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Bioelectrical impedance sphygmography for hydrostatic toe pressure measurement: a new non-invasive method to assess
1Diabetes-Fussambulanz, MNR-Klinik, Heinrich-Heine-University Düsseldorf, Germany.
Background:
Hydrostatic measurement of systolic toe blood pressure (HSTBP) is reliable in feet with calcified arteries, when sphygmomanometry fails. When leg is lifted above heart level, weaning of the big toe's arterial pulsations indicates HSTBP.
Patients And Methods:
Electrical bio-impedance was assessed to monitor the weaning of arterial pulsations (Medis GmbH, Ilmenau, Germany). In a pilot study in 30 healthy volunteers, a 12 cm cuff was placed above the ankle and inflated to 200 mmHg; ultrasound (8 MHz) and impedance sphygmography (ISG) were used simultaneously to detect arterial pulsations in the big toe, in the 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) with suspected peripheral arterial occlusive disease, subjected to arteriography before vascular surgery.
Results:
In the pilot study, ultrasound and ISG signals were detected at nearly identical systolic pressure levels (difference 2.4 [SEM 0.6] mmHg, r = 0.99, p < 0.001). In the clinical study, HSTBP < or = 50 mmHg was associated with multiple occlusions (2 legs with < or = 1, 9 legs with 2, and 13 legs with > 2 arteries occluded); by contrast, HSTBP > 50 mmHg indicated single occlusions (16 legs with < or = 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 < or = 50 mmHg indicates severe peripheral arterial disease occlusive (> or = 2 arteries occluded).