| Imposed work of breathing during ventilator failure. | |
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MedLine Citation:
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PMID: 12036436 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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INTRODUCTION: Ventilators possess an anti-asphyxia valve that allows spontaneous breathing of ambient air during ventilator failure. This study examined the imposed work of breathing and pressure-time product of 8 critical care and 9 portable ventilators, using a laboratory simulation of spontaneous breathing during ventilator failure. METHODS: A test lung was modified to simulate spontaneous breathing with a tidal volume of 0.5 L and peak inspiratory flow of 60 L/min. A pneumotachograph and pressure tap were placed at the proximal airway between the breathing circuit and endotracheal tube. Flow was derived from the pressure drop across the pneumotachograph. Signals were amplified, integrated, and saved to a spreadsheet program, and imposed work of breathing and pressure-time product were calculated. Also measured were the inspiratory pressure required to open the anti-asphyxia valve (cracking pressure), time to cracking pressure, maximum negative inspiratory pressure, and time to maximum negative inspiratory pressure. RESULTS: For the critical care ventilators the mean +/- SD imposed work of breathing ranged from 213.07 +/- 3.53 to 890.63 +/- 0.88 mJ/L and the pressure-time product ranged from 2.67 +/- 0.01 to 13.37 +/- 0.01 cm H(2)O x s/L. For the portable ventilators the mean +/- SD imposed work of breathing ranged from 361.37 +/- 1.22 to 969.60 +/- 22.70 mJ/L and the pressure-time product ranged from 4.52 +/- 0.01 to 16.70 +/- 0.37 cm H(2)O x s/L. CONCLUSIONS: Spontaneous breathing during ventilator failure may impose work approximating the physiologic work of breathing. This imposed work may prevent effective breathing through the anti-asphyxia valve during mechanical ventilator failure due to electrical failure. These results reinforce the need to properly monitor mechanically ventilated patients and to have in place sufficient back-up power supplies and a method of manual ventilation. |
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Authors:
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Paul N Austin; Robert S Campbell; Jay A Johannigman; Richard D Branson |
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Publication Detail:
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Type: Journal Article |
Journal Detail:
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Title: Respiratory care Volume: 47 ISSN: 0020-1324 ISO Abbreviation: Respir Care Publication Date: 2002 Jun |
Date Detail:
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Created Date: 2002-05-30 Completed Date: 2002-08-02 Revised Date: 2004-11-17 |
Medline Journal Info:
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Nlm Unique ID: 7510357 Medline TA: Respir Care Country: United States |
Other Details:
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Languages: eng Pagination: 667-74 Citation Subset: IM |
Affiliation:
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Department of Nurse Anesthesia, Graduate School of Nursing, Uniformed Services University of the Health Sciences, Silver Spring, Maryland 20910, USA. paustin@usuhs.mil |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Equipment Design Equipment Failure Humans Materials Testing Models, Biological Respiration, Artificial* / adverse effects, instrumentation Ventilators, Mechanical* / adverse effects Work of Breathing* |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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