The following is a summary of “Partial Pressure of End-Tidal Oxygen and Blood Lactate During Cardiopulmonary Exercise Testing in Healthy Older Participants and Patients at Risk of Cardiac Disease,” published in the February 2024 issue of Cardiology by Kominami et al.

The partial pressure of end-tidal oxygen (PETO₂) and end-tidal oxygen concentration (ETO₂) are measured in exhaled gas analysis, while the difference in PETO₂ from rest to ventilatory anaerobic threshold (VAT) might reflect peripheral oxygen availability, but evidence is weak for this.

Researchers started a retrospective study to investigate if increased blood lactate and PETO₂ dynamics during CPET are related, suggesting potential links to decreased muscle and mitochondrial oxygen availability.

They administered symptomatic limited CPET to all participants, assessing their BLa levels. Using the V-slope method, they calculated DeltaPETO₂ and DeltaETO₂ (the difference in PETO₂ and ETO₂ from rest to VAT), then compared these values with the increase in BLa attributable to exercise testing.

The results showed 22 healthy older participants (9 males, 69.4 ± 6.8 years) and 11 cardiovascular risk patients (8 males, 73.0 ± 8.8 years). DeltaPETO₂ and DeltaETO₂ showed no disparity between the groups (P=0.355 and P=0.369, respectively). No correlation between BLa increase from rest to VAT, but a significant correlation emerged with BLa increase from rest to exercise end (DeltaPETO₂, P=0.030; DeltaETO₂, P=0.029). This correlation was notably evident among those at cardiovascular risk (DeltaPETO₂, P=0.012; DeltaETO₂, P=0.011).

Investigators concluded that DeltaPETO₂and DeltaETO₂ from rest to VAT during CPET might be helpful indicators of skeletal muscle’s capacity to utilize oxygen.

Source: cardiologyres.org/index.php/Cardiologyres/article/view/1597