Mannitol is a sugar alcohol used in medicine for its unique properties. It functions as an osmotic diuretic, drawing water from tissues into the bloodstream for kidney excretion. This action makes mannitol useful in reducing elevated intracranial pressure and high intraocular pressure. It also promotes urine production in acute kidney failure. Filtration during mannitol administration is a significant patient safety consideration.
Why Mannitol Requires Filtration
Mannitol’s chemical nature contributes to its tendency to crystallize. This crystallization occurs when solutions are exposed to lower temperatures or are in higher concentrations, typically 15% or greater. Crystals can range from visible particles to microscopic formations, posing a challenge for safe intravenous administration.
As the solution’s temperature drops, mannitol molecules may come out of solution and form solid particles. These particles are problematic because they can be introduced directly into a patient’s bloodstream during infusion.
Types of Filters and When to Use Them
Filtration of mannitol solutions is often necessary to prevent the administration of harmful crystals. An in-line filter with a pore size of 5 microns or smaller is commonly recommended, especially for concentrations of 15% or more. This filter effectively traps particulate matter, including mannitol crystals, before they enter the patient’s circulatory system.
While filtration is generally recommended, it becomes mandatory if visible crystals are present. Even if crystals are not apparent, a filter helps ensure no microscopic particles are infused. This filtration is typically performed as a terminal filter, the final step before the solution enters the patient.
Risks of Unfiltered Mannitol Administration
Administering mannitol without proper filtration, especially with crystals present, carries several patient risks. Particulate matter introduced into the bloodstream can lead to various adverse effects. These particles can irritate blood vessel linings, potentially causing venous irritation or phlebitis (inflammation of the vein).
Beyond localized irritation, these particles can act as microemboli, small blockages that travel through the circulatory system. This can lead to severe complications, such as pulmonary emboli if particles reach the lungs, potentially obstructing blood flow. Unfiltered crystals may also contribute to damage in organs like the kidneys or lungs, compromising patient health.
Best Practices for Mannitol Handling
Proper handling of mannitol solutions minimizes crystal formation and ensures safe administration. Solutions are typically stored at room temperature, 20 to 25°C (68 to 77°F), and protected from freezing. Before administration, visually inspect the solution for any signs of crystallization or particulate matter.
If crystals are observed, do not administer the solution immediately. The vial can often be warmed in a dry heat cabinet or warm water bath, followed by vigorous shaking, to dissolve crystals. However, warming only dissolves visible crystals and does not eliminate the need for filtration. The solution must also be cooled to body temperature before infusion.