Respiration and State of Wakefulness in Normals, Studied by Spirography, Capnography and EEG: A preliminary report

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Abstract
Bülow K. and D. H. Ingvar. Respiration and state of wakefulness. studied by spirography, capnography and EEG.In sixteen normal subjects the relation between the state of wakefulness and the respiration was studied by recording continuously the ventilation (spirography), the alveolar carbon dioxide tension (capnography) and the EEG. Records were obtained in the resting state awake, in drowsiness and, in nine of the subjects, in sleep and during arousal. It was confirmed that ventilation decreases and that the alveolar carbon dioxide tension increases in sleep (Magnussen 1944). When the EEG showed a stable pattern of e. g. alpha‐activity, or sleep waves, the breath to breath variations in ventilation and alveolar carbon dioxide tension were small at respective levels. There was in all the sixteen cases a close correlation in time between sudden changes in EEG and changes in the respiratory variables recorded. The findings suggest a close functional relationship between the respiratory centers of the brain stem and the reticular activating system which supposedly controls the cortical state of excitability.