Effectiveness of albumin versus normal saline as a test of volume responsiveness in post-cardiac surgery patients

Purpose: A volume challenge is useful for determining whether cardiac outpu t will respond to further volume loading by the Frank-Starling mechanism. T o properly test this mechanism, there must be an increase in right atrial p ressure (Pra) but this requires variable amounts of normal saline. The purp ose of this study was to determine if 100 mL of 25% albumin would reliably provide a predictable increase in Pra and to compare this with a volume cha llenge with normal saline. As in a previous study, we also examined the pot ential for the pattern of respiratory variation of Pra to predict the respo nse to a fluid challenge. Materials and Methods: Twenty-eight stable patients following cardiopulmona ry bypass surgery were studied in a randomized, nonblinded interventional s tudy in an intensive care unit. All patients had pulmonary artery Rotation catheter as part of their routine management and were breathing spontaneous ly, They were randomized to receive sufficient normal saline to increase Pr a by 2 mm Hg (n = 15) or 100 mL of 25% albumin (n = 13), We also tested the ability of the respiratory variation in Pra to predict the response to a f luid challenge. They had to have an inspiratory fall in the pulmonary capil lary wedge pressure of more than 2 mm Hg as an indication that they had an adequate inspiratory effort. They were classified as either having or not h aving an inspiratory fall in Pra, We predicted that patients without an ins piratory fall in Pra should not respond to volume loading.(1) Results: In contrast to our prediction, the increase in Pra with albumin wa s less than the increase with normal saline, However, the cardiac output in creased more with albumin, which suggests that there was an increase in car diac function with the hypertonic, hyperosmolar albumin solution. In the sa line group, a lack of inspiratory fall in Pra successfully predicted that c ardiac output would fail to increase with an increase in Pra in 8 out of 10 patients given saline, and 5 of 6 patients given albumin. Conclusion: A hyperoncotic albumin solution appears to have an inotropic ef fect in patients following cardiopulmonary bypass procedures. We also again show that the pattern of respiratory variation in right atrial pressure is a useful guide to predict response to volume loading. Copyright (C) 1999 b y W.B. Saunders Company.