The Science Journal of the American Association for Respiratory Care

2009 OPEN FORUM Abstracts

CAPNOGRAPHIC MONITORING OF POST-OP NORWOOD STAGE 1 DURING EXTRACOPOREAL LIFE SUPPORT (ECLS)

Roy Ramirez, Sam Frens, John Cleary, James Cappon; Respiratory Care Services, CHOC Children’s Hospital of Orange, Orange, CA

INTRODUCTION: Following Norwood Stage 1 surgical palliation of Hypoplastic Left Heart Syndrome (HLHS), pulmonary blood flow (Qp) is critically dependent on a synthetic shunt between the innominate artery systemic circulation and the ipsilateral pulmonary artery. By utilizing capnography in such patients and measuring end tidal CO2 (ETCO2), we can use Alveolar Minute Ventilation and Volumetric CO2 monitoring to determine if changes in CO2 elimination are due to ventilation or Qp alterations1. CASE SUMMARY: A term 3.1 kg neonate with prenatally-diagnosed HLHS underwent Norwood repair including a 3.5 mm “central” shunt (CS). Due to post-operative instability, the patient was placed on Veno- Arterial (V-A) ECLS, including restrictive band placement around the CS. Post-op day (POD) 2, the ETCO2 decreased to 0 mmHg (Fig.) with unchanged blood gas results, including normal PaCO2. Echocardiography demonstrated decreased CS flow. The restrictive band was removed and ETCO2 increased to10 mmHg for a few hours. On POD 3, a CT angiogram revealed absence of blood flow in the CS and proximal pulmonary arteries, with good pulmonary venous blood return. The patient was taken to the OR on POD 4 for CS thrombectomy, with subsequent modest improvement in ETCO2 to 12 mmHg. Subsequent ECLS weaning efforts were unsuccessful however, and ETCO2 remained extremely low, further raising the question of adequate Qp. The patient was taken to the cardiac cath lab POD 6, where diffuse thrombi within the shunt were noted and addressed. DISCUSSION: Capnography is useful in post-operative cardiac management, especially in cases with V-A ECLS support. Low or absent ETCO2 with a normal PaCO2 in the ECLS patient suggest a dramatically reduced Qp2; in this case, due to an occluded CS. V-A ECLS can both mask and support post-operative cardiac patients with the pathophysiological consequences of diminished or absent Qp. Sponsored Research - None

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