• H Abdul-Khaliq, D Troitzsch, S Schubert, A Wehsack, W Böttcher, E Gutsch, M Hübler, R Hetzer, and P E Lange.
• Department of Congenital Heart Disease and Paediatric Cardiology, Department of Thoracic and Cardiovascular Surgery, German Heart Institute Berlin, Germany. abdul-khaliq@dhzb.de
• Thorac Cardiovasc Surg. 2002 Apr 1;50(2):77-81.

BackgroundThis study was undertaken to investigate the physiological effects of cardiopulmonary bypass (CPB) and deep hypothermic circulatory arrest (DHCA) on cerebral oxygen metabolism estimated by near-infrared spectroscopy (NIRS).MethodsTen newborn piglets (2.1 to 2.6 kg) were monitored with right frontal NIRS; the right jugular bulb was cannulated for intermittent sampling of jugular venous blood. All animals underwent CPB, cooling to a core temperature below 15 degrees C, 60 minutes of DHCA followed by subsequent reperfusion and rewarming. Continuously recorded NIRS data and intermittent jugular venous blood values were compared.ResultsNIRS performance was examined over the jugular venous oxygen saturation (SjvO2) range of 40 to 98 %, a linear correlation was found between SjvO2 and NIRS-derived regional cerebral oxygen saturation (rSO2) (r = 0.91, p < 0.001). A correlation was observed between the cellular oxidation NIRS-parameter cytochrome oxidase aa3 (CytOx) slope during the DHCA period in relation to rectal and nasopharyngeal temperature immediately before the onset of DHCA (r = 0.75 and 0.85, p < 0.001).ConclusionsThis study suggests that NIRS-measured hemoglobin oxygenation parameters may reflect functional changes in cerebral hemodynamics and brain tissue oxygenation, while CytOx values represent related effects on intracellular oxidative metabolism.

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