Microcirculatory haemodynamics before and after vascular surgery in severe limb ischaemia—The relation to post-operative oedema formation

Abstract

To determine whether postoperative oedema could be predicted preoperatively by microcirculatory parameters, we studied nutritive capillary blood flow in 21 patients before and after limb salvage procedures. All patients had severe lower limb ischaemia and underwent femoro-popliteal or femoro-crural bypass surgery. The systolic ankle-branchial arm index and systolic toe pressure were used as macrocirculatory parameters. Intravital capillary microscopy was used to measure red blood cell (RBC) and peak RBC velocity and time to peak RBC velocity after release of a 1 min arterial occlusion in the nailfold of the toe. Transcutaneous pO2 was measured on the dorsum of the foot at rest, during oxygen inhalation and following a release of a 5 min occlusion. After surgery the mean systolic ankle-brachial index and systolic toe pressure and all transcutaneous pO2 parameters improved significantly (P less than 0.001). Mean peak RBC velocity increased from 0.156 mm/s to 0.310 mm/s (P less than 0.05), indicating that the reactive hyperaemic response in the capillary bed had improved. Eleven patients developed postoperative oedema. There were no differences in postoperative macro and microcirculatory parameters between the patients with oedema (n = 11) and those without oedema (n = 10). However, preoperatively RBC velocity and peak RBC velocity were significantly lower (P less than 0.05) and time to peak RBC velocity was significantly longer (P less than 0.01) in patients who developed oedema. These findings show that in patients with severe limb ischaemia vascular surgery improves both macro- and microcirculatory blood flow, but that these patients develop oedema after vascular surgery when microcirculatory blood flow is compromised preoperatively.