Effect of rSO 2-guided low-dose norepinephrine on postoperative cognitive dysfunction in elderly patients undergoing hip replacement under general anesthesia / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effect of regional oxygen saturation (rSO 2)-guided low-dose norepinephrine on postoperative cognitive dysfunction (POCD) in elderly patients undergoing hip replacement under general anesthesia. Methods:One hundred and twenty patients of both sexes, aged 65-80 yr, with body mass index of 18-24 kg/m 2, of American Society of Anesthesiologists physical statusⅠ-Ⅲ, scheduled for hip replacement under general anesthesia, were divided into 2 groups ( n=60 each) using a random number table method: control group (group C) and low-dose norepinephrine guided by rSO 2 group (group RN). The patients in both groups received superior inguinal fascial space block combined with general anesthesia under laryngeal mask placement.In group C, the fluctuation range of mean arterial pressure (MAP) was not more than 20% of the baseline, vasoactive agents were administered according to the changes in blood pressure, rSO 2 was monitored continuously, but the change rate of rSO 2 was not used as the regulating index.In group RN, norepinephrine was infused continuously via the central vein at 0.01-0.10 μg·kg -1·min -1 after anesthesia induction, the dose was adjusted according to rSO 2, the rSO 2 change rate was maintained≤10%, the fluctuation range of mean arterial pressure was not more than 20% of the baseline, and vasoactive agents were administered when necessary.MAP, end-tidal pressure of carbon dioxide (P ETCO 2) and rSO 2 were recorded after inhalation of oxygen (T 0), at 5 min after anesthesia induction (T 1), at 30 min after skin incision (T 2), at the end of surgery (T 3) and after recovery and extubation (T 4), and the change rate of rSO 2 was calculated.The occurrence of adverse events and amount of vasoactive drugs used were recorded.The cognitive function was assessed using Montreal Scale at 1 day before surgery and 7 days after surgery, and the development of postoperative cognitive dysfunction (POCD) was calculated using Z score.The postoperative hospital stay time was recorded. Results:Compared with group C, MAP and rSO 2 were significantly increased, and the change rate of rSO 2 was decreased at T 1, 2 in group RN ( P<0.05). Compared with group C, the requirement for intraoperative vasoactive drugs was significantly decreased, the consumption of norepinephrine was increased, MoCA total score, attention and delayed recall sub-score were increased at 7 days after surgery, the incidence of POCD was decreased, and the postoperative hospital stay time was shortened in group RN ( P<0.05). Conclusion:Low-dose norepinephrine guided by rSO 2 can decrease the development of POCD in elderly patients undergoing hip replacement under general anesthesia.