Toe blood pressure by photoplethysmography: an index of healing in forefoot amputation.

The relative merits of toe systolic blood pressure and ankle systolic pressure in predicting the result of forefoot amputation were evaluated in 30 limbs of 27 patients who underwent digit or transmetatarsal amputation. Twenty-four (89%) patients were diabetic. An infrared photoplethysmograph placed distal to a pneumatic digit occluding cuff allowed rapid, simple preoperative assessment of toe systolic pressures. Ankle pressures was measured by Doppler ultrasound. Twenty (67%) amputations healed primarily, whereas 10 ultimately required reamputation at the below-knee level. The mean ankle pressure of limbs with healing of forefoot amputation, 136 +/- 39 mm Hg (+/- SD), did not differ significantly from those that failed to heal, 121 +/- 72 mm Hg (P greater than 0.4). Failure of an amputation to heal occurred in association with ankle pressures ranging from 60 to over 300 mm Hg. The mean value of toe pressures associated with healing of forefoot amputation, 86 +/- 39 mm Hg, was significantly higher than those not healing, 25 +/- 18 mm Hg (P less than 0.001). Failure of a forefoot amputation to heal occurred in all eight limbs with toe pressures less than 45 mm Hg, and in two of eight (25%) limbs with toe pressure between 45 and 55 mm Hg. Primary healing occurred in all 14 limbs with toe pressures greater than 55 mm Hg. These data suggest that toe pressure measurement may be a useful hemodynamic correlate of the healing potential of a forefoot amputation.