Document Detail


Fluid shift by lower body positive pressure increases pharyngeal resistance in healthy subjects.
MedLine Citation:
PMID:  16998093     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
INTRODUCTION: Fluid displacement into nuchal and peripharyngeal soft tissues while recumbent may contribute to narrowing and increased airflow resistance of the pharynx (Rph), and predispose to pharyngeal collapse in patients at risk for obstructive sleep apnea. OBJECTIVES: To determine whether displacement of fluid from the lower body to the neck will increase both neck circumference and Rph in healthy subjects. METHODS: In 11 healthy, nonobese subjects, studied while awake and supine, leg fluid volume, neck circumference, and Rph were measured at baseline. Subjects were then randomized to a control period or to application of lower body positive pressure (LBPP) of 40 mm Hg via antishock trousers to displace fluid from the legs, after which they crossed over to the other arm. Baseline measurements were repeated at 1 and 5 min during the control and LBPP periods. RESULTS: Compared with the control period, application of LBPP caused a significant reduction in leg fluid volume (p < 0.001) and a significant increase in neck circumference (p = 0.004). Rph remained stable during the control period, but increased significantly from baseline after 1 and 5 min of LBPP (from 0.43 +/- 0.10 to 0.60 +/- 0.11 cm H(2)O/L/s, p = 0.034, and to 0.87 +/- 0.19 cm H(2)O/L/s, p < 0.001, compared with baseline, respectively). CONCLUSIONS: Fluid displacement from the legs by LBPP increases neck circumference and Rph in healthy subjects. These findings suggest the hypothesis that fluid displacement to the upper body during recumbency may predispose to pharyngeal obstruction during sleep, especially in fluid overload states, such as heart and renal failure.
Authors:
Kuo-Liang Chiu; Clodagh M Ryan; Satomi Shiota; Pimon Ruttanaumpawan; Michael Arzt; James S Haight; Christopher T Chan; John S Floras; T Douglas Bradley
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Publication Detail:
Type:  Journal Article; Randomized Controlled Trial; Research Support, Non-U.S. Gov't     Date:  2006-09-22
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  174     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-12-12     Completed Date:  2007-01-26     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1378-83     Citation Subset:  AIM; IM    
Affiliation:
Sleep Research Laboratory, Toronto Rehabilitation Institute, Canada.
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MeSH Terms
Descriptor/Qualifier:
Adult
Airway Resistance / physiology*
Female
Fluid Shifts / physiology*
Humans
Male
Middle Aged
Neck / physiology
Pharynx / physiology*
Pressure*

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