How long can someone be asphyxiated/revived before a human dies?

[WSEN 0]

I saw on the news how some suspects in countries with little regard for human rights are tortured with plastic bags over their heads until they pass out, then revived back again and this process repeated. It kept me awake at night thinking about it because I feel like the sheer number of times this could happen would be one of the worst forms of torture.

My question is this:

Can a person who is healthy and is force fed, be tortured until death from old age?

Let's say that heart rate monitors were applied so as to make sure that the tortured victim doesn't die from heart failure.

How long can it go on? What if the individual was not knocked to the point of unconsciousness and therefore no brain death? Would the individual still lose brain cells and thus, eventually brain death (albeit a long one)?

I was wondering that maybe waterboarding would be even worse because there is no real asphyxiation and thus no brain damage and thus no chance of death. Heck, there could even be a simple machine that pours water intermittently even without anyone there to do anything! A device that pours water for a few seconds and stops.... The machine stops when the heart rate monitor beeps. The victim is force fed by having an IV solution into their veins so they're well fed. Oh my imagination is just too wild. Please save me from myself, I can't sleep.

 

 

[Prometheus 499]

With adequate medical 'supervision' i suspect someone could be kept alive for a long time, but less time than they should otherwise live. To give specific examples: an I.V. solution would only be enough to hydrate, not feed. A nasogastric tube could be placed for feeding, or Total Parenteral Nutrition given I.V. - but these are both easy to rip out. The victim would then need to restrained - this lack of mobility would eventually lead to developing clots, or pneumonia (as commonly seen in hospitals). I'm sure there would be many other 'lifestyle' complications. Still, we are talking decades. It would require significant medical equipment and personnel though.