title: Effect of maturation on the extrathoracic airway stability of infants.
abstract: The influence of maturation on extrathoracic airway (ETA) stability during quiet sleep was determined in 13 normal preterm infants of 1.41 +/- 0.14 (SD) kg birth weight and 32 +/- 2 wk estimated gestational age. Studies began in the first week of life and were performed three times at weekly intervals. A drop in intraluminal pressure within the ETA was produced by external inspiratory flow-resistive loading (60 cmH2O.l-1 x s at 1 l/min); an increase in intrinsic resistance, indicating airway narrowing, was sought as a measure of ETA instability. Baseline total pulmonary resistance was not significantly different between weeks 1, 2, and 3 (88 +/- 35, 65 +/- 24, and 61 +/- 17 cmH2O.l-1 x s, respectively) but increased markedly above baseline with loading to 144 +/- 45 cmH2O.l-1.s during week 1 (P < 0.001), 89 +/- 28 cmH2O.l-1 x s at week 2 (P < 0.01), and 74 +/- 25 cmH2O.l-1 x s at week 3 (n = 10). The increment with loading was significantly greater during week 1 than during weeks 2 or 3 (P < 0.02). Similar studies were also done in seven full-term infants in the first week of life to evaluate the influence of gestational maturity on ETA stability. Despite a relatively greater drop in intraluminal pressure within the ETA of term vs. preterm infants with loading (P < 0.001), total pulmonary resistance failed to increase (68 +/- 21 to 71 +/- 32 cmH2O.l-1.s). These data reveal that ETA instability is present in preterm infants at birth and decreases with increasing postnatal age. Full-term neonates, by comparison, display markedly greater ETA stability in the immediate neonatal period.
authors: Department of Pediatrics, University of Miami School of Medicine, Florida 33101.
authors: S
authors: S
authors: Duara
authors: G
authors: G
authors: Silva Neto
authors: N
authors: N
authors: Claure
authors: T
authors: T
authors: Gerhardt
authors: E
authors: E
authors: Bancalari
mesh_terms: D000375:Aging / Q000502:physiology; D000403:Airway Resistance / Q000502:physiology; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007234:Infant, Premature; D012143:Respiratory Physiological Phenomena; D012137:Respiratory System / Q000254:growth & development; D012890:Sleep / Q000502:physiology