Document Detail

Factors influencing the tracheal fluctuation of inhaled nitric oxide in patients with acute lung injury.
MedLine Citation:
PMID:  9357884     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Inhaled nitric oxide (NO) improves arterial oxygenation in patients with acute lung injury (ALI) by selectively dilating pulmonary vessels perfusing ventilated lung areas. It can be hypothesized that NO uptake from the lung decreases with increasing ventilation perfusion mismatch. This study was undertaken to determine the factors influencing the fluctuation of tracheal NO concentration over the respiratory cycle as an index of NO pulmonary uptake in patients with ALI. METHODS: By using a prototype system (Opti-NO) delivering a constant flow of NO only during the inspiratory phase, 3 and 6 ppm of NO were administered during controlled mechanical ventilation into a lung model and to 11 patients with ALI. All patients had a thoracic computed tomography (CT) scan. Based on an analysis of tomographic densities, lungs were divided into three zones: normally aerated (-1.000 to -500 Hounsfield units [HU]), poorly aerated (-500 to -100 HU), and nonaerated (-100 to +100 HU), and the volume of each zone was computed. Concentrations of NO in the inspiratory limb and trachea were continuously measured by a fast-response chemiluminescence apparatus. RESULTS: In the lung model, tracheal NO concentration was stable with minor fluctuation. In contrast, in patients, tracheal NO concentration fluctuated widely during the respiratory cycle (55 +/- 10%). Because uptake of NO from the lungs was absent in the lung model but present in the patients, this fluctuation was considered as an index of pulmonary uptake of NO. This was further substantiated by (1) the coincidence of the peak and minimum tracheal NO concentration with the end-inspiratory and end-expiratory phases, respectively, and (2) continued decrease of tracheal NO concentration during prolonged expiratory phase. In patients with ALI, the fluctuation of tracheal NO concentration expressed as the difference between inspiratory and expiratory NO concentrations divided by inspiratory NO concentration was greater at 6 ppm than at 3 ppm (P < 0.01), was linearly correlated with normally aerated lung volume, inversely correlated with alveolar dead space and with poorly aerated lung volume. CONCLUSION: In patients with ALI, fluctuation of tracheal NO concentration over the respiratory cycle can be considered as an index of NO uptake from the lungs that depends on aerated lung volume and perfusion of ventilated lung areas. At bedside, it may be used to follow the evolution of ventilation-perfusion mismatch.
G S Umamaheswara Rao; L Gallart; J D Law-Koune; Q Lu; L Puybasset; P Cluzel; P Coriat; J J Rouby
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Anesthesiology     Volume:  87     ISSN:  0003-3022     ISO Abbreviation:  Anesthesiology     Publication Date:  1997 Oct 
Date Detail:
Created Date:  1997-11-20     Completed Date:  1997-11-20     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  1300217     Medline TA:  Anesthesiology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  823-34     Citation Subset:  AIM; IM    
Unité de Réanimation Chirurgicale (Department of Anesthesiology), Hôpital de la Pitié-Salpétrière, University of Paris VI, France.
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MeSH Terms
Administration, Inhalation
Lung / metabolism
Lung Volume Measurements
Middle Aged
Nitric Oxide / administration & dosage,  metabolism*
Respiration, Artificial
Respiratory Distress Syndrome, Adult / metabolism*
Tomography, X-Ray Computed
Trachea / metabolism*
Reg. No./Substance:
10102-43-9/Nitric Oxide

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

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