Use of a low-resistance compliant thoracic artificial lung in the pulmonary artery to pulmonary artery configuration

Background: Thoracic artificial lungs have been proposed as a bridge to transplant in patients with end-stage lung disease. Systemic embolic complications can occur after thoracic artificial lung attachment in the pulmonary artery to left atrium configuration. Therefore, we evaluated the function of a compliant thoracic artificial lung attached via the proximal pulmonary artery to distal main pulmonary artery configuration. Methods: The compliant thoracic artificial lung was attached to 5 sheep (63 ± 0.9 kg) in the proximal pulmonary artery to distal main pulmonary artery configuration. Device function and animal hemodynamics were assessed at baseline and with approximately 60%, 75%, and 90% of cardiac output diverted to the compliant thoracic artificial lung. At each condition, dobutamine (0 and 5 μg·kg^-1·min^-1) was used to simulate rest and exercise conditions. Results: At rest, cardiac output decreased from 6.20 ± 0.53 L/min at baseline to 5.40 ± 0.43, 4.66 ± 0.31, and 4.05 ± 0.27 L/min with 60%, 75%, and 90% of cardiac output to the compliant thoracic artificial lung, respectively (P < .01 for each flow diversion vs baseline). During exercise, cardiac output decreased from 7.85 ± 0.70 L/min at baseline to 7.46 ± 0.55, 6.93 ± 0.51, and 5.96 ± 0.44 L/min (P = .82, P = .19, and P < .01 with respect to baseline) with 60%, 75%, and 90% of cardiac output to the compliant thoracic artificial lung, respectively. The artificial lung resistance averaged 0.46 ± 0.02 and did not vary significantly with blood flow rate. Conclusions: Use of a compliant thoracic artificial lung may be feasible in the proximal pulmonary artery to distal main pulmonary artery setting if its blood flow is held at less than 75% of cardiac output. To ensure a decrease in cardiac output of less than 10%, a blood flow rate less than 60% of cardiac output is advised.