Will injecting ice cold water into a vein kill someone?

Answer 1

It can. It depends on how much and if there is sodium chloride (Salt) in the water. The salt turns the water into a saline solution. Your blood is also has salinity. If you throw off the salinity of the blood too much then yes, it can kill you.

Straight ice water into the veins will cause the salinity in your blood to dive quickly from water intoxication and hyponatremia. Your cells no longer have enough electrolytes so they start to absorb electrolytes from fluids in your body via osmosis which in turn causes them to swell up. The swelling will increase your intercranial pressure (The pressure inside your skull). Once the pressure increases too high, the bloodflow to your brain is interrupted causing a cerebral edema (Increase in blood in the surrounding space of your brain and cranium). The increased pressure will start putting pressure against your brain which will throw off your nervous system and will eventually cause, best case scenario, seizures and brain damage. Worst case; coma and death.

Even with a saline solution, it is possible to still cause death due to your kidneys being unable to excrete enough fluids (1L/hour is about the max your kidneys can excrete). However this can be avoided through the use of diuretics to increase the amount of fluids excreted (Makes you urinate a lot).