Abstract
Ischaemic ulcers and necrosis tend to appear first in the most distal part of the
feet in patients with chronic critical limb ischaemia (CLI), indicating that derangements
in local microcirculation are focally distributed. In the present study the veno-arteriolar
response (VAR), as an indicator of microcirculatory regulation, was obtained in three
different areas of critically ischaemic feet. Five women and seven men, mean age 75
years, with unilateral CLI were included. Two groups including young and age-matched
healthy participants served as controls. Laser Doppler flux (LDF) was recorded simultaneously
at the pulp of the first toe (site 1), the level of the second metatarsal body (site
2), and the anterolateral part of the ankle (site 3). LDF was recorded with the investigated
limb in supine and dependent positions. Orthostatic response (OR) was calculated at
all measuring sites as perfusion (LDF) in the dependent foot divided by perfusion
in the supine position. There was no difference in OR between the control groups,
or between sites within each group. Median OR was about 0.5, indicating that perfusion
was reduced to 50% during dependency. In patients with CLI, VAR was not present in
the afflicted foot and ankle, and OR at the three sites were significantly greater
than in controls (p < 0.0005). Median OR at site 1 was 3.7, indicating considerably
increased local perfusion when the foot was lowered. At site 2 the increase was moderate,
and there was no increase present at site 3 (median OR=1.0). There was a significant
trend towards normal values (OR < 0.8) after vascular reconstruction at all sites.
Abolished VAR and increased local perfusion in ischaemic limbs assist in explaining
why patients with ischaemic rest pain obtain relief of pain with dependency. The recovery
of VAR following reconstructive surgery indicates that the microcirculatory derangement
is reversible.
