Document Detail

Effects of duration and amount of lung stretch at biophysical, biochemical, histological, and transcriptional levels in an in vivo rabbit model of mild lung injury.
MedLine Citation:
PMID:  17372857     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to characterize the effects of doubling minute ventilation (either by doubling ventilator frequency [Freq] or tidal volume [V T]) and of normal minute ventilation prolonged to 12-fold duration, synchronously at biophysical, biochemical/cellular, histological, and transcriptional levels in a model of mild lung injury. A prospective, randomized study was performed on adolescent New-Zealand white rabbits. The rabbits were randomly assigned to one of the following groups: control (normal minute ventilation for 0.5 hours); 1 x V T, 12-fold prolongation at normal V T (normal minute ventilation for 6 hours [12 x 0.5 hours]); 2 x Freq at normal V T (double minute ventilation for 6 hours); and 2 x V T at normal Freq (double minute ventilation for 6 hours). Normocapnia was maintained throughout the experiment. At the biophysical level, gas exchange (alveolar-arterial O2-tension difference [ AaDO2]) deteriorated by 23, 51, and 95%, and respiratory compliance decreased by 6.0, 18.4, and 26% in the 1 x V T, 2 x Freq, and 2 x V T group, respectively, during 6 hours of ventilation. Concomitantly, at the biochemical-cellular level, interleukin-8 (IL-8) in the bronchoalveolar lavage fluid increased 44-fold, 150-fold, and 275-fold ( P = 0.02), respectively. The white blood cell count decreased significantly in all three intervention groups. At the histological level, the influx of leukocytes as well as the tissue water content increased in proportion to the degree of injury. At the transcriptional level, lung IL-8 mRNA expression increased 11-fold in the 2 x V T group ( P = 0.002), 9-fold ( P = 0.02) in the 2 x Freq group, and 4-fold in the 1 x V T group as compared with control. Not only doubling V T, but also doubling Freq at normal V T injures the lung significantly, although to a lesser extent. A concept of weighted risk for increases of V T and Freq is proposed.
George Simbruner; Rashmi A Mittal; Johan Smith; Gerd Maritz; Johan van Rensberg; Bernadette Simbruner; Andreas Holzinger
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-03-19
Journal Detail:
Title:  American journal of perinatology     Volume:  24     ISSN:  0735-1631     ISO Abbreviation:  Am J Perinatol     Publication Date:  2007 Mar 
Date Detail:
Created Date:  2007-03-28     Completed Date:  2007-05-22     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  8405212     Medline TA:  Am J Perinatol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  149-59     Citation Subset:  IM    
Department of Neonatology, Medical University Innsbruck, Innsbruck, Austria.
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MeSH Terms
Bronchoalveolar Lavage Fluid / chemistry
Carbon Dioxide / blood
Interleukin-8 / genetics
Prospective Studies
Pulmonary Gas Exchange
RNA, Messenger / metabolism
Random Allocation
Respiration, Artificial* / adverse effects,  methods
Respiratory Distress Syndrome, Adult / etiology,  metabolism,  pathology,  physiopathology*
Tidal Volume
Time Factors
Transcription, Genetic
Reg. No./Substance:
0/Interleukin-8; 0/RNA, Messenger; 124-38-9/Carbon Dioxide
Comment In:
Am J Perinatol. 2007 Mar;24(3):147-8   [PMID:  17372856 ]

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