Figure 2.

Algorithm for the diagnosis and treatment of hepatopulmonary syndrome (HPS). All arterial blood gas (ABG) parameters are expressed in mmHg. P_A–a,O2: alveolar–arterial oxygen difference for the partial pressure of oxygen; CE-TTE: contrast-enhanced transthoracic echocardiogram; LT: liver transplant; MAA: ^99mTc radiolabelled macro-aggregated albumin scan; P_a,O2: arterial oxygen tension. ^#: if doubt exists regarding an atrial septal defect, trans-oesophagseal echocardiography is recommended; ^¶: pulmonary function tests and chest radiographs or computed tomography scans as appropriate; ⁺: determination of orthodeoxia is recommended where available; ^§: MAA is also useful in the absence of lung disease to quantify the intrapulmonary shunt and for prognostication.