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Volume Overload

By James L. Lewis, III, MD

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Volume overload generally refers to expansion of the ECF volume. ECF volume expansion typically occurs in heart failure, nephrotic syndrome, and cirrhosis. Renal Na retention leads to increased total body Na content. This increase results in varying degrees of volume overload. In heart failure, the increased ECF volume results in decreased effective circulating volume, which in turn causes decreased organ perfusion leading to clinical sequelae. Serum Na concentration can be high, low, or normal in volume-overloaded patients (despite the increased total body Na content).

An increase in total body Na is the key pathophysiologic event. It increases osmolality, which triggers compensatory mechanisms that cause water retention. When sufficient fluid accumulates in the ECF (usually > 2.5 L), edema (see Edema ) develops.

Among the most common causes of ECF volume overload are the following:

  • Heart failure

  • Cirrhosis

  • Kidney failure

  • Nephrotic syndrome

  • Premenstrual edema

  • Pregnancy

Clinical features include weight gain and edema. Diagnosis is clinical.

Treatment aims to correct the cause. Dietary sodium intake is restricted. Diuretics are given in heart failure, cirrhosis, renal insufficiency, and nephrotic syndrome. The location and amount of edema are dependent on many factors, including whether the patient has been sitting, lying, or standing recently. Daily weights are the best way to follow the progress of therapy for ECF volume overload. The speed of correction of ECF volume overload should be limited to 0.25 to 0.5 kg body weight/day, depending on the degree of volume overload (faster with a copious excess, slower with less excess) and the patient's other medical problems (slower with hypotension and renal insufficiency).

* This is the Professional Version. *