Hepatopulmonary syndrome: What we know and what we would like to know

Table 1 Diagnosis methods for hepatopulmonary syndrome

Diagnosis methods	Findings in HPS patients	Limitations	Aims
Arterial blood gas analysis	AaO2≥ 15 mmHg or ≥ 20 mmHg in patients over 64 years old	Consensus criteria	Diagnosis of HPS
		Invasive
Pulse oximetry	O2 Saturation < 96% or 97%	Low sensitivity	Screening HPS and follow up
Contrast echocardiography	Bubbles in the left cavities between the fourth and sixth beat	Various agents used	Diagnosis of IPVD
		Transthoracic vs transoesophageal
99mTc-MAA	Cerebral uptake ≥ 6%	Low sensitivity	Diagnosis and quantify of IPVD
Thoracic X-ray	Interstitial markings	Unspecific	Rule out other concomitant pulmonary diseases
Thorax CT scan	Measurement of the caliber of the peripheral arteries and the bronchial/arterial relationship	More studies needed	Rule out other concomitant pulmonary diseases
	Vascular patterns		Location of IPVD
Pulmonary arteriography	Vascular patterns	Low sensitivity	Type II HPS suspected
		Invasive	Embolotherapy?
Respiratory function tests	Normal or reduction FVC or FEV1	Unspecific	Rule out other concomitant pulmonary diseases
	Reduction in DLCOco	Low sensitivity
Laboratory tests	von Willebrand factor antigen elevated	More studies needed	Screening HPS

AaO₂: Alveolar-arterial oxygen gradient; DLCOco: Corrected diffusing capacity for carbon monoxide; FEV1: Maximum forced expiratory volume during the first second; FVC: Forced vital capacity; HPS: Hepatopulmonary syndrome;

^99mTc-MAA: Macroaggregated albumin lung perfusion scan.