Purpose: To assess the effect of regional versus general anesthesia on transcranial cerebral oxygen saturation (rSO₂) in elderly patients undergoing fractured proximal femur repair.

Materials and Methods: Prospective, randomized, open-label study. 60 geriatric patients were randomized to receive either general (Group GA) or spinal (Group S) anesthesia. In all cases frontal rSO₂ (INVOS^® 5100, SOMANETICS, Troy, Michigan, USA) was measured for a 10 minute pre-operative control period, throughout the surgical procedure and for 10 minutes postoperatively. If a drop in rSO₂ below baseline occurred, the following were instituted in order to improve cerebral oxygenation: normotension was ensured, the neck vessels were checked and cleared of extrinsic obstruction and the F_IO₂ was increased.

Results: The incidence of a decrease in rSO₂ below base-line preoperative levels was significantly (p < 0.0001) higher in Group S. However, the number of patients in whom at least one dip below baseline was recorded was similar between the groups. By contrast, general anesthesia was associated with a significantly higher rSO₂ when compared to spinal anesthesia. This is attributed to the volatile anesthetic agent induced reduction in the cerebral metabolic rate. Logistic regression revealed no correlation between changes in blood pressure, heart rate or peripheral oxygen saturation and the incidence of rSO₂ dips below baseline.

Conclusion: rSO₂ is likely patient specific and independent of the anesthetic technique administered. Therefore we support the utility of cerebral oximetry in this population in order to detect cerebral desaturation and correct reversible causes such as relative hypotension and neck vessel obstruction. Choice of anesthetic technique should still be tailored to individual patient needs.