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.
