USE OF NEAR-INFRARED SPECTROSCOPY TO MONITOR THE REGIONAL CEREBRAL OXYGEN SATURATION DURING INFRARENAL AORTIC CROSS-CLAMPING IN PIGLETS

Abstract

The hemodynamic changes induced by infrarenal aortic cross-clamping have been well documented, but the effects of such cross-clamping on cerebral perfusion are unknown. To investigate these effects, we used near-infrared spectroscopy (NIRS) to monitor the regional cerebral oxygen saturation (rSO2) during infrarenal aortic cross-clamping in a piglet model. Methods: The study involved 19 piglets, each weighing 7.8 ± 1 kg. The NIRS sensor was placed on each animal's forehead. General anesthesia was induced, and the infrarenal abdominal aorta was mobilized through a laparotomy. After heparin (1 mg/kg) was administered, cross-clamps were applied proximally and distally. A 2-mm segment was resected from the proximal aortic stump, and an aorto-aortic anastomosis was performed. Results: Cross-clamping lasted for 30.6 ± 6.7 minutes. Between the time of baseline measurement and clamp application, the rSO2 did not decrease significantly (65.4% ± 8.9% vs. 62.4% ± 7.8%). However, significant decreases in the rSO2 occurred between baseline measurement and clamp removal (65.4% ± 8.9% versus 55.7% ± 8.9%; P < 0.01), between baseline measurement and the end of surgery (65.4% ± 8.9% vs. 57.7% ± 7.5%; P < 0.01), and between clamp application and removal (62.4% ± 7.8% vs. 55.7% ± 8.9%; P < 0.01). At these same intervals, no inter-animal differences occurred in the temperature, heart rate, or mean arterial pressure. Conclusion: Infrarenal aortic cross-clamping significantly decreases the rSO2. NIRS, which has the advantages of being noninvasive and continuous, may be useful for monitoring this variable intraoperatively.