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Respiratory muscle function during emesis in awake canines
1Respiratory Research Group, University of Calgary, Alberta, Canada.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|June 1, 1994
Summary
Vomiting (emesis) involves coordinated muscle activity, including respiratory muscles, to expel stomach contents. This study reveals synchronized muscle activation during emesis, highlighting brainstem control over respiration and vomiting.
Area of Science:
- Physiology
- Neuroscience
Background:
- Emesis necessitates complex coordination between gastrointestinal, airway, and respiratory muscles.
- Understanding the precise muscular and respiratory dynamics during emesis is crucial for elucidating its neural control.
Purpose of the Study:
- To investigate the coordinated electromyographical and mechanical activity of respiratory muscles during induced emesis in canines.
- To characterize the distinct respiratory phases associated with the emesis process.
Main Methods:
- Electromyography and muscle segment length were measured in awake canines during apomorphine-induced emesis.
- Respiratory muscle activity was analyzed across four identified phases: Baseline Ventilation, Hyperventilation, Prodrome, and Expulsion.
Main Results:
- Emesis exhibited four distinct respiratory phases, with ventilation suppressed during expulsive events.
- Synchronous activation of inspiratory and expiratory muscles occurred during expulsive maneuvers, differing from normal ventilation.
- Significant muscle shortening was observed in diaphragm segments and transversus abdominis, with the crural diaphragm showing a biphasic length change.
Conclusions:
- The findings demonstrate a tightly coordinated interplay between respiratory and emetic control centers in the brainstem.
- Emesis involves a unique, coordinated recruitment and activation pattern of respiratory muscles, distinct from normal breathing patterns.