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Effects of the components of positive airway pressure on work of breathing during bronchospasm.

Miro, AM and Pinsky, MR and Rogers, PL (2004) Effects of the components of positive airway pressure on work of breathing during bronchospasm. Critical care (London, England), 8 (2).

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INTRODUCTION: Partial assist ventilation reduces work of breathing in patients with bronchospasm; however, it is not clear which components of the ventilatory cycle contribute to this process. Theoretically, expiratory positive airway pressure (EPAP), by reducing expiratory breaking, may be as important as inspiratory positive airway pressure (IPAP) in reducing work of breathing during acute bronchospasm. METHOD: We compared the effects of 10 cmH2O of IPAP, EPAP, and continuous positive airwaypressure (CPAP) on inspiratory work of breathing and end-expiratory lung volume (EELV) in a canine model of methacholine-induced bronchospasm. RESULTS: Methacholine infusion increased airway resistance and work of breathing. During bronchospasm IPAP and CPAP reduced work of breathing primarily through reductions in transdiaphragmatic pressure per tidal volume (from 69.4 +/- 10.8 cmH2O/l to 45.6 +/- 5.9 cmH2O/l and to 36.9 +/- 4.6 cmH2O/l, respectively; P < 0.05) and in diaphragmatic pressure-time product (from 306 +/- 31 to 268 +/- 25 and to 224 +/- 23, respectively; P < 0.05). Pleural pressure indices of work of breathing were not reduced by IPAP and CPAP. EPAP significantly increased all pleural and transdiaphragmatic work of breathing indices. CPAP and EPAP similarly increased EELV above control by 93 +/- 16 ml and 69 +/- 12 ml, respectively. The increase in EELV by IPAP of 48 +/- 8 ml (P < 0.01) was significantly less than that by CPAP and EPAP. CONCLUSION: The reduction in work of breathing during bronchospasm is primarily induced by the IPAP component, and that for the same reduction in work of breathing by CPAP, EELV increases more.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Miro, AM
Pinsky, MRpinsky@pitt.eduPINSKY0000-0001-6166-700X
Rogers, PL
Date: 1 January 2004
Date Type: Publication
Journal or Publication Title: Critical care (London, England)
Volume: 8
Number: 2
Schools and Programs: School of Medicine > Critical Care Medicine
Refereed: Yes
PubMed Central ID: PMC420031
PubMed ID: 15025781
Date Deposited: 05 Apr 2012 21:57
Last Modified: 30 Jan 2020 16:55


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