Document Detail


Longitudinal dispersion in model of central airways during high-frequency ventilation.
MedLine Citation:
PMID:  1852987     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We have measured the longitudinal dispersion of boluses of helium, acetylene and sulphur hexafluoride in a plastic model of the human airways--generations zero through six--during high frequency ventilation (HFV). HFV was maintained by a piston pump. Frequency f and tidal volume VT ranged from 2.5 to 25 Hz and from 5 to 20 ml, respectively. Boluses were injected near the entrance of the zeroth generation (trachea), and the dispersion curves were measured by mass spectrometry at the end of the sixth airway generation. The shapes of the bolus dispersion curves could be well described with Gaussian distribution functions. With the exception of the HFV-conditions with VT = 5 ml, the effective dispersion coefficient DDISP appeared to be independent of the molecular diffusion coefficient. This independency was also found by other investigators in studies with dogs and human subjects. The measured results for DDISP for different f and VT could be satisfactorily described with the empirical equation DDISP = 0.0617 f0.8VT1.38 [cm2S-1]. Application of this equation to f and VT values normally applied in man resulted in DDISP values which should be considered to be too small for maintaining eucapnic ventilation in vivo. On the basis of this result we believe that during HFV in intubated subjects gas transport by longitudinal dispersion will be limited to the instrumental dead space--the endotracheal tube inclusive--and a few generations of large bronchi.
Authors:
A M van der Kooij; S C Luijendijk
Related Documents :
7559237 - Neuromechanical regulation of respiratory motor output in ventilator-dependent c1-c3 qu...
1934937 - Blood volume distribution during head-up tilt induced central hypovolaemia in man.
455997 - Patterns of ventilation in postoperative and acutely ill patients.
3690977 - Is low-level respiratory resistive loading during exercise perceived as breathlessness?
24149627 - The role of post-exercise nutrient administration on muscle protein synthesis and glyco...
23826997 - Effects of medullary administration of a nitric oxide precursor on cardiovascular respo...
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Respiration physiology     Volume:  84     ISSN:  0034-5687     ISO Abbreviation:  Respir Physiol     Publication Date:  1991 Apr 
Date Detail:
Created Date:  1991-08-20     Completed Date:  1991-08-20     Revised Date:  2009-11-11    
Medline Journal Info:
Nlm Unique ID:  0047142     Medline TA:  Respir Physiol     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  13-29     Citation Subset:  IM    
Affiliation:
Department of Medical Physiology, State University of Utrecht, The Netherlands.
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Descriptor/Qualifier:
Acetylene / metabolism
Diffusion
Helium / metabolism
High-Frequency Ventilation*
Humans
Mathematics
Models, Anatomic
Pulmonary Gas Exchange*
Pulmonary Ventilation*
Sulfur Hexafluoride / metabolism
Chemical
Reg. No./Substance:
2551-62-4/Sulfur Hexafluoride; 74-86-2/Acetylene; 7440-59-7/Helium

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


Previous Document:  Local airway heat and water vapour losses.
Next Document:  Diffusivity, respiratory rate and tidal volume influence inert gas expirograms.