Sustained low diffusing capacity in hepatopulmonary syndrome after liver transplantation

To study the presence of sustained low diffusing capacity (DL(CO)) after liver transplantation (LT) in patients with hepatopulmonary syndrome (HPS).

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).

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).

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.