Systolic ankle artery pressure measured classically by cuff-manometry and Doppler ultrasound in patients with severely ischemic legs may be falsely elevated because of impaired compressibility of the arteries. We evaluated a hydrostatic blood pressure or so-called pole pressure test by correlating the ankle artery pressure as well as tcpO2 with the pole pressure.
We enrolled 29 patients (18 male, 11 female, 10 diabetics) with critical leg ischaemia. The pole pressure was obtained by elevating the leg, and measuring the height at which the Doppler signal disappears by means of a calibrated pole (recalculating cm H2O for mmHg). We used an 8 MHz cw-Doppler device. Only pole pressure values up to 70 cm H2O were included. In addition tcpO2 at 45 degrees C was recorded at the forefoot of the same leg.
When we included the values of the ten diabetic patients the pole pressure of 57.9 +/- 16.2 mmHg (mean +/- SD) was significantly lower by 40.7 mmHg than the ankle pressure of 98. +/- 38.4 mmHg, p < 0.0001 (paired t-test). Without the diabetics the difference was 33.7 mmHg. The correlation coefficient between pole pressure and ankle pressure was 0.546 including the patients with diabetes, and 0.609 excluding the diabetics. The correlation of tcpO2 with the pole pressure, however, was 0.624 regardless of the inclusion of diabetics, while that between tcpO2 and ankle pressure was only 0.250.
The pole pressure test is an easy, inexpensive and fast method providing a meaningful, quantitative measure independent of the compressibility of the arteries.