| Influence of body position on pressure and airflow generation during hypoxia and hypercapnia in man. | |
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MedLine Citation:
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PMID: 8229846 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. Inspiratory oesophageal pressure and ventilatory responses to hyperoxic, progressive hypercapnic rebreathing (HCVR) and isocapnic, progressive hypoxic rebreathing (HVR) were studied in five normal males in both supine and upright seated positions. 2. No significant differences were found in the ventilatory response to hypercapnia between the supine and upright position. The slopes of the relationship between minute ventilation (VI) and the increase of end tidal PCO2 (delta P(ET), CO2) were 3.27 +/- 0.23 and 2.76 +/- 0.24 1 min-1 mmHg-1 supine and upright, respectively. However, the change in oesophageal pressure from the end expiratory level observed during quiet breathing to that at peak inspiration (delta P(oes), I) in relationship to delta P(ET),CO2 was greater supine than upright (1.23 +/- 0.07 versus 0.79 +/- 0.11 cmH2O mmHg-1, P < 0.01). 3. In contrast, during hypoxia-stimulated breathing the slope of the minute ventilation versus oxyhaemoglobin saturation curve (VI-Sa,O2) was flatter supine than upright (1.00 +/- 0.03 versus 1.75 +/- 0.05 l min-1 (percentage fall in Sa,O2)-1, P < 0.0001), but delta P(oes), I in relation to Sa,O2 during hypoxic rebreathing was similar supine and upright (0.38 +/- 0.03 versus 0.40 +/- 0.04 cmH2O (percentage fall in Sa,O2)-1, respectively. 4. It is concluded that body position does not affect the ventilatory response to progressive hyperoxic hypercapnia but does affect the relationship between delta P(oes), I and delta P(ET),CO2. In contrast, body position affects the ventilatory response to isocapnic progressive hypoxia, but does not affect the relationship between delta P(oes), I and Sa,O2. |
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Authors:
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A Xie; Y Takasaki; J Popkin; D Orr; T D Bradley |
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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: The Journal of physiology Volume: 465 ISSN: 0022-3751 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 1993 Jun |
Date Detail:
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Created Date: 1993-11-29 Completed Date: 1993-11-29 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 477-87 Citation Subset: IM; S |
Affiliation:
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Sleep Research Laboratory, Queen Elizabeth Hospital, Toronto, Ontario, Canada. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Adult Air Pressure Anoxia / physiopathology* Carbon Dioxide / blood Esophagus / physiology Humans Hypercapnia / physiopathology* Male Posture / physiology* Respiratory Mechanics / physiology Supine Position / physiology Tidal Volume / physiology |
| Chemical | |
Reg. No./Substance:
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124-38-9/Carbon Dioxide |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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