Effects of ephedrine on indocyanine green clearance during spinal anesthesia: evaluation by the finger piece method.

We measured indocyanine green (ICG) clearance in 20 patients scheduled for elective surgery during spinal anesthesia to determine whether ephedrine affects the hepatic circulation during spinal anesthesia. The clearance was measured by a new noninvasive finger piece method. We found that a decrease in arterial blood pressure secondary to spinal anesthesia significantly reduced ICG, whereas there were no significant changes in ICG clearance in the patients whose arterial blood pressures were maintained at preanesthetic levels by ephedrine. Other hemodynamic variables, heart rate, cardiac index, and stroke volume index, did not change significantly in either group. We conclude that hepatic blood flow is decreased by hypotension due to spinal anesthesia and can be attenuated by ephedrine administration.