EFFECT OF HYPOTENSION PRECEDING DEATH ON THE FUNCTION OF LUNGS FROM DONORS WITH NONBEATING HEARTS

Background: A shortage of suitable brain-dead donors continues to seve rely limit lung transplantation. Use of donors with nonbeating hearts has been suggested as a solution. Lungs are unique, in that aerobic me tabolism can continue in the absence of blood circulation because oxyg en is present in airways and alveoli. Animal studies have shown reason able cadaveric graft function up to several hours after sudden death b y drug administration. However, hemodynamic instability before death m ay worsen lung function through activation and pulmonary sequestration of neutrophils and release of inflammatory mediators. Because many po tential cadaveric donors experience hypotension before death, this stu dy was undertaken to assess the effect of hypotensive shock on cadaver ic lung viability. Methods: A rat isolated lung reperfusion model was used to assess pulmonary function over 3 hours of reperfusion or until gross pulmonary edema developed. Twenty-five rats were randomly alloc ated to the following study groups, which were based on status before lung harvest: (1) control: no interventions; (2) hypotensive: 1 hour o f hypotension by exsanguination to a mean blood pressure of 30 to 40 m m Hg; (3) cadaver: death by cervical dislocation followed by 3 hours o f in situ lung ischemia; (4) hypotensive + 3 hours cadaver: 1 hour of hemorrhagic shock, followed by death and 3 hours of in situ ischemia; (5) hypotensive + 2 hours cadaver: similar to group 4, except the in s itu ischemia was abbreviated to 2 hours. Results: No significant diffe rences were found among group 1, 2, or 3 lungs with regard to wet to d ry weight ratios, gas exchange, and pulmonary arterial or airway press ures. However all group 4 lungs became grossly hemorrhagic and develop ed severe pulmonary edema within 10 minutes of reperfusion. Group 5 lu ngs fared only marginally better, with two of five lungs tolerating 3 hours of reperfusion. Conclusions: A period of hypotension before deat h severely impairs cadaveric lung viability.