Background: Intravenously administered indocyanine green (ICG) may cause misreadings of cerebral oximetry and pulse oximetry in patients undergoing carotid endarterectomy under general anesthesia. The present study determined the effects of two different doses (12.5 mg vs. 25 mg) of ICG on regional cerebral tissue oxygen saturation (SctO2) and percutaneous peripheral oxygen saturation (SpO2).
Methods: Twenty-six patients receiving ICG for videoangiography were divided into two groups according to the dosage (12.5 mg and 25 mg, n = 13 in each group). Heart rate, arterial blood pressure, SctO2, and SpO2 were measured before and after an intravenous bolus administration of ICG.
Results: Following the dye administration, no changes in heart rate or arterial blood pressure were noted in either group. SctO2 was increased in both groups; however, the magnitude of the increase was greater (21.6 ± 5.8% vs. 12.6 ± 4.1%, P < 0.0001) and more prolonged (28.4 ± 9.6 min vs. 13.8 ± 5.2 min, P < 0.0001) in the 25 mg group than in the 12.5 mg group. In contrast, SpO2 was decreased in both groups; the magnitude of the decrease was greater in the 25 mg group than in the 12.5 mg group (4.0 ± 0.8% vs. 1.6 ± 1.0%, P < 0.0001). There were no differences in the time to reach the peak SctO2 or to reach the nadir SpO2 between the two groups.
Conclusions: In patients given ICG for videoangiography, a 25 mg bolus results in a greater and more prolonged increase in SctO2 and a greater reduction in SpO2 than a 12.5 mg bolus, with no differences in the time to reach the peak SctO2 or to reach the nadir SpO2.
Keywords: Cerebral oximetry; Cerebral oxygenation; Indocyanine green; Near-infrared spectroscopy; Pulse oximetry.