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Ventilatory response to consecutive short hypercapnic challenges in children with obstructive sleep apnea
1Division of Neonatology and Pediatric Pulmonology, Childrens Hospital Los Angeles, University of Southern California School of Medicine 90027, USA.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|November 1, 1995
Summary
Healthy children adapt breathing patterns to repeated CO2 challenges, increasing tidal volume and decreasing respiratory rate. Children with obstructive sleep apnea syndrome (OSAS) show a blunted response, suggesting pre-existing adaptations due to airway issues.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Sleep Medicine
Background:
- Healthy adults exhibit a specific ventilatory pattern during repeated hypercapnic challenges, involving increased tidal volume (VT) and decreased respiratory rate (RR) while minute ventilation (VE) remains constant.
- Obstructive sleep apnea syndrome (OSAS) in children is associated with chronic alveolar hypoventilation and increased upper airway resistance, potentially altering ventilatory responses.
Purpose of the Study:
- To investigate whether children with OSAS display a blunted ventilatory pattern compared to healthy children when subjected to repeated hypercapnic challenges.
- To compare the temporal changes in ventilatory parameters (VT, RR, VE) in response to intermittent CO2 exposure between children with OSAS and healthy controls.
Main Methods:
- Ventilatory responses to five sequential 2-minute challenges of 5% CO2 in O2 were measured in nine children with OSAS and eight healthy controls.
- Breathing intervals of room air separated the CO2 challenges, allowing assessment of adaptation over time.
- Key parameters including tidal volume (VT), respiratory rate (RR), expiratory time (TE), and minute ventilation (VE) were analyzed.
Main Results:
- All children showed increased VE during CO2 challenges compared to baseline.
- Healthy controls demonstrated progressive increases in VT and decreases in RR, with a significant increase in VE over repeated challenges.
- Children with OSAS did not show consistent changes in VT, RR, or TE, and their VE remained similar across challenges, differing significantly from controls.
Conclusions:
- Healthy children adapt their ventilatory strategy to repeated hypercapnic stimuli by altering VT and RR.
- The blunted temporal ventilatory response observed in children with OSAS suggests that mechanisms for adaptation may be chronically engaged due to underlying airway issues.
- These findings highlight differences in respiratory control plasticity between children with and without OSAS.