| Spontaneously breathing anesthetized patients with a laryngeal mask airway: positive end-expiratory pressure does not improve oxygen saturation. | |
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MedLine Citation:
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PMID: 20835692 Owner: NLM Status: In-Process |
Abstract/OtherAbstract:
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Spontaneous ventilation is a popular mode of ventilation for patients with the laryngeal mask airway (LMA). Studies have shown, however, that spontaneous ventilation impairs gas exchange and that assisting or controlling ventilation results in higher oxygen saturation. Atelectasis during general anesthesia is a well described mechanism which impacts on gas exchange. Positive end-expiratory pressure (PEEP) increases the lung volume available for gas exchange. This study investigated whether the application of PEEP leads to an improvement of oxygen saturation in unassisted spontaneously breathing patients with a LMA. A total of 80 adult patients under general anesthesia were prospectively randomized into two groups. Both groups were left to breathe spontaneously. In group 1 the adjustable pressure limiting (APL) valve was opened resulting in zero end-expiratory pressure. In group 2 the valve was set to a PEEP of +7 cm H₂O. Oxygen saturation was measured by pulse oxymetry at four different phases: pre-induction, after induction and insertion of the LMA, during maintenance and in recovery. The application of PEEP did not improve oxygen saturation. In both groups the mean oxygen saturation was similar (97.2±1.8% in group 1 versus 97.2±1.9% in group 2, p=0.941) during maintenance. No effect on oxygen saturation in recovery could be found either (96.0±1.8% in group 1 versus 96.1±2.0% in group 2, p=0.952) and hemodynamics were unaffected by the application of PEEP. The application of a PEEP of +7 cm H₂O with a LMA under spontaneous ventilation cannot be recommended. Limitations of our study were the selection of healthy patients and omitting pre-oxygenation before induction which might have limited the development of atelectasis. In addition arterial partial pressure of oxygen (p(a)O₂) measurements could have revealed subtle changes in oxygenation. |
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Authors:
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B Froessler; J Brommundt; J Anton; R Khanduja; R Kuhlen; R Rossaint; M Coburn |
Publication Detail:
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Type: Journal Article Date: 2010-09-11 |
Journal Detail:
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Title: Der Anaesthesist Volume: 59 ISSN: 1432-055X ISO Abbreviation: Anaesthesist Publication Date: 2010 Nov |
Date Detail:
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Created Date: 2010-11-24 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 0370525 Medline TA: Anaesthesist Country: Germany |
Other Details:
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Languages: eng Pagination: 1003-4, 1006-7 Citation Subset: IM |
Affiliation:
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Department of Anaesthesia, Lyell McEwin Hospital, Haydown Road, 5112 Elizabeth Vale, South Australia. bernd.froessler@health.sa.gov.au |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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