Management



The general principles of management of acutely ill patients have been discussed else­where. There are absolute and relative indications for dialysis. Dialytic therapy should be instituted for uremic symptoms such as encephalopathy or pericarditis. Other indications for dialysis in­clude severe fluid overload, hyperkalemia, met­abolic acidosis, and life-threatening abnormali­ties in serum concentrations of electrolytes that cannot be effectively managed by conservative means. In a patient who is asymptomatic and without the above clinical and laboratory findings, a trial of conservative nondialytic manage­ment may be attempted. In a patient who is ca-tabolic with increases of BUN of greater than 20 mg/dl/day, it is reasonable to institute dialysis prior to the development of severe clinical symp­toms. Moreover, sustained serum concentrations of BUN greater than 70 mg/dl are associated with platelet dysfunction, poor function of white blood cells, poor wound healing, and possibly a higher rate of mortality and morbidity. If instituted, di­alysis (hemodialysis or peritoneal dialysis) should be performed as often as is required to ob­tain the therapeutic goal.
The principles and techniques involved in he­modialysis and peritoneal dialysis are discussed in Chapter 33. The following considerations relate to the use of hemodialysis or peritoneal dialysis in the acute clinical situation. Hemodialysis re­quires the use of heparin to prevent the clotting of blood during its extracorporeal circulation. He­modialysis is absolutely or relatively contrain-dicated in patients with acute intracerebral hemorrhage or active gastrointestinal bleeding and in the immediate postoperative period. Hemodi­alysis must also be used with caution in patients with pericarditis and/or pericardial effusions, acute myocardial infarctions, and underlying bleeding disorders. In the above clinical circum­stances, peritoneal dialysis may be the preferred type of dialytic therapy.

The relative inefficiency of peritoneal dialysis may render this form of dialysis suboptimal in the acute treatment of very catabolic patients, in pa­tients with marked hyperkalemia, and in patients with severe metabolic acidosis. Peritoneal di­alysis is also not the preferred treatment option when dialvsis is being performed for drug over­doses. Whether or not dialysis is instituted, there are several distinct clinical problems unique to the patient with ATN.

Sodium and Water Balance. The dietary or in­travenous administration of sodium and water should be matched to the urine output and non-urinary losses of the patient once a nearly normal state of hydration is achieved. Diuretic adminis­tration may be attempted to increase the urine out­put if the above measures are not effective and the extracellular fluid volume is expanded (see below). If diuretics are unsuccessful in preventing expansion of the extracellular fluid volume, di­alysis is required. In patients who require large amounts of intravenously infused fluids, such as patients receiving intravenous alimentation, di­alysis may be required on a daily basis. When di­alysis is instituted, the removal of sodium and water by dialysis must be considered in the cal­culation of the net water and sodium balance of the patient.