The effect of pneumoperitoneum and Trendelenburg position on acute cerebral blood flow-carbon dioxide reactivity under sevoflurane anaesthesia

This study compared cerebral blood flow-carbon dioxide (CBF-CO2) reactivities in the supine and modest Trendelenburg position under pnemoperitoneum during sevoflurane anaesthesia. After induction of anaesthesia in 25 patients, mechanical ventilation was adjusted to increase PaCO2 from 4.7 (T-1) to 6.0 kPa (T-2) in the supine position, and the change in jugular bulb oxygen saturation was measured as an index of CBF. Then, after establishment of pneumoperitoneum and 30 degrees Trendelenburg position, the CO2 step and measurement of CBF were repeated. The CBF-CO2 reactivity was 7.5 (3.3) %.kPa(-1) (% change in jugular bulb oxygen saturation per unit change in PaCO2) in the supine position and 6.8 (2.3) %. kPa(-1) in the 30 degrees Trendelenburg-pneumoperitoneum condition (p = 0.086). We conclude that CBF-CO2 reactivity is unchanged by the modest Trendelenburg position under pneumoperitoneum during sevoflurane anaesthesia.