Background: Oedema formation in lower limbs of patients with chronic critical limb ischaemia (CLI) is a common clinical feature. The rate of fluid filtration through the capillary wall depends on the capillary permeability, i.e. capillary filtration coefficient (CFC). In order to elucidate the pathogenesis of this ischaemic oedema, CFC was measured in the limbs with CLI and oedema and was compared with CFC measurements both in the contralateral sides and in the lower limbs of a control group.
Patients and methods: Eleven women and 4 men, with a mean age of 75 +/- 8.8 years, with unilateral CLI and leg and foot oedema were included. Leg and foot volume was measured with water displacement volumetry (WDV). CFC was measured in both limbs by strain-gauge plethysmography using a double-stranded mercury in silicone strain gauge around the middle portion of the foot. As a control group, 8 patients, 5 women and 3 men, with a mean age of 77 +/- 7.6 years with a proximal femur fracture were included and the CFC in this group was measured in the foot of the non-fractured limb.
Results: Mean CFC in the limbs with CLI and oedema was 0.0036 +/- 0.001 ml/min.100 ml.mmHg, significantly greater than both the contralateral limbs (0.0019 +/- 0.0003 ml/min.100 ml.mmHg, p < 0.01) and mean CFC in the control limbs (0.0017 +/- 0.0002 ml/min.100 ml.mmHg, p < 0.003). There was a mean volume difference of 13 +/- 9% between limbs with CLI and contralateral sides measured by WDV. There was no significant correlation between total leg-foot volume and CFC (p > 0.05).
Conclusion: CFC in the ischaemic limb was twice as great as both the contralateral side and the limbs of the control group. It is therefore concluded that an increased CFC is probably one of the important factors in the development of this ischaemic oedema.