When administered intravenously, these solutions provide a source of water and electrolytes.
Solutions which provide an isotonic concentration of sodium chloride are suitable for parenteral maintenance or replacement of water and electrolyte requirements.
Isotonic concentrations of sodium chloride are suitable for parenteral replacement of chloride losses that exceed or equal the sodium loss. Sodium chloride in water dissociates to provide sodium (Na+) and chloride (Cl‾) ions. Sodium (Na+) is the principal cation of the extracellular fluid and plays a large part in the therapy of fluid and electrolyte disturbances. Chloride (Cl‾) has an integral role in buffering action when oxygen and carbon dioxide exchange occurs in the red blood cells. The distribution and excretion of sodium (Na+) and chloride (Cl‾) are largely under the control of the kidney which maintains a balance between intake and output.
Water is an essential constituent of all body tissues and accounts for approximately 70% of total body weight. Average normal adult daily requirements range from two to three liters (1.0 to 1.5 liters each for insensible water loss by perspiration and urine production).
Water balance is maintained by various regulatory mechanisms. Water distribution depends primarily on the concentration of electrolytes in the body compartments and sodium (Na+) plays a major role in maintaining physiologic equilibrium.