Can VE45 & VT30 predict abnormality during cardio-pulmonary exercise testing?

Aims : 1. To validate Cotes9 hypothesis that VE45 (minute ventilation at 1.0L/min VO2) & Vt30 (tidal volume at a ventilation of 30L/min VO2) can identify abnormalities in exercise earlier than V02 peak 2. To distinguish between respiratory & cardiac abnormalities using VE45 & Vt30. Methods : VE45 & Vt30 were identified in 105 consecutive, routine Cardio Pulmonary Exercise Tests (CPETs). Predictive diagnoses from VE45 & Vt30 were compared to the diagnosis at VO2 peak . ROC analysis was performed to determine the sensitivity/specificity of VE45 & Vt30. VE45 & Vt30 data from healthy subjects was compared to previously published normal ranges by Cotes (1). Results : A significant correlation was observed between VE45 & VO2 peak in exercise-limited patients, but not in healthy subjects. No correlation was observed between Vt30 & VO2 peak in all subjects. Calculated ranges for VE45 in normal subjects were different from published normal ranges(1). VE45 was highly sensitive and accurately predicted abnormality in the majority of patients with exercise limitation at VO2 peak. However, it did not accurately predict normality in healthy subjects. Conclusions : It was not possible to distinguish between respiratory & cardiac abnormality using VE45, but it was possible to distinguish between those with and without limitation. Vt30 did not accurately predict abnormality. Our results differ significantly from previously published normal ranges(1). 1. Cotes, J.E., (1993). Lung Function: Assessment and Application in Medicine, 5th edition. Oxford: Blackwell scientific publishing p429.