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home - Liver - Hepatopulmonary Disorders - Hepatopulmonary Syndrome Written by Dr Sebastian Zeki

Hepatopulmonary Syndrome

HepatoPulmonary Syndrome Hepatopulmonary syndrome (HPS) is considered to be present in patients with the following triad :1. Liver disease2. Increased alveolar-arterial gradient while breathing room air3. Evidence for intrapulmonary vascular abnormalities, referred to as intrapulmonary vascular dilatations (IPVDs)Prevalence of HPS is 4 to 47 %, depending upon the diagnostic criteria and methods used.Severe hypoxemia (PaO2 <60 mmHg) is uncommon and, in the absence of associated cardiopulmonary disease, should strongly suggest HPS. Medical therapy —No successful current medical therapyLiver transplantation —HPS can improve following liver transplant within days to 14 months- this used to be a contraindication Results in Intrapulmonary shunt as blood passes through but oxygen doesnt diffuse through to centre Diagnostic options:Contrast Enhanced (Microbubble) Echocardiography —If there is a right to left shunt, contrast will opacify right and left heart chambers.Technetium-labeled macroaggregated albumin in >20um so gets trapped in pulmonary bed ; if found in kidney or brain, then shunt must exist.Pulmonary angiography —An alternative but invasive.Chest imaging —Usually normal.Pulmonary function tests —Patients have non-specific PFT changes.Spirometry —Normal FEV1 and FVC.Diffusing capacity for carbon monoxide—this is mildly to severely impaired.Shunt fraction —This is increased.Arterial blood gases —PaO2 <8 on room air with A-a gradient >20 mmHg. Dilatation Upregulation of endothelial nitric oxide synthase (eNOS) in the intralobar pulmonary arteries Less endotoxin cleared due to portal systemic shunting and immunocom-promised state Clincal Manifestations80% present with CLD, 20% with dyspnoea.There is no correlation between Child-Pugh score and shunt presence.The presence of HPS independently worsens the prognosis of patients with cirrhosis. The hepatopulmonary syndrome (HPS) encom-passes a spectrum of gas exchange abnormalities that have been partitioned into three components :-Ventilation-perfusion mismatch-Intrapulmonary shunting-Limitation of oxygen diffusion A number of factors have been postulated to cause IPVDs :-Failure of the damaged liver to clear circulating pulmonary vasodilators-Production of a circulating vasodilator by the damaged liver-Inhibition of a circulating vasoconstrictive substance by the damaged liver Pulmonary findings Get dyspnea, sometimes accompanied by platypnea(worse dyspnoea when standing) and orthodeoxia (upright desaturation)= (platypnea-orthodeoxia syndrome).Hypoxemia can be life threatening, and can progress without an associated decline in liver function.It is hypothesized that orthodeoxia in HPS is caused by preferential perfusion of IPVDs in the lung bases when the patient is upright.Orthodeoxia also seen in:Post-pneumonectomyRecurrent pulmonary emboliAtrial septal defects (including patent foramen ovale)Chronic lung disease. Pathogenesis Hepatic findingsTwo hemodynamic complications of liver dysfunction are frequently seen in HPS:Spider nevi —(Is a marker of IPVDs associated with HPS)Hyperdynamic circulation Also inc L atrial volume (>50ml). Written by Dr Sebastian Zeki It is based on trying to detect IPVD's. Treatment

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