Document Detail

Redox status of cytochrome a,a3: a noninvasive indicator of dysoxia in regional hypoxic or ischemic hypoxia.
MedLine Citation:
PMID:  10199539     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: Multiwavelength near infrared (NIR) spectrophotometry can monitor the redox state of cytochrome a,a3 (cyt a,a3) in vivo. Because cyt a,a3 is the most immediate reductant of oxygen, this technique has been proposed to evaluate tissue oxygenation. The purpose of this study was to examine the relationship between cyt a,a3 oxidation level as an indicator of dysoxia and oxygen uptake (VO2) when oxygen delivery (DO2) was progressively lowered in an in situ vascularly isolated hindlimb. DESIGN: Prospective, randomized, laboratory study. SETTING: University research laboratory. SUBJECTS: Fourteen pigs. INTERVENTIONS: Measurement of critical values for both VO2 and cyt a,a3 oxidation during ischemic and hypoxic hypoxia. MEASUREMENTS AND MAIN RESULTS: The right hindlimb of anesthetized, paralyzed, and ventilated pigs was subjected to progressive ischemic or hypoxic hypoxia for 100 mins by ten stepwise decreases in DO2. In ischemic hypoxia (n = 7), arterial inflow (Q) from a pump-membrane oxygenator system was lowered from 50 to 0 mL/min, with PaO2 maintained at 100 mm Hg. In hypoxic hypoxia (n = 6), PaO2 was lowered from 100 mm Hg to 0 mm Hg. Hindlimb DO2 was calculated as the product of Q and arterial oxygen content, and VO2 as the product of Q and arteriovenous difference. The cyt a,a3 oxidation level was measured every 10 secs with a four-wavelength spectrophotometer. These parameters were measured 9 mins after each change of DO2. Critical values for both VO2 and cyt a,a3 oxidation level as a function of DO2 were determined in each animal by dual linear regression analysis. In ischemic and hypoxic hypoxia, a strong correlation was found between cyt a,a3 oxidation level and VO2 in both ischemic and hypoxic hypoxia (r2 =.90 and .87, respectively). Hindlimb vascular resistance increased in ischemic hypoxia and decreased in hypoxic hypoxia when DO2 reached critical DO2. CONCLUSIONS: From these results, we concluded that monitoring the cyt a,a3 redox state by NIR spectrophotometry is, in this experimental setting, a sensitive indicator of dysoxia during regional hypoxic or ischemic hypoxia.
B P Guery; J Mangalaboyi; P Menager; S Mordon; B Vallet; C Chopin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Critical care medicine     Volume:  27     ISSN:  0090-3493     ISO Abbreviation:  Crit. Care Med.     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-04-27     Completed Date:  1999-04-27     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  0355501     Medline TA:  Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  576-82     Citation Subset:  AIM; IM; S    
Service de Réanimation Médicale et Maladies Infectieuses, Soins Intensifs de Cardiologie, Centre Hospitalier de Tourcoing, France.
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MeSH Terms
Anoxia / diagnosis,  enzymology,  metabolism*
Electron Transport Complex IV / metabolism*
Hindlimb / blood supply*
Ischemia / metabolism
Linear Models
Muscle, Skeletal / metabolism
Oxygen Consumption*
Random Allocation
Spectroscopy, Near-Infrared
Reg. No./Substance:
EC Transport Complex IV
Comment In:
Crit Care Med. 1999 Mar;27(3):469-71   [PMID:  10199519 ]

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

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