[Plasma concentration of endothelin-1 after myocutaneous latissimus dorsi-transplantation -- role in reperfusion injury].

The success of a free flap transplantation is based on a sufficient microanastomosis which meets the following requirements: a pedicle placed without kinking or twisting, a good drainage, a well defined recipient vessel and integrity of the endothelium. The aim of this study was to determine whether operation-related ischaemia through flap transplantation and tourniquet induces an increase of Endothelin-1 plasma levels as one cause of vasospasm during microvascular procedures. We focused our attention in particular on the reperfusion period which is often limited to an irreversible perfusion failure of microcirculation due to free radicals, interleukin and Endothelin-1. Twenty-one patients with tissue injury of the lower leg were included in our study, fourteen underwent a latissimus dorsi muscle transplantation with a combined ischaemia, seven patients had a tourniquet ischaemia for tumour resection, debridement and local flap transfer. The duration of ischaemia varied due to the course of operation. The withdrawal of venous blood via central vein catheter, flap vein and wound bed followed a fixed time table pre- and post-reperfusion (T1: preoperative day via cubital vein, T2: 6th postoperative day, T3: 5 min, T4: 10 min, T5: 15 min, T6: 1 h post-declamping and after tourniquet ischaemia via central vein catheter and T7: within 5 min from the flap vein immediate after recharging the flap). The vessel anastomosis determined the withdrawal from the local wound bed. ET-1 in venous blood samples were measured with ELISA. The duration of ischaemia in the tourniquet group ranged from 22 min up to 210 min with a mean of 76.58 min and in the latissimus group from 87 min up to 203 min with a mean of 139.21 min. The mean ET-1 plasma concentration measured systemically before operation in the 21 patients was 0.51 +/- 0.08 pg/ml (Mean +/- SD). This result corresponds with data published in literature. The locally measured plasma levels of ET-1 after tourniquet and flap ischaemia were increased with 0.34 up to 3.90 pg/ml (0.95 +/- 0.79 pg/ml [Mean +/- SD]) for the tourniquet group and with 0.34 up to 14.87 pg/ml (1.85 +/- 3.64 pg/ml [Mean +/- SD]) for the latissimus group. This is an increase compared to systemically measured values as 0.75 +/- 0.06 pg/ml (Mean +/- SD) for the tourniquet group and 0.58 +/- 0.21 pg/ml (Mean +/- SD) for the latissimus group. We conclude that Endothelin-1 is increased locally in the early reperfusion period after free latissimus dorsi-transplantation.