| 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? 58607 - Anaerobic metabolism of the common cockle, cardium edule. i.--the utilization of glycog... 23479117 - Carnosine: from exercise performance to health. |
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.