Sustained low diffusing capacity in hepatopulmonary syndrome after liver transplantation.

AIM: To study the presence of sustained low diffusing capacity (DL(CO)) after liver transplantation (LT) in patients with hepatopulmonary syndrome (HPS).
METHODS: Six patients with mild-to-severe HPS and 24 without HPS who underwent LT were prospectively followed before and after LT at mid-term (median, 15 mo). HPS patients were also assessed at long-tem (median, 86 mo).
RESULTS: Before LT, HPS patients showed lower PaO(2) (71 +/- 8 mmHg), higher AaPO(2) (43 +/- 10 mmHg) and lower DL(CO) (54% +/- 9% predicted), due to a combination of moderate-to-severe ventilation-perfusion (V(A)/Q) imbalance, mild shunt and diffusion limitation, than non-HPS patients (94 +/- 4 mmHg and 19 +/- 3 mmHg, and 85% +/- 3% predicted, respectively) (P<0.05 each). Seven non-HPS patients had also reduced DL(CO) (70% +/- 4% predicted). At mid- and long-term after LT, compared to pre-LT, HPS patients normalized PaO(2) (91 +/- 3 mmHg and 87 +/- 5 mmHg), AaPO(2) (14 +/- 3 mmHg and 23 +/- 5 mmHg) and all V(A)/Q descriptors (P<0.05 each) without changes in DL(CO) (53% +/- 8% and 56% +/- 7% predicted, respectively). Post-LT DL(CO) in non-HPS patients with pre-LT low DL(CO) was unchanged (75% +/- 6% predicted).
CONCLUSION: While complete V(A)/Q resolution in HPS indicates a reversible functional disturbance, sustained low DL(CO) after LT also present in some non-HPS patients, points to persistence of sub-clinical liver-induced pulmonary vascular changes.