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Hering-Breuer reflex and respiratory system compliance in the first year of life: a longitudinal study
P S Rabbette1, M E Fletcher, C A Dezateux
1Intensive Therapy and Respiratory Medicine Unit, Institute of Child Health, London, United Kingdom.
Insights
The Hering-Breuer reflex (HBR) persists in infants throughout their first year, though its strength diminishes. Respiratory system compliance increases with age, but this change is not linked to HBR strength decline.
Area of Science:
- Pediatric Pulmonology
- Respiratory Physiology
- Infant Development
Background:
- The Hering-Breuer reflex (HBR) is crucial for measuring infant respiratory mechanics.
- Evidence on HBR persistence beyond the newborn period is inconsistent.
- Understanding HBR maturational changes is vital for infant respiratory assessments.
Purpose of the Study:
- To evaluate maturational changes in HBR activity in healthy infants during the first year of life.
- To assess changes in passive total respiratory system compliance (Crs) alongside HBR development.
- To investigate the relationship between HBR strength and Crs changes over the first year.
Main Methods:
- Assessed HBR strength via expiratory time changes during airway occlusions in sedated infants.
- Measured passive total respiratory system compliance (Crs) using the multiple-occlusion technique.
- Collected paired HBR and Crs data from 30 infants at 4-8 weeks and 1 year of age.
Main Results:
- Significant HBR activity persisted in all infants throughout the first year.
- The relative strength of HBR response decreased significantly from ~6 weeks to 1 year (P < 0.001).
- Passive total respiratory system compliance (Crs) increased significantly with age in all infants.
Conclusions:
- The Hering-Breuer reflex remains active throughout the first year of infant life.
- A decline in HBR response strength occurs with maturation, independent of Crs changes.
- These findings have implications for respiratory mechanics measurements in infants.
Abstract:
The airway occlusion technique for measuring passive respiratory mechanics in infants relies on an ability to evoke the Hering-Breuer lung inflation reflex (HBR). However, there is conflicting evidence regarding the persistence of the HBR beyond the early newborn period. This study was designed to assess maturational changes in HBR activity and passive total respiratory system compliance (Crs) in healthy infants during the 1st yr of life. The strength of the HBR was assessed from the relative change in expiratory time (TE) after brief end-inspiratory airway occlusions compared with resting TE during spontaneous breathing. Crs was measured using the multiple-occlusion technique. Paired measurements of HBR activity and Crs were obtained during sedated sleep in 30 infants at 4-8 wk and at 1 yr of age. Significant HBR activity during tidal breathing persisted throughout the 1st yr of life, with TE increasing during occlusion by at least 26% in every infant. However, the relative strength of the reflex response decreased from a mean of 88.3% (range, 34-160%) at approximately 6 wk to 50.3% (range, 26-125%) by 1 yr of age (P < 0.001). All infants showed an increase in Crs with age, with mean Crs increasing from 60.1 +/- 8.9 (SD) to 149.0 +/- 20.6 ml/kPa between 6 wk and 1 yr. However, there was no apparent relationship between the magnitude of decline in HBR response and the age-related changes in Crs.(ABSTRACT TRUNCATED AT 250 WORDS)