The Effects of Spinal Anesthesia on Cerebral Blood Flow in the Very Elderly

Abstract

Aging and disease may make elderly patients particularly susceptible to hypotension during spinal anesthesia. However, the impact of small-dose bupivacaine on cerebral hemodynamics is not known. In this study, we assessed the effects of spinal anesthesia on cerebral blood flow (CBF) in very elderly patients. We prospectively studied 20 patients aged >75 yr who underwent open surgical repair of a hip fracture and compared them with a control group of patients younger than 60 yr. Patients were placed in the lateral decubitus position to receive spinal anesthesia at L4-5 level. Noninvasive automated arterial blood pressure, heart rate, and transcranial Doppler measurements were recorded before spinal anesthesia (baseline = T0), 5 min after the end of local anesthetic injection (T1), 10 min after spinal anesthesia (T2), and in the postanesthesia care unit (T3). Systolic blood pressure significantly decreased at T1 (115 +/- 25 mm Hg) and T2 (114 +/- 24 mm Hg) compared with T0 (136 +/- 21 mm Hg) in the elderly group. Systolic and diastolic velocities significantly decreased compared to baseline values (at T1, T2). Significant modifications of the pulsatility index (PI) and resistance index occurred at T2 for PI and resistance index. No patient experienced an episode of bradycardia. Heart rate variations were not significantly different compared to T0. Neither hemodynamics nor cerebral effects were observed in the control group. In summary, spinal anesthesia results in a very small but statistically significant reduction of CBF velocity in very elderly patients.