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Developmental pattern of hypercapnic and hypoxic ventilatory responses from childhood to adulthood
C L Marcus1, W B Glomb, D J Basinski
1Division of Neonatology and Pediatric Pulmonology, Childrens Hospital Los Angeles, University of Southern California School of Medicine 90027.
Insights
Children exhibit higher hypercapnic and hypoxic ventilatory responses (HCVR and HOVR) than adults. These key breathing control mechanisms mature through childhood and adolescence into adulthood.
Area of Science:
- Physiology
- Respiratory Physiology
- Developmental Physiology
Background:
- The developmental trajectory of ventilatory control, specifically hypercapnic (HCVR) and hypoxic (HOVR) ventilatory responses, from childhood through adulthood remains largely uncharacterized.
- Understanding these developmental patterns is crucial for assessing respiratory health across the lifespan.
Purpose of the Study:
- To investigate the developmental patterns of hypercapnic (HCVR) and hypoxic (HOVR) ventilatory responses in humans.
- To compare these responses between children and adults, accounting for body size differences.
Main Methods:
- Studied 59 subjects (ages 4-49 years, including 35 children) to measure HCVR and HOVR.
- Responses were correlated with body weight, vital capacity, and body surface area.
- Data were scaled for body weight (HCVR/WT and HOVR/WT) to normalize for body size disparities.
Main Results:
- HCVR correlated significantly with weight, vital capacity, and body surface area, but not height.
- Both HCVR/WT and HOVR/WT decreased with age, indicating higher responses in children.
- Children demonstrated significantly higher HCVR/WT and HOVR/WT compared to adults, along with increased respiratory and heart rate responses to hypercapnia and hypoxia.
Conclusions:
- Rebreathing hypercapnic (HCVR) and hypoxic (HOVR) ventilatory responses are significantly higher in children compared to adults.
- Ventilatory control mechanisms undergo developmental changes from childhood into adulthood.
- These findings highlight important age-related differences in respiratory control.
Abstract:
The developmental pattern of ventilatory responses, through childhood and puberty into adulthood, is not known. Therefore we studied hypercapnic (HCVR) and hypoxic ventilatory responses (HOVR) in 59 subjects (29 males and 30 females) 4-49 yr of age, of whom 35 were children ( < 18 yr old). There was a significant correlation between HCVR and weight (r = 0.33, P < 0.02), vital capacity (r = 0.30, P < 0.05), and body surface area (r = 0.30, P < 0.05) but not height (r = 0.22, NS). There was no correlation between HOVR and any of the correcting factors. To account for disparities in body size, volume-related results were scaled for body weight. The HCVR corrected for weight (HCVR/WT) decreased with age (r = -0.57, P < 0.001). HCVR/WT was significantly higher in children than in adults (0.056 +/- 0.024 vs. 0.032 +/- 0.015 l.kg-1 x min-1. Torr end-tidal PCO2-1, P < 0.001). The (tidal volume/inspiratory duration)/weight, respiratory rate, and heart rate responses to hypercapnia were increased in the children, and the CO2 threshold was lower (36 +/- 5 vs. 40 +/- 6 Torr, P < 0.05). Similarly, the HOVR corrected for weight (HOVR/WT) decreased with age (r = 0.34, P < 0.05), and HOVR/WT was significantly higher in children than in adults (-0.035 +/- 0.017 vs. -0.024 +/- 0.016 l.kg-1 x min-1.% arterial O2 saturation-1, P < 0.02). The respiratory rate and heart rate responses to hypoxia were increased in the children. We conclude that rebreathing HCVR and HOVR are higher during childhood than during adulthood.