Cardiac output, stroke volume, and arteriovenous oxygen difference: Estimation using exercise heart rate, oxygen uptake, and hemoglobin concentration

Abstract

In this study, I aimed to estimate the cardiac output (Q), stroke volume (SV), and arteriovenous oxygen difference (a-vDO₂) during submaximal and maximal exercise using oxygen uptake (VO₂), heart rate (HR), and hemoglobin concentration (Hb) during exercise. This study was based on 1) Whipp et al. (1996), who found that maximal stroke volume (SVmax) can be estimated from HR, VO₂, and arterial oxygen content (CaO₂) during submaximal exercise, and 2) Durand (1980), who found that the slope of the linear relationship between VO₂ and Q is the reciprocal of CaO₂. In the present study, we used the Q during submaximal and maximal exercise reported by Åstrand et al. (1964) as a validity criterion and investigated the validity of the Q estimated using the present method from the VO₂, HR, and Hb data they reported simultaneously. Excluding the data of the two subjects detected as outliers, the bias, precision, and percentage errors of Q were -0.01±2.10 L/min, 4.1 L/min, and 25.1%, respectively. Data where the difference between estimated Q and measured Q was within ±20% represented 88.9% of the total. These results were similar to those of previous studies that examined the validity of Q during exercise using the impedance method. Outliers can be avoided by assessing the value of ΔVO₂/ΔHR based on the SVmax presumed from the subject’s characteristics. For laboratories that routinely perform exercise stress tests, the addition of Hb measurements allows the estimation of Q, SV, and a-vDO₂ during exercise.