Effects Of Dexmedetomidine On Operative Stress And Postoperative Sleep In Elderly Patients

Objects:Dexmedetomidine, an alpha 2-adrenergic and more a2 specificity agonist, has dose-dependently sedative and analgesic properties, which was associated with reduction of anesthetics.Dex provides effects analgesia, sympathetic blocking, and stress inhibition by activating a2 adrenoceptors in central and peripheral nervous system. This prospective randomized study was designed to evaluate the effects of dexmedetomidine on the stress, cytokines and the postoperative sleep quality in elderly patients, and evaluate its clinical dose-effect relationship.Methods:Twenty-four elderly patients aged 60-80 years, ASAⅠ-Ⅱ. The subjects were randomly divided into three groups:Ⅰ(control group),Ⅱ(loading group),Ⅲ(loading+maintenance group),each group had 8 cases. All patients were injected phenobarbital 0.1g, atropine 0.5mg,30 minutes before surgery. Group I did not use Dex. GroupⅡreceived IV dexmedetomidine 0.5 ug/kg over 10 minutes before anaesthesia; groupⅢreceived IV dexmedetomidine 0.5ug/kg over 10 minutes before anaesthesia and as a continuous infusion dose of 0.5ug/kg.h during operation. GA was performed in a standard way.Three groups received midazolam 0.04-0.05mg/kg, fentanyl 5-6ug/kg, vecuronium0.1-0.15mg/kg, and etomidate 0.2-0.25 mg/kg for induction. Maintenance of anesthesia:Fentanyl was given to 10-15ug/kg in the first half couse of the surgery, and remifentanil, propofol and vecuronium were given according to the haemodynamics, maintaining the AEP 20-30 throughout the procedure. Subjects were sent to PACU after surgery and given PCA after extubation. Mean arterial pressure (MAP), heart rate (HR), peripheral oxygen saturation (SpO2) at T1 (before anesthesia), T2 (lOmin after extubation), T3 (24h after surgery), T4 (48h after surgery) were recorded,and concentrations of COR, ACTH, GH, BS, IL-1β, IL-6, TNF-a were measured. The Pittsburgh Sleep Quality Indext was assessed Preoperative,48h after postoperative and before discharging from hospital.24h and 48h after surgery observed the Ramsay sedation score, VAS score, vomiting score, and calculated the total demand of fentanyl in PCA pump.Results:The three groups were similar regarding patient characteristics and procedure-related details (P>0.05). The operative fentanyl requirements were significantly lower in GroupⅡ(0.71±0.58 mg),Ⅲ(0.65±0.05mg) than that in GroupⅠ(0.90±0.72mg)(P<0.05), but there was no significant between GroupⅡandⅢ(P>0.05). The operative remifentanyl requirements were significantly lower in Group II (1.15±0.74mg),Ⅲ(1.02±0.70mg) than that in GroupⅠ(1.35±0.80mg) (P<0.05), but there was no significant between GroupⅡandⅢ(P>0.05).The postoperative dosages of fentanyl has significant defferences in three groups, as GroupⅢ(0.55±0.16mg), GroupⅡ (0.84±0.19mg), GroupⅠ(0.98±0.37mg). there were no significant differences in the total doses of propofol and vecuronium. (P>0.05) Pittsburgh Sleep Quality Index scores, RSS scores,VAS scores, and vomiting scores did not reach statistical significance (P>0.05) in the groups. Mean arterial pressure significantly decreased compared to the baseline throughout the procedure in three groups, except MAP of GroupⅠat T2 increased little ann then decrease (P<0.05). Although heart rate were higher at T3,T4 in GroupⅢ, none of these differences reached statistical significance (P>0.05) in the groups. The time to discharge from the postanesthesia care unit (PACU) to the ward in GroupⅡandⅢwas significantly longer (P<0.05) than that in GroupⅠ, but the time of extubation had no difference. Although statistically significant values were not detected among the three groups with regard to COR, GH, BS, IL-1β, IL-6, TNF-a, ACTH were the highest in GroupⅠat T2 (P>0.05)Conclusion:The study showed that dexmedetomidine was associated with reduction of operative stress response. Dexmedetomidine did not significantly improve the postoperative sleep in elderly patients with colorectal surgery, Dexmedetomidine, with a loading dose of 0.5ug/kg and maintenance dose of 0.5ug/kg.h, seems to be an effective adjunct to anesthetic agents during major elective open colorectal surgery in elderly patients.