Discussion seems to agree it doesn't work. What works is calling 911 (or local emergency number), which gets help and instruction over the phone from experts in the latest. I've been doing CPR classes every few years for 30 years - a lot has changed over that time (but not once did I hear this for CPR - shock yes, but not heart problems), but they still teach CPR over the phone to surprisingly good results.

Yeah I doubt you would look like someone who could be trusted with saving a life if you did this in an emergency scenario

See my post. Using a passive leg raise does shift venous blood from both the legs and the splanchnic bed toward the central circulation, but this was generally a thing for hypovolemic shock (hence the comparison to transfusion, which otherwise seems odd to measure for a non-traumatic cardiac arrest), but generally discredited, even for that, 20+ years ago.

Most arrest patients are primary arrhythmic or hypoxic - there's not a volume issue.

Defib. Compressions. 911. No more, no less.

Is your patient conscious, pulsatile with suspected non-traumatic hypovolemia or vasovagal syncope? Then try a PLR. If not, or you stare blankly at those words, don't.

(Retired paramedic of 14 years.)