Diagnostic algorithm for hepatopulmonary syndrome

HPS: hepatopulmonary syndrome; SpO₂: peripheral arterial oxygen saturation; ABG: arterial blood gas analysis; A-a gradient: Alveolar-arterial gradient; PaO₂: partial arterial pressure of oxygen.
* Suspected HPS – HPS should be suspected in patients with chronic liver disease and/or portal hypertension. HPS is rare in patients with acute liver disease. All patients who undergo evaluation for liver transplant should be evaluated for HPS. Common manifestations include dyspnea, platypnea, orthodeoxia, and spider nevi.
¶ Some patients may have low grade shunt in the absence of hypoxemia which warrants continued monitoring in the event of progression to HPS.
Δ Some clinicians additionally perform lying and standing oximetry and ABGs which, when positive, can indicate the presence of a shunt.
◊ Contrast echocardiography typically involves the intravenous administration of agitated saline, followed by imaging with transthoracic echocardiography. Visualization of microbubbles in the left atrium within three to six cardiac cycles after their appearance in the right atrium usually indicates an intrapulmonary shunt and provides strong evidence in favor of the presence of intrapulmonary vascular shunts consistent with HPS. Other forms of shunt assessment are rarely needed (refer to UTD text for details).
§ It is prudent to exclude contributing etiologies (eg, cardiac failure, intrinsic lung disease, pulmonary arteriovenous malformations; refer to UTD text for details).