Intraoperative fluid balance during cardiopulmonary bypass: effects of different mean arterial pressures

Abstract

Financial support . This study was financially supported by The Western Norway Regional Health Authority, The Norwegian Council on Cardiovascular Diseases, Faculty of Medicine, University of Bergen and The Frank Mohn Foundation, Norway. Introduction. This study investigated whether two levels of mean arterial pressure (MAP) during cardiopulmonary bypass did influence per-operative fluid shifts. Methods. Sixteen pigs underwent 60 minutes of normothermic cardiopulmonary bypass (CPB) followed by 90 minutes of hypothermic CPB. Eight animals had a MAP of 60—80 mmHg by norepinephrine (HP group). Another 8 animals had a MAP of 40—45 mmHg by phentolamine (LP group). Blood chemistry, plasma/interstitial colloid osmotic pressures, plasma volume, fluid balance, fluid extravasation rate and tissue water content were measured or calculated. Results. The plasma volume was significantly lower in the HP group compared with the LP group after 60 minutes of CPB. Net fluid balance was 0.18 (0.05) ml·kg ^- ¹·min ^- ¹ in the HP group and 0.21 ml·kg ^- ¹·min ^- ¹ in the LP group (P > 0.05) while fluid extravasation rate was 1.18 (0.5) and 1.13 (0.4) ml·kg ^- ¹·min ^- ¹ in the HP group and the LP group during CPB (P > 0.05). Conclusion. Net fluid balance and fluid extravasation rate were similar in the animals with elevated and with lowered MAP during CPB. Perfusion (2007) 22, 273—278.

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