Effect of hypoxia on respiratory system impedance in dogs

B. A. Simon, P. B. Zanaboni, D. P. Nyhan

Research output: Contribution to journalArticle

Abstract

The effects of hypoxia on lung and airway mechanics remain controversial, possibly because of the confounding effects of competing reflexes caused by systemic hypoxemia. We compared the effects of systemic hypoxemia with those of unilateral alveolar hypoxia (with systemic normoxemia) on unilateral respiratory system impedance (Z) in intact, anesthetized dogs. Independent lung ventilation was obtained with a Kottmeier endobronchial tube. Individual left and right respiratory system Z was measured during sinusoidal forcing with 45 ml of volume at frequencies of 0.2-2.1 Hz during control [100% inspired O2 fraction (FI(O2))], systemic hypoxemia (10% FI(O2)), and unilateral alveolar hypoxia (0% FI(O2) to left lung, 100% FI(O2) to right lung). During systemic hypoxemia, there was a mean Z magnitude increase of 18%. This change was entirely attributable to a decrease in the imaginary component of Z; there was no change in the real component of Z. Administration of atropine (0.2 mg/kg) did not block the increase in Z with systemic hypoxemia. In contrast, there was no change in Z in the lung subjected to unilateral alveolar hypoxia. We conclude that alveolar hypoxia has no direct effect on lung mechanical properties in intact dogs. In contrast, systemic hypoxemia does increase lung impedance, apparently through a noncholinergic mechanism.

Original languageEnglish (US)
Pages (from-to)451-458
Number of pages8
JournalJournal of applied physiology
Volume83
Issue number2
StatePublished - Aug 1 1997

Keywords

  • Atropine
  • Compliance
  • Hypoxemia
  • Hypoxic pulmonary vasoconstriction
  • Lung mechanics
  • Resistance

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

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