Background: Pulse oximetry with oxygen saturation (SpO2) ≤96% is recommended as a screening test to identify patients (pts) with severe hepatopulmonary syndrome (HPS) to be eligible for MELD exceptions. However, diagnosis of milder forms requires contrast-enhanced echocardiography (CE-TTE) and arterial blood gas (ABG).

Goals: 1) To investigate the prevalence of intrapulmonary vascular dilatations (IPVD) and HPS in pts with cirrhosis evaluated for liver transplantation (OLT) and 2) To compare the results of SpO2 with ABG measurements.

Methods: The study included 972 consecutive pts (2013-2021) who completed pre-OLT evaluation including CE-TTE, SpO2 and ABG. IPVD was defined as the appearance of microbubbles in the left heart within 3-5 cardiac cycles and HPS by an alveolar arterial O2 gradient ≥ 15 mm Hg or ≥ 20 if age > 64 and absence of pulmonary chronic diseases. HPS was considered as mild, moderate or severe according to PaO2 (>80, 60-80 and <60 respectively).

Results: The prevalence of IPVD was 15.4% (150/972) and of HPS 7.8% (76/972). Age of pts with HPS was 47±3 years (57% males) and MELD-Na 17± 1.HCV, alcoholism and autoimmune hepatitis were the most frequent etiologies of cirrhosis (22% each). Among pts with HPS 59 (78%) were mild (PaO2 108 ±22), 13 (17%) moderate (73 ±4) and 4 severe (55.5±3). SpO2 was ≤96% in 26% (20/76), 15% in mild (9/59), 54% in moderate (8/13) and 100% in severe (4/4) HPS. Unexpectedly, of 20 pts with Spo2 ≤96% only 4 had PaO2 <60 mmHg.

Conclusions: Universal testing with CE-TTE followed by ABG in patients with cirrhosis evaluated for OLT resulted in a lower prevalence than reported of HPS, most likely due to the preponderance of mild clinical forms with normal SpO2. Using the recommended cut-off value of Spo2 ≤96% we found a poor correlation between pulse oximetry and ABG measurement.