Optimal LV venting flow rate during VA ECMO depends on your goal: bridge to long term support or weaning. Of course LV flow depends on the ECMO flow and on the underlying cardiopathy.
You must monitor continuously left atrial pressure. In case you have no left atrial line, you can use a connector with a side luer to connect the vent to the circuit and introduce in a retrograde way a catheter into the left atrium.
For a bridge, LV venting should decrease left atrial pressure around 10 to 12 mm Hg. The goal is to maintain a pulsatile flow, with LV preload avoiding distension of the left cavities.
For short term ECMO:
Initially, left atrial pressure should be low, less than 6 mm Hg for at least 24 to 48 hours . With such a low left atrial pressure there is no more opening of the aortic valve and the flow is continuous rather than pulsatile. The ventricle is "at rest" with a low myocardial oxygen consumption.
After one or two days, a "weaning test" should be done every 12 hours: you decrease progressively venting flow and look at central venous, left atrial and arterial pressure to assess ventricular improvement. You can stop venting when left atrial pressure is less than 10 mm hg and stable. You can decrease vent flow and perform pulsatile ECMO with ejection from the heart as far as left atrial pressure is below 8 mm Hg.
Thank you so much for your kind comments.
let me ask you some questions.
I agree with you.however, how do you control LV venting flow (by any device or catheter change, ECMO flow change?)?
I use transaortic valve catheter for not LA and LV venting.
The best option for a continuous monitoring is to add a Doppler on the vent line, Transonic is the most popular. You can also have an instantaneous evaluation by acute change in ECMO flow when you add vent flow, but vent flow is likely to vary during ECMO.
With most things being said already, let me just add some minor remarks.Effective venting of the left ventricle is even more important in cases with transfemoral canulation compared to central canulation, as the retrograde flow leads even earlier to a closure of the aortic valve and may thus cause a distension of the left ventricle. We do recently use a small 2.5 Impella(R) pump for an active venting of the LV at a rate of
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