| Abstrakt: |
This study was performed because of observed differences between dye dilution cardiac output and the Fick cardiac output, calculated from estimated oxygen consumption according to LaFarge and Miettinen, and to find a better formula for assumed oxygen consumption. In 250 patients who underwent left and right heart catheterization, the oxygen consumption VO (ml. min) was calculated using Fick's principle. Either pulmonary or systemic flow, as measured by dye dilution, was used in combination with the concordant arteriovenous oxygen concentration difference. In 130 patients, who matched the age of the LaFarge and Miettinen population, the obtained values of oxygen consumption VO(dd) were compared with the estimated oxygen consumption values VO(lfm), found using the LaFarge and Miettinen formulae. The VO(lfm) was significantly lower than VO(dd); − 21.8 ±29.3 ml. min(mean±SD), P<0.001, 95% confidence interval (95% CI) −26.9 to −16.7, limits of agreement (LA) −80.4 to 36.9. A new regression formula for the assumed oxygen consumption VO(ass) was derived in 250 patients by stepwise multiple regression analysis. The VO(dd) was used as a dependent variable, and body surface area BSA (m), Sex (0 for female, 1 for male), Age (years), Heart rate (min) and the presence of a left to right shunt as independent variables. The best fitting formula is expressed as: VO(ass)=(157.3 × BSA+10.0 × Sex −10.5 × In Age+4.8) ml. min, where In Age=the natural logarithm of the age. This formula was validated prospectively in 60 patients. A non-significant difference between VO(ass) and VO(dd) was found; mean 20±23.4ml.min, P=0.771, 95% CI= −4.0 to +8.0, LA −44.7 to +48.7. In conclusion, assumed oxygen consumption values, using our new formula, are in better agreement with the actual values than those found according to LaFarge and Miettinen's formulae. [ABSTRACT FROM PUBLISHER] |
