Document Detail

Theoretical and experimental comparison of constant inspired concentration and pulsed delivery in NO therapy.
MedLine Citation:
PMID:  11030169     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: Inhaled NO therapy of artificially ventilated patients has been established as being based on constant inspired concentration of NO. In this study a new volumetrically controlled pulsed NO delivery mode is compared with the established concentration-based concept. DESIGN: To evaluate the relationship between NO delivery parameters, alveolar NO fraction, and patient uptake, a mathematical lung model was created where NO delivery can be simulated in varying ventilator settings, delivery modes, and lung properties. This model and the efficacy of pulsed delivery in inducing pulmonary capillary vasodilatation were examined experimentally. SETTING: Animal laboratory, Department of Medical Sciences, Clinical Physiology. SUBJECTS: The experimental study was performed with nine pigs of mixed breed weighing 25-35 kg. INTERVENTIONS: The pigs were anaesthetised and artificially ventilated. Pulmonary vasoconstriction was induced by hypoxia. NO was delivered periodically in the various delivery modes. MEASUREMENTS AND RESULTS: In simulation, in all delivery modes the NO uptake was found to be dependent on the ventilator settings and the volume of the dead space. Measured from pulmonary artery pressure, the pulsed delivery was as effective in reducing the induced pulmonary vasoconstriction as the constant inspired concentration delivery. The amount of NO that could reduce the vasoconstriction back to baseline was 105 nmol x min(-1). By delivering in the early part of the inspiration, ambient contamination by the exhaust gas is avoided. The expired NO values obtained in the simulation and the experiments were equal. Based on the simulation, the alveolar NO fraction and the NO uptake depend on the ventilator settings and the dead space in both volumetric- and concentration-based delivery. CONCLUSIONS: With pulsed delivery, a therapeutic effect comparable to constant inspired concentration delivery is achieved, NO gas is used more effectively, and environmental exhausts are reduced. The theoretical model shows that the NO delivery does not predict alveolar NO fraction and the NO uptake. However, it still remains an open question if the online measurement of these parameters would provide useful information, having added value in predicting and controlling the efficacy of the NO treatment.
E Heinonen; M Högman; P Meriläinen
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Intensive care medicine     Volume:  26     ISSN:  0342-4642     ISO Abbreviation:  Intensive Care Med     Publication Date:  2000 Aug 
Date Detail:
Created Date:  2001-01-12     Completed Date:  2001-02-01     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7704851     Medline TA:  Intensive Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1116-23     Citation Subset:  IM    
Department of Medical Sciences, Clinical Physiology, Uppsala University, Sweden.
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MeSH Terms
Computer Simulation
Drug Delivery Systems*
Models, Cardiovascular
Nitric Oxide / administration & dosage*,  metabolism
Pulmonary Alveoli / drug effects
Pulmonary Wedge Pressure / drug effects
Regression Analysis
Respiration, Artificial*
Respiratory Mechanics / drug effects
Respiratory Therapy / instrumentation*,  methods
Vasodilator Agents / administration & dosage*,  metabolism
Reg. No./Substance:
0/Vasodilator Agents; 10102-43-9/Nitric Oxide

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