P < 0.05）. There was no statistically significant difference in the safety comparison among the three groups （P > 0.05）. Conclusions 1.0 μg/kg dexmedetomidine combined with ropivacaine ultrasound guided TPVB had certain advantages in reducing the degree of pain of general anesthesia thoracoscopic surgery patients， reducing the dosage of remifentanil and propofol and the number of postoperative self-controlled analgesia， while 0.5 μg/kg dexmedetomidine combined with ropivacaine ultrasound guided TPVB had certain advantages in improving patients' vital signs， reducing immunosuppression， stress reaction and promoting post-anesthesia awakening. Clinical anesthesia protocols could be rationally selected according to the actual situation of patients.

Key words: thoracoscopic surgery, general anesthesia, dexmedetomidine, ropivacaine, ultrasound, thoracic parathoracic nerve block, vital signs, stress response