Table 2 Eligibility criteria

Inclusion criteria

1. Moderate HPS:

(a) Liver disease (evidence of synthetic liver dysfunction and/or portal hypertension on biochemistry and/or imaging)

(b) Moderate hypoxemia

▪ PaO₂ < 80 mmHg

▪ AaDO₂ ≥ 15 mmHg or ≥ 20 mmHg if age > 64 [1]

(c) Intrapulmonary vascular dilatations (microbubbles seen in the left heart ≥ 3 cycles after the right heart on saline contrast echocardiography)

2. Presence of orthodeoxia (PaO₂ decrease by > 4 mmHg when the patient moves from supine to upright position)

Exclusion criteria

1. Pulmonary hypertension

(a) Echocardiographic estimated right ventricular systolic pressure ≥ 50 mmHg

(b) Right heart catheterization mean pulmonary artery pressure > 25 mmHg with pulmonary capillary wedge pressure ≤ 15 mmHg

2. Significant obstructive ventilatory impairment (FEV1/FVC ratio < 0.65) [14]

3. Known significant coronary artery disease

4. Significant neurologic, orthopedic, or rheumatological disorders preventing the use of a cycle ergometer

5. Other absolute contraindications to submaximal exercise testing [24]

(a) Uncontrolled cardiac arrhythmia with hemodynamic compromise

(b) Symptomatic severe aortic stenosis

(c) Decompensated heart failure

(d) Acute cardiopulmonary illness (e.g., venous thromboembolism, myocarditis, pericarditis, endocarditis, acute aortic dissection)

6. Moderate or severe ascites