Pulmonary Function and Electrolyte Balance Following Spironolactone Treatment in Preterm Infants with Chronic Lung Disease. • 321

Oral diuretic therapy is often required by premature infants with chronic lung disease (CLD). Although spironolactone (SP) is frequently used in combination with chlorthiazide (CT), the effects of SP on electrolyte losses, electrolyte supplementation and pulmonary function have not been evaluated. We tested the hypothesis that the addition of SP to CT administration will not improve pulmonary mechanics or minimize the need for dietary electrolyte supplementation. 16 infants received CT + placebo, and 17 infants received CT+ SP in a randomized, double-blind study. Baseline mean measurements in the two groups: BW 859 vs 837 gm, GA 26 vs 26 wks, PCA 32.5 vs 33 wks, lung compliance (C_L)(1.15 vs 1.14 ml/cmH₂O/kg), total lung resistance(R_L) (56.8 vs 52.5 cmH₂O/1/sec), FiO₂ 0.25 vs 0.27 and serum electrolytes were similar (p=ns). Mean data after 14 days of treatment:Table

Table 1

Serum and urine chemistries, total fluid intake and urine output, and the amount of NaCl (32 vs. 40 mEq/kg) or KCl supplementation (12.8 vs 15.2 mEq/kg) administered to infants in each group were not different (p=ns). The% change from baseline for compliance (-8.7 vs. 4.7%) and resistance (14.8 vs. 5.2%) were similar (p=ns). These data show that the addition of SP to a diuretic regimen consisting of CT did not improve pulmonary mechanics or decrease the use of dietary electrolyte supplementation. Since the immature kidney is poorly responsive to aldosterone, the inability of its synthetic antagonist SP to prevent potassium secretion is consistent with these results. Omission of SP may avoid drug-related side effects and costs without compromising respiratory function or electrolyte balance in the preterm infant with chronic lung disease.

(Funded by Newborn Pediatrics Research Fund)