More on the Management of Ascites

Abstract

Malignant disease accounts for approximately 10% of all cases of ascites, which is defined as an abnormal accumulation of fluid in the peritoneal cavity. It most commonly occurs in advanced ovarian carcinoma as well as in breast, lung, and gastrointestinal cancers, although 1 in 5 patients with malignant ascites may have cancers of unknown origin. Troublesome symptoms include abdominal distension, early satiety, dyspnea, nausea, and reduced mobility. The pathophysiology of malignant ascites is complex and multifactorial. Ascites may result from the mechanical obstruction of lymphatic drainage by tumor cells leading to incomplete absorption of intraperitoneal fluid and protein, especially in patients with breast cancer and lymphoma. Due to the high protein content of the fluid, increased vascular permeability has been implicated in the etiology. The accumulation of ascites from obstructed lymphatics can lead to a reduction in the circulating blood volume which, in turn, activates the rennin–angiotensin–aldosterone system causing sodium retention. It is for this reason that sodium restriction and diuretics are most often used to manage ascites. There is no generally accepted gold standard for the management of malignant ascites. Paracentesis and diuretics are most commonly employed followed by peritoneovenous (PV) shunting or permanent drainage, dietary measures, and systemic or intraperitoneal chemotherapy. In 2006, Becker et al published an article trying to make sense of the treatment of malignant ascites as well as offering some management guidelines. They undertook a literature search for articles published between 1966 and August 2005, utilizing strict inclusion criteria including the use of abdominal paracentesis, diuretics, and PV shunting in the treatment of symptomatic ascites. Thirty-two studies were identified and none were randomized clinical trials. Abdominal paracentesis provides symptomatic relief in 90% of the patients. Complications of this procedure include secondary peritonitis, pulmonary embolism, and hypotension. It is this last complication that is most concerning to clinicians especially with regard to infusion fluids or albumin during the procedure. Becker et al note that studies in the setting of liver disease report that up to 5 L of ascitic fluid can be removed quickly without the risk of significantly affecting the plasma volume or kidney function. Also, symptomatic improvement occurs with the removal of a few liters, ranging from 0.8 to 15 L, with a mean of 5.3 L and median of 4.9 L. In this issue, Zama and Edgar report a case series of homebased paracentesis in 6 hospice patients. Of 6 patients, 4 had chronic liver disease and the remaining 2 patients had breast cancer and soft tissue sarcoma, respectively. All had failed diuretics and prior paracentesis. The median survival from last paracentesis to death was 38.4 days with a range of 6 to 57 days. The procedure was done without ultrasound guidance and any untoward complications. In this first of a kind report, the authors conclude that home-based therapeutic paracentesis in symptomatic patients is both safe and effective, providing less burden to the patient and family. The use of diuretics in the management of malignant ascites is inconsistent. As noted by Becker et al, a survey of physicians on the use of diuretics showed that 61% prescribed them, however, only 45% felt them to be effective. Overall, slightly less than half (43%) of the patients respond no matter what the underlying tumor be. Spironolactone is a commonly used diuretic and raises the plasma rennin level which, as noted previously, can be lowered causing sodium retention. Furthermore, there is a suggestion that ascites due to extensive liver metastases responds better to diuretics than ascites caused by peritoneal carcinomatosis or chylous ascites. After failing paracentesis and diuretics, PV shunting becomes a consideration. The PV shunts were first developed to control the ascites associated with cirrhosis and later used in patients with malignant ascites. The concept of the PV shunt is quite simple and involves draining the fluid in the abdominal cavity back into the systemic circulation. There are 2 types of shunts, that is, the LeVeen and the Denver shunts. The LeVeen shunt drains the fluid into the superior vena cava via a 1-way valve opening at a pressure of 3 cm H2O. Although the Denver shunt was developed to prevent occlusion by proteinaceous material, the valve opens at a positive pressure gradient of 1 cm H2O preventing detectable reflux. Contraindications include hemorrhagic ascites, high ascitic fluid protein content (greater than 4.5 g/L), loculated ascites, portal hypertension, bleeding disorders, and cardiac and renal failures. About 6% of the patients will sustain a major complication such as pulmonary edema, pulmonary emboli, clinically relevant disseminated intravascular coagulation (DIC), and infection. When PV shunting was initially reported, there was great concern that