Measurement of foot artery blood pressure by micromanometry in normal subjects and in patients with arterial occlusive disease.

Blood pressure was measured continuously in the posterior tibial or dorsalis pedis arteries using an isovolumetric system (steel cannulas of 0.18 mm, external diameter). The systolic values in the ankle arteries of 13 normal subjects at rest (154.3 +/- 22.3 mm Hg) exceeded the systolic arm pressure (128.9 +/- 20.1 mm Hg, P less than 0.001), while diastolic values (69.9 +/- 8.7 mm Hg) were not significantly different from the arm pressure. In 13 patients with arterial occlusive disease (AOD) the dicrotic notch, normally situated close to the footpoint of the downslope, was either displaced upward or abolished. Both mean systolic and diastolic values (94.9 +/- 35.9 mm Hg and 62.5 +/- 18.5 mm Hg, respectively) and also mean pressure amplitude were reduced compared to the corresponding arm values (158.5 +/- 28.2 mm Hg and 87.7 +/- 6.0 mm Hg, respectively, all P less than 0.001). Comparison between the systolic pressure values measured by micromanometry and by an indirect technique using Doppler ultrasound showed a good correlation (r = 0.87). During postocclusive reactive hyperemia, the initial pressure values were markedly diminished in normal subjects and reached control values within 40 sec. In patients with AOD, however, this reduction in pressure was more pronounced and prolonged. Flow measurements using plethysmography showed flow diversion from the foot to the calf as long as pressure values ranged below 40 mm Hg. This almost painless method appears useful for experimental and diagnostic studies in low pressure areas of the peripheral circulation.