Branched-chain amino acids and respiratory pattern and function in the neonate.

Branched-chain amino acids (BCAA) increase respiratory drive in adults and improve diaphragmatic function in vitro. This study was designed to examine the effects of increased amounts of BCAA in intravenous nutrition on respiratory function and episodes of apnea in premature infants. An open cross-over design was used, with each patient serving as his own control. Ten premature infants, 34 weeks' gestation or less, were observed. Mean gestational age was 30.6 weeks (range 27 to 33 weeks), mean birth weight was 1487 gm +/- 300 gm, and the age at study was 5 to 33 days. For three consecutive 24-hour periods, the infants received routine total parenteral nutrition (TPN) (30% BCAA), enriched TPN (53% BCAA), and routine TPN (30% BCAA). Pulmonary function, apnea frequency, blood chemistry, and amino acid pattern were measured. Enriched TPN resulted in significant increases in all infants in dynamic compliance, from 2.41 +/- 1.07 to 4.55 +/- 2.78 ml/cm H2O (p < 0.025), and in specific dynamic compliance from 1.67 +/- 0.64 to 3.1 +/- 1.51 ml/cm H2O/kg (p < 0.005). Total pulmonary resistance decreased from 40.3 +/- 23.3 to 24.0 +/- 20.9 cm H2O/L/sec (p < 0.05), and peak-to-peak pressure decreased from 5.96 +/- 0.93 to 4.09 +/- 2.34 cm H2O (p < 0.05). All values returned to baseline with resumption of the routine TPN. In four infants with significant apnea, the average number of episodes of apnea decreased from 58 during standard TPN to 11 with the enriched solution infusion during matched 12-hour periods (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)