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Extrathoracic airway stability during resistive loading in preterm infants
S Duara1, T Gerhardt, E Bancalari
1Department of Pediatrics, University of Miami School of Medicine, Florida 33101.
Insights
Extrathoracic airway (ETA) narrowing occurs in preterm infants when a breathing load is applied after extubation. This study shows that measuring total pulmonary resistance with an inspiratory flow-resistive load is a simple test for ETA stability.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Neonatal Care
Background:
- Preterm infants are susceptible to airway instability.
- Extrathoracic airway (ETA) collapse can compromise breathing.
- Assessing ETA stability is crucial for managing respiratory distress in neonates.
Purpose of the Study:
- To evaluate the stability of the extrathoracic airway (ETA) in preterm infants during sleep.
- To determine if external inspiratory loads induce airway narrowing.
- To assess the role of the ETA in changes in pulmonary resistance.
Main Methods:
- Tested 10 preterm infants during sleep using an external inspiratory flow-resistive load (IRL).
- Measured total pulmonary resistance as an indicator of airway narrowing.
- Compared pulmonary resistance with and without the IRL, both intubated and extubated.
Main Results:
- Total pulmonary resistance decreased with loading in intubated infants but significantly increased in extubated infants.
- Intraluminal pressure in the ETA dropped significantly with loading in both conditions.
- Extubated infants showed ETA narrowing with loading, even without overt obstructive apnea.
Conclusions:
- The extrathoracic airway (ETA) narrows in response to inspiratory loading in extubated preterm infants.
- Measurements of total pulmonary resistance using an inspiratory flow-resistive load (IRL) serve as a straightforward test for ETA stability.
- Findings highlight the importance of assessing airway dynamics in preterm neonates post-extubation.
Abstract:
Extrathoracic airway (ETA) stability was tested in 10 preterm infants during sleep with a drop in intraluminal pressure produced by the application of an external inspiratory flow-resistive load (IRL, 125 cmH2O.1-1.s at 1 l/min). An increase in total pulmonary resistance was sought as the measure of airway narrowing. The role of the ETA in the increased pulmonary resistance with loading was examined by testing the same infants while endotracheally intubated and after extubation. Total pulmonary resistance decreased with loading during the intubated studies (102.5 +/- 41.2 to 82.4 +/- 33.3 cmH2O.1-1.s, P less than 0.05), whereas a significant increase in pulmonary resistance was seen with loading in the extubated studies (101 +/- 58.1 to 128 +/- 68.6 cmH2O.1-1.s, P less than 0.01). Intraluminal pressure in the ETA, measured by the lowest proximal airway pressure, fell significantly with loading in both conditions, with values changing from -0.7 +/- 0.3 to -4.7 +/- 2.7 cmH2O in the intubated infants and from -0.9 +/- 0.3 to -4.6 +/- 0.9 cmH2O) in the extubated infants (P less than 0.01). The results suggest ETA narrowing with loading in extubated infants despite the absence of overt obstructive apnea. Measurements of total pulmonary resistance with IRL can be used as a simple test of ETA stability.