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Respiratory changes induced by prolonged laryngeal stimulation in awake piglets
Journal of Applied Physiology (Bethesda, Md. : 1985)
|September 1, 1986
Summary
The laryngeal reflex significantly impacts breathing in piglets, causing reduced respiratory rate and pauses, but does not threaten cardiovascular stability. This reflex is sustained by arousal mechanisms during stimulation.
Area of Science:
- Cardiorespiratory Physiology
- Neuroscience
- Developmental Biology
Background:
- The laryngeal reflex plays a crucial role in protecting the airway and modulating cardiorespiratory function.
- Understanding its specific effects in developing mammals is essential for neonatal care and respiratory research.
Purpose of the Study:
- To investigate the cardiorespiratory effects of superior laryngeal nerve (SLN) stimulation in young piglets.
- To determine the role of arousal in sustaining breathing during laryngeal reflex activation.
Main Methods:
- Bilateral electrical stimulation of SLN in unanesthetized, instrumented piglets (n=10, 5-14 days old).
- Recording of ventilation (whole-body plethysmography), electroencephalogram, electrocardiogram, blood pressure, and arterial blood gases.
- Analysis of cardiorespiratory parameters during a 1-hour SLN stimulation period.
Main Results:
- SLN stimulation led to a 40-75% decrease in respiratory frequency with regular apneas.
- Minute ventilation decreased by 57%, PaO2 dropped by 68 Torr, and PaCO2 increased by 19 Torr.
- Mean blood pressure and heart rate remained stable, with breathing episodes linked to arousal (eye opening, movements).
Conclusions:
- Low-threshold SLN afferents primarily affect respiration with minimal cardiovascular impact.
- Breathing during laryngeal reflex activation is sustained by an arousal system.
- The laryngeal reflex does not pose an immediate threat to awake, young animals.