January 13, 2010 (Miami, Florida) — Carotid artery (CA) cannulation for veno-arterial extracorporeal membrane oxygenation (ECMO) is associated with a higher risk for central nervous system (CNS) injury than femoral artery or aorta cannulations in all pediatric patients younger than 18 years of age, according to a study presented here at the Society of Critical Care Medicine 39th Critical Care Congress.
"In fact, we found that whether you're a neonate or a teenager, you had the same increased risk of neurologic injury after carotid artery cannulation, including clinical or EEG seizures, hemorrhage, or infarction, " lead author Sarah Teele, MD, from the cardiac intensive care unit at Children's Hospital Boston in Massachusetts, and an instructor in pediatrics at Harvard Medical School, told meeting attendees.
"We are a big referral center and do a lot of ECMO," Dr. Teele told Medscape Critical Care. "Our outcomes are very reasonable, but they can always be better. I think the natural bias for us is to use the carotid artery as the cannulation site for younger patients, for the neonates, with the idea that an older patient would have a higher risk of having neurologic injury. That's what was assumed. So we wanted to look at whether age really does play a difference and to get a sense of what we were up against."
For this study, the investigators examined data from 2977 patients (18 years or younger) from the international Extracorporeal Life Support Organization (ELSO) registry who underwent veno-arterial ECMO in 2007 or 2008. These data were then evaluated to determine the differences in arterial cannulation sites in patients with CNS injury.
Veno-arterial ECMO was performed in the study patients for pulmonary (47%), cardiac (39%), and support of cardiopulmonary resuscitation (14%) reasons.
The 3 cannulation sites used were the femoral artery (4%), aorta (32%), and carotid artery (64%). The CA cannulation patients included 71% of the neonates (n = 1276), 54% of the infants (n = 316), 66% of those between the ages of 1 and 5 years (n = 186), and 47% of those between 5 and 18 years (n = 143).
CA Cannulation Increased Risk
At the end of the evaluation, the investigators found that, overall, 611 patients (21%) had a CNS injury and that the incidence of this injury differed significantly by site used: 15% of those undergoing femoral cannulation (n = 18), 17% of those undergoing aorta cannulation (n = 160), and 23% of those undergoing CA cannulation (n = 433; P = .001).
"In other words, CA cannulation was associated with higher odds of CNS injury [odds ratio, 1.4; 95% confidence interval, 1.1 - 1.7]," reported Dr. Teele. "Importantly, the odds of CNS injury following CA cannulation did not differ significantly between the age groups [P = .4]."
She added that "it was a little bit of a surprise to us that the neonates were found to be at as high a risk as if I had been cannulated via the carotid artery."
However, she noted that the carotid artery is still an important site for cannulation. "Plus, the femoral artery has its own set of problems in terms of a cannulation site. So we're not recommending that people not use the carotid artery. We're just recommending that people be that much more vigilant in following those patients."
"Overall, I think, given the needs of ECMO right now, particularly the vascular needs of ECMO, we're committed to using the carotid artery. Until that should change, I think it's important to sort out how kids are followed while they're on ECMO in terms of their neurologic status, and how you can prevent some of the injuries."
Decisions Should Be Made Carefully
"I thought this was a well done abstract and an excellent use of the ELSO database," said Steven Simpson, MD, associate professor of medicine and director of fellowship training and pulmonary and critical care at the University of Kansas Medical Center in Kansas City.
"I think my overall takeaway message from this study is that clinicians should be careful and should probably not use veno-arterial ECMO in circumstances that don't require it. Specifically, they should not use carotid veno-arterial ECMO unless it's the only possible source of cannulation," said Dr. Simpson, who was not involved with the study.
He added: "Any time you're talking about using extracorporeal life support in any patient, that means that they are some of the most seriously critically ill people that there are. What we should bear in mind is that these are presumably cases that would not have managed to survive without the establishment of [ECMO]. And one does not care for these types of people without complications of one sort or another. On the other hand, understanding that certain sites of cannulation are associated with a higher risk to the patient, of course one should always attempt to use those sites that are of lower risk."
Although he found this to be a good study, Dr. Simpson said that he would have liked to have seen more information on the specific complications found in each age group — information that he thinks can be found in the ELSO database.
"With a database that is as robust as this one, with sufficient data points, a prospective trial may not even be necessary to guide a change in therapy," he concluded.
Dr. Teele and Dr. Simpson reported no relevant financial relationships.
Society of Critical Care Medicine (SCCM) 39th Critical Care Congress: Abstract 13. Presented January 10, 2010.
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Cite this: Carotid Artery Cannulation for ECMO Can Increase Risk for Neurologic Injury in Children - Medscape - Jan 13, 2010.