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Investigating the complexity of respiratory patterns during the laryngeal chemoreflex
Andrei Dragomir1, Yasemin Akay, Aidan K Curran
1Harrington Department of Bioengineering, Ira A. Fulton School of Engineering Arizona State University, Tempe, AZ 85287, USA. Andrei.Dragomir@asu.edu
Insights
The laryngeal chemoreflex in piglets shows reduced neural complexity during airway protection reflexes like cough and swallow. This indicates synchronized neural activity, contrasting with the more random patterns of normal breathing.
Area of Science:
- Neuroscience
- Respiratory Physiology
- Infant Development
Background:
- The laryngeal chemoreflex is a critical infant airway defense mechanism against liquid aspiration.
- Prolonged apnea during this reflex may be linked to sudden infant death syndrome.
Purpose of the Study:
- To quantify respiratory neural network output during the laryngeal chemoreflex in piglets.
- To test if airway clearance reflexes (cough, swallow) involve synchronized neural activity with lower complexity.
Main Methods:
- Recorded diaphragm EMG, genioglossal EMG, and other physiological signals in early postnatal piglets.
- Utilized nonlinear dynamic analysis (approximate entropy) to assess respiratory pattern complexity.
Main Results:
- Diaphragm EMG complexity was significantly lower during cough (p < 0.05) and swallow (p < 0.01) compared to eupnea.
- Lower complexity suggests synchronized, homogeneous neural network activity during these reflexes.
Conclusions:
- Reduced neural complexity during cough and swallow indicates synchronous activity of specific neuronal groups.
- Higher complexity during eupnea reflects the integrated, more random action of multiple neuronal networks.
Background:
The laryngeal chemoreflex exists in infants as a primary sensory mechanism for defending the airway from the aspiration of liquids. Previous studies have hypothesized that prolonged apnea associated with this reflex may be life threatening and might be a cause of sudden infant death syndrome.
Methods:
In this study we quantified the output of the respiratory neural network, the diaphragm EMG signal, during the laryngeal chemoreflex and eupnea in early postnatal (3-10 days) piglets. We tested the hypothesis that diaphragm EMG activity corresponding to reflex-related events involved in clearance (restorative) mechanisms such as cough and swallow exhibit lower complexity, suggesting that a synchronized homogeneous group of neurons in the central respiratory network are active during these events. Nonlinear dynamic analysis was performed using the approximate entropy to asses the complexity of respiratory patterns.
Results:
Diaphragm EMG, genioglossal activity EMG, as well as other physiological signals (tracheal pressure, blood pressure and respiratory volume) were recorded from 5 unanesthetized chronically instrumented intact piglets. Approximate entropy values of the EMG during cough and swallow were found significantly (p < 0.05 and p < 0.01 respectively) lower than those of eupneic EMG.
Conclusion:
Reduced complexity values of the respiratory neural network output corresponding to coughs and swallows suggest synchronous neural activity of a homogeneous group of neurons. The higher complexity values exhibited by eupneic respiratory activity are the result of a more random behaviour, which is the outcome of the integrated action of several groups of neurons involved in the respiratory neural network.
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