Document Detail

Static and dynamic upper airway obstruction in sleep apnea: role of the breathing gas properties.
MedLine Citation:
PMID:  12869358     Owner:  NLM     Status:  MEDLINE    
Increased upper airway collapsibility in the sleep apnea/hypopnea syndrome (SAHS) is usually interpreted by a collapsible resistor model characterized by a critical pressure (Pcrit) and an upstream resistance (Rup). To investigate the role played by the upstream segment of the upper airway, we tested the hypothesis that breathing different gases would modify Rup but not Pcrit. The study was performed on 10 patients with severe SAHS (apnea-hypopnea index: 59 +/- 14 events/hour) when breathing air and helium-oxygen (He-O2) during non-REM sleep. The continuous positive airway pressure that normalized flow (CPAPopt) was measured. Rup and Pcrit were determined from the linear relationship between maximal inspiratory flow VImax and nasal pressure (PN):VImax = (PN - Pcrit)/Rup. Changing the breathing gas selectively modified the severity of dynamic (CPAPopt, Rup) and static (Pcrit) obstructions. CPAPopt was significantly (p = 0.0013) lower when breathing He-O2 (8.44 +/- 1.66 cm H2O; mean +/- SD) than air (10.18 +/- 2.34 cm H2O). Rup was markedly lower (p = 0.0001) when breathing He-O2 (9.21 +/- 3.93 cm H2O x s/L) than air (15.92 +/- 6.27 cm H2O x s/L). Pcrit was similar (p = 0.039) when breathing He-O2 (4.89 +/- 2.37 cm H2O) and air (4.19 +/- 2.93 cm H2O). The data demonstrate the role played by the upstream segment of the upper airway and suggest that different mechanisms determine static (Pcrit) and dynamic (Rup) upper airway obstructions in SAHS.
Ramon Farré; Jordi Rigau; Josep M Montserrat; Lara Buscemi; Eugeni Ballester; Daniel Navajas
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't     Date:  2003-07-17
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  168     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  2003 Sep 
Date Detail:
Created Date:  2003-09-09     Completed Date:  2003-10-17     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  659-63     Citation Subset:  AIM; IM    
Unitat de Biofísica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Spain.
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MeSH Terms
Airway Obstruction / physiopathology*
Airway Resistance / physiology*
Follow-Up Studies
Middle Aged
Prospective Studies
Pulmonary Gas Exchange*
Risk Assessment
Sampling Studies
Severity of Illness Index
Sleep Apnea Syndromes / diagnosis*,  physiopathology
Sleep Stages

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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