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Measurement of ventilatory system compliance in infants and young children
Insights
Ventilatory system compliance (Crs) in infants and young children is best predicted by height, not age. The Breuer-Hering reflex, which inhibits inspiration, decreases with age in this pediatric group.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Assessing ventilatory system compliance (Crs) is crucial for understanding respiratory mechanics in infants and young children.
- Previous studies have focused on age-related changes, but the relationship with physical parameters like height requires further investigation.
Purpose of the Study:
- To measure Crs in sedated, spontaneously breathing infants and young children.
- To investigate the correlation between Crs and physical parameters such as height and age.
- To assess the Breuer-Hering inspiratory inhibitory reflex and its relationship with age.
Main Methods:
- Ventilatory system compliance (Crs) was measured in 32 infants and young children (3-54 months) using airway occlusion techniques during spontaneous breathing via a face mask.
- Airway pressure was measured at different lung volumes above functional residual capacity (FRC) to calculate the pressure-volume relationship.
- The Breuer-Hering reflex was evaluated by measuring the percent increase in occluded expiratory time, correlating it with age.
Main Results:
- Crs values ranged from 4.5 to 21.8 ml/cm H2O, showing a strong correlation with height (H) (Crs = 5.36 x 10(-4) H^2.27, r = 0.94).
- The Breuer-Hering reflex index ranged from 4% to 100% and demonstrated a significant negative correlation with age (r = -0.50, P < 0.01).
Conclusions:
- Height is a more accurate predictor of ventilatory system compliance than age in infants and young children.
- The strength of the Breuer-Hering inspiratory inhibitory reflex diminishes with increasing age in this pediatric population.
Abstract:
Ventilatory system compliance (Crs) was measured in 32 sedated sleeping infants and young children aged 3-54 months breathing spontaneously through a face mask. Airways were occluded during expiration at different lung volumes above FRC and the corresponding airway pressure was measured. A pressure-volume relationship was then calculated by the least square method. To ensure the presence of the Breuer-Hering inspiratory inhibitory reflex, the percent increase of occluded expiratory time relative to the preceding unoccluded breath was calculated in 28 subjects where several end inspiratory occlusions had been maintained up to the next inspiratory effort. This index ranged from 4 to 100% and correlated negatively with age (r = -0.50, P less than 0.01). Crs ranged from 4.5 to 21.8 ml/cm H2O and correlated best with height (H) (Crs = 5.36 X 10(-4) H2.27, r = 0.94).