Continuous measurement of coronary sinus oxygen saturation after cardiac surgery.

To estimate the balance of myocardial oxygen supply and demand after cardiac surgery, we used fiberoptic reflection oximetry to measure continuously the coronary sinus oxygen saturation (ScsO2) in six patients. ScsO2 decreased with massive bleeding, atrial fibrillation, after DC countershock, and continuous iv infusion of hydralazine, phentolamine, and dibutyryl cyclic-AMP. ScsO2 increased with iv infusion of nicardipine or nitroglycerin, suggesting an improved oxygen metabolism in the myocardium. Continuous ScsO2 measurement provides such on-line information on myocardial oxygenation in postoperative patients.