Development of an ambulatory artificial lung in an ovine survival model.

We are developing an artificial lung (AL) as an eventual bridge to lung transplant or recovery. The device is rigidly housed, noncompliant, and has a very low resistance to blood flow. In eight sheep, arterial cannulae were anastomosed end-to-side to the proximal and distal main pulmonary artery, and attached to the AL. A pulmonary artery snare between anastomoses diverted full pulmonary blood flow through the AL. Eight of eight sheep survived the preparation. Mean pressure gradient across the AL was 8 mm Hg (3 Wood units; 8 mm Hg/2.8 L/min). Four of eight sheep tolerated immediate full diversion of blood flow and died at 24 and 40 hours (exsanguination) or 168 and 168 hours (elective sacrifice). Four of eight sheep were intolerant of full flow: two died of right heart failure at <8 hours with full flow through the device (full snare); the other two survived with partial device flow (partial snare), but the device clotted. These two then underwent successful closed-chest cannula thrombectomy and device change-out at 53 and 75 hours, and subsequently tolerated full flow. Long-term (up to 7 day) survival with complete diversion of pulmonary blood flow through a non-compliant, low-resistance AL is possible. Initial right heart failure in this model was 50% (4 of 8).