Di Gennaro et al.1 provide a compelling case that carotid cannulation for extracorporeal life support (ECLS) is associated with a higher risk of stroke compared to femoral arterial cannulation. The analysis of registry data from 1,518 patients with an age range of 6–40 years includes several variables characterizing the presupport status of the patient as well as complications during support. The authors provide a good explanation of the perceived pros and cons of carotid versus femoral cannulation and acknowledge the limitations of this type of analysis. It would seem the matter is settled and the case closed—maybe, maybe not.
The Extracorporeal Life Support Organization (ELSO)—Euro-ELSO Neurologic Outcomes Working Group’s 2018 report included 30,000 ECLS runs in patients with ages from 0 to 18 years: 14,517 with carotid cannulation; 7,237 with aortic cannulation; and 917 with femoral cannulation.2 There were 806 runs with carotid cannulation in patients with ages ranging from 12 to 18 years. They concluded that “when correcting for patient related factors, carotid cannulation is not associated with an increase in stroke or neurologic complications and that carotid cannulation should be re-examined as a cannulation technique for older pediatric patients.”
So which study do we believe to represent the truth? Is a study with 30,000 runs conducted by a working group specifically designed to study neurologic outcomes easier to believe than one with 1,518 runs? Maybe, maybe not, but it probably is. Unfortunately, neither study reports outcomes of limb complications with femoral cannulation, which can be quite high in the pediatric population.3 Moreover, stroke or central nervous system (CNS) hemorrhage nor limb complications are functionally binary. A small stroke with no functional deficits at 6 months of follow-up (but yes, it is a stroke) is not the same as permanent hemiplegia. Rescue distal perfusion with a good outcome (but yes, it is a limb complication) is not the same as a below-knee amputation. Most would likely agree that a small stroke with no deficits is far better than a below-knee amputation, yet the literature to date provides no such granular outcome comparisons. Therefore, in my opinion, the matter remains unresolved. To imply that registry data for the index admission only (survival notwithstanding—and neither study compared survival nor specified if stroke status was ascertained in those who died) with CNS events or limb complications as binary outcomes is an oversimplification at best.
I will share some personal opinions on cannulation issues, but want to be very clear that in so doing, I recognize that other perspectives or approaches are not wrong and, in fact, may be better. I do not like to ligate carotid arteries or jugular veins. In the absence of cardiopulmonary resuscitation (CPR), I use pursestrings and short snares, bury the snares in the neck (snares doubled over and secured with heavy ligature), and leave the vessels in continuity, hopefully with some preserved flow; and, with rare exception, repair the vessels with decannulation. I have not encountered problems with leaving snares in the wound, even for prolonged runs. Perhaps the extreme vascularity of the neck renders it more resistant to infection. I currently do not favor groin cannulation for a variety of reasons. When I do use it (usually only an older teenager), I make an incision and expose the vessels and follow two principles: 1) do not oversize the venous cannula—I have seen as many ischemic issues from venous congestion as I have from inadequate antegrade arterial flow and 2) if there is no CPR, I place a chimney graft to allow bidirectional perfusion; or if there is CPR, get the patient on support promptly and then proceed to place an antegrade cannula.
Until we have more definitive, granular, longer-term follow-up data to suggest otherwise, it is my opinion that we should maintain a position of equipoise and select our cannulation vessels not based on the fear of stroke risk. Regardless of which vessels we use, we should employ strategies which both provide good support and minimize risk of serious morbidity, be it brain or leg.
1. Di Gennaro JL, Chan T, Farris RWD, Weiss NS, McMullan DM. Increased stroke risk in children and young adults on extracorporeal life support with carotid cannulation. ASAIO J 2019.65: 718–724.
2. Johnson K, Jarboe MD, Mychaliska GB, et al.; ELSO/Euro-ELSO Neurologic Outcomes Working Group: Is there a best approach for extracorporeal life support cannulation: A review of the extracorporeal life support organization. J Pediatr Surg 2018.53: 1301–1304.
3. Gander JW, Fisher JC, Reichstein AR, et al. Limb ischemia after common femoral artery cannulation for venoarterial extracorporeal membrane oxygenation: An unresolved problem. J Pediatr Surg 2010.45: 2136–2140.