Document Detail


Influence of respiratory rate and end-expiratory pressure variation on cyclic alveolar recruitment in an experimental lung injury model.
MedLine Citation:
PMID:  22248044     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
ABSTRACT: INTRODUCTION: Cyclic alveolar recruitment (R/D) is an important mechanism of ventilator associated lung injury. In experimental models this process can be measured with high temporal resolution by detection of respiratory-dependent oscillations of the paO2 ([increment] paO2). A previous study showed that end-expiratory collapse can be prevented by an increased respiratory rate in saline-lavage rabbits. The current study compares the effects of increased PEEP versus an individually titrated respiratory rate (RRind) on intra-tidal amplitude of [increment] paO2 and on average paO2 in saline-lavaged pigs. METHODS: Acute lung injury was induced by bronchoalveolar lavage in 16 anaesthetized pigs. R/D was induced and measured by a fast-responding intra-aortic probe measuring paO2.Ventilatory interventions (RRind (n=8) versus extrinsic PEEP (n=8)) were applied for thirty minutes to reduce [increment] paO2. Haemodynamics, spirometry and [increment] paO2 were monitored and the Ventilation/Perfusion distributions were assessed by multiple inert gas elimination. The main endpoints average and [increment] paO2 following the interventions were analysed by Mann-Whitney-U-Test and Bonferroni's correction. The secondary parameters were tested in an explorative manner. RESULTS: Both interventions reduced [increment] paO2. In the RRind group [increment] paO2 was significantly smaller (p<0.001). The average paO2 continuously decreased following RRind and was significantly higher in the PEEP group (p<0.001). A sustained difference of the Ventilation/Perfusion distribution and shunt fractions confirms these findings. The RRind application required less vasopressor administration. CONCLUSION: Different recruitment kinetics were found compared to previous small animal models and these differences were primarily determined by kinetics of end-expiratory collapse. In this porcine model, respiratory rate and increased PEEP were both effective in reducing the amplitude of paO2 oscillations. In contrast to a recent study in a small animal model, however, increased respiratory rate did not maintain end-expiratory recruitment and ultimately resulted in reduced average paO2 and increased shunt fraction.
Authors:
Erik K Hartmann; Stefan Boehme; Alexander Bentley; Bastian Duenges; Klaus U Klein; Amelie Elsaesser; James E Baumgardner; Matthias David; Klaus Markstaller
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-1-16
Journal Detail:
Title:  Critical care (London, England)     Volume:  16     ISSN:  1466-609X     ISO Abbreviation:  -     Publication Date:  2012 Jan 
Date Detail:
Created Date:  2012-1-17     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9801902     Medline TA:  Crit Care     Country:  -    
Other Details:
Languages:  ENG     Pagination:  R8     Citation Subset:  -    
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