The Effect of Isoflurane or Spinal Anesthesia on Indocyanine Green Disappearance Rate in the Elderly

This study was designed to measure the disappearance rate of indocyanine green (ICG) as an indicator of hepatic blood flow in elderly patients undergoing internal fixation of fractured neck of femur. All patients were aged 60–90 yr and were randomized to receive either spinal (n = 10) or isoflurane (n = 10) anesthesia. In both groups systolic arterial blood pressure was maintained within 15% of resting levels by administration of fluids intravenously without vasoactive drugs. Patients were excluded if they required vasopressors to maintain arterial blood pressure. ICG disappearance rate was calculated using a single bolus technique before induction of anesthesia, and at 30, 60, and 120 min after induction of anesthesia. Sixteen patients completed the study. There were no statistically significant changes in ICG disappearance rate in either group at any time during the study, indicating that hepatic blood flow is not significantly altered by either spinal or isoflurane anesthesia provided that arterial blood pressure is maintained.