USE OF ASSUMED VERSUS MEASURED OXYGEN-CONSUMPTION FOR THE DETERMINATION OF CARDIAC-OUTPUT USING THE FICK PRINCIPLE

Citation
A. Wolf et al., USE OF ASSUMED VERSUS MEASURED OXYGEN-CONSUMPTION FOR THE DETERMINATION OF CARDIAC-OUTPUT USING THE FICK PRINCIPLE, Catheterization and cardiovascular diagnosis, 43(4), 1998, pp. 372-380
Citations number
17
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cardiac & Cardiovascular System
ISSN journal
0098-6569
Volume
43
Issue
4
Year of publication
1998
Pages
372 - 380
Database
ISI
SICI code
0098-6569(1998)43:4<372:UOAVMO>2.0.ZU;2-L
Abstract
Assumed oxygen consumption (VO2) is increasingly used as a convenient surrogate for measured VO2 for calculation of cardiac output. This sub stitution is often based on empirical formulae, previously validated o nly in relatively young patients. To assess the inaccuracy introduced by extrapolating these formulae to older patients, we compared measure d VO2 with assumed VO2 in 57 patients. VO2 was measured using an open circuit analyzer. Assumed VO2 was calculated according to the LaFarge or Bergstra formulae. Agreement between both methods was assessed acco rding to the method of Bland and Altman. The mean difference of measur ed VO2 minus assumed VO2 was 7.9 ml/min/m(2) (P < 0.02) using the LaFa rge formula, and -15.6 ml/min/m(2) (P < 0.0002) using the Bergstra for mula across a range of measured VO2 from 70 to 176 ml/min/m(2). A syst ematic error was introduced by assumed VO2 from both formulae of under estimating higher and overestimating lower values of VO2, resulting in poor overall agreement with measured VO2. The same error and poor agr eement was found when analyzing subgroups of patients greater than or equal to 60 or <70 years of age. In summary, use of assumed VO2 introd uces large, unpredictable errors in adult patients, suggesting require ment for measurement of VO2 when calculating cardiac output. (C) 1998 Wiley-Liss, Inc.