Document Detail


Volume-dependent compliance and ventilation-perfusion mismatch in surfactant-depleted isolated rabbit lungs.
MedLine Citation:
PMID:  11176175     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVE: Volume-dependent alterations of lung compliance are usually studied over a very large volume range. However, the course of compliance within the comparably small tidal volume (intratidal compliance-volume curve) may also provide relevant information about the impact of mechanical ventilation on pulmonary gas exchange. Consequently, we determined the association of the distribution of ventilation and perfusion with the intratidal compliance-volume curve after modification of positive end-expiratory pressure (PEEP). DESIGN: Repeated measurements in randomized order. SETTING: An animal laboratory. SUBJECTS: Isolated perfused rabbit lungs (n = 14). INTERVENTIONS: Surfactant was removed by bronchoalveolar lavage. The lungs were ventilated thereafter with a constant tidal volume (10 mL/kg body weight). Five levels of PEEP (0-4 cm H2O) were applied in random order for 20 mins each. MEASUREMENTS AND MAIN RESULTS: The intratidal compliance-volume curve was determined with the slice method for each PEEP level. Concurrently, pulmonary gas exchange was assessed by the multiple inert gas elimination technique. At a PEEP of 0-1 cm H2O, the intratidal compliance-volume curve was formed a bow with downward concavity. At a PEEP of 2 cm H2O, concavity was minimal or compliance was almost constant, whereas higher PEEP levels (3-4 cm H2O) resulted in a decrease of compliance within tidal inflation. Pulmonary gas exchange did not differ between PEEP levels of of 0, 1, and 2 cm H2O. Pulmonary shunt was lowest and perfusion of alveoli with a normal ventilation-perfusion was highest at a PEEP of 3-4 cm H2O. Deadspace ventilation did not change significantly but tended to increase with PEEP. CONCLUSIONS: An increase of compliance at the very beginning of tidal inflation was associated with impaired pulmonary gas exchange, indicating insufficient alveolar recruitment by the PEEP level. Consequently, the lowest PEEP level preventing alveolar atelectasis could be detected by analyzing the course of compliance within tidal volume without the need for total lung inflation.
Authors:
G Mols; G Hermle; J Schubert; W Miekisch; A Benzing; M Lichtwarck-Aschoff; K Geiger; D Walmrath; J Guttmann
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Critical care medicine     Volume:  29     ISSN:  0090-3493     ISO Abbreviation:  Crit. Care Med.     Publication Date:  2001 Jan 
Date Detail:
Created Date:  2001-01-25     Completed Date:  2001-02-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0355501     Medline TA:  Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  144-51     Citation Subset:  AIM; IM    
Affiliation:
Department of Anesthesiology and Critical Care Medicine, University of Freiburg, Germany.
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MeSH Terms
Descriptor/Qualifier:
Animals
Bronchoalveolar Lavage
Disease Models, Animal
Lung Compliance*
Matched-Pair Analysis
Positive-Pressure Respiration / methods*
Pulmonary Gas Exchange*
Rabbits
Random Allocation
Respiratory Distress Syndrome, Adult / therapy*
Respiratory Mechanics
Statistics, Nonparametric
Tidal Volume
Ventilation-Perfusion Ratio*

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


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