Setting roller pump occlusion with the transonic HT109 flowmeter.

Setting the occlusion of a roller pump may be facilitated using the TRansonic HT109 Ultrasonic Flowmeter (Transonic Systems, Inc. Ithaca, NY) with non-invasive transducer. The process addresses the need to set occlusion quickly and accurately before initiation of extracorporeal membrane oxygenation (ECMO). This can be performed with the circuit tubing before blood prime and does not require opening the fluid filled ECMO apparatus to air. The principle is based on the fact that fluid flow through the tubing will change with roller occlusion. Using the Transonic flowmeter, a pre determined (partially occlusive) setting can be achieved by first determining the point of total occlusion, then decreasing occlusion a small percentage from this maximum (i.e., total) occlusion. Clinical application in 35 neonatal ECMO cases has shown the practice to be safe, reliable, and efficient.