Artificial lung prototype development

We are developing a low-resistance artificial lung for ambulatory medium-term use (weeks to months) as a potential bridge to transplant or recovery using a sheep survival model. Ventricular assist device (VAD) arterial cannulae are anastomosed to the proximal and distal main pulmonary artery, and an inflatable occluder is placed between, which, when inflated, diverts full main pulmonary artery flow through the artificial lung. The cannulae attach via 5/8' connectors to a rigidly housed, low resistance, microporous hollow fiber membrane gas exchanger (artificial lung, MC3, Inc. Ann Arbor, MI: 2.25m², priming volume 350cc). 8/8 animals have survived the implant. Two were electively sacrificed after 7 days. The others died either of late exsanguination (3 sheep), insanguination into the chest from a late anastomotic dehiscence (surgical technique error, 1 sheep), or right heart failure (two sheep). Causes of exsanguination were broken blood ports (2 deaths) or cannula disconnection (1 death). Based on this experience, we have made 3 separate modifications: 1) removal of blood sampling ports; 2) change from slip-on cannula connectors to a more secure collet-nut configuration; and 3) lower resistance artificial lung (mean gradient at total PA flow from 8 mmHg to 6 mmHg) by improving blood flow patterns. A rigidly housed, low-resistance gas exchanger can function as a chronic artificial lung when interposed to accommodate total pulmonary artery blood flow.