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Central respiratory carbon dioxide chemosensitivity does not decrease during sleep.
R A Parisi1, N H Edelman, T V Santiago
1Department of Medicine, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, New Brunswick 08903-0019.
The American Review of Respiratory Disease
|April 1, 1992
Summary
Central CO2 chemosensitivity remains intact during sleep, despite reduced ventilatory responses. Increased brain blood flow during REM sleep, not altered chemoreceptor sensitivity, explains these changes in breathing regulation.
Area of Science:
- Physiology
- Neuroscience
- Sleep Medicine
Background:
- Ventilatory response to CO2 decreases during slow-wave sleep (SWS) and rapid-eye-movement (REM) sleep.
- The extent to which decreased CO2 chemoreflex sensitivity contributes to this is unknown.
- Mechanical factors or altered brain blood flow (BBF) during sleep may affect ventilatory output.
Purpose of the Study:
- To investigate the central CO2 chemosensitivity during different sleep-wake states.
- To determine the role of diaphragmatic electromyogram (EMGdI) and BBF in ventilatory changes during sleep.
- To differentiate between altered chemosensitivity and mechanical factors influencing breathing during sleep.
Main Methods:
- Measurements of ventilatory (VI), diaphragmatic electromyogram (EMGdI), and BBF responses to CO2 rebreathing in 10 goats across wakefulness, SWS, and REM sleep.
- Analysis of the relationship between VI, EMGdI, and BBF changes relative to PaCO2.
- Correlation analysis between EMGdI and BBF responses, and relationship of EMGdI to cerebral venous PCO2.
Main Results:
- Ventilatory response to CO2 (delta VI/delta PaCO2) decreased significantly from wakefulness to SWS and REM sleep.
- Diaphragmatic activity response to CO2 (delta EMGdI/delta PaCO2) decreased only during REM sleep.
- Brain blood flow response to CO2 (delta BBF/delta PaCO2) increased during REM sleep, with a significant inverse correlation between delta EMGdI/delta PaCO2 and delta BBF/delta PaCO2.
Conclusions:
- Central CO2 chemosensitivity is intact during all sleep-wake states.
- Increased BBF during REM sleep, rather than reduced chemosensitivity, contributes to the blunted ventilatory response.
- The findings suggest that neural control of breathing during sleep is maintained, with adjustments in cerebrovascular and respiratory muscle activity.
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