Document Detail

Variations in flows and pressures during jet ventilation in the infant: a model study.
MedLine Citation:
PMID:  8196999     Owner:  NLM     Status:  MEDLINE    
Ventilatory flow rates with either He-O2 (heliox) or N2-O2 (nitrox) mixtures during high frequency jet ventilation (HFJV) were calculated using a mathematical model, and were measured in a physical monoalveolar model of the infant lung. A constant flow was delivered to the model (Vd) drawing with it an entrained flow (Ve). When the inspiratory time (Tl) was long, a back flow (Vr) was generated that increased progressively as the alveolar pressure increased. In order to reduce Vr, the reflux time (Tr), i.e., the time needed for the injected gas to reflux, was measured (Trm) and calculated (Trc) with the model. The Tr depends on both chest-lung compliance and resistance to reflux as well as on the Ve/Vd ratio. For a given setting of the ventilator, values of Trm and Trc were significantly lower with heliox than nitrox (P < 0.01), and the correlation between Trm and Trc were fair with both gases. Tidal volume (VT) was calculated when the Tl was interrupted at Tr. The values of VT were significantly higher with helix than nitrox (P < 0.05). It is concluded that the evaluation of Tr during HFJV may provide useful information for setting the ventilator.
A Belaguid; H Guenard
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Pediatric pulmonology     Volume:  17     ISSN:  8755-6863     ISO Abbreviation:  Pediatr. Pulmonol.     Publication Date:  1994 Mar 
Date Detail:
Created Date:  1994-06-30     Completed Date:  1994-06-30     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  8510590     Medline TA:  Pediatr Pulmonol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  183-8     Citation Subset:  IM    
Physiology Laboratory, Victor Pachon Faculty, University of Bordeaux, France.
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MeSH Terms
Airway Resistance / drug effects,  physiology
Helium / pharmacology*
High-Frequency Jet Ventilation*
Infant, Newborn
Lung / drug effects*,  physiology*
Lung Compliance / drug effects,  physiology
Models, Theoretical
Nitrogen / pharmacology*
Oxygen / pharmacology*
Physical Phenomena
Pulmonary Alveoli / drug effects,  physiology
Pulmonary Ventilation / drug effects,  physiology
Tidal Volume / drug effects,  physiology
Time Factors
Reg. No./Substance:
37291-87-5/nitrox; 58933-55-4/heliox; 7440-59-7/Helium; 7727-37-9/Nitrogen; 7782-44-7/Oxygen

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

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