Crystalloids: Uses, Types, Routes of administration by Nursesnote

 Crystalloids

A crystalloid fluid is an aqueous solution of mineral salts and other small, water soluble molecules. Most commercially available crystalloid solutions are isotonic to human plasma. These fluids approximate concentrations of various solutes found in plasma and do not exert an osmotic effect in vivo. Crystalloid fluids function to expand intravascular volume without disturbing ion concentration or causing significant fluid shifts between intracellular, intravascular, and interstitial spaces.

Crystalloids Fluids Types

• Balanced electrolyte: e.g Ringer's lactate
• Saline: e.g. 0.9% saline, 0.18% saline in 4% glucose.
• Glucose: e.g. 5%, 10%, 20%, 50%.
• Sodium bicarbonate: e.g 1.26%, 8.4%.

Uses of Crystalloids

• Crystalloid fluids to provide daily requirements of water and electrolytes. Thy should be given to critically ill patients as a continuous background infusion to supplement fluid given during feeding or to carry drugs.
• Higher concentration glucose infusion may be used to prevent hypoglycemia.
• Crystalloid fluids may contain potassium chloride supplements.
• Sodium bicarbonate may be used to correct metabolic acidosis, for urinary alkalinisation, etc 

Common Routes of administration

• IV

Nurses notes

• Significant plasma volume deficit should be replaced with colloid solutions since crystalloid are rapidly lost from the plasma particularly during periods of increased capillary leak, e.g sepsis.
• As most plasma substitutes are carried in saline solutions, any additional salt containing crystalloid infusion is only needed to replace excess sodium losses.
• The sodium content of 0.9% saline is equivalent to that of extracellular fluid. Therefore, salt- containing solutions distribute throughout the extracellular fluid space.
• Ringer's lactate solution avoid hyperchloraemic acidosis caused by the relative excess chloride infused with 0.9% saline. Hyperchloraemic acidosis may adversely affect coagulation and renal function though human data are lacking.
• A daily requirement of 70-80 mmol sodium is normal although there may be excess loss in sweat and from the gastrointestinal tract. This can be provided as saline or balanced electrolyte solution.
• 5% glucose is used to supply intravenous water requirements. Since there are no electrolytes to favour distribution to one space or another, water distributes uniformly throughout the extracellular and intracellular space. The 50g/L glucose content ensures an isotonic solution, but only provides 200Ca/L. Normal requirement is approximately 1.5-2L/d.
• Water loss in excess of electrolytes is uncommon but occurs in excess sweating , fever, hyperthyroidism, diabetes insipidus, and hypercalcaemia. 5% glucose is an appropriate replacement fluid for water loss.
• Potassium chloride must be given in slowly since rapid injection may cause fatal arrhythmias. The frequency of infusion is dictated by plasma potassium measurement.