Bioelectrical impedance sphygmography for hydrostatic toe pressure measurement: a new non-invasive method to assess limb ischaemia

Background: Hydrostatic measurement of systolic toe blood pressure (HSTBP) is reliable in feet with calcified arteries, when sphygmomanometry fails. W hen leg is lifted above heart level, weaning of the big toe's arterial puls ations indicates HSTBP. Patients and methods: Electrical bio-impedance was assessed to monitor the weaning of arterial pulsations (Medis GmbH, Ilmenau,Gennany). In a pilot st udy in 30 healthy volunteers, a 12 cm cuff was placed above the ankle and i nflatet to 200 mmHg; ultrasound (8 MHz) and impedance sphygmography (ISG) w ere used simultaneously to detect arterial pulsations in the big toe, in th e sitting and supine position after deflating the cuff. In a clinical study : HSTBP was assessed by big toe ISG in 50 legs (43 of diabetic patients) wi th suspected peripheral arterial occlusive disease, subjected to arteriogra phy before vascular surgery. Results: In the pilot study ultrasound and ISG signals were detected at nea rly identical systolic pressure levels (difference 2.4 [SEM 0.6] mmHg, r = 0.99, p < 0.001). In the clinical study, HSTBP I 50 mmHg was associated wit h multiple occlusions (2 legs with 11, 9 legs with 2, and 13 legs with > 2 arteries occluded); by contrast, HSTBP > 50 mmHg indicated single occlusion s (16 legs with less than or equal to 1, 8 legs with 2, and 2 legs with > 2 occluded arteries; chi(2) contingency p < 0.02). Conclusions: assessment of big toe arterial pulsation by ISG was reliable. HSTBP I 50 mmHg indicates severe peripheral arterial disease occusive (grea ter than or equal to 2 arteries occluded).