Alterations in capillary permeability in the lower limb of patients with chronic critical limb ischaemia and oedema

Background: Oedema formation in lower limbs of patients with chronic critic al limb ischaemia (CLI) is a common clinical feature. The rate of fluid fil tration through the capillary wall depends on the capillary permeability ie . capillary filtration coefficient (CFC). In order to elucidate rite pathog enesis of this ischaemic oedema, CFC was measured in the limbs with CLI and oedema and was compared with CFC measurements both in the contralateral si des 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 m easured in both limbs by strain-gauge plethysmography using a double-strand ed 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 thi s group was measured in the foot of the non-fractured limb. Results: Mean CFC in the limbs with CLI and oede ma was 0.0036 +/- 0.001 ml /min 100 ml mmHg, significantly greater than both the contralateral limbs ( 0.0019 +/- 0.0003 ml/min 100 mi mmHg, p < 0.01) and mean CFC in the control limbs (0.0017 +/- 0.0002 ml/min 100 mi mmHg, p < 0.003). There was a mean volume difference of 13 +/- 9 % between limbs with CLI and contralateral si des 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 contra lateral 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 devel opment of this ischaemic oedema.