Comparison of visual, automatic and semiautomatic methods to determine ventilatory indices in 50 to 60 years old adults

The aim of this study was to compare different methods of detecting ventilatory indices (VI) and to investigate the impact of cardiorespiratory fitness (CRF) level on VI detection. Fifty females and fifty males completed a graded exercise test until volitional exhaustion with continuous gas-exchange measurement. The first and second ventilatory indices (VI-1, VI-2) were detected through different single automatic methods and through a semiautomatic method which combines visual and automatic detection methods. Additionally, the VIs were detected visually by two experts which served as the study specific gold standard. When comparing the semiautomatic method at VI-1 (intraclass correlation coefficients (ICC) 0.88 [0.81, 0.92], Bland-Altman bias +/- limits of agreement (LoA) 55 +/- 334 ml O-2 center dot min(-1)) and VI-2 (ICC 0.97 [0.96, 0.98], LoA 1 +/- 268 ml O-2 center dot min(-1)) to the visually detected VI, high levels of agreements and no significant differences were found. This was not the case for any of the other automatic methods. Additionally, we couldn't find any relevant differences regarding the CRF level. We therefore concluded that the semiautomatic detection method should be used for VI detection, as results are more accurate than in any of the single-automatic methods.