Internal Carotid Artery Blood Flow Response to Anaesthesia, Pneumoperitoneum and Head-Up Tilt During Laparoscopic Cholecystectomy: A Clinical Study

Abstract

Background: Control of cerebral blood flow (CBF) is complex and is only beginning to be elucidated. There is paucity of information on how implementation of pneumoperitoneum and head-up tilt under general anaesthesia affects CBF. This study was designed to observe changes that occur in the internal carotid artery (ICA) blood flow with pneumoperitoneum and head-up position and corelate these changes with changes in cardiac output in patients undergoing laparoscopic cholecystectomy.Methods: ICA blood velocity and diameter was measured by Doppler ultrasound in 35 ASA grade I and II patients undergoing laparoscopic cholecystectomy, at four time points: awake, after anaesthesia induction, after induction of pneumoperitoneum, and after head-up tilt; and ICA blood flow was calculated. Simultaneously, heart rate, blood pressure, and end-tidal carbon dioxide (ETCO2) were recorded, and cardiac output was calculated.Results: ICA blood flow decreased upon anesthesia induction from 164 mL/minute to 151 ml/minute (p>0.05). ICA blood flow increased with pneumoperitoneum (from 164 mL/minute to 179ml/minute p= 0.04). Head-up tilt resulted in decrease in ICA blood flow (from 164 mL/minute to 151ml/ minute, P = 0.09).Conclusion: ICA blood flow significantly increased after the creation of pneumoperitoneum in patients undergoing elective laparoscopic cholecystectomy under general anaesthesia. Induction of anaesthesia and head-up tilt, however, did not have any significant change in ICA blood flow. We suggest that ICA blood flow during anaesthesia is influenced by an interplay of actions of anaesthetic agents, positive pressure ventilation and patient position besides the changes in blood pressure, ETCO2 and cardiac output.