The determination of required pressure level to provide an optimum treatment is an important task for vascular clinicians. This thesis is a first investigation including both venous and arterial femoral velocities and distal microcirculation of the forefoot to evaluate the effects of varying uniform external compression applied to the whole lower limb in humans. The ultrasound technique has been used to evaluate the maximal venous and arterial velocities in femoral common vessels. The microcirculation and the cutaneous oxygenation of the forefoot were recorded by laser Doppler fluxmetry and transcutaneous oxygen and carbon dioxide pressure measurements respectively. The findings of the present investigation support the concept that a uniform pressure applied to the full length of a healthy leg when the subject is in recumbent position should probably not exceed 10 mmHg, since significant impairment of both macro and microcirculation can be found. A database of information collected from twenty eight healthy subjects was established. Using this database and regression analysis, a new empirical model was produced which gave a hierarchical description of oxygen in terms of applied pressure and subject's characteristics. The developed model was expressed in terms of a cubic polynomial and was analysed in the content of catastrophy theory. This was appropriate to account for sudden changes in the data. Although the results obtained were based on this preliminary study, it appears that the predictive results are extremely encouraging and form a solid basis for future research. The observations of cubic forms in medical statistics as well as the inclusion of micro and macro in a single model are approaches that have been neglected in the past. A further area of apparent neglect appears to be in the careful selection of the sampling intervals to optimise information content of the database.