- Lumbar sympathectomy has a controversial place in the management of severe limb ischemia for limb preservation. In a consecutive clinical series laser Doppler (LD) blood flow was measured at the distal limit of an anterior below knee skin flap in 21 patients. Amputation level was selected by clinical judgement. Mean LD value in 15 patients who had primary BK healing was 42V (range 20-85) compared to 11V (9-20) in six patients who proceeded to AK amputation (p < 0.001) establishing 20V as a critical value for BK healing. To examine the effect of chemical sympathectomy 21 further patients with severe ischemia had LD measurements at the same BK site before and one week after chemical sympathectomy. LD values rose significantly from 26V (10-75) to 50V (10-100), (p < 0.001). In particular seven patients had initial LD levels below 20V and in five chemical sympathectomy produced elevation to levels commensurate with BK healing. We conclude that chemical sympathectomy can improve below knee skin blood flow and may enhance primary wound healing.