Background: Patency and limb salvage after synthetic bypass to the arteries below-knee are inferior to that which can be achieved with autologous vein. Use of a vein collar at the distal anastomosis has been suggested to improve patency and limb salvage, a problem that is analysed in this randomised clinical study. Methods: Patients with critical limb ischaennia undergoing polytetrafluoroethylene (PTFE) bypass to below-knee arteries were randomly either assigned a vein collar or not in two groups bypass to the popliteal artery below-knee (femoro-popliteal below-knee (FemPopBK)) and more distal bypass (femoro-distal bypass (FemDist)). Follow-up was scheduled until amputation, death or at most 5 years, whichever event occurred first. Results: In the FemPopBK and in the FemDist groups, 115/202 and 72/150 were randomised to have a vein collar, respectively. Information was available for 345 of 352 randomised patients (98%). At 3 years, primary patency was 26% (95% confidence interval (CI) 18-38) with a vein collar and 43 (33-58) without a vein collar for femoro-popliteal bypass and 20 (11-38), and 17 (9-33) for femoro-distal bypass, respectively. The corresponding figures for limb salvage were 64 (54-75) and 61(50-74) for femoro-popliteal bypass, and 59 (46-76) and 44 (32-61) for femoro-distal bypass with and without a vein collar, respectively. Log-rank-test for the whole Kaplan-Meier life table curve showed no statistically significant differences with or without vein collar primary patency: p = 0.0853, p = 0.228; secondary patency: p = 0.317, p = 0.280; limb salvage: p = 0.757, p = 0.187 for FemPopBK and FemDist, respectively. The use of a vein collar did not influence patency or limb salvage. Conclusion: This study failed to show any benefit for vein collar with PTFE bypass to a below-knee artery.

Symtomgivande

benartärsjukdom (BAS) innebär, förutom ofta handikappande symtom och i vissa fall risk för förlorad extremitet, en till följd av den generella aterosklerossjukdomen signifikant ökad risk för allvarliga ateroskleroshändelser som hjärtinfarkt och slaganfall samt förtida död.

Symtomgivande

benartärsjukdom är vanlig i primärvården. Då sekundärpreventiva insatser är betydelsefulla för denna patientgrupp, är det angeläget att tillståndet identifieras.

Ett sänkt ankel–brakialindex

(ABI) har hög sensitivitet och specificitet för benartärsjukdom, och ankeltrycksmätning och beräkning av ABI bör utföras i alla fall där symtom som kan ge misstanke om BAS föreligger.

Ankeltrycksmätning är

en underutnyttjad undersökningsmetod i primärvården. Ett av de viktigare, och åtgärdbara, skälen till detta är brist på utbildning och träning.

 Abstract 4615. European Heart J 2006.

An automated method for ankle systolic pressure measurement, less operator dependent than the standard continuous wave (CW) Doppler technique, would imply an advantage both in patient measurements and in epidemiological studies. We present a new photoplethysmographic (PPG) probe that uses near-infrared light (880 nm) to detect pulsatory blood flow underneath the distal end of a standard pneumatic cuff. The probe is adapted to the anatomical conditions at the ankle, permitting recording of pressures in both ankle arteries separately. The validity of the equipment was tested with CW Doppler-derived systolic pressures and invasive blood pressure measurements for reference. In 20 healthy subjects, visual analysis of the PPG curves revealed a mean difference between CW Doppler and PPG measurements of –0.5 mmHg (SD 6.9). Corresponding results for the anterior and posterior tibial arteries separately were –1.8 mmHg (SD 6.2) and 0.9 mmHg (SD 7.3), respectively. A correct probe position was essential for the results. In direct recordings from the dorsalis pedis artery in 10 intensive care patients, PPG underestimated systolic pressure in the anterior tibial artery by 4.5 mmHg (SD 12.1). With further development, the PPG probe, integrated in the pneumatic cuff, may simplify measurements of ankle systolic pressures.

Objective

To evaluate a new technique using a photoplethysmographic (PPG) probe for automatic ankle pressure measurements.

Design

Comparative study on two techniques for ankle pressure measurement.

Setting

University hospital.

Material

Thirty-five patients with leg arterial disease and eight healthy volunteers. Ankle-brachial indices (ABPI) were measured using conventional CW Doppler technique and PPG-based prototype equipment for the ankle pressure recordings.

Chief outcome measures

ABPIs calculated from CW Doppler and PPG ankle pressure measurements. The PPG signals were analysed both by visual judgement and by a software based, automatic algorithm.

Main results

The mean difference between ABPIs calculated from CW Doppler recordings and PPG (visual analysis) was −0.01 (limits of agreement (±two standard deviations) +0.16 to −0.19). The correlation coefficient was 0.93. When the algorithm was used, the mean difference (CW Doppler−PPG) was 0.05 (limits of agreement 0.28 to −0.18, r=0.89).

Conclusions

The PPG method is a promising technique with an inherent potential for automatisation of the ankle pressure measurements, thereby reducing the observer-dependency in ABPI recordings.

Photoplethysmography (PPG) can be used to measure systolic blood pressure at the brachial artery. With a specially designed probe, positioned in the most distal position beneath a pressure cuff on the upper arm, this is possible. The distance between the light source (880 nm) and the photodetector was 20 mm. A test was performed on neuro-intensive care patients by determining blood pressure from the PPG curves, and, when it was compared with systolic blood pressure obtained from inserted indwelling arterial catheters, a correlation factor of r=0.95 was achieved. The difference between blood pressure obtained using PPG and invasive blood pressure measurement was 3.9±9.1 mmHg (mean±SD), n=19. The depth to the brachial artery was 13.9±4.1 mm (mean±SD), n=18. A digital PPG system utilising pulsating light was also developed.