What hemodynamic parameters or RHC numbers do you use to prompt venting the LV emergently with an Impella overnight for patients on VA-ECMO?

Put simply, the role of adjunctive mechanical left ventricular unloading in a patient supported by peripheral VA ECMO is to treat left ventricular failure refractory to medical therapy (e.g., inotropes and diuretics). There are multiple clinical, imaging, and invasive hemodynamic parameters which can be useful to make this diagnosis.

The question, as phrased, presupposes three things:

1. Emergency
2. Overnight timing
3. Use of a microaxial flow pump specifically

I feel obliged to challenge these three poi...