Leg reperfusion technique optimization and ischemia diagnosis using ultrasound in patients treated with extracorporeal life support for refractory cardiac arrest – An observational cohort study

Objectives: Lower limb ischemia after extracorporeal life support for refractory cardiac arrest may be prevented by effective distal perfusion catheter (DPC) placement. We describe the prevalence of cannulated lower limb ischemia, the DPC technique and its improvements over time, and the blood flow velocities by doppler ultrasound associated with ischemia. Methods: Retrospective single-centre study including patients ≥18 years-old receiving extracorporeal life support under cardiopulmonary resuscitation. Data is expressed as frequencies (percentages), compared using Fisher's exact test. Logistic regression evaluated technical improvements associated with absence of ischemia. Blood flow velocity cutoffs associated with ischemia were determined according to receiver operator characteristics curves. Results: We included 338 patients, 6050-66 years-old. Survival to discharge was 24%.DPC was placed under ultrasound guidance using stiff wires: initial technique. This was improved resulting in the optimized technique by distal perfusion catheter heparin perfusion, using >12 cm-long sheaths, and using braided sheaths to avoid kinking. Cannulated lower limb ischemia occurred in 23/338 6.8 % in the overall population, in 10/7713 % with the initial technique and 13/2615 % with the optimized technique, p = 0.01. Braided sheaths were associated with absence of ischemia in multivariable analysis, odds ratio 0.18, 95 % confidence interval 0.045-0.65, p = 0.001. Blood flow velocity associated with ischemia was ≤17 cm/s in the mid-superficial femoral artery, and ≤12 cm/s in the more distal arteries. Conclusions: Using the optimized distal perfusion catheter technique, ischemia prevalence was 5 %. Braided catheters were associated with absence of lower limb ischemia. Blood flow velocity thresholds associated with cannulated lower limb ischemia were ≤17 cm/s.