Abstract 2597: Aortic Atresia Is Associated with an Inferior Postoperative Systemic, Cerebral and Splanchnic Oxygen Transport Status in Neonates with Hypoplastic Left Heart Syndrome after the Norwood Procedure

Abstract

Aortic atresia (AA) has been identified as a risk factor for mortality after the Norwood procedure. We compared postoperative systemic and regional (cerebral and splanchnic) oxygen transport profiles in neonates with hypoplastic left heart syndrome with or without AA after the Norwood procedure. Systemic oxygen consumption (VO 2 ) was measured using respiratory mass spectrometry postoperatively for 72 hrs in 17 neonates (n=9 in AA group and 8 in non-AA group). Arterial, superior vena cava, and pulmonary venous blood gases and pressures were measured at 2– 4 hr intervals to calculate cardiac output (CO), systemic vascular resistance (SVR), oxygen delivery (DO 2 ) and oxygen extraction ratio (ERO 2 ). Cerebral (ScO 2 ) and splanchnic (SsO 2 ) oxygen saturations were measured using near infrared spectroscopy. The doses of dopamine, vasopressin (up to 0.0008 unit/kg/min), phenoxybenzamine and milrinone were noted. When compared to non-AA group, AA group had lower CO (p=0.03), higher systolic arterial blood pressure (p=0.01) and SVR (p=0.002), lower DO 2 (p=0.07), VO 2 (p=0.003) and ScO 2 during the first 30 to 40 hrs. There was no significant difference in SsO 2 (p=0.12, n=7 in AA group and 3 in non-AA group). Despite a similar ERO 2 (p=0.5), AA group had higher lactate over 72 hrs (p=0.01). AA group received higher doses of vasopressin (p=0.005) and milrinone (p<0.0001), lower doses of dopamine (p=0.07), with similar use of phenoxybenzamine. Furthermore, VO 2 negatively correlated with vasopressin (p=0.05), positively correlated with milrinone (p=0.03) and dopamine (p<0.0001). When including the drugs, the inferior status in all the oxygen transport variables remained, and additionally adversely correlated with vasopressin (p from <0.0001 to 0.06), except for ScO 2 that positively correlated with dopamine, but not with other drugs. Aortic atresia is associated with an inferior status of systemic, cerebral and splanchnic oxygen transport in neonates after the Norwood procedure. Aggressive use of vasopressin worsens systemic and splanchnic oxygen transport status. Postoperative management strategies should be directed to improve both systemic and regional oxygen transport in this special group of patients.