Determining an optimal central cannulation strategy for ambulatory veno-venous extracorporeal life support

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is the most prevalent chronic end stage lung disease. There are few long-term treatment options for end stage COPD due to donor lung scarcity. Durable artificial lung therapies may provide alternatives for long-term respiratory support. Veno-venous extracorporeal membrane oxygenation can provide physiologic support, but current cannulation configurations are suboptimal for durable support. METHODS: We designed, fabricated, and evaluated four different central cannulation strategies in an acute sheep model of veno-venous extracorporeal membrane oxygenation. They consisted of single site or dual site cannulation systems, inserted through a custom-made graft-patch sewn onto the right atrium, that drained from the right atrium and reinfused either into the right atrium with flow directed at the tricuspid valve or past the tricuspid valve into the right ventricle. After cannulation, sheep subjects were connected to the circuit and monitored for at least 5 h (N=4 to 6 per configuration) at 2.0±0.1 L/min of flow. Circuit performance, hematological parameters, and animal hemodynamics were analyzed. RESULTS: Eighteen of twenty-two subjects completed the monitoring period. Dual site strategies had 0% attrition. Right ventricular reinfusion with single site cannulation significantly affected pressure flow characteristics (p<0.001). Dual site cannulation with right ventricular reinfusion had the lowest average recirculation (22.8±16.7%) and the lowest plasma free hemoglobin values (1.7±0.3 mg/dL). CONCLUSIONS: Our results suggest a dual site cannulation configuration with right atrial drainage and right ventricular reinfusion may be optimal for durable ambulatory extracorporeal membrane oxygenation. Future studies will evaluate the cannula in longer-duration, ambulatory models.