title: Expirograms of O2, CO2 and intravenously infused C2H2 and Freon-22 during panting in dogs.
abstract: To study pulmonary gas transport in panting, expirograms of several inert and respiratory gases were simultaneously measured in panting dogs. The experiments were performed on 5 conscious dogs (mean body weight 34.4 kg) provided with a chronic tracheostomy. Panting at a mean frequency of 312/min (5.2 Hz) was induced by elevated room temperature (mean 28.1 degrees C). Isotonic saline equilibrated with 50% acetylene and 50% Freon-22 was infused intravenously at a constant rate (4 ml/min). Fractional concentrations in the tracheostomy tube were measured by a respiratory mass spectrometer, using a special sampling system designed for quasi-continuous analysis of rapidly changing gas concentrations. Air flow was monitored by an ultrasonic transit-time flowmeter. A tracing of expired gas concentrations versus expired volume showed no alveolar plateau, displaying a steep increase of Freon-22, acetylene and CO2 (decrease of O2) up to the onset of inspiration. The small but statistically highly significant differences between the expirograms of CO2 and O2, and of Freon-22 and acetylene, could be qualitatively explained by ventilation-perfusion inequalities with sequential emptying, by Taylor dispersion and by reversible solution in airway mucosa in the course of the respiratory cycle.
authors.affiliation: Abteilung Physiologie, Max-Planck-Institut für experimentelle Medizin, Göttingen, F.R.G.
authors.forename: I
authors.initials: I
authors.lastname: Sipinková
authors.forename: G
authors.initials: G
authors.lastname: Hahn
authors.forename: A
authors.initials: A
authors.lastname: Hillebrecht
authors.forename: M
authors.initials: M
authors.lastname: Meyer
authors.forename: J
authors.initials: J
authors.lastname: Piiper
mesh_terms: D000114:Acetylene / Q000008:administration & dosage* / Q000378:metabolism; D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism*; D005617:Chlorofluorocarbons, Methane / Q000008:administration & dosage*; D004058:Diffusion; D004285:Dogs; D005260:Female; D007262:Infusions, Intravenous; D008168:Lung / Q000378:metabolism / Q000502:physiology*; D008176:Lung Volume Measurements / Q000379:methods; D008297:Male; D010100:Oxygen / Q000378:metabolism*; D012119:Respiration / Q000502:physiology*; D012129:Respiratory Function Tests; D013696:Temperature
chemical_list: D005617:Chlorofluorocarbons, Methane; D002245:Carbon Dioxide; C009755:fluorocarbon 22; D000114:Acetylene; D010100:Oxygen