Document Detail

Density dependence of forced expiratory flows in healthy infants and toddlers.
MedLine Citation:
PMID:  10562624     Owner:  NLM     Status:  MEDLINE    
In older children and adults, density dependence (DD) of forced expiratory flow is present over the majority of the full flow-volume curve. In healthy subjects, DD occurs because the pressure drop from peripheral to central airways is primarily dependent on turbulence and convective acceleration rather than laminar resistance; however, an increase in peripheral resistance reduces DD. We measured DD of forced expiratory flow in 22 healthy infants to evaluate whether infants have low DD. Full forced expiratory maneuvers were obtained while the subjects breathed room air and then a mixture of 80% helium-20% oxygen. Flows at 50 and 75% of expired forced vital capacity (FVC) were measured, and the ratio of helium-oxygen to air flow was calculated (DD at 50 and 75% FVC). The mean (range) of DD at 50 and 75% FVC was 1.37 (1.22-1.54) and 1.23 (1.02-1.65), respectively, values similar to those reported in older children and adults. There were no significant relationships between DD and age. Our results suggest that infants, compared with older children and adults, have similar DD, a finding that suggests that infants do not have a greater ratio of peripheral-to-central airway resistance.
S Davis; M Jones; J Kisling; R Castile; R S Tepper
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Publication Detail:
Type:  Clinical Trial; Journal Article    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  87     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1999 Nov 
Date Detail:
Created Date:  1999-12-22     Completed Date:  1999-12-22     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:  1796-801     Citation Subset:  IM    
James Whitcomb Riley Hospital for Children, Indianapolis, Indiana 46202-5225, USA.
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MeSH Terms
Aging / physiology*
Airway Resistance / physiology
Forced Expiratory Flow Rates / physiology*
Residual Volume / physiology
Sex Characteristics
Vital Capacity / physiology
Reg. No./Substance:
7440-59-7/Helium; 7782-44-7/Oxygen

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

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