The beach chair position for shoulder surgery in intravenous general anesthesia and controlled hypotension: Impact on cerebral oxygenation, cerebral blood flow and neurobehavioral outcome

Study objectives: The aim of this study was to assess the impact of intravenous general anesthesia and controlled hypotension on cerebral saturation (rScO(2)), cerebral blood flow measured as middle cerebral artery blood flow velocity (Vmax MCA) and neurobehavioral outcome in patients scheduled for shoulder surgery in beach chair position. Design: Prospective, assessor-blinded observational study. Setting: University hospital, shoulder surgery operating room. Patients: Forty ASA I-II patients scheduled for shoulder surgery in beach chair position and controlled hypotension. Interventions: Neurological and neurobehavioral tests were performed prior and the day after surgery. The baseline data for near-infrared spectroscopy, bispectral index, cerebral blood flow, PaCO2 and invasive blood pressure (radial artery) were taken prior anesthesia and after anesthesia induction, after beach chair positioning and all 20 min after surgery start until discharge of the patient. Measurements: Neurological and neurobehavioral tests, cerebral saturation (rScO(2)) using near-infrared spectroscopy, BIS, cerebral blood flow using Doppler of the middle cerebral artery (Vmax MCA), PaCO2 and invasive blood pressure assessed at heart and at the external acoustic meatus level. Main results: The incidence of cerebral desaturation events (CDEs) was 25%. The blood pressure drop 5 min after beach chair position measured at the acoustic meatus level in the CDE group was higher compared to patients without CDEs (p = 0.009) as was the rScO(2) (p = 0.039) and the Vmax MCA (p = 0.002). There were no neurological deficits but patients with CDEs showed a greater negative impact on neurobehavioral tests 24 h after surgery compared to patients without CDEs (p = 0.001). Conclusions: In ASA I-II patients intravenous general anesthesia and controlled hypotension in the beach chair position affects cerebral blood flow and cerebral oxygenation with impact on the neurobehavioral outcome.