Donor lungs from ventilated cadavers: impart of a free radical scavenger

The shortage of donors for lung transplantation may be alleviated with the use of lungs retrieved from cadavers. The purpose of this study was to determine whether a free radical scavenger, dimethylthiourea, would improve the function of lungs retrieved from ventilated cadavers.

Left lung transplantation was performed in 21 dogs. Donors were sacrificed then ventilated with 100% oxygen. After 2 hours, donor lungs were flushed in a blinded fashion with 2 L of modified Euro-Collins solution, with either dimethylthiourea (n = 10) or saline solution (n = 11) added, then harvested. A donor right lung lobe was perfused with trypan blue vital dye to assess cell viability at harvest and after the transplantation. Percentage of nonviability was similar in the dimethylthiourea and control groups (13 versus 20 at retrieval and 38 versus 41 at graft reperfusion). After transplantation, the right pulmonary artery and bronchus were occluded, rendering the recipient on the pulmonary graft. The recipient's lungs were ventilated for 8 hours, with the inspired oxygen fraction maintained at 0.4.

Seven of ten dogs in the dimethylthiourea group survived the 8-hour period, compared with 4 of 11 dogs in the control group. Compared with the control survivors (n = 4) at 8 hours after the operation, the dimethylthiourea survivors (n = 7) had a higher mean arterial oxygen pressure (144 +/- 21 versus 98+/- 12 mm Hg) and cardiac output (2.2 +/- 0.2 versus 1.6 +/- 0.2 L/min) and a lower mean pulmonary vascular resistance (946 +/- 96 versus 1414 +/- 128 dynes.sec-1.cm5, p < 0.05) and extravascular lung water (10.6 +/- 1.2 versus 12.3 +/- 3.2 ml/kg). Differences between groups during the 8-hour period were usually insignificant.

This model imposes a rigorous challenge to the single transplanted lung, and yet cadaver lungs still supported life in half of the recipients. Dimethylthiourea may confer a benefit to recipients of cadaver lungs.