Thirty-day in-parallel artificial lung testing in sheep.

Background: Thirty-day testing of the MC3 Biolung (MC3 Inc, Ann Arbor, MI) total artificial lung (TAL) was performed to prepare for future clinical testing.

Methods: TAL inlet and outlet grafts were sewn to the pulmonary artery and left atrium of 8 sheep (35.6 +/- 1.6 kg), and the TAL was attached the next day. Hemodynamic and sheep blood gas data were measured every 1 to 4 hours. TAL blood gases were measured twice daily, and organ function was assessed three times per week. The TAL was replaced if its resistance increased 300% or if the oxygen content difference across the TAL decreased 25% versus baseline. After 30 days, the sheep were euthanized and necropsied.

Results: Five sheep survived 30 days. Three sheep were euthanized before 30 days due to bleeding, mechanical graft failure, or gastric distress. Survivors had normal, stable hemodynamics and blood gases. Average device use was 9.5 +/- 2.1 days. TAL oxygen transfer was 108 +/- 9.2 mL/min with 51% +/- 6.3% of cardiac output flowing to the TAL. TAL resistance and flow were 1.3 +/- 0.3 mm Hg x min/L and 2.4 +/- 0.2 L/min at baseline versus 2.6 +/- 0.9 mm Hg x min/L and 2.0 +/- 0.2 L/min for the remaining 30 days. Platelet and white blood cell counts increased 88% and 84% from baseline, respectively, after 10 days and were stable thereafter. Ischemic lesions in the kidney were seen in most sheep at necropsy, but organ function was normal.

Conclusions: Thirty-day respiratory support was feasible with the Biolung, but improvements in biocompatibility and anticoagulation regimen are warranted to reduce the thrombogenicity of the device.