Ex-vivo perfusion and ventilation of rat lungs from non-heart-beating donors before transplant

Abstract

Background: We developed an ex-vivo circuit to evaluate human lungs retrieved from non-heart-beating donors. We assessed the effect of a similar circuit on the function of transplanted rat lungs retrieved from non-heart-beating donors.

Methods: One hour after death, Sprague-Dawley rat heart-lung blocks were flushed with 20 mL of cold Perfadex, stored cold for 1 hour, then warmed to 37 degrees C in a circuit perfused with Earle's crystalloid solution with or without washed porcine erythrocytes (hematocrit 12% to 15%). At 37 degrees C, lungs were ventilated for 15 minutes with alveolar gas, perfusion-cooled to 20 degrees C, flushed again with cold Perfadex, and then stored cold for 2.5 hours. The left lung was transplanted using a modified cuff technique with flow probes on the main and left pulmonary arteries. After 1 hour of reperfusion, arterial blood gases from the left pulmonary vein and wet/dry weight ratio (W/D) of both donor lungs were determined. Lungs transplanted after retrieval from heart-beating or non-heart-beating donors served as controls (n = 6 per group).

Results: Lungs gained weight in the circuit but W/D and PO2 were similar after transplantation for all groups. After transplantation, vascular resistance was higher and dynamic compliance was lower for lungs perfused in the circuit. Myeloperoxidase and conjugated diene levels were modestly elevated in lungs transplanted from non-heart-beating donors irrespective of perfusion in the circuit.

Conclusions: Rat lungs are suitable for transplant after ex-vivo perfusion and ventilation. This model closely mimics methods used to evaluate the function of lungs retrieved from human non-heart-beating donors and can economically evaluate ex-vivo therapies for lungs retrieved from non-heart-beating donors.