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Effect of maturation on the extrathoracic airway stability of infants
S Duara1, G Silva Neto, N Claure
1Department of Pediatrics, University of Miami School of Medicine, Florida 33101.
Insights
Extrathoracic airway (ETA) instability in preterm infants decreases with age. Full-term neonates exhibit greater ETA stability, indicating maturation significantly impacts airway function during sleep.
Area of Science:
- Neonatal Physiology
- Respiratory Medicine
- Pediatric Pulmonology
Background:
- Airway stability is crucial for infant respiratory health.
- Maturation influences the development and stability of the extrathoracic airway (ETA).
- Understanding ETA stability in preterm infants is vital for assessing respiratory risks.
Purpose of the Study:
- To investigate the influence of postnatal maturation on extrathoracic airway (ETA) stability in preterm infants during quiet sleep.
- To compare ETA stability between preterm and full-term neonates.
Main Methods:
- Assessed ETA stability in 13 preterm infants weekly during the first three postnatal weeks.
- Applied external inspiratory flow-resistive loading to induce a drop in intraluminal pressure and measure changes in intrinsic resistance.
- Compared ETA stability in 7 full-term infants during their first week of life.
Main Results:
- Preterm infants showed significant ETA instability at birth, indicated by a marked increase in pulmonary resistance with loading.
- ETA instability in preterm infants decreased significantly with increasing postnatal age (week 1 vs. weeks 2 & 3).
- Full-term neonates demonstrated greater ETA stability, with no significant increase in pulmonary resistance despite a larger pressure drop.
Conclusions:
- Extrathoracic airway (ETA) instability is a characteristic of preterm infants at birth.
- Postnatal maturation leads to improved ETA stability in preterm infants.
- Full-term neonates possess superior ETA stability in the neonatal period compared to preterm 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.