title: Intra-operative Doppler flow measurement do not predict 'at-risk' status of infrainguinal bypass grafts.
abstract: OBJECTIVE
  Patients undergoing infrainguinal arterial reconstruction using vein conduits, frequently undergo intra-operative Doppler flow measurements to determine technical adequacy. The aim of this study was to determine the proportion of vein grafts with normal intra-operative haemodynamic parameters that were subsequently discovered to be 'at risk' on post-operative duplex surveillance scanning.
  
  
  METHODS
  We prospectively collected data on 82, primary infrainguinal vein bypass grafts. Post papaverine graft flow and peripheral resistance were measured using the Scimed Opdop intra-operative Doppler machine. All grafts were determined to be technically adequate on the basis of measured peripheral resistance units (mPRU) being < or =1. At 1 week, a post-operative duplex surveillance scan was performed. At risk status was determined and compared to the intra-operative Doppler flow measurement. Statistical analysis was performed using the Mann-Whitney U-test.
  
  
  RESULTS
  The post-operative duplex scan demonstrated that 53 (65%) of the 82 vein bypass grafts were diagnosed as being 'not at risk'; and 29 (35%) were regarded as at risk. When the groups were compared, there was no significant difference in intra-operative haemodynamic parameters between those not at risk and those at risk (P=0.19, Mann-Whitney U-test). The 1 month primary patency rate was 79% with a secondary patency rate of 100%.
  
  
  CONCLUSIONS
  Despite normal intra-operative Doppler flow measurements, 35% of vein grafts were regarded as being at risk at the 1 week post-operative duplex surveillance scan. No single value may be universally applicable for identifying at risk grafts intraoperatively. Indeed, graft failure appears to be a multifactorial process.
authors.affiliation: Department of Vascular and Endovascular Surgery, St James' University Hospital, Lincoln Wing, Leeds LS9 7TF, UK.
authors.forename: V P
authors.initials: VP
authors.lastname: Jagadesham
authors.forename: S
authors.initials: S
authors.lastname: Snowdon
authors.forename: M J
authors.initials: MJ
authors.lastname: Weston
authors.forename: P J
authors.initials: PJ
authors.lastname: Kent
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001157:Arterial Occlusive Diseases / Q000000981:diagnostic imaging / Q000503:physiopathology* / Q000601:surgery; D001783:Blood Flow Velocity; D001807:Blood Vessel Prosthesis; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007264:Inguinal Canal / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D011150:Popliteal Artery / Q000000981:diagnostic imaging / Q000601:surgery; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D012501:Saphenous Vein / Q000637:transplantation*; D016896:Treatment Outcome; D018616:Ultrasonography, Doppler, Duplex; D014654:Vascular Patency