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.

背景：静脉-动脉体外膜肺氧合（Venoarterial extracorporeal membrane oxygenation, VA ECMO）是一种用于心肺衰竭的有效机械循环支持手段。传统外周静脉-动脉体外膜肺氧合治疗中，为实现完全循环支持，通常会置入直径超过15Fr的动脉插管。但目前关于插管尺寸对临床及操作结局的影响，相关研究数据仍较为有限。方法：2014年1月至2016年4月期间，本单中心注册研究纳入了165例行股动脉穿刺外周VA ECMO的患者。根据动脉插管尺寸将患者分为两组：「小口径插管组」（14~15Fr，n=87）与「大口径插管组」（16~21Fr，n=78），并比较两组患者的临床结局与操作相关并发症。结果：两组患者的院内死亡率（小口径插管组48.3% vs 大口径插管组42.3%；p=0.44）与撤机成功率（小口径插管组70.1% vs 大口径插管组64.1%；p=0.41）均无显著统计学差异。小口径插管组的初始泵流量显著更低[3.2（2.5~3.7）vs 3.5（3.0~4.0）L/min；p=0.02]，且ECMO支持时长更短[2.6（0.7~5.2）vs 4.0（1.3~7.8）天；p<0.01]。此外，小口径插管组的下肢缺血发生率显著低于大口径插管组（4.6% vs 15.4%；p=0.02）。但其余并发症（包括插管部位或非插管部位出血、血栓事件、凝血病或脓毒症）在两组间均无显著差异。结论：在外周VA ECMO治疗中，相较于大口径插管策略，小口径动脉插管策略可获得相似的临床结局，并降低下肢缺血的发生风险。