1995 OPEN FORUM Abstracts
LUNG VOLUME STABILITY DURING POSTNATAL GROWTH IN PRETERM INFANTS WITH RESPIRATORY DISTRESS SYNDROME
Mary McGowan RRT, Regina Ykoruk CRTT, Emidio M. Sivieri MS, Soraya Abbasi MD and Vinod K. Bhutani MD. Newborn Pediatrics, Pennsylvania Hospital, Dept. of Pediatrics, Thomas Jefferson University, Philadelphia, Pennsylvania. USA.
We measured functional residual capacity (FRC) in 14 neonates (1496 ± 227g birthweight, 31.6 ± 1.0 weeks gestational age) who had a clinical diagnosis of RDS, 8 of these were treated with surfactant. A computerized helium dilution technique was used to measure FRC. The infant was connected to the helium dilution circuit via a solenoid valve which was automatically triggered at end expiration. Four to 6 sequential measurements were used to obtain a mean FRC value for each study. FRC was measured during the first two weeks of life (early) and then at discharge. The mean ± SD data for study age, lung compliance (C_L), FRC adjusted to body weight (kg) and length (cm) are:
study age C_L FRC FRC/kg FRC/cm
(days) (mL/cmH_2O) (mL)(mL/kg)(mL/cm)
Early 9.9 ± 3.4 2.33 ± 0.9529.7 ± 6.920.0 ± 2.8 0.68 ± 0.15
Discharge 32.5 ± 5.1 2.26 ± 0.4144.5 ± 7.1* 21.7 ± 4.1 0.96 ± 0.17*
These data show stable lung function (C_L) and a significant (p < 0.0001)^* change in FRC including FRC normalized to length but not to body weight. It is to be noted that 6/14 infants (43%) showed an apparent ~10% decrease in FRC. This decrease may be suggestive of air trapping (which would indicate a false reduction in lung volume) and is consistent with expiratory airflow limitation previously observed in some low birthweight infants (LBW) secondary to airway barotrauma. Gradual increases in lung volume occur with post natal age and increase with somatic growth, but these may be influenced by a history of barotrauma.