ABSTRACT
Objective To evaluate the effects of different positions on cerebral blood flow in patients undergoing laparoscopic surgery.Methods Thirty patients of both sexes,aged 23-64 yr,of American Society of Anesthesiologists physical status Ⅰ or Ⅱ,scheduled for elective laparoscopic surgery,were included.Patients' position was changed using a random number table after induction of anesthesia.Patients were placed in the supine position and tilted 15° head-up or 15° head-down,and the parameters of the middle cerebral artery were monitored using the transcranial Doppler ultrasound.After admission to the operating room (baseline),after induction of anesthesia and before pneumoperitoneum,in the supine position,at head-up tilt and at head-down tilt,the mean blood flow velocity,pulsatility index,resistance index,mean arterial blood pressure (MAP) and heart rate were recorded.Results Compared with the baseline in the supine position,the MAP and bilateral mean blood flow velocity were significantly decreased at head-up tilt,and the MAP and bilateral pulsatility and resistance indices were significantly increased at head-down tilt (P＜0.05).Conclusion During laparoscopic surgery,head-up tilt can lead to a decrease in cerebral blood flow,and head-down tilt exerts no effect on cerebral blood flow.