Hepatopulmonary syndrome (HPS) consists of the triad of liver dysfunction, otherwise unexplained hypoxemia, and intrapulmonary vascular dilation (IPVD).A useful diagnostic test is contrast echocardiography. Intravenous microbubbles (> 10 micrometers in diameter) from agitated normal saline that are normally obstructed by pulmonary capillaries (normally <8 to 15 micrometers) rapidly transit the lung and appear in the left atrium of the heart within 7 heart beats. Similarly, intravenous technetium (99mTc) albumin aggregated may transit the lungs and appear in the kidney and brain. Pulmonary angiography may reveal diffusely fine or blotchy vascular configuration. The distinction has to be made with an intracardiac right-to-left shunt. Treatment
Currently the only definitive treatment is liver transplantation. Alternative treatments such as supplemental oxygen or somatostatin to inhibit vasodilation remain anecdotal. Prognosis
With liver transplantation, the 5 year survival rate is 74%, which is comparable to patients who undergo liver transplants who do not suffer from hepatopulmonary syndrome. See also
Gastric antral vascular ectasia
Hepatitis
Hepatorenal syndrome

References
Further reading
Rodríguez-Roisin, Roberto; Krowka, Michael J. (29 May 2008). "Hepatopulmonary Syndrome — A Liver-Induced Lung Vascular Disorder" (PDF). New England Journal of Medicine. 358 (22): 2378–2387. doi:10.1056/NEJMra0707185. PMID 18509123.
A number of other trade names of subcutaneous immunoglobulin have since been approved, although some small-scale studies have indicated that a particular cohort of patients with common variable immunodeficiency (CVID) may develop intolerable side effects with subcutaneous immunoglobulin (SCIg) that they do not with intravenous immunoglobulin (IVIg).Although intravenous was the preferred route for immunoglobulin therapy for many years, in 2006, the US Food and Drug Administration (FDA) approved the first preparation of immunoglobulin that was designed exclusively for subcutaneous use. Mechanism of action
The precise mechanism by which immunoglobulin therapy suppresses harmful inflammation is likely multifactorial. For example, it has been reported that immunoglobulin therapy can block Fas-mediated cell death.Perhaps a more popular theory is that the immunosuppressive effects of immunoglobulin therapy are mediated through IgGs Fc glycosylation. By binding to receptors on antigen presenting cells, IVIG can increase the expression of the inhibitory Fc receptor, FcgRIIB, and shorten the half-life of auto-reactive antibodies. The ability of immunoglobulin therapy to suppress pathogenic immune responses by this mechanism is dependent on the presence of a sialylated glycan at position CH2-84.4 of IgG. Specifically, de-sialylated preparations of immunoglobulin lose their therapeutic activity and the anti-inflammatory effects of IVIG can be recapitulated by administration of recombinant sialylated IgG1 Fc.Sialylated-Fc-dependent mechanism was not reproduced in other experimental models suggesting that this mechanism is functional under a particular disease or experimental settings. On the other hand, several other mechanisms of action and the actual primary targets of immunoglobulin therapy have been reported.