Expanded gentamicin volume of distribution in patients with indicators of malnutrition

Visceral protein, body weight, and body composition were assessed in patients receiving gentamicin to determine whether a meaningful analysis of nutritional status can be used to identify patients with an expanded gentamicin volume of distribution (V). Adults with gram-negative infections were selected sequentially from among hospitalized patients being treated with gentamicin. Serum gentamicin concentrations before and after an intravenous dose of gentamicin were determined by an enzyme-mediated immunoassay. Noncompartmental analysis was used to determine pharmacokinetic variables. Body composition was assessed by bioelectric impedance techniques. Of 26 patients, 10 were considered to be at high risk of malnutrition by meeting at least two of the following criteria: serum albumin concentration, less than or equal to 3.5 g/dL; actual weight, less than 80% of ideal weight; and ratio of exchangeable sodium to exchangeable potassium (Nae/Ke), greater than 1.22. The non-high-risk group (n = 16) had a gentamicin V at steady state of 0.294 +/- 0.105 L/kg (mean +/- S.D.), which was significantly lower than that observed in the high-risk group (0.415 +/- 0.294 L/kg). The accuracy of the high risk classification in identifying patients with an expanded gentamicin V was improved by revising the definition of the high-risk group. In the revised definition, patients were considered to be at high risk for malnutrition if they met at least two of the following criteria: serum albumin concentration, less than or equal to 3.1 g/dL; actual weight, less than 90% of ideal weight; and Nae/Ke' greater than 1.22.(ABSTRACT TRUNCATED AT 250 WORDS)