Related Experiment Videos
Prolongation of inspiration during lower airway occlusion in children
Insights
The Hering-Breuer reflex, which inhibits inspiration based on lung volume, is present in children beyond the neonatal period. End-expiratory occlusions prolonged inspiratory time, indicating this reflex remains active.
Area of Science:
- Pediatric Respiratory Physiology
- Neuroscience of Breathing
Background:
- The Hering-Breuer reflex, mediated by vagal afferents, strongly inhibits inspiration in neonates and animals due to lung volume.
- This reflex is less active in adult humans during normal breathing.
Purpose of the Study:
- To investigate the presence and activity of volume-related inspiratory inhibition (Hering-Breuer reflex) in children beyond the neonatal period.
Main Methods:
- Nine asleep children (2-29 months) with airway tubes underwent end-expiratory occlusions.
- Simultaneous recordings included airflow, tidal volume, occlusion pressure, and diaphragm electromyogram (DIA EMG).
Main Results:
- End-expiratory occlusions consistently increased both mechanical and neural inspiratory times.
- Peak DIA EMG amplitude increased during occluded efforts, but the initial rate of rise did not change.
- Prolonged inspiration suggests release from volume-related inhibition, not facilitation.
Conclusions:
- The Hering-Breuer reflex is demonstrably present in children beyond the neonatal period.
- This study provides evidence for the continued activity of inspiratory inhibition related to lung volume in early childhood.
Abstract:
Inspiration is strongly inhibited by volume-related vagal afferents in human neonates and animals, but this reflex is not as active in human adults during normal breathing. To determine whether volume-related inspiratory inhibition occurs beyond the neonatal period, we performed 10 +/- 1 end-expiratory occlusions in nine asleep children, ages 2-29 mo, with cuffed tracheostomy or endotracheal tubes in place. Airflow, tidal volume, occlusion pressure, and surface diaphragm electromyogram (DIA EMG) were simultaneously recorded. Occlusion consistently increased mechanical (P less than 0.002) and neural inspiratory times (P less than 0.001). During occluded respiratory efforts, peak amplitude of DIA EMG increased by 22 +/- 10% (P less than 0.002). In contrast, initial rate of rise of DIA EMG did not change. We conclude that in children with isolated lower airways, end-expiratory occlusions prolonged inspiratory duration as measured by both mechanical and neural parameters. The lack of an associated increase in rate of rise of DIA EMG strongly suggests that inspiration is prolonged by release of volume-related inhibition of inspiration rather than by facilitation. These data provide evidence for the presence of the Hering-Breuer reflex beyond the neonatal period.