Detection of severe intraoperative hypoxemia after single-lung transplantation for primary pulmonary hypertension

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p m g F e b d w t t UNG TRANSPLANTATION IS one of the current therapeutic options for primary pulmonary hypertension PPH).1 Heart-lung (HL), bilateral-lung (BL), and single-lung SL) transplantation are the surgical procedures used at present n most transplant centers. According to the 18th official report rom the International Society for Heart and Lung Transplanation, PPH was the reason for 25% of HL transplants, 9% of L transplants, and only 4% of SL transplants.2 SL transplant is less frequently used for PPH because most roups are concerned with the higher degree of mismatch etween ventilation and perfusion, whereas BL transplant ofers the advantage of overall better lung function and long-term urvival.3 Furthermore, there is some evidence that, after graft eperfusion, blood flow is preferentially shifted to the translanted lung, whereas ventilation remains evenly distributed etween the 2 lungs; this was shown by V/Q scans performed uring the follow-up of patients who received an SL transplant, n whom values of perfusion to the transplanted lung in the ange of 80% to 90% of the entire cardiac output were found.4,5 hese data were, however, collected a few months (at least 3) fter transplantation, in stable patients during spontaneous reathing; whereas to the authors’ knowledge, no data regardng the presence and the magnitude of this blood flow shift mmediately after graft reperfusion have yet been reported. his lack of attention may be caused by the general belief that, ecause the native lung is in the dependent position, in princile gravitational forces should limit the blood shift caused by he variation in pulmonary artery resistance. Two cases of SL transplant for PPH are reported in which the ccurrence of intraoperative hypoxemia could be explained by severe ventilation/perfusion mismatch, thus providing indiect evidence of this blood flow shift following graft eperfusion.