Abstract
LaFarge/Miettinen's formula for the assumption of oxygen consumption (VO2) is one of the most used in hemodynamic calculations. Considering the importance of VO2 for the calculation of hemodynamics needed for disease evaluation (e.g. pulmonary hypertension), the need for an acceptable agreement between assumed and measured VO2 becomes obvious. A well known variation of the original formula is the one by Bergstra. In both equations, age, sex and BSA are factors determining the VO2, plus the heart rate (HR) in the original formula.
We compared directly measured VO2 with values calculated by both the LaFarge/Miettinen and the Bergstra equations.
VO2 of 122 volunteers (20-65y) was directly measured by the Innocor™(Innovision). VO2 was then recalculated by both the equations. Directly measured VO2 (VO2INN) was 363±84ml/min in males, 224±52ml/min in females. VO2 calculated by Bergstra was 298±24ml/min in males, and 233±24ml/min in females. VO2 by LaFarge/Miettinen was 258±24ml/min in males, 182±21ml/min in females. Direct comparison of VO2INN with calculated VO2 showed significant differences between all the methods. Factors found to be influencing the VO2 in our cohort included sex, HR and BSA whereas age seemed to have no effects. Significant correlations were found between VO2 and hemoglobin, oxygen saturation (SpO2), fitness level and systolic blood pressure.
Comparison of directly measured VO2 values with assumed data obtained by both the LaFarge/Miettinen and Bergstra equations showed that none of the formula is satisfying in terms of agreement with measured data. Using VO2 equations may result in major bias of hemodynamics and we therefore urge that resulting data should be interpreted critically.
- © 2012 ERS