(Page 5 of 7)

To control the formation of ascites, patients must eliminate more sodium than they acquire through diet. Patients with cirrhosis and ascites tend to retain sodium very efficiently, and most patients need to have dietary sodium restricted to less than 2 grams per day (88 mEq [milliequivalent, or the number of grams of solute dissolved in one milliliter of solution]). To prevent additional ascites, a patient who is following a 2-gram sodium diet needs to lose at least 78 mEq sodium per day through the urine in addition to the 10 mEq that are lost regularly through the skin. Research has shown that if a person is eliminating a ratio of sodium to potassium through urine that is greater than 1, that person will be eliminating at least 78 mEq sodium per day in urine. To be able to eliminate this amount of sodium, most patients need to take diuretics.

Patients who have no swelling of the extremities should not lose more than half a kilogram of weight per day in order to control ascites. Those who have swelling in the extremities may be able to lose up to 1 kilogram per day. Fluid restriction is not required except in patients with very low sodium concentration in the blood. So that patients will not become dehydrated, the dose of diuretics is adjusted based on the patients' response to the medication to obtain a zero balance of sodium once the ascites has been controlled. Once a patient has developed ascites, he or she is at high risk of death. For that reason, liver transplantation should be contemplated if the patient is a suitable candidate.

Spontaneous Bacterial Peritonitis (SBP)

Of patients hospitalized with ascites, between 10 percent and 30 percent will develop SBP. This infection is thought to occur either by spontaneous passage of normal bacteria that reside in the gut into the ascitic fluid, or by seeding of bacteria into the blood from a distant source (a urinary infection or lung infection), leading to growth of this bacteria in the ascitic fluid.

Patients who have low protein concentrations in the ascites are at higher risk of developing SBP. Once a patient has had an episode of SBP, there is a 7 in 10 chance that a new episode will occur within the next year. With every episode, 2 to 3 of every 10 patients will die from complications of the infection, and only 3 of every 10 are expected to survive for 2 years.

The diagnosis of SBP is made when high numbers of a type of white blood cell that is especially protective against bacterial infections (polymorphonuclear cells [PMN]) are found in the ascitic fluid. Patients are diagnosed as having SBP if bacteria are found in the ascitic fluid, but the concentration of bacteria in the fluid is extremely low - an estimated 1 bacterium per milliliter of fluid - so that the bacteria cannot be seen by examining the fluid under the microscope. In order to have a reasonable chance of getting a positive culture, the fluid should be injected at the bedside into blood culture bottles specially designed to recover small amounts of bacteria. This technique will detect the vast majority of infections. If improper techniques are used (sending the fluid to the laboratory to be placed on a culture plate), chances of proper diagnosis decrease to 4 out of 10.

Patients with SBP may not have symptoms, or manifestations of the infection may appear to be unrelated to the abdominal cavity. For example, SBP patients may have confusion, changes in kidney function, poorly controlled ascites, or overall progressively deteriorating health. Despite the fact that more than half of the patients with SBP complain of some degree of abdominal pain or discomfort, the physical exam of the abdomen usually is completely benign.

Usually only one type of bacteria appears in the culture of patients who have SBP. Clinicians should suspect the possibility of a secondary peritonitis (some intra-abdominal perforation or abscess formation in the abdomen) if 1. multiple kinds of bacteria are recovered from the culture, or 2. the patient develops an infection consistent with SBP but in the presence of total protein concentration in the ascitic fluid of more than 1.5 g/dl, or 4. the patient fails to respond promptly to proper antibiotic therapy. A secondary infection also should be suspected if direct examination of fluid under the microscope shows bacteria because, as mentioned, the concentration of bacteria in SBP is so low that bacteria should not be detectable by microscopic examination.

Patients who develop SBP are at extremely high risk of developing kidney dysfunction and hepatorenal syndrome. Expansion of the volume within the blood vessels (the intravascular volume) using intravenous albumin infusions has been shown to decrease the frequency of hepatorenal syndrome and, for that reason, improves survival rates in patients who develop SBP. Because of concerns about kidney toxicity, it is important to avoid antibiotics or other medications that may exacerbate kidney damage. Current therapy for SBP includes use of the antibacterial drug cefotaxime.

Patients at special risk for SBP are those who are hospitalized and have a total protein concentration in the ascitic fluid that is less than 1.5 g/dl, those who have gastrointestinal bleeding from any source, and those who have had previous episodes of SBP. Prophylactic therapy is indicated for all these groups of patients.

Tags: Alcoholism

About the Author

NIH is the nation's medical research agency - making important medical discoveries that improve health and save lives. The National Institutes of Health (NIH), a part of the U.S. Department of Health and Human Services, is the primary Federal agency for conducting and supporting medical research.