The position you're referring to is known as the Trendelenburg Position. The benefits were thought to lie not so much with increasing perfusion to the brain, but bringing more blood back to the heart (known as preload), thereby increasing cardiac output and increasing blood flow to vital organs. If you're interested in this, there's some neat physiology called the Frank-Starling law [0].
However, it turns out that in practice, cardiac output doesn't actually improve. In fact, this position also increases the risk of fluid build up in the lungs (pulmonary oedema) and can worsen cerebral perfusion [1]. Therefore, it's falling out of favour in the context of shock. A compromise might be to elevate solely the legs, but its efficacy is also being questioned.
This illustrates a recurring theme in modern medicine; the human body & disease is so complex and poorly modelled, that it's often not possible to translate intuition or first principles of physiology into treatment. Instead, one relies on real world studies like those reviewed in [1] - AKA 'evidence-based medicine'.
[0] https://en.wikipedia.org/wiki/Frank%E2%80%93Starling_law
[1] https://www.cambridge.org/core/services/aop-cambridge-core/c...
I am not a dr (IANAD?) but the idea is that you inflate the pants around a patient's legs which helps both push and keep blood out of the lower limbs and closer to the hear and brain. In principle, you could do the same by tying a tourniquet around each leg but the MASTs probably cause less tissue damage and are more adjustable.
[0] - https://en.wikipedia.org/wiki/Military_anti-shock_trousers
Effectively, you could artificially keep the patient alive by using MAST pants, but they inevitably crash when they were removed. My old service had a few pairs tucked back in a closest, but none on any of the rigs. I'm quite certain they aren't in allowable by protocol in most places at this point.
A pretty wild device, nonetheless!
EDIT: Quick edit to throw in that I have heard tales from the old heads of using them to stabilize pelvic fractures, too.
> Passive leg raise, also known as shock position, is a treatment for shock...
"If the face is red, raise the head. If the face is pale, raise the tail."
So, if this is a generic thing about low blood-pressure, including—potentially—low blood-pressure from shock... then could inverting someone who's going into shock in the field (where an ambulance is not yet arrived), be neuroprotective—ensuring they keep some oxygenated blood near their blood-brain barrier to feed their brain, long enough to stave off brain damage until EMTs can arrive and get a saline+steroid IV into them? Would it work for all types of shock? Toxic shock, for example?
I know that in the case of the article, the cause turned out to be a malfunction of the pacemaker itself, but is the doctor's original line of thinking still valid?