Pediatric arterial femoral cannulations for extracorporeal membrane oxygenation: Does size really matter?

Background: : No studies exist comparing various femoral artery cannula sizes in children on ECMO. We hypothesize that smaller arterial cannulas provide adequate flow in children while decreasing vascular complications. Methods: : We performed a retrospective review of the ELSO database from 2012–2017. We included children undergoing femoral venoarterial ECMO between ages 12 and 18 years and weighing more than 30 kg. Arterial cannula sizes were grouped as: 15-16Fr, 17–18Fr, 19–20Fr and ≥21Fr. Arterial pump flow, bleeding complications, limb ischemia, and mechanical complications were compared by cannula size. Distal perfusion catheter and percutaneous placement were also compared for complications. Results: : A total of 429 patients were included with 28.2% 15–16Fr, 32.2% 17–18Fr, 22.8% 19–20Fr, and 16.8% ≥ 21Fr arterial femoral cannulas. Median age was lower in the 15–16Fr group compared to the largest cannula group (14.7 years vs 15.5 years, p < 0.01). The overall mean arterial flow was 57.4 +/- 17.0 mL/kg/min with no difference in mean arterial flow rates among the cannula size groups (p = 0.85). There were no significant differences in all complications, bleeding or mechanical complications by arterial cannula size group. However, there was an increased risk of limb ischemia in the ≥21Fr group compared to the 15–16Fr group (OR 4.38, 95% CI 1.24–15.43; p = 0.02). Distal perfusion catheter was shown to increase the risk of mechanical complications (OR 1.78; 95% CI 1.03–3.07; p = 0.04) but did not make a statistically significant difference in limb ischemia (OR 0.37; 95% CI 0.12–1.11; p = 0.07). Conclusion: : Review of the ELSO database demonstrates that the use of larger arterial cannulas compared to 15-16Fr cannulas are not needed to achieve similar pump flows for hemodynamic support but the largest cannula sizes may increase the risk of ischemic complications.