Sodium chloride irrigation, often called saline solution, is a foundational tool in both professional healthcare and routine home care. This simple mixture of salt and water is widely utilized due to its unique compatibility with the human body. It is frequently employed for cleansing, moistening, and flushing various tissues and devices, from washing out minor wounds to preparing surgical sites.
Defining the Solution
Sodium chloride irrigation is a sterile preparation consisting of sodium chloride (NaCl), which is common table salt, dissolved in sterile water. The concentration used for most medical irrigation purposes is precisely 0.9% by weight (9 grams of salt per liter of water). This specific concentration is termed “normal saline” because it mimics the natural salt concentration found in human blood plasma and other bodily fluids. The solution is manufactured to be nonpyrogenic, meaning it does not contain substances that cause fever, and is intended for external washing and flushing.
Common Medical Uses
The primary function of this solution is to provide a gentle, mechanical cleansing action for sensitive tissues and surfaces. Medically, it is used extensively for irrigating body cavities, tissues, and wounds during surgical procedures to remove debris and contamination. Professionals also use it to flush indwelling devices, such as urinary catheters and surgical drainage tubes, to maintain their patency.
For the general public, a common application is nasal irrigation, or sinus rinsing, which helps clear mucus and allergens from the nasal passages. The solution is also appropriate for cleaning minor cuts, scrapes, and abrasions. It cleanses without the sting or tissue damage that can be caused by harsh antiseptics. It can be used to moisten surgical dressings or to rinse contact lenses.
Understanding Isotonicity
The concentration of 0.9% makes the solution isotonic, meaning it has the same osmotic pressure as the fluid inside human cells. Human plasma typically has an osmolarity ranging from 280 to 300 milliosmoles per liter (mOsm/L), and 0.9% sodium chloride is approximately 308 mOsm/L, making it physiologically compatible. This balance prevents the movement of water across cell membranes, which can cause cellular damage.
If a hypotonic solution, like plain sterile water, were used, the lower salt concentration would cause water to rush into the body’s cells, leading to swelling and potential rupture. Conversely, a hypertonic solution would draw water out of the cells, causing them to shrink. By matching the body’s natural salt balance, the 0.9% sodium chloride solution ensures that the cells maintain their normal volume and function during the cleansing process.
Guidance for Use and Storage
Maintaining sterility is the most important factor for safe use, especially when the solution is used on open wounds or sensitive areas like the eyes or sinuses. Commercially prepared solutions are guaranteed to be sterile and nonpyrogenic until the container is opened. Once opened, any unused portion should be promptly discarded to minimize the possibility of bacterial growth, as the solution contains no antibacterial agents.
If preparing a solution at home for nasal rinsing, it is recommended to use distilled, sterile, or previously boiled and cooled water. Non-sterile tap water can harbor organisms that may cause serious infections in the nasal passages. The prepared solution should be stored in a clean, sealed container at room temperature, away from excessive heat or freezing. For most home preparations, any remaining solution should be discarded within 24 hours to ensure safety.