Impact of cannula size on clinical outcomes in peripheral venoarterial extracorporeal membrane oxygenation

Background: Venoarterial extracorporeal membrane oxygenation (VA ECMO) is an effective mechanical circulatory support for cardiopulmonary failure. Conventionally, an arterial cannula over 15Fr is inserted for full circulatory support in peripheral VA ECMO. However, limited data are available regarding the impact of cannula size on clinical and procedural outcomes. Methods: Between January 2014 and April 2016, 165 patients underwent peripheral VA ECMO with femoral artery cannulation were enrolled in a single-center registry. We classified patients into 2 groups according to the arterial cannula’s size: ‘Small cannula group’ (14-15Fr, n = 87) and ‘Large cannula group’ (16-21Fr, n = 78). We compared the clinical outcomes and procedural-related complications between the two groups. Results: Neither the in-hospital mortality (48.3% in the small cannula group vs. 42.3% in the large cannula group; p = 0.44) nor the weaning success rate (70.1% in the small cannula group vs. 64.1% in the large cannula group; p = 0.41) were significantly different between the two groups. The small cannula group showed significantly lower initial pump flow (3.2 [2.5-3.7] vs. 3.5 [3.0-4.0] L/min; p = 0.02) and shorter ECMO duration time (2.6 [0.7-5.2] vs. 4.0 [1.3-7.8] day; p < 0.01). Also, lower limb ischemia was significantly lower in the small cannula group than in large cannula group (4.6% vs. 15.4%; p = 0.02). But other complications (including cannula site or non-cannula site bleeding, thrombotic events, coagulopathy, or sepsis) were not significantly different between the two groups. Conclusions: In peripheral VA ECMO, as compared with the large cannula strategy, the small arterial cannula strategy showed similar clinical outcomes and a decrease in lower limb ischemia.