Posture and the arterial pressure in the ischaemic foot.

Systolic blood pressures were measured at the ankle by Doppler ultrasound sphygmomanometry in a series of elderly patients. Twenty-four limbs were affected by severe occlusive arterial disease and in 15 limbs there was no good evidence of significant peripheral vascular insufficiency. The pressures were measured in the supine position and again with the subject sitting upright or standing. In both series there was, as anticipated, a marked increase in the pressure, so that the sitting/erect range of pressures in the ischaemic limbs overlapped considerably with the supine pressure range in the healthy limbs and were then higher than the values usually associated with rest pain and non-healing skin lesions. This postural effect almost certainly does not reflect a corresponding rise in blood flow in the normal extremity, but in the ischaemic foot it may offer a simple means of improving perfusion.