Effects of different doses of dexmedetomidine infused at nighttime on early postoperative cognitive dysfunction in elderly patients undergoing radical resection of malignant gastrointestinal tumors / 中华麻醉学杂志

ABSTRACT

Objective:To evaluate the effects of different doses of dexmedetomidine infused at nighttime on early postoperative cognitive dysfunction (POCD) in elderly patients undergoing radical resection of malignant gastrointestinal tumors.Methods:Eighty American Society of Anesthesiologists physical status Ⅱ or Ⅲ patients of either sex, aged 65-75 yr, with body mass index of 18-24 kg/m 2, scheduled for elective radical resection of malignant gastrointestinal tumors, were divided into 4 groups ( n=20 each) using a random number table method: control group (group C) and different doses of dexmedetomidine groups (D 1-3 groups). Dexmedetomidine 0.1, 0.2 and 0.3 μg·kg -1·h -1 (infusion rate 4 ml/h) were intravenously infused from 21: 00 on the day of surgery and the first day after surgery until 6: 00 in the next morning.Normal saline was given instead of dexmedetomidine in group C. The period of sleep and the number of awakening at night were recorded before surgery and at 2 and 7 days after surgery.Cognitive function was assessed at 1 day before surgery and 7 days after surgery.The concentrations of plasma cortisol were measured at 16: 00 before surgery and 2 and 7 days after surgery and at 8: 00 in the corresponding morning of the next day.The difference in the plasma cortisol concentration measured at 8: 00 every day and at 16: 00 of the previous day were calculated. Results:The incidence of POCD was significantly lower in D 2, 3 groups than in group C ( P<0.05). The number of awakening at night was significantly decreased at 2 days after surgery in group D 3 as compared with the other three groups ( P<0.05). The difference in the plasma cortisol concentration was significantly decreased at 2 and 7 days after surgery in D 2, 3 groups when compared with group C and group D 1 ( P<0.05). Compared with group D 2, no significant change was found in the difference in the plasma cortisol concentration at each time point in group D 3 ( P>0.05). There were no significant differences in the incidence of hypotension, hypertension, bradycardia, and tachycardia among the four groups ( P>0.05). Conclusion:Infusing dexmedetomidine 0.2 or 0.3 μg·kg -1·h -1 at the nighttime can reduce the development of POCD in the elderly patients undergoing radical resection of malignant gastrointestinal tumors.