Regional blood flow and oxygen transport in patients with the low cardiac output syndrome after cardiac surgery

Abstract

To assess systemic and regional oxygen transport after open heart surgery in patients with the low cardiac output syndrome who are receiving vasoactive drugs and in patients with normal hemodynamics during spontaneous rewarming. Prospective, nonrandomized controlled trial. Tertiary care center. Sixteen patients aged 53.1 +/- 8.4 yrs were studied after coronary artery bypass operations: ten patients with a cardiac index of < 1.75 L/min/m2 and six control patients with a cardiac index of > 1.75 L/min/m2. The patients with a cardiac index of < 1.75 L/min/m2 received either dobutamine alone (n = 5) or in combination with nitroprusside (n = 5). The control patients with a cardiac index of > 1.75 L/min/m2 did not receive vasoactive treatment. The systemic oxygen consumption was measured by indirect calorimetry and the regional blood flow was measured by primed continuous infusion of indocyanine green. Both splanchnic and femoral blood flows increased (p < .05) in parallel with cardiac output during vasoactive drug therapy. High splanchnic oxygen extraction in patients with low cardiac index and flow-dependent splanchnic oxygen consumption in some patients indicated marginal splanchnic oxygen delivery. In addition, femoral blood flow was low and oxygen consumption changed in parallel with oxygen delivery in patients with the low cardiac output syndrome. In low cardiac output syndrome after cardiac surgery, splanchnic oxygen delivery was marginal and was maintained at the expense of peripheral oxygen delivery. Dobutamine, both alone and in combination with sodium nitroprusside, improved splanchnic oxygen delivery.