Flow characteristics of reperfusion sheaths when utilizing large bore mechanical circulatory support devices.

BACKGROUND

Reperfusion sheaths are commonly utilized to prevent acute limb ischemia (ALI) when using large bore mechanical circulatory support devices, though little is known about flow characteristics of these sheaths.

METHODS

The purpose of this assessment was to characterize the flow rates of various femoral to femoral (fem-fem) bypass circuits. We devised a test setup that maintains a preset input pressure for test devices to enable an accurate comparison of bypass techniques.

RESULTS

Negligible flow rate increases were observed in active or passive ipsilateral and contralateral circuits when donor or receiver sheaths were sequentially increased in size. When using a contralateral fem-fem bypass circuit, the use of a Merit Prelude Pro 8F sheath paired with a 5F Arrow reperfusion sheath provided 167 ml/min of flow. If the reperfusion sheath was exchanged to a 6F sheath the flow rate was 169 ml/min, 175 ml/min with a 7F sheath and 179 ml/min with an 8F sheath, a total difference of 7 %. When maintaining a 6F reperfusion sheath as a constant, the use an ipsilateral fem-fem bypass circuit using an Abiomed 14F Low profile sheath provided 215 ml/min of flow, a 27 % higher flow than a contralateral 8F circuit. The use of an active pressure bypass system using an 18F ECMO cannula provided 356 ml/min, a 66 % higher flow than a 14F ipsilateral fem-fem bypass and 110 % higher flow than an 8F contralateral fem-fem bypass.

CONCLUSION

Flow rate through a fem-fem bypass circuit is contingent upon the smallest diameter along the pathway which is typically the side port of the sheath. There are negligible changes in flow rate based on increasing donor or receiver sheath sizes. Novel, purpose-built reperfusion sheath taking these flow characteristics into account are needed to improve such systems.