Hepatopulmonary syndrome: which blood gas analysis criteria and position should we use for diagnosis?

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.