Effects of volume expansion on cardiac output in the preterm infant

Clinical and echocardiographic haemodynamic evaluations of response to volume expansion are described in 12 preterm neonates aged < 7 days presenting without cardiac dysfunction and with a low cardiac output. They received 10% albumin solution (20 ml kg-1) for 3 h. Measurements were made before infusion, at volumes 5, 12.5 and 20 ml kg-1 and 1 h later. All infants increased significantly their cardiac output (CO) (from a median of 177 to 283 ml kg-1 min-1). The rise of CO decreased with the volume infused. The index of systemic vascular resistance (SVR = ratio of mean arterial pressure to the CO) decreased for the six patients without PDA (from 272 to 193 mmHg l-1 kg-1 min-1, p < 0.05) showing that the hypovolaemic preterm infant is able to shut down peripherally in response to hypovolaemia. The four hypotensive infants responded by increasing mean arterial blood pressure (from 29 to 44 mmHg). Cutaneous refilling time decreased during infusion (from 6.7 to 3.8 s. p < 0.01). One infant had an haemodynamically significant ductus arteriosus revealed by volume expansion, another one developed myocardial dysfunction.