Hepatopulmonary syndrome - A prospective study of relationships between severity of liver disease, Pao(2) response to 100% oxygen, and brain uptake after Tc-99m MAA lung scanning

Background: Because of the spectrum of intrapulmonary vascular dilation that characterizes hepatopulmonary syndrome (HPS), Pao(2) while breathing 100% oxygen varies. Abnormal extrapulmonary uptake of Tc-99m macroaggregated albumin (MAA) after lung perfusion is common. Goal: To describe relationships between (1) severity of liver disease measured by the Child-Pugh (CP) classification; (2) Pao(2) while breathing room air (RA) and 100% oxygen on 100% oxygen; and (3) extrapulmonary (brain) uptake of Tc-99m MAA after lung scanning. Methods and patients: We prospectively measured Pao(2) on Rh, Pao(2) on 100% oxygen, and brain uptake after lung perfusion of Tc-99m MAA in 25 consecutive HPS patients. Results: Mean Pao(2) on RA, Pao(2) on 100% oxygen, Paco(2) on RA, and Tc-99m MAA brain uptake were similar when categorized by CP classification. Brain uptake was abnormal (greater than or equal to 6%) in 24 patients (96%). Brain uptake was 29 +/- 20% (mean +/- SD) and correlated inversely with Pao(2) on RA (r = -0.57; p < 0.05) and Pao(2) on 100% oxygen (r = -0.41; p < 0.05). Seven patients (28%) had additional nonvascular pulmonary abnormalities and lower Pao(2) on 100% oxygen (215 +/- 133 mm Hg vs 391 +/- 137 mm Hg; p < 0.007). Eight patients (32%) died. Mortality in patients without coexistent pulmonary abnormalities was associated with greater brain uptake of Tc-99m MAA. (48 +/- 18% vs 25 +/- 20%; p < 0.04) and lower Pao(2) on RA (40 +/- 7 mm Hg vs 57 +/- 11 nnm Hg; p < 0.001). Conclusion: The degree of hypoxemia associated with BPS was not related to the CP severity of liver disease, HPS patients with additional nonvascular pulmonary abnormalities exhibited lower Pao(2) on 100% oxygen. Mortality was associated with lower Pao(2) on RA, and with greater brain uptake of Tc-99m MAA.