Arterial oxygenation associated with portopulmonary hypertension

To characterize arterial oxygenation in patients referred to Mayo Clinic for liver transplantation with a diagnosis of portopulmonary hypertension (portoPH).

Prospective study.

Liver transplantation program and pulmonary hypertension clinic in a tertiary referral center.

Twenty consecutive patients with abnormal pulmonary hemodynamics documented by right-heart catheterization (mean pulmonary artery pressure [MPAP] > or = 25 mm Hg, pulmonary vascular resistance [PVR] > or = 120 dyne.s.cm(-5), and pulmonary capillary wedge pressure [PCWP] < or = 15 mm Hg). Liver transplant candidates with normal pulmonary hemodynamics via screening Doppler echocardiography (n = 40) served as control subjects. A subgroup of patients underwent postural and inspired 100% oxygen blood gas analysis, contrast echocardiography, and technetium-labeled macroaggregated albumin ((99m)TcMAA) lung/brain scanning to identify and quantitate the degree of intracardiac or intrapulmonary shunting.

portoPH was moderate to severe (MPAP > 35 mm Hg) in 18 of 20 patients (90%). Arterial-alveolar oxygen pressure gradient (P[A-a]O(2)) was abnormal (> or = 20 mm Hg) in 16 of 20 patients (80%). PaO(2) was abnormal (< or = 70 mm Hg) in 3 of 20 patients (15%). Pa0(2) was significantly less and P(A-a)O(2) was significantly greater compared to control subjects (p < 0.001). All patients had normal (99m)TcMAA brain uptake (< 6%) and negative transthoracic contrast echocardiographic findings. No significant correlations were found between oxygenation and hemodynamic variables (MPAP, PVR, PVR index, and transpulmonary gradient).

Arterial oxygenation associated with portoPH was frequently abnormal and significantly worse when compared to patients with normal pulmonary hemodynamics by Doppler echocardiography. Hypoxemia, as measured by PaO(2) and P(A-a)O(2), was usually mild even in the setting of moderate-to-severe portoPH.