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Changes in respiratory mechanics with age
1Division of Clinical Sciences, Western Australian Research Institute for Child Health, Perth.
Insights
Respiratory system resistance and airway resistance decrease with height in children. Respiratory system compliance increases with height, while tissue resistance (Pdif) changes with age.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Mechanical Ventilation
Background:
- Understanding respiratory mechanics in children is crucial for optimizing mechanical ventilation.
- Age-related changes in lung function can significantly impact ventilation strategies.
Purpose of the Study:
- To investigate age-related changes in respiratory mechanics in mechanically ventilated children.
- To differentiate between airway resistance and tissue viscoelastic resistance.
Main Methods:
- A cross-sectional study of 51 children (3 weeks to 15 years) undergoing anesthesia.
- Utilized single- and two-compartment models, multilinear regression, and the interrupter technique.
- Measured respiratory system resistance (Rrs), airway resistance, and tissue viscoelastic resistance (Pdif).
Main Results:
- Respiratory system resistance (Rrs) and airway resistance decreased with increasing height.
- Respiratory system compliance progressively increased with height.
- Tissue viscoelastic resistance (Pdif) decreased in the first two years of life and increased after age five.
Conclusions:
- Respiratory mechanics change significantly with age and height in children.
- Height is a key determinant of respiratory system resistance and compliance.
- Age-specific patterns exist for tissue viscoelastic resistance in pediatric patients.
Abstract:
A cross-sectional survey involving 51 children, ranging in age from 3 wk to 15 yr, was performed to examine the changes in respiratory mechanics with age in mechanically ventilated children, using both a single-compartment model of the respiratory system and a more sophisticated two-compartment model. Children were studied while under anesthesia for urological surgery and were considered to have normal lungs. They were paralyzed and mechanically ventilated throughout measurements. Respiratory mechanics were measured during ventilation by applying a single-compartment model and by using multilinear regression to calculate dynamic compliance and respiratory system resistance (Rrs). We then used the interrupter technique, which allowed us to partition Rrs into airway resistance and a tissue viscoelastic component known as Pdif. A static volume-pressure curve was constructed from multiple occlusions made at different lung volumes throughout expiration, and static compliance was determined. Rrs and airway resistance decreased as height increased. There was a progressive increase in respiratory system compliance with height. Pdif fell in the first 2 yr of life and then subsequently increased after the age of approximately 5 yr.