Ankle-brachial index (ABI) and leg blood flow following epidural anaesthesia

The influence of the severity of occlusive arterial disease, as evaluated from the ankle-brachial index (ABI) values, on blood flow and the distribution of blood flow within the lower limb following epidural block to the level of Th 4 to 6 was studied in 48 patients (ABI values ranging from 0.45-1.62). Leg (LBF) and foot (FBF) blood flows were measured with plethysmography and skin blood flow (SBF) was evaluated from laser-Doppler flowmetry and temperature recordings. The resting control LBF, FBF and SBF values were similar for all patients. Following the epidural block mean arterial blood pressure (MAP) decreased by about 20 mmHg. LBF, FBF and SBF all increased. There were significant correlations between the ABI values and the changes following the epidural block in LBF and FBF but not between ABI and SBF changes as evaluated from laser-Doppler flowmetry.