RESUMO
BACKGROUND: Children with end-stage lung disease are commonly managed with extracorporeal life support (ECLS) as a bridge to lung transplantation. A pumpless artificial lung (MLung) is a portable alternative to ECLS and it allows for ambulation. Both ECLS and pumpless artificial lungs require systemic anticoagulation which is associated with hemorrhagic complications. We tested the MLung with a novel Nitric Oxide (NO) Surface Anticoagulation (NOSA) system, to provide local anticoagulation for 72 h of support in a pediatric-size ovine model. METHODS: Four mini sheep underwent thoracotomy and cannulation of the pulmonary artery (inflow) and left atrium (outflow), recovered and were monitored for 72hr. The circuit tubing and connectors were coated with the combination of an NO donor (diazeniumdiolated dibutylhexanediamine; DBHD-N2O2) and argatroban. The animals were connected to the MLung and 100 ppm of NO was added to the sweep gas. Systemic hemodynamics, blood chemistry, blood gases, and methemoglobin were collected. RESULTS: Mean device flow was 836 ± 121 mL/min. Device outlet saturation was 97 ± 4%. Pressure drop across the lung was 3.5 ± 1.5 mmHg and resistance was 4.3 ± 1.7 mmHg/L/min. Activated clotting time averaged 170 ± 45s. Methemoglobin was 2.9 ± 0.8%. Platelets declined from 590 ± 101 at baseline to 160 ± 90 at 72 h. NO flux (x10-10 mol/min/cm2) of the NOSA circuit averaged 2.8 ± 0.6 (before study) and 1.9 ± 0.1 (72 h) and across the MLung 18 ± 3 NO flux was delivered. CONCLUSION: The MLung is a more portable form of ECLS that demonstrates effective gas exchange for 72 h without hemodynamic changes. Additionally, the NOSA system successfully maintained local anticoagulation without evidence of systemic effects.
