From the Guidelines
Isotonic saline is a sterile solution containing 0.9% sodium chloride (NaCl) in water, which has the same osmotic pressure as human blood plasma, as defined in the context of fluid therapy for hyperglycemic crises and infectious diarrhea 1.
Definition and Composition
Isotonic saline, commonly known as normal saline, contains 9 grams of sodium chloride per liter of water, providing 154 mEq/L each of sodium and chloride ions. This concentration makes it isotonic, meaning it won't cause cells to shrink or swell when administered.
Clinical Use
It is widely used in healthcare for:
- Intravenous fluid replacement
- Medication dilution
- Wound irrigation
- As a flush solution for intravenous lines
Physiological Compatibility
Isotonic saline is considered physiologically compatible with the body because its concentration closely matches that of extracellular fluid, making it safe for most patients requiring fluid therapy. However, large volumes can potentially cause hyperchloremic metabolic acidosis in some patients, so monitoring is important during high-volume administration, as noted in guidelines for managing hyperglycemic crises 1 and infectious diarrhea 1.
Administration
In cases of severe dehydration, shock, or altered mental status, isotonic intravenous fluids such as lactated Ringer’s and normal saline solution should be administered, according to the 2017 Infectious Diseases Society of America clinical practice guidelines 1.
Availability
Isotonic saline is available in various container sizes ranging from small flush syringes to large-volume bags for intravenous infusion. Given the most recent and highest quality evidence from 1 and 1, the use of isotonic saline is recommended for fluid replacement in specific clinical scenarios, prioritizing patient safety and effective management of dehydration and fluid balance.
From the Research
Definition of Isotonic Saline
Isotonic saline is a type of intravenous fluid that has the same concentration of solutes as human blood.
- It is also known as 0.9% sodium chloride solution, as it contains 0.9% sodium chloride (NaCl) in water.
- Isotonic saline is considered an isotonic crystalloid, meaning it has the same osmotic pressure as human blood and does not cause hemolysis (breakdown of red blood cells) when administered intravenously 2.
- It is often used as a vehicle for drug administration, for rehydrating patients, and for maintaining fluid balance in critically ill patients.
Properties and Uses
- Isotonic saline has a neutral pH and is compatible with most medications and blood products.
- It is commonly used in medical settings, including hospitals and clinics, for a variety of purposes, such as:
- Rehydrating patients who are dehydrated or at risk of dehydration
- Maintaining fluid balance in critically ill patients
- Administering medications intravenously
- Irrigating wounds and surgical sites
- Isotonic saline is generally considered safe and effective when used as directed, but it can cause adverse effects, such as fluid overload, if not used properly 3, 4.