[Determination of vascular resistance in bypass operations with infragenual anastomosis: is prediction of early occlusion possible with this value?].

Peripheral outflow resistance (OR) was assessed intraoperatively in 75 infrainguinal bypass procedures to the below knee popliteal artery (20) or a single crural artery (55). OR measurement was done after completion of the distal anastomosis. For that purpose, the graft was perfused with Ringer solution at constant flow rates of 100 and 150 ml/min using a roller pump. During infusion, arterial pressure was recorded. In this way distal (DOR) and total (TOR) outflow resistance in E/S anastomoses was calculated before and after vasodilatation with papaverine. DOR at a flow rate of 100 ml/min was found to be most discriminant as a predictor of early graft thrombosis: 1. In the limbs with a thrombosed graft at 30 days OR was significantly higher than in the limbs with a patent graft (1828 +/- 418 vs. 1472 +/- 221 mPRU; p less than 0.01, Mann-Whitney U-Test). 2. The cut-off value of 1700 mPRU, which was determined by ROC curves, was 100% sensitive and 81% specific in the group of femoro-crural grafts to predict early graft failure. A better discrimination by the application of papaverine could not be achieved. We concluded from our results that OR might be an important factor in early graft thrombosis. But still there is more experience required to select patients for primary amputation or adjunctive procedures (av-fistula, sequential graft) on the basis of the present available data.