Document Detail


Effect of surface tension of mucosal lining liquid on upper airway mechanics in anesthetized humans.
MedLine Citation:
PMID:  12626492     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Upper airway (UA) patency may be influenced by surface tension (gamma) operating within the (UAL). We examined the role of gamma of UAL in the maintenance of UA patency in eight isoflurane-anesthetized supine human subjects breathing via a nasal mask connected to a pneumotachograph attached to a pressure delivery system. We evaluated 1). mask pressure at which the UA closed (Pcrit), 2). UA resistance upstream from the site of UA collapse (RUS), and 3). mask pressure at which the UA reopened (Po). A multiple pressure-transducer catheter was used to identify the site of airway closure (velopharyngeal in all subjects). UAL samples (0.2 microl) were collected, and the gamma of UAL was determined by using the "pull-off force" technique. Studies were performed before and after the intrapharyngeal instillation of 5 ml of exogenous surfactant (Exosurf, Glaxo Smith Kline). The gamma of UAL decreased from 61.9 +/- 4.1 (control) to 50.3 +/- 5.0 mN/m (surfactant; P < 0.02). Changes in Po, RUS, and Po - Pcrit (change = control - surfactant) were positively correlated with changes in gamma (r2 > 0.6; P < 0.02) but not with changes in Pcrit (r2 = 0.4; P > 0.9). In addition, mean peak inspiratory airflow (no flow limitation) significantly increased (P < 0.04) from 0.31 +/- 0.06 (control) to 0.36 +/- 0.06 l/s (surfactant). These findings suggest that gamma of UAL exerts a force on the UA wall that hinders airway opening. Instillation of exogenous surfactant into the UA lowers the gamma of UAL, thus increasing UA patency and augmenting reopening of the collapsed airway.
Authors:
Jason P Kirkness; Peter R Eastwood; Irene Szollosi; Peter R Platt; John R Wheatley; Terence C Amis; David R Hillman
Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't     Date:  2003-03-07
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  95     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2003 Jul 
Date Detail:
Created Date:  2003-06-09     Completed Date:  2004-02-02     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  357-63     Citation Subset:  IM    
Affiliation:
Ludwig Engel Centre for Respiratory Research, Westmead Hospital and University of Sydney, Westmead, New South Wales, 2145, Australia. jason_kirkness@wmi.usyd.edu.au
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MeSH Terms
Descriptor/Qualifier:
Adult
Anesthesia*
Electromyography
Female
Humans
Male
Middle Aged
Muscle, Skeletal / drug effects,  physiology
Pharynx / physiology
Pulmonary Surfactants / pharmacology
Respiration, Artificial
Respiratory Mechanics / physiology*
Respiratory Mucosa / physiology*
Surface Tension
Chemical
Reg. No./Substance:
0/Pulmonary Surfactants

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


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