[The effects of spinal anesthesia on liver blood flow measured by the ICG clearance meter]

ICG (indocyanine green) clearance meter is a new equipment that can measure the plasma disappearance of ICG through a photopiece attached to the tip of the finger. In this study we evaluated the effects of spinal anesthesia on liver blood flow using this method in 12 adult patients who were scheduled for elective surgery under spinal anesthesia. ICG clearance was read from an ICG clearance meter RK-1000 (Sumitomo Electric) following intravenous administration of ICG (0.5 mg.kg-1). The data are shown as the plasma disappearance rate (K) and the 15-minute retention rate (R15). The measurements were performed prior to spinal anesthesia and when the sensory level of anesthesia reached Th5. Spinal anesthesia was performed with tetracaine (12-15 mg). Heart rate, arterial blood pressure, and cardiac output (measured by NCCOM) were recorded simultaneously. Mean arterial pressure, heart rate and ICG clearance decreased significantly but cardiac index was unchanged. Our results suggest that high spinal anesthesia causes circulatory disturbance of the liver, and that this is probably followed by a drop in arterial blood pressure.