Hormonal abnormalities affecting sodium and water balance in acute respiratory failure due to chronic obstructive...

The pathogenesis of edema and hyponatremia associated with chronic obstructive lung disease (COLD) is poorly understood. In ten edematous COLD patients with acute respiratory failure (ARF), we monitored plasma renin activity (PRA), aldosterone (PA), and antidiuretic hormone (arginine vasopressin, AVP) for six days. Six patients receiving supplemental oxygen and antibiotics had near normal PRA, PA, and AVP, and diuresed Na+ and H2O and lost weight; only one patient was hyponatremic (PNa+ less than 130 mEq/L). On the same therapy, nonresponders (n = 4), with persistently elevated PRA, PA, and AVP, demonstrated no loss of Na+, H2O, or weight; three patients were hyponatremic. The PRA and PA correlated inversely with sodium loss; AVP correlated inversely with free water clearance. These studies suggest that in patients with COLD, edema, and ARF (1) lack of sodium diuresis may be contributed to by secondary hyperaldosteronism; and (2) hyponatremia can be explained by inappropriately elevated plasma AVP.