Hepatic hydrothorax: Current concepts

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Abbreviations

MELD

Model for End‐Stage Liver Disease

TIPS

transjugular intrahepatic portosystemic shunt

VATS

video‐assisted thoracoscopy.

Portal hypertension is a complication of end‐stage liver disease. The most common symptoms are ascites and variceal hemorrhage, which develop in 47% and 25% of patients, respectively. Hepatic hydrothorax is a less common complication of portal hypertension, with a prevalence of only 5% to 10%.1 Despite its infrequency, its presence portends a poor outcome, and treatment remains a challenging problem for clinicians.

Definition of Hepatic Hydrothorax

Hepatic hydrothorax is defined as a transudative pleural effusion, usually greater than 500 mL in patients with portal hypertension without any other underlying primary cardiopulmonary cause. The presence of ascites is not required; up to 20% of patients with hepatic hydrothorax have no clinically significant ascites.

The location of the pleural effusion can be useful in distinguishing a hepatic hydrothorax from other causes of pleural effusions. As opposed to pleural effusions of cardiac origin that are typically bilateral, 70% of patients with hepatic hydrothorax are right‐sided only, 18% are left‐sided only, and only 12% are bilateral.2

Pathophysiology

Several observations point toward the presence of diaphragmatic defects as the most likely cause of hepatic hydrothorax. Diaphragmatic defects can be demonstrated both grossly and microscopically in these patients. Typically, the defects are < 1 cm and occur on the right side.3 This right‐sided predominance is likely due to the close anatomical relationship of bare areas of the liver with the diaphragm and the fact that the left side of the diaphragm is thicker and more muscular than the right side.4

Diaphragmatic defects occur in up to 20% of the noncirrhotic population. The presence of ascites alters the pressure gradient between the intrathoracic and intraabdominal regions. In patients with ascites, the increasing abdominal pressure and the diaphragmatic thinning secondary to malnutrition in cirrhotic patients enlarge these diaphragmatic defects, allowing for more passage of fluid from the abdomen to the pleural space. Fluid also can leak directly from the liver into the pleural space when bare areas of the liver are in contact with the defects in the diaphragm; this might explain why 20% of patients with hepatic hydrothorax do not have ascites.

Diagnosis and Clinical Presentation

When a patient first presents with a hepatic hydrothorax, it is important to always perform a thoracentesis. In a study of 60 cirrhotic patients admitted to the hospital with pleural effusions, only 70% were found to have an uncomplicated hepatic hydrothorax (without infection, blood, or pus).5 Of the other 18 patients, nine had spontaneous bacterial empyema, two had pleural tuberculosis, two had adenocarcinoma, two had parapneumonic effusion, and three were undiagnosed exudates. When the effusion was right‐sided, 80% of the patients were an uncomplicated hepatic hydrothorax; but when the effusion was‐left sided, only 35% of the patients were an uncomplicated hepatic hydrothorax. Pleural fluid analysis is mandatory for diagnosis and symptom control.

The characteristics and the interpretation of pleural fluid in hepatic hydrothorax are described in Table 1. In uncomplicated hepatic hydrothorax, the polymorphonuclear cell count is less than 250 cells/mm³, and the total protein concentration is less than 2.5 g/dL. Lactate dehydrogenase levels also are low, consistent with a transudate. Total protein and albumin may be slightly higher in hepatic hydrothorax compared to levels in the ascitic fluid.6

Table 1.

Laboratory Features of the Pleural Fluid in Hepatic Hydrothorax

Uncomplicated Fluid

Polymorphonuclear count < 250 cells/mm3

Total protein < 2.5 g/dL

Pleural fluid total protein/serum total protein ratio < 0.5

Pleural fluid lactate dehydrogenase/serum lactate dehydrogenase < 0.6

Serum‐to‐pleural fluid albumin gradient > 1.1 g/dL

pH 7.4‐7.55

Pleural fluid/serum bilirubin ratio < 0.6

Glucose level similar to that of serum

Spontaneous Bacterial Pleuritis

Positive pleural fluid culture and a polymorphonuclear count > 250 cells/mm3

Negative pleural fluid culture and a polymorphonuclear count > 500 cells/mm3

Hepatic hydrothorax can present asymptomatically or with cough, dyspnea, hypoxia, or respiratory failure depending on the volume of fluid in the pleural space, the rapidity of the accumulation of the pleural fluid, and the presence of coexistent cardiopulmonary diseases. Most of these effusions tend to be small to moderate in size, with only 6% of patients having effusions that occupy greater than half of a hemithorax. Although patients with ascites can often tolerate 5 to 8 liters of fluid in their abdomens before becoming significantly symptomatic, a patient with a hepatic hydrothorax will develop symptoms when only 1 to 2 liters of fluid accumulates in the pleural space. It is for this reason that this complication of portal hypertension is so challenging for both patients and clinicians.

Management

Medical Management

The mainstay of treatment is similar to that of patients with ascites: low salt diet and diuretics (Table 2). As patients are unable to tolerate significant volume in their pleural space, this often is not enough. Approximately 20% of patients will develop refractory hepatic hydrothorax, compared with only 10% of patients with ascites who will develop refractory ascites.7

Table 2.

Treatment Options for Hepatic Hydrothorax

Medical Management

Salt restriction (< 2000 mg/day of sodium)

Diuretics (furosemide and spironolactone)

Thoracentesis

Transjugular intrahepatic portosystemic shunt

Surgical Management

Pleurodesis

VATS with surgical correction of diaphragm defects

Liver Transplantation

Please note that placement of a chest tube or other percutaneous drain, which is left in situ after thoracentesis, is not a treatment option unless there is frank pus in the pleural space.

Any patient with a hepatic hydrothorax should be referred for a transplant evaluation because it signals worsening portal hypertension and a poorer prognosis.

Thoracentesis and Paracentesis

In patients who are symptomatic, a thoracentesis is performed to relieve dyspnea, respiratory distress, or hypoxia. There are well‐documented risks associated with a thoracentesis, including a pneumothorax and hemothorax, but it is usually safe and well tolerated.

No more than 2 liters of fluid are usually removed because of the risk of pulmonary edema and hypotension. However, this 2‐liter rule was developed in patients with causes of pleural effusion other than cirrhosis; patients with cirrhosis may be able to tolerate the removal of larger volumes of fluid. Given the relatively small volume of fluid removed at thoracentesis, intravenous albumin is not necessary to prevent circulatory dysfunction.

A large‐volume paracentesis can also offer similar rapid relief of respiratory distress in those with ascites and hepatic hydrothorax and should be attempted prior to a thoracentesis. There can be a significant increase in total lung capacity and symptomatic improvement within 2 hours after an average of 3.5 L of ascitic fluid is removed by a paracentesis.8

Percutaneous Drains

Chest tube placement and other percutaneous drains should be avoided in patients with hepatic hydrothorax. Multiple authors have cautioned clinicians about placing drains in patients with cirrhosis because they are fraught with multiple complications: pneumothorax, hemothorax, empyema, electrolyte abnormalities, and hepatorenal syndrome. It should also be noted that the presence of spontaneous bacterial pleuritis is not an indication for a chest tube placement unless the features of empyema are present. In a single‐center experience of cirrhotic patients undergoing chest tube placement for pleural effusions, 80% of the patients developed complications and 33% died.9

Transjugular Intrahepatic Portosystemic Shunt (TIPS)

TIPS has become the mainstay of treatment for hepatic hydrothorax. It can be a life‐saving treatment as patients are waiting for a liver transplant, with a success rate of 70% to 80%.7, 10 Contraindications to placing a TIPS are age > 70 years, significant hepatic encephalopathy, large portal vein thrombosis, right‐sided heart failure, elevated pulmonary arterial pressures, and an elevated Model for End‐Stage Liver Disease (MELD) score. It is worth noting that in patients with hepatic hydrothorax, the pre‐TIPS MELD cutoff is ≤ 15, compared with a higher pre‐TIPS MELD cutoff of ≥ 19 in patients who are in need of a TIPS for other indications.11 A lack of response in the hydrothorax after TIPS placement is associated with an increased mortality rate.

Video‐Assisted Thoracoscopy (VATS)

Evaluation for defects in the diaphragm by open thoracotomy and by videothoracoscopy has been used to identify diaphragmatic defects. If the defect can be identified, biologic glue or sutures can be used to close and seal these defects. Pleurodesis, a technique that consists of ablation of the space between the parietal and visceral pleura with a sclerosing agent, is often performed at the same time. One small study had a success rate of 48%, but the morbidity (57.1%) and mortality (38.9%) were high during a follow‐up period of 3 months, raising questions about the utility of such an approach.12 This should be reserved for situations when medical therapy and TIPS are not an option. An algorithm for the treatment of hepatic hydrothorax is proposed in Fig. 1.

Figure 1.

Management of hepatic hydrothorax.

Summary

Hepatic hydrothorax is a challenging clinical problem. The development of this complication warrants a referral to a transplant center. The mainstay of treatment is diuretics and salt restriction. Thoracentesis and TIPS are usually indicated in these patients. Surgical repair of the diaphragmatic holes, along with pleurodesis and percutaneous drain placement, should be avoided given the high mortality and morbidity associated with these procedures.