Effects of hyperinflation and CPAP on work of breathing and respiratory failure in dogs

E. Shade, Y. Kawagoe, Roy G Brower, S. Permutt, Henry Eric Fessler

Research output: Contribution to journalArticle

Abstract

Increased end-expiratory lung volume (EELV) and airway resistance are both characteristic features of obstructive lung disease. Increased EELV alone loads the respiratory muscles and may cause respiratory failure, changes that could be reversed by continuous positive airway pressure (CPAP). To study the effects of elevated EELV on respiration without increased airway resistance, we used a mechanical analogue of airway closure to increase EELV in six spontaneously breathing anesthetized dogs. Hyperinflation of 0.84 ± 0.11 liter for 30 min decreased minute ventilation from 4.8 ± 0.37 to 3.5 ± 0.21 l/min and increased arterial PCO2 from 40.3 ± 1.5 to 73.2 ± 8.1 Torr (both P <0.01). Inspiratory work per breath increased 3-fold, work per liter increased 3.7-fold, and work per minute increased 2.8-fold (all P <0.01). CPAP at 15 cmH2O restored minute ventilation to 4.3 ± 0.3 l/min and reduced arterial PCO2 to 54 ± 6.6 Torr (NS vs. baseline). All measurements of inspiratory work were also restored to baseline, but cardiac output was reduced (baseline 3.09 ± 0.36, hyperinflation 2.71 ± 0.36, hyperinflation + CPAP 1.94 ± 0.29 l/min; P <0.05, baseline vs. hyperinflation + CPAP). We conclude that increases in EELV mimic important features of airway obstruction, increase inspiratory work, and can cause respiratory failure independent of increased airway resistance. This respiratory failure is reversed by CPAP at the potential expense of hemodynamic compromise.

Original languageEnglish (US)
Pages (from-to)819-827
Number of pages9
JournalJournal of Applied Physiology
Volume77
Issue number2
StatePublished - 1994

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Work of Breathing
Continuous Positive Airway Pressure
Respiratory Insufficiency
Airway Resistance
Dogs
Lung
Ventilation
Respiration
Obstructive Lung Diseases
Respiratory Muscles
Airway Obstruction
Cardiac Output
Hemodynamics

Keywords

  • continuous positive airway pressure
  • hypercapnia
  • pleural pressure
  • ventilation

ASJC Scopus subject areas

  • Endocrinology
  • Physiology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Effects of hyperinflation and CPAP on work of breathing and respiratory failure in dogs. / Shade, E.; Kawagoe, Y.; Brower, Roy G; Permutt, S.; Fessler, Henry Eric.

In: Journal of Applied Physiology, Vol. 77, No. 2, 1994, p. 819-827.

Research output: Contribution to journalArticle

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