Case 5

The most likely cause is pump head thrombosis, evidenced by the visible clots and characteristic noise before flow cessation. The three general categories of pump failure are: 

(1) Console/driver failure—power loss or electronic malfunction leading to loss of blood flow. 

(2) Pump head mechanical issues—the pump head not being properly seated within the driver or not coupled with the magnet, compromising operation. 

(3) Pump head thrombosis or air embolism (airlock)—clot formation in the pump head impairs impeller function, or air deprimes the pump, both leading to loss of blood flow.

Answer: B. The correct sequence is: clamp the return tubing (to isolate the patient from the circuit and prevent any clot from embolizing to the patient), call for help (need personnel for both patient and circuit management), then attempt hand crank if available. However, hand cranking is not appropriate for pump head thrombosis specifically. 

Increasing pump speed (A) will not overcome a thrombosed pump head. Starting ACLS first (C) delays the critical step of clamping the return line. Unclamping and flushing (D) is not an appropriate approach and risks clot embolization.

Hand cranking is NOT appropriate for pump head thrombosis (or airlock or pump head disengagement) because turning the impeller with clot in the pump head risks fragmenting and embolizing the thrombus into the patient through the return cannula. Instead, the pump head with the thrombus must be replaced. 

The correct approach is: 

(1) Keep the return line clamped. 

(2) Provide the patient with conventional cardiopulmonary support (ACLS). 

(3) Replace the thrombosed pump head (or the entire circuit if needed). 

(4) Once the new pump head is in place and the circuit is de-aired, unclamp the return line and restore ECMO support. Hand cranking is only appropriate for console or driver failure where the pump head itself is functional and free of clot or air.

This patient on VV ECMO with cardiac arrest requires full ACLS because the VV ECMO circuit provides no direct circulatory support—blood is drained from and returned to the venous system without bypassing the heart. With the circuit down, both respiratory and hemodynamic support are needed. This differs from VA ECMO, where the circuit provides both respiratory and circulatory support. On VA ECMO, if the circuit is functioning during cardiac arrest, the patient may be adequately supported even with cardiac standstill—no ACLS is needed, and blood flow can simply be increased. If the VA ECMO circuit is also the problem, then ACLS is required just as in this VV ECMO scenario. For refractory arrest in VV ECMO, conversion to VA ECMO should be considered if resources and expertise are available.

Answer: B. The key distinction is that in true pump failure, blood flow genuinely ceases and the patient loses ECMO support, leading to cardiopulmonary decompensation. In a flow sensor malfunction, the pump continues to function appropriately and the patient remains supported on ECMO—the only issue is that circuit blood flow is not being properly monitored or displayed. In this case, the flow meter needs to be addressed, but it is not an emergency. 

Choice A is incorrect because the patient remains stable in flow sensor malfunction. Choice C is incorrect because sensor malfunction only requires sensor repair. Choice D is incorrect because pump failure can occur from power loss or mechanical issues without visible clots.