Intraoperative measurement of vascular graft resistance as a predictor of early outcome.

The quality of distal run-off is one of the most important factors influencing the early outcome of femorodistal vein grafting. During femoropopliteal and infrapopliteal bypass, assessment of graft resistance and flow were made using a combination of Doppler flowmeter recordings and measurements of arterial pressure. In a series of 100 reconstructions there were 12 early failures. The mean (95 per cent confidence interval (c.i.)) maximal flow measurement in the group of grafts that failed when anastomosed to the popliteal artery or tibioperoneal trunk was 125 (74-176) ml/min compared with 256 (223-289) ml/min in successful grafts (P = 0.006). The corresponding figures for grafts inserted into a single crural vessel were 99 (72-126) and 165 (137-193) ml/min (P < 0.02). In the group that failed the mean (95 per cent c.i.) resistance after papaverine injection was 1.02 (0.82-1.22) peripheral resistance units (p.r.u.) compared with 0.47 (0.44-0.51) p.r.u. in the successful group (P < 0.001). Using a combination of resistance > 0.9 p.r.u. and capacity loss ratio after papaverine injection < 10 per cent to identify grafts that subsequently failed, the sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 92, 97, 85, 99 and 97 per cent respectively. These results confirm that haemodynamic measurements can be used at operation to identify a group of patients in whom bypass is likely to fail.