Oxygen Uptake Efficiency Slope and Prediction of Post-operative Morbidity and Mortality in Patients with Lung Cancer

Peak oxygen consumption is a very valuable cardiopulmonary functional parameter in pre-operative evaluation of patients with lung cancer. However, it has several critical limitations for operability decision due to failure in achieving maximal level of exercise test for cases. The aim of this study was to reveal the importance of more accurate cardiopulmonary parameters that can be calculated from data of submaximal level test, such as oxygen uptake efficiency slope (OUES) and to determine whether it could be used in the operability decision phase for borderline cases by means of morbidity and mortality.

One hundred and twenty-five patients who were scheduled to undergo lung surgery due to lung cancer were included in the study. Peak oxygen uptake (pVO₂), heart rate at the anaerobic threshold, and oxygen consumption volume at anaerobic threshold values were obtained after performing the cardiopulmonary exercise test. The OUES value was calculated from the ratio of the peak VO₂ value and logarithmic equivalent of the ventilatory volume (VE). The following equation was used for determining OUES: VO₂/log₁₀ VE.

The peak VO₂ mean value was 21.37 ± 4.20 mL/min/kg in patients. However, OUES mean value was 12.44 ± 2.11. When the metabolic parameters of the patients were compared, a significant correlation was determined between the peak VO₂ value and peak VE, OUES, and survival (p < 0.01).

This study demonstrated that OUES is significantly correlated with peak VO₂ and it does not require the performance of maximal exercise and can be used together with peak VO₂ in this patient population when there is difficulty in making decision for surgery in patients with lung cancer.