Question

Why is an isotonic IV used to replace fluid lost to hemorrhage?

Answer 1

According to the concentration of the solute, the water move across the membrane (osmosis), this ability of osmosis to draw water to build up certain pressure is called osmotic pressure. So, water always moves to maintain uniform pressure in and outside of the membrane to maintain isotonicity.

The fluids having lower osmotic pressure than the body fluids are known as hypotonic solutions. If cells are placed in hypotonic solution, they draw water from the solution and swell.

The fluids having more osmotic pressure than the body fluids are known as hypertonic solutions. The cells placed in hypertonic solutions shrink as they lose water into the surrounding hypertonic solution.

Isotonic solutions do not make the cells to swell or lose the intracellular fluid. So, the intravenous isotonic solutions can be used to replace the fluid lost to hemorrhage (increase the fluid volume).