Transcapillary forces and the development of oedema in the lower limb of patients with chronic critical limb ischaemia (CLI)

Objective: factors regulating transcapillary fluid transport were investiga ted to elucidate the causes of oedema in CLI. Material: sixteen patients, 6 men and 10 women (mean age of 79 +/- 10.3 yea rs) with unilateral CLI and peripheral pitting oedema. Methods: measurements were performed in both limbs. Interstitial fluid was collected by applying blister suction cups on the dorsolateral part of the foot and colloid osmotic pressure of this fluid (COPif) was measured ill a colloid oncometer. Plasma colloid osmotic pressure (COPpl) was obtained fro m venous blood. Interstitial fluid pressure (P-if) was measured by wick-in- needle technique. Results: mean COPif in the limbs with CLI was 2.3 S.D. 0.5 mmHg, significan tly lower than in the limbs without CLI (3.1 S.D. 0.7 mmHg, p<0.0001). Mean COPpl was 21.1 S.D. 1.8 mmHg, which was lower than in healthy controls. Me an plasma albumin concentration was 30 S.D. 6 g/l which was lower than the reference values. Mean P-if in the limbs with CLI was 0.7 S.D. 1.6 mmHg, si gnificantly higher than in the limbs without CLI (- 1.4 S.D. 1.4 mmHg, p<0. 0001). The calculated mean reabsorption pressure (P-r) in the limbs with CL I was 19.6 S.D. 1.7 mmHg, significantly higher than in the contralateral li mbs (16.7 S.D. 2.1 mmHg, p<0.001). Conclusion: a low, plasma albumin concentration in patients with CLI agrees with the reduction in COPpl but cannot explain the oedema formation, since it is unilateral. The high P-r may cause a high transcapillary pressure, r esulting in a relatively great net filtration and subsequent oedema formati on.