Research on hypertonic solutions for the treatment of cerebral edema and lowering intracranial pressure began in 1919. And mannitol, now the most clinically used osmotic dehydrating agent, has become the drug of choice for the treatment of intracranial hypertension. Mannitol is an osmotic dehydrating agent that is effective in lowering intracranial pressure. It may work through the following three aspects: 1. After mannitol liquid is injected into the vein, it rapidly increases plasma osmolality, creating an osmotic pressure difference between plasma and brain tissue fluid, which allows brain tissue fluid to enter the circulation, thus reducing the volume of the brain and lowering intracranial pressure; 2. The effect of volume expansion causes a decrease in hematocrit, reduces blood viscosity, alters red blood cell rheology, improves brain perfusion, reduces cerebral blood volume and 3.After intravenous infusion of mannitol, the plasma osmolality increases and inhibits the production of cerebrospinal fluid, thus reducing intracranial pressure.
In order to rapidly increase plasma osmolality and effectively eliminate tissue edema, it is generally required to infuse 250 mL of 20% mannitol within 25-30 min, with an input rate of 10-15 mL/min. 20% mannitol has a fast and strong dehydrating effect and a long duration of action, with intracranial pressure starting to fall in 10-20 min after administration, reaching a peak in 30 min, and starting to rise after 1 h, and then rising in 4 h. Therefore, in order to strive for continuous reduction of cranial hypertension, repeated dripping at intervals of 4-6 hours can also be supplemented with other cranial pressure-lowering drugs between doses, and continuous dosing should preferably not exceed 1 week.
2, the choice of blood vessels and needles: should choose thick, straight large blood vessels, No. 9 scalp needle, in order to maintain the drip rate and avoid local irritation. In order to reduce the pain caused by repeated venipuncture to patients, improve the efficiency and prevent serious puncture complications, you can choose to apply intravenous indwelling needle.
3, to prevent extravasation: mannitol is a hypertonic fluid, if extravasated, the local tissue appears red and swollen, and in serious cases, degenerative necrosis. Therefore, the injection site should be frequently inspected when input, if redness, swelling, pain should be replaced at the injection site, redness and swelling hot compress or closed with 0.25% procaine or wet compress with 50% magnesium sulfate.
4, to prevent water-electrolyte disorders: rapid injection of large amounts of mannitol can cause the accumulation of mannitol in the body, a large increase in blood volume rapidly, leading to heart failure, dilutive hyponatremia, in addition, mannitol has a diuretic effect, a large amount of urine discharge while taking away a large amount of potassium. In addition, mannitol has a diuretic effect, and a large amount of urine is excreted and a large amount of potassium is taken away. During the application process, attention should be paid to the observation and regular blood biochemistry to detect and correct the water and electrolyte disorders in time to keep them in balance.
5. Maintain the balance of intake and output: Mannitol is a dehydrating drug, if the supplemental fluid is not enough, it will probably lead to blood volume deficiency and blood pressure drop.
The osmotic pressure of brain tissue is increased by the continuous input of hypertonic substances. Once discontinued, the osmotically active substances in the plasma are continuously excreted by the kidneys and consumed in the body, causing the plasma osmotic pressure to be lower than the brain tissue, resulting in the return of water in the plasma to the brain tissue, causing brain edema again, also known as rebound after dehydration. It causes serious consequences!