[Refractory ascites and dilutional hyponatremia: current management and new aquaretics]

Ascites is the most common complication of cirrhosis and is associated with 50% mortality at 2 years if patients do not receive orthotopic liver transplantation. Recently the International Ascites Club defined ascites into three groups: In grade I ascites fluid is detected only by ultrasound; in grade II, ascites is moderate with symmetrical distention of the abdomen; and in Grade 3 ascites is large or tense with marked abdominal distention. About 10% of patients with ascites are refractory to treatment with diuretics. In refractory ascites, patients do not respond to highest doses of diuretics (spironolactone 400 mg/day and furosemide 160 mg/ day) or develop side effects (hyperkalemia, hyponatremia, hepatic encephalopathy, or renal failure) that prohibit their use. Patients may be treated either by repeated large volume paracentesis plus albumin or transjugular intrahepatic portosystemic shunts (TIPS). Dilutional hyponatremia in cirrhotic patients is defined as serum sodium < or = 130 mEq/L in the presence of an expanded extracellular fluid volume, as indicated by the presence of ascites and/or edema. This complication of cirrhotic patients with ascites has recently gained attention given that several reports indicate that when serum sodium concentration is combined with the Model for End-Stage liver disease (MELD) it improves the prognostic accuracy of MELD score in patients awaiting orthotopic liver transplant (OLT). The first step in the management of dilutional hyponatremia is fluid restriction and discontinuation of diuretics. Water restriction at 1,000 mL/day helps prevent the progressive decrease in serum sodium concentration but usually does not correct hyponatremia in most cases. Actually are developing drugs that are active orally and act by selectively antagonizing the specific receptors (V2 receptor) of arginine vasopressin. These agents act in the distal collecting ducts of the kidneys, by increasing solute free water excretion and, thus, improving serum sodium concentration in hyponatremic patients.