Venous-Arterial Extracorporeal Membrane Oxygenation
◆ Arterial cannulation is achieved via the ultrasound-guided Seldinger technique in the common femoral artery. A small 15 F or 17 F arterial cannula should be used to allow some distal limb perfusion.
◆ To ensure adequate distal limb perfusion, an antegrade catheter can be placed in the superficial femoral artery, or a small retrograde catheter can be placed in the posterior tibial artery (Fig. 2.16).7
Step 4. Postoperative Care
◆ Surgeons should understand the pathophysiology of cardiopulmonary bypass to recognize the broad impact of this technology on virtually every organ system.
◆ Effective bypass should be married to proactive blood conservation strategies, including cell salvage and the use of appropriate antifibrinolytics. Surgeons may also be expected to supervise novel related techniques, such as ultrafiltration5 and retrograde autologous priming,8 and must understand the importance of well-executed cannulation to the success of these modalities.
Step 5. Pearls and Pitfalls
◆ Sites of arterial cannulation should be chosen with consideration about how the site of vascular entrance can be repaired should complications such as bleeding or tearing occur. For example, in the ascending aorta, the surgeon should consider whether the site chosen would be amenable to a partial occluding clamp to repair this area.
◆ Communication among the surgeon, perfusionist, and anesthetist is essential, particularly in complex cases. Potential strategies should be well prepared, with the appropriate equipment available in the room, in case cannulation sites change or emergency bypass needs to be initiated.
◆Atrial cannulation sites should be chosen carefully, particularly in fragile tissues, in anticipation of inadvertent tearing, which can extend to the atrioventricular junction, into the second cannulation site or, if too far inferiorly, into the IVC. On the insertion of the IVC cannula, always err on directing the cannula posteriorly, “marching” the cannula slowly forward, because initial anterior forced misplacement may lead to coronary sinus perforation, which can be lethal.
◆ Care must be taken when encircling the SVC and IVC to prevent posterior damage of these vessels. With the SVC, the tissue overlying the right pulmonary artery between the aorta and SVC can be divided with cautery, and a right-angled instrument can be used to create the plane. Damage to the azygos vein may be extremely difficult to repair. The SVC cannula tip should be inserted only so far so that when encircled, complete drainage will occur. Similarly, care must be taken with encircling the IVC to ensure that damage to the posterior wall does not ensue. If the seal with the snare is inadequate, often a second snare will accomplish the task.
◆ Placement of the retrograde cannula can be facilitated by restricting venous return somewhat to fill the right atrium. This will allow entrance of the catheter into the coronary sinus by palpation or via assistance with TEE.