Plasma antidiuretic hormone in acute respiratory failure

The role of antidiuretic hormone (ADH) in the pathogenesis of renal impaired water excretion in acute respiratory failure has not been clearly delineated. Plasma sodium concentration and plasma ADH levels (radioimmunoassay) were therefore serially measured in 13 patients with acute respiratory failure (10 with acute exacerbations of chronic lung disease and three with acute lung disease) and eight "control" patients admitted ot the intensive care unit with suspected myocardial infarction. None of the patients had systemic hemodynamic, hepatic or renal dysfunction. ADH levels were significantly elevated in patients with acute respiratory failure (15.1 +/- 5.2 pg/ml versus 5.7 +/- 1.9 pg/ml, p less than 0.05) when compared with levels in control patients. The elevated ADH levels occurred despite significantly lower plasma sodium concentration (133 +/- 1 meq/liter versus 138 +/- 2 meq/liter, p less than 0.05) compared wit control values. Moreover, markedly increased ADH values (range 1.1 to 13.0 pg/ml) were often encountered in patients with acute respiratory failure despite significant hyposmolality (263 to 275 mOsm/kg H2O). This was not observed in any control patients. These results suggest that patients with acute respiratory failure are susceptible to water retention and hyposmolality due to nonosmotic release of antidiuretic hormone.