Single lung transplantation in experimental and human emphysema

Single lung transplantation is thought contraindicated in emphysema because the resulting ventilation perfusion (V/Q) imbalances have been considered unavoidable. Studies were carried out in two groups of dogs with papain induced experimental emphysema to determine whether these V/Q imbalances were due mainly to the physiologic setting or to some preventable process such as allograft rejection. In one group of dogs, papain emphysema was produced in both lungs and documented. The left lung of three of these animals was replaced with an allograft under immunosuppression. After operation, serial chest roentgenograms, V/Q scans and determinations of arterial blood gases were obtained. In the second group of dogs, unilateral emphysema was produced in the right lung with papain and the emphysema was documented. The animals then underwent autotransplantation of their left lung and were serially studied thereafter. After autografting and allografting, transplant perfusion and ventilation decreased transiently but usually returned to preoperative levels, with the transplant receiving the majority of the pulmonary blood flow and being ventilated as well or better than the emphysematous lung. Arterial hypoxemia, indicative of venous admixture and V/Q imbalance, was only present when the transplanted lungs had roentgenographic infiltrates due to rejection, infection, or the reimplantation response. Single lung transplants were performed on two human emphysematous patients. Significant V/Q imbalances and arterial hypoxemia did not occur unless the transplant was heavily involved by rejection, infection, or the reimplantation response. One patient survived 6 mth with much improved respiratory function. Thus, single lung transplants do not produce obligatory V/Q imbalances in emphysematous recipients.