Evaluation of a modified 6 minute walk test with mobile spiroergometry

Abstract

Cardiopulmonary exercise testing (CPET) is an important tool for evaluation of exercise capacity and clinical significance for resurgery in patients with congenital heart disease. Classical 6 minute walktest (6mWT) results only in the walking distance, but is patient-selfcontrolled for workload intensity. Treadmill-spiroergometry delivers precise parameters like oxygen-uptake (VO₂), oxygen-pulse (O₂/HR) and parameters of breathing (i.e. minute volume, (VE)). However, patients have to follow a definite protocol rising the workload, but not all oft hem can physically or mentally follow such a distinct protocol. The combination of classical 6mWT with a mobile CPET system (JAGER Oxycon mobile) gives additional telemetric information about VO₂, O₂/HR, MV, SpO₂ and 12channel ecg continuously. In a pilot study parameters at anaerobic threshhold (AT-vslope) obtained from 26 healthy volunteers (12m, 14f), age 18-45 years, weight 70,7±12,1kg, height 173,5±7,7cm walking sequentially by chance either 6mwt or treadmill-CPET (DGPK-protocol) on 2 following visits were compared.

Results: (mean±SD at AT)

There was a good correlation of r=0,59 for VO₂/kg/min at AT and a linear regression of VO_2-6mwt=12,34+(0,438*VO_2-treadmill) with a significant difference (p=0,019, paired t-test). In spite oft the necessity of high motivation of the volunteers and prospectively patients, both tests provided comparable data.

Thus, the modified 6mwt combined with mobile CPET may provide more safety for those (handicapped) patients, contributing additional data on exercise tolerance and hemodynamics.