Identification of respiratory vagal feedback in awake normal subjects using pseudorandom unloading

Departments of 1  Physiology and 2  Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03756 Evidence of the Hering-Breuer reflex has been found in humans during anesthesia and sleep but not during wakefulness. Cortical influences, present during wakefulness, may mask the effects of this ref...

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Bibliographic Details
Published in:Journal of applied physiology (1985) 2001-06, Vol.90 (6), p.2330-2340
Main Authors: BuSha, Brett F, Judd, Brooke G, Manning, Harold L, Simon, Peggy M, Searle, Brian C, Daubenspeck, J. Andrew, Leiter, J. C
Format: Article
Language:English
Subjects:
Adult
Air Pressure
Biological and medical sciences
Cardiorespiratory control. Arterial mecano- and chemoreceptor
Feedback - physiology
Fundamental and applied biological sciences. Psychology
Humans
Lungs
Models, Biological
Nervous system
Reflexes
Respiration, Artificial
Respiratory Mechanics - physiology
Respiratory system
Respiratory therapy
Software
Tidal Volume - physiology
Vagus Nerve - physiology
Vertebrates: respiratory system
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Summary:Departments of 1  Physiology and 2  Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03756 Evidence of the Hering-Breuer reflex has been found in humans during anesthesia and sleep but not during wakefulness. Cortical influences, present during wakefulness, may mask the effects of this reflex in awake humans. We hypothesized that, if lung volume were increased in awake subjects unaware of the stimulus, vagal feedback would modulate breathing on a breath-to-breath basis. To test this hypothesis, we employed proportional assist ventilation in a pseudorandom sequence to unload the respiratory system above and below the perceptual threshold in 17 normal subjects. Tidal volume, integrated respiratory muscle pressure per breath, and inspiratory time were recorded. Both sub- and suprathreshold stimulation evoked a significant increase in tidal volume and inspiratory flow rate, but a significant decrease in inspiratory time was present only during the application of a subthreshold stimulus. We conclude that vagal feedback modulates respiratory timing on a breath-by-breath basis in awake humans, as long as there is no awareness of the stimulus. proportional-assist ventilation; system identification; vagus; control of respiration
ISSN:8750-7587
1522-1601
DOI:10.1152/jappl.2001.90.6.2330