Canadian Journal of Anesthesia, Vol 21, 454-460, Copyright © 1974 by Canadian Anesthesiologists' Society

Periodic Analysis of Mixed Venous Oxygen Tension to Monitor the Adequacy of Perfusion During and After Cardiopulmonary Bypass

¹ Department of Anesthesiology and Division of Artificial Organs, the University of Utah College of Medicine, 50 North Medical Drive, Salt Lake City, Utah 84132

Periodic PvO₂ analysis was evaluated with periodic SvO₂ analysis and compared with the standard technique of maintaining blood flow at a rate of 40-60 ml/kg/min, as methods of regulating blood flow during cardiopulmonary bypass. Both analytical methods resulted in significantly smaller sodium bicarbonate requirements, greater urine outputs and blood pH that was more frequently normal during cardiopulmonary bypass than those values obtained when a fixed flow rate was maintained. Periodic PvO₂ monitoring appeared to be slightly better than SvO₂ monitoring during bypass in that urine output and blood pH were better with the former than with the latter. Postoperatively, however, both methods were equally good in predicting inadequate total blood flows. These findings suggest that periodic PvO₂ analysis is superior as a method of controlling bypass blood flow rates and as a sensitive means of monitoring the adequacy of postoperative cardiac output to meet tissue metabolic needs.