[Responses of the respiratory system to changes in gas density at different inspiratory flow rates].
The effect of altered gas density on the respiratory function was investigated in relation to the velocity of gas flows in airways. In the normal man breathing of normoxic He-O2 (with a density of 0,34 as compared to air) slightly decreased and inhalation of SF6-O2 (with a density of 4.2) significantly increased the metabolic rate of 1 1 ventilation. These effects were distinct when inspiratory flows reached threshold values. In anesthesized cats, He-O2 breathing reduced inspiratory activity upon forced respiration, and SF6-O2 breathing increased it upon quiet respiration. These findings can be used to predict limiting densities of respiratory mixtures for a normal man performing physical work of a certain load undersea.
D000818:Animals; D001696:Biomechanical Phenomena; D002415:Cats; D005740:Gases; D006371:Helium; D006801:Humans; D008297:Male; D008451:Maximal Voluntary Ventilation; D010100:Oxygen; D012123:Pulmonary Ventilation; D012143:Respiratory Physiological Phenomena; D013459:Sulfur Hexafluoride; D014939:Work of Breathing
D005740:Gases; D006371:Helium; D010100:Oxygen; D013459:Sulfur Hexafluoride
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