Using the oxygen-cost diagram in ramp-slope selection for dyspneic patients

Background Maximal incremental exercise testing should be completed within 8-12 minutes. The rampslope influences the exercise duration. Oxygen-cost diagram (OCD) is a scoring scale for the capability of daily activity performed and therefore can be used to estimate the ramp-slope. Methods The OCD-algorithm and the reported-algorithm were used prospectively in random order for selecting optimal ramp-slope: Ramp-slope_OCD=Score_OCD×weight in kg/40 for men and weight/50 for women and Ramp-slope_reported=(Predicted V̇O_2peak-V̇O_2unloaded)/100. Fifty-three dyspneic patients and 16 normal controls were enrolled to perform a ramp-pattern exercise. Fourteen patients not reaching maximum exercise levels were excluded. The exercise capacity, exercise time, and success rate of loaded exercise between 8 and 12 minutes were measured. Results Comparing the reported-algorithm to the OCD-algorithm in normal controls, the only difference was that the ramp-slope was higher in males; in patients, the ramp-slope was higher in males, the exercise time shorter and the success rate lower (8.6±3.3 vs. 9.4±2.1 min, 61.5% vs. 84.6%, both p<0.05); in obese patients, the ramp-slope was lower and the exercise time longer. Conclusion OCD score can predict the ramp-slope selection for exercise testing in normal controls and dyspneic patients. This may be affected by gender and body weight when using the reported algorithm for dyspneic patients.