Femoral artery cannulation is probably the most common approach for ECMO implantation because of its ease and the large diameters of this vessel. Femoral cutdown is the traditional surgical approach (Fig. 5.4a). A transverse or longitudinal skin incision is made over the femoral vessels and below the inguinal ligament. Dissection is undertaken so as to isolate the femoral artery and vein, proximal and distal control of each vessel is obtained through loops, and a purse-string suture is placed. After heparinization, the common femoral artery is clamped proximally and distally, and a transverse arteriotomy is made, leaving the posterior one third of the artery intact. A 15–21-Fr arterial cannula is directly inserted. Some authors prefer the use of an 8–10-mm PTFE or Dacron “chimney graft” sewn in an end-to-side way on the arterial vessel [4] (Fig. 5.4c). Afterwards, the chimney graft can be tunneled under the skin or extended over it; the cannula is then inserted and the wound is closed. The cannula position must be fixed to the skin with multiple ligatures. Such a technique is recommended in patients with small vessels likely to be occluded by arterial cannulas (children, thin adults, peripheral artery disease), patients in whom ischemia develops after percutaneous cannulation, or patients who undergo cannulation in the operating room with vessels already exposed for CPB [5, 6]. The technique lowers the risk of distal leg ischemia and vessel dissection and simplifies decannulation. Unfortunately, this approach requires a longer preparation time, and it cannot be used in case of emergency. In such a situation, a pre-sealed short vascular prosthesis can be bevelled at its distal end and passed over the cannula. The cannula is then inserted into the vessel, and when ECMO is stable the vascular prosthesis around the cannula is lowered onto the femoral artery. In this moment, the prosthesis is anastomosed to the artery, and the arterial cannula can be withdrawn carefully, positioning its distal end within the prosthesis at the level of the anastomosis [7]. In the semi-Seldinger technique (Fig. 5.4b), a small transverse incision is made over the femoral artery and deepened so as to expose a short length of the common femoral artery. The arterial puncture needle is introduced via a separate stab incision 2 cm distal to the incision, and it is inserted into the artery under direct vision. The following steps are the same as described for Seldinger technique. A purse-string suture on the artery could be used to assure hemostasis, and the wound is then closed. This method of insertion allows the arterial cannula to lie nearly parallel to the artery and prevents over-angulation and kinking at the entry site.

After weaning from bypass, the operative field is opened again. The cannulas are removed and the cannulation sutures tied; running or interrupted sutures are placed as appropriate. To ensure peripheral perfusion, the arterial vessel is palpated distal to the former cannulation site immediately after decannulation. In case of distal malperfusion or pulselessness, reconstructive procedures are performed. If a chimney graft is present, after the cannula removal, the side graft can be closed with staples or a snare about 1 cm above the anastomosis and the residual part can be cut. If ECMO is still necessary, a new graft may be sutured to the stump of the old graft [4]. In cases of percutaneous cannulation, some authors suggest an open repair of the vessel in order to prevent bleeding and hematoma development [8]. Open repair of vessels also allows evaluation for potential areas of stenosis and ability to perform patch angioplasty if needed [8].

Femoral vein cannulation is more often percutaneously performed. Surgical isolation is performed when percutaneous approach fails or if femoral vessels are already exposed. Some authors suggest the cannulation of right femoral vein because of the easier placement of the cannula up to the right atrium, due to the relationship of the iliac vein and inferior vena cava to the iliac crest [9]. Some others suggest the cannulation of the contralateral femoral vein as opposite to the cannulated femoral artery to avoid a cluttered field [10]. The skin incision and the dissection techniques are the same as described above. Venous cannulation is performed first. A circumferential purse-string suture is placed in the anterior wall of the vein; the common femoral vein is then clamped proximally and distally. A venotomy is made within the purse string, the venous cannula is inserted, and the proximal and distal clamps are removed. The cannula is finally advanced up to the right atrium. Once properly positioned, the venous cannula is fixed, the arterial cannulation is performed, and the wound is closed. Cannula diameter size is from 19 to 25 Fr.

Ischemic complications using different approaches for femoral cannulation varied between 10 and 70 % [11]. Peripheral arterial disease is an independent predictor of vascular complications, and assessment of ankle–brachial index before ECMO implantation is recommended whenever possible [11]. During ECMO support a nursing protocol for early detection of vascular complication is suggested. Bisdas et al. [11] established the following protocol: (1) clinical examination of feet and legs for temperature, color, capillarity, and compartment syndrome and, additionally, continuous measurement of oxygen saturation of toe and comparison with the respective finger; (2) Doppler detection of peripheral pulses/arterial blood flow by an experienced physician every 6 h; (3) measurement of myoglobin and creatine kinase every 8 h; and (4) if items 1–3 reveal any problems, color Duplex ultrasonography is used, or in case of inconsistent results, contrast-enhanced computed tomography angiography. The same protocol is followed during the first 48 h after ECMO explantation. Therefore, distal limb perfusion is critical, and many authors recommend its implantation at the time of ECMO start or following specific criteria. Huang et al. [12] measured the mean arterial pressure of the superficial femoral artery by puncturing the vessel distal to the ECMO cannula with a 23-gauge needle. If the pressure was under 50 mmHg, a distal perfusion cannula was recommended. Similarly, a larger cannula size-to-BSA ratio could predict which patients could develop ischemia [13]. Surgical approach to solve such a problem may interest the femoral artery, the tibial artery, or the dorsalis pedis artery. If the femoral vessels are already isolated, the chimney graft anastomosed to the femoral artery could guarantee the distal perfusion of the leg. Otherwise, a cannula can be placed in the distal femoral artery or in the superficial femoral artery with the same technique described before [14–16].