| Paradoxical responses to positive end-expiratory pressure in patients with airway obstruction during controlled ventilation. | |
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MedLine Citation:
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PMID: 16003057 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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OBJECTIVE: To reevaluate the clinical impact of external positive end-expiratory pressure (external-PEEP) application in patients with severe airway obstruction during controlled mechanical ventilation. The controversial occurrence of a paradoxic lung deflation promoted by PEEP was scrutinized. DESIGN: External-PEEP was applied stepwise (2 cm H(2)O, 5-min steps) from zero-PEEP to 150% of intrinsic-PEEP in patients already submitted to ventilatory settings minimizing overinflation. Two commonly used frequencies during permissive hypercapnia (6 and 9/min), combined with two different tidal volumes (VT: 6 and 9 mL/kg), were tested. SETTING: A hospital intensive care unit. PATIENTS: Eight patients were enrolled after confirmation of an obstructive lung disease (inspiratory resistance, >20 cm H(2)O/L per sec) and the presence of intrinsic-PEEP (> or =5 cm H(2)O) despite the use of very low minute ventilation. INTERVENTIONS: All patients were continuously monitored for intra-arterial blood gas values, cardiac output, lung mechanics, and lung volume with plethysmography. MEASUREMENTS AND MAIN RESULTS: Three different responses to external-PEEP were observed, which were independent of ventilatory settings. In the biphasic response, isovolume-expiratory flows and lung volumes remained constant during progressive PEEP steps until a threshold, beyond which overinflation ensued. In the classic overinflation response, any increment of external-PEEP caused a decrease in isovolume-expiratory flows, with evident overinflation. In the paradoxic response, a drop in functional residual capacity during external-PEEP application (when compared to zero-external-PEEP) was commonly accompanied by decreased plateau pressures and total-PEEP, with increased isovolume-expiratory flows. The paradoxic response was observed in five of the eight patients (three with asthma and two with chronic obstructive pulmonary disease) during at least one ventilator pattern. CONCLUSIONS: External-PEEP application may relieve overinflation in selected patients with airway obstruction during controlled mechanical ventilation. No a priori information about disease, mechanics, or ventilatory settings was predictive of the response. An empirical PEEP trial investigating plateau pressure response in these patients appears to be a reasonable strategy with minimal side effects. |
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Authors:
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Maria Paula Caramez; Joao B Borges; Mauro R Tucci; Valdelis N Okamoto; Carlos R R Carvalho; Robert M Kacmarek; Atul Malhotra; Irineu Tadeu Velasco; Marcelo B P Amato |
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Publication Detail:
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Type: Journal Article; Research Support, Non-U.S. Gov't |
Journal Detail:
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Title: Critical care medicine Volume: 33 ISSN: 0090-3493 ISO Abbreviation: Crit. Care Med. Publication Date: 2005 Jul |
Date Detail:
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Created Date: 2005-07-08 Completed Date: 2005-08-11 Revised Date: 2011-03-14 |
Medline Journal Info:
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Nlm Unique ID: 0355501 Medline TA: Crit Care Med Country: United States |
Other Details:
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Languages: eng Pagination: 1519-28 Citation Subset: AIM; IM |
Affiliation:
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Respiratory and Emergency Intensive Care Unit, Emergency Department, Hospital das Clínicas, University of São Paulo Medical School, Brazil. |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Adult Aged Aged, 80 and over Airway Obstruction / complications*, physiopathology, therapy* Asthma / complications, physiopathology, therapy Female Hemodynamics Humans Lung Volume Measurements Male Middle Aged Monitoring, Physiologic Positive-Pressure Respiration / adverse effects* Pulmonary Disease, Chronic Obstructive / complications, physiopathology, therapy Ventilators, Mechanical |
| Grant Support | |
ID/Acronym/Agency:
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K23 AG024837-02/AG/NIA NIH HHS; R01 HL073146-02/HL/NHLBI NIH HHS |
| Comments/Corrections | |
Comment In:
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Crit Care Med. 2005 Dec;33(12):2860
[PMID:
16352983
]
Crit Care Med. 2005 Jul;33(7):1652-3 [PMID: 16003082 ] |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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