The result of this treatment will decrease the osmotic pressure of the blood, causing the cell is losing water molecule by osmosis.
Administering pure water as resuscitation fluid might also lower the concentration of electrolyte in the blood, causing electrolyte imbalance. It is recommended to use normal saline(0.9% NaCl) solution for resuscitation as the solution is having the same osmotic pressure, thus won't inducing osmosis.