In an absolute emergency, coconut water can be used as an alternative to blood plasma. One case in the recent medical literature involved a man who had recently suffered a stroke - in the remote Solomon Islands. He had difficulty in swallowing and choked on both liquids and solids. He was rehydrated with regular IV fluids, and fed via a tube directly into his stomach. After 36 days in hospital, he could no longer tolerate the feeding tube. Unfortunately, the hospital had run out of IV fluids, and because of its remoteness, would not get supplies for two days.
Over these next two days, the doctors infused about two-and-a-half litres of coconut water, to tide him over the crisis. He recovered the ability to swallow, and was discharged from hospital on day 39.
But even though coconut water it's not an optimal IV solution for rehydration because it doesn't have enough sodium content to stay in the bloodstream and besides this, it could cause elevated calcium and potassium, which could be dangerous, doctors are recommending it to patients as an oral rehydration therapy.