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Background: The macro-aggregated albumin lung perfusion scan (99mTc-MAA) is a diagnostic method for hepatopulmonary syndrome (HPS). Aim: To determine the sensitivity of 99mTc-MAA in diagnosing HPS, to establish the utility of 99mTc-MAA in determining the influence of HPS on hypoxemia in patients with concomitant pulmonary disease and to determine the correlation between 99mTc-MAA values and other respiratory parameters. Methods: Data from 115 cirrhotic patients who were eligible for liver transplantation (LT) were prospectively analyzed. A transthoracic contrast echocardiography and 99mTc-MAA were performed in 85 patients, and 74 patients were diagnosed with HPS. Results: The overall sensitivity of 99mTc-MAA for the diagnosis of HPS was 18.9% (14/74) in all of the HPS cases and 66.7% (4/6) in the severe to very severe cases. In HPS patients who did not have lung disease, the degree of brain uptake of 99mTc-MAA was correlated with the alveolar-arterial oxygen gradient (A-a PO2) (r = 0.32, p < 0.05) and estimated oxygen shunt (r = 0.41, p < 0.05) and inversely correlated with partial pressure of arterial oxygen (PaO2) while breathing 100% O2 (r = -0.43, p < 0.05). The 99mTc-MAA was positive in 20.6% (7/36) of the patients with HPS and lung disease. The brain uptake of 99mTc-MAA was not associated with mortality and normalized in all cases six months after LT. Conclusions: The 99mTc-MAA is a low sensitivity test for the diagnosis of HPS that can be useful in patients who have concomitant lung disease and in severe to very severe cases of HPS. It was not related to mortality, and brain uptake normalized after LT.

Introduction: Different blood gas criteria have been used in the diagnosis of hepatopulmonary syndrome (HPS). Patients and methods: Arterial blood gases were prospectively evaluated in 194 cirrhotic candidates for liver transplantation (LT) in the supine and seated position. Three blood gas criteria were analyzed: classic (partial pressure of oxygen [PaO2] < 70 mmHg and/or alveolar-arterial gradient of oxygen [A-a PO2] ≥ 20 mmHg), modern (A-a PO2 ≥ 15 mmHg or ≥ 20 mmHg in patients over 64) and the A-a PO2 ≥ threshold value adjusted for age. Results: The prevalence of HPS in the supine and seated position was 27.8% and 23.2% (classic), 34% and 25.3% (modern) and 22.2% and 19% (adjusted for age), respectively. The proportion of severe and very severe cases increased in a seated position (11/49 [22.4%] vs 5/66 [7.6%], p = 0.02). No difference was observed in the pre-LT, post-LT and overall mortality in patients with HPS, regardless of the criteria used. Conclusion: Obtaining blood gas measurements in the supine position and the use of modern criteria are more sensitive for the diagnosis of HPS. Blood gas analysis with the patient seated detects a greater number of severe and very severe cases. The presence of HPS was not associated with an increase in mortality regardless of blood gas criterion used.