Of the crystalloid solutions only 0.9 % sodium chloride and Hartmann's solution contain sufficient electrolytes to keep the fluid in the extracellular space.

For 5 % glucose and 0.18 % sodium chloride/4 % glucose, the glucose is rapidly taken up into cells leaving little or no electrolyte content. Most of the water therefore passes rapidly into the cells leaving little in the extracellular space. They are therefore not suitable fluids for resuscitation.

Note: 0.18 % sodium chloride/4 % glucose contains only around 1/5th of the concentration of Na⁺ in plasma and is not suitable as a sole maintenance fluid.