Daily sequential changes in plasma atrial natriuretic factor concentrations in mechanically ventilated...

Plasma atrial natriuretic factor (ANF) concentrations are elevated in mechanically ventilated infants. To test the hypothesis that changes in pulmonary compliance affect ANF concentration, we measured plasma ANF concentrations sequentially in low-birth-weight, ventilated infants who either received surfactant replacement or placebo on day 1. ANF concentrations were elevated as compared to adult controls on day 1 and increased significantly on days 2 and 3 before declining. Day 5 concentrations were not different from day 1. Several infants had ANF concentrations greater than 1,280 pg/ml on days 2-4. There were no significant differences in ANF concentrations between surfactant-treated and non-treated infants on any day. ANF concentrations increased in parallel with changes in salt and water balance, but no significant relationships were apparent between absolute ANF concentrations and parameters of salt and water balance. The results suggest that ANF secretion is elevated in infants with pulmonary disease. While the temporal relationship between the initial rise in ANF concentration and increase in salt and water excretion suggest that ANF is involved in this diuresis, the role it may play is unclear from the present data.