New reactive hyperaemia parameters computed thanks to wavelets in laser Doppler studies

Many studies have been carried out on reactive hyperaemia parameters in laser Doppler flowmetry (LDF) analysis. For the diagnosis of peripheral arterial occlusive diseases, the most important parameters are the time to peak flow (tpLDF) and the peak flow value (pLDF). However, the determination of these parameters is very often subjective due to the presence of marked oscillations on LDF signals. The present work shows that the de-noising of the concentration of moving blood cell signals (CMBC) can be of great interest in determining new reliable reactive hyperaemia parameters (tpCMBC and pCMBC). 40 CMBC signals recorded on 10 healthy subjects and on 10 patients with peripheral arterial occlusive diseases are thus smoothed using wavelets. For a 1 min occlusion, the parameters computed are tpCMBC_healthy = 20.9 s, pCMBC_healthy = 40.3 arbitrary units (a.u.), tpCMBC_patient = 31.2 S, pCMBC_patients = 31.5 a.u. After 2 min of occlusion, tpCMBC_healthy = 28.7 s, pCMBC_healthy = 61.0 a.u., tpCMBC_patient = 38.8 s, pCMBC_patient = 41.7 a.u. The 2 new parameters, tpCMBC and pCMBC, are computed on de-noised signals. Therefore, they can improve the diagnosis of peripheral arterial occlusive diseases.