Application skills of mannitol in the treatment of acute cerebrovascular diseases

Mannitol is a macromolecule similar in structure to starch.
It is mainly used for intravenous osmotic diuresis and reduces the water content of brain tissue through osmotic dehydration
.

After the medication, the plasma osmotic pressure is increased, and the water in the intercellular space can be quickly moved into the blood vessel, causing the tissue to be dehydrated

When to use mannitol

When to use mannitol

At present, most hospitals in China regard mannitol as the main dehydration drug in the early stage of acute cerebrovascular disease
.

Under normal circumstances, there are different degrees of cerebral edema after the onset of acute cerebrovascular disease, regardless of its severity, and anti-cerebral edema drugs should be used

Acute and chronic intracranial pressure increase due to pathological factors, including brain edema, cerebral hemorrhage, cerebral infarction, intracranial tumor, hydrocephalus, intracranial infection, hypoxic ischemic encephalopathy, venous sinus thrombosis, etc.
At times, patients who still have intracranial hypertension after the implementation of basic treatment for lowering intracranial pressure may also consider using mannitol to further lower intracranial pressure
.

Diseases without pathophysiological changes of intracranial pressure, acute pulmonary edema or severe pulmonary congestion, combined with renal impairment or latent nephropathy, congestive heart failure, metabolic edema, hypotension, pregnant women, the elderly, are prohibited or Use mannitol with caution

Mannitol application skills

Mannitol application skills

01 Acute cerebral hemorrhage

The mannitol package insert clearly states that it is forbidden for patients with active intracranial hemorrhage (except during intracranial surgery)
.

This is because the space-occupying effect of hematoma during intracerebral hemorrhage is the primary factor in the mechanism of intracranial pressure increase.

02 Acute cerebral infarction

The dose of mannitol should not be too large, and the course of treatment should not be too long, because in the early stage of cerebral infarction, the mechanism of cerebral edema is mainly cytotoxic edema.
In the later stage, it is mainly angiogenic edema.
Cerebral infarction can often be seen in clinical practice.
The patient has converted to cerebral hemorrhage.
If mannitol continues to be used at this time, mannitol can accumulate in the damaged tissue due to the destruction of the integrity of the blood-brain barrier.
The osmotic pressure in the brain tissue exceeds the osmotic pressure in the plasma, which can aggravate the brain Edema
.

03 Close monitoring

■1 Intracranial pressure monitoring: It is of great significance to guide the treatment of mannitol.
If the intracranial pressure after mannitol use is less than 20 mmHg, no additional and repeated use of mannitol is required; if the intracranial pressure is greater than 20 mmHg, long-term use of mannitol is required; If the intracranial pressure remains above 25 mmHg for more than 30 minutes after treatment, CT should be reviewed or a higher-level intracranial pressure reduction treatment plan should be initiated
.

Regardless of whether there is intracranial pressure monitoring, it needs to be evaluated in combination with clinical and imaging examinations.

■2 Osmotic pressure monitoring: After mannitol is used, there can be changes in electrolytes, internal environment, capacity status and plasma osmotic pressure levels
.

When osmotic treatment is performed for increased intracranial pressure, the target value of plasma osmotic pressure should be maintained at 300-320 mOsm/L

■3 Effect of diabetes insipidus: As patients with severe brain injury often develop central diabetes insipidus and secondary massive diuresis, and severe hypernatremia (serum sodium ≥165 mmol/L) when clinically progressing to brain death, Therefore, in the clinical use of mannitol, for patients with high urine output and hypernatremia, care should be taken to exclude diabetes insipidus
.

The diagnosis of diabetes insipidus is very important, and the diagnosis of central diabetes insipidus may be confused with patients who use mannitol for diuresis

Main points of using mannitol

Main points of using mannitol

■1 The use time of mannitol is generally 7-10 days
.

If the temperature of mannitol is too low, snowflake-like precipitation can form, which needs to be heated to dissolve before infusion

■2 In order to achieve the best effect of mannitol, the speed of medication is very important
.
It is generally recommended that the 250 ml liquid volume be dripped in 20 minutes
.
Twenty minutes after the medication, intracranial pressure began to decrease, reaching a peak in 2 to 3 hours, and its effect lasted for about 6 hours, and intracranial pressure could be reduced by 46% to 55%; however, the effect of reducing intracranial pressure was generally short because of blood The sugar in it will slowly infiltrate the brain and allow the water to filter through the gradient to reach equilibrium
.
In order to prevent the reversal of the gradient effect of water filtration and the re-entry of water into the brain, it is necessary to maintain a continuous hypertonic state
.
Therefore, if osmotic therapy is still needed to lower intracranial pressure after the first administration, the intracranial pressure and plasma osmotic pressure should be monitored and the administration should be repeated 4-6 hours later
.
If the control target is still not achieved after repeated administration, other methods of lowering intracranial pressure should be used
.

■3 The dosage can be determined according to the size of the lesion, the degree of cerebral edema and intracranial pressure; for those with lesions larger than 3 cm in diameter, a certain amount of mannitol should be given daily; for those with large lesions, severe cerebral edema or with intracranial hypertension, give 1～2 g/(kg? times), it can be used repeatedly every 4～6 hours; for patients with cerebral herniation, the dose can be larger; especially for patients with cerebral hemorrhage and cerebral hernia, using mannitol to lower intracranial pressure can be Follow-up surgical treatment wins time
.

■4 Mannitol infusion regimen includes continuous infusion or pulsed administration, the latter is better than the former; pulsed administration of 0.
25 g/kg mannitol can achieve the same level of cranial lowering as 0.
5～1.
0 g/kg continuous infusion Low-dose mannitol can also avoid osmotic pressure imbalance and severe dehydration, and can effectively improve cerebral hemodynamics
.
Therefore, pulsed administration is often recommended.
The initial dose is 0.
25-1 g/kg via a peripheral or central venous catheter within 10-20 minutes, and a low dose of 0.
25-0.
5 g/kg can be given every 4-6 hours for maintenance
.
In the case of sudden increase in intracranial pressure, higher doses can be used, generally about 60 g (1 g/kg) dose
.
It should be emphasized that when the patient's plasma osmotic pressure is greater than 330 mOsm/L, it should be discontinued; because at this time, no matter what dose of mannitol is given, it is impossible to have a dehydration effect
.

■5 Bounce phenomenon
.
For those with extremely increased permeability, mannitol may penetrate into the brain tissue and rebound; in order to prevent the rebound phenomenon, one intravenous injection of hypertonic glucose or dexamethasone during two mannitol administrations can be used to maintain Its role in lowering intracranial pressure
.
Studies have found that the high-dose group (760 mg/kg) has different degrees of rebound after 1 to 1.
5 hours of medication.
The mannitol concentration in the cerebrospinal fluid is measured (0.
91±0.
64) mmol/L; while the low-dose group (400 mg/kg) kg) no rebound phenomenon, the concentration of mannitol in the cerebrospinal fluid was lower (0.
65±0.
53) mmol/L, and the percentage of cerebral pressure drop was better than that of the high-dose group
.
Therefore, some scholars believe that in patients with intracranial hypertension, when intravenously injecting mannitol to lower cerebral pressure, the dose should be 400 mg/kg, and the infusion rate should not exceed 50 mg/(kg?min).
This can achieve the best blood pressure reduction effect, but also It can prevent the pressure in the brain from rebounding
.

Precautions for mannitol application

Precautions for mannitol application

■1 Avoid mannitol nephropathy, which is mainly manifested as hematuria, oliguria, anuria, proteinuria, and elevated urea nitrogen during medication
.
Some patients died of renal failure instead of cerebrovascular disease, some of which were related to mannitol
.
Therefore, it should be used with caution for patients with original renal impairment; do not use too much when not necessary, and do not use it for too long; closely monitor relevant indicators during medication; reduce or stop when problems are found; once acute renal failure occurs, Hemodialysis should be the first choice, and most patients can recover after dialysis
.

■2 Patients with cerebrovascular disease and cardiac insufficiency should be cautious when using mannitol to avoid heart failure caused by rapid transfusion or increased blood volume
.
When cerebrovascular disease is accompanied by insufficient blood volume, mannitol should be used as appropriate after blood volume supplementation
.
When cerebrovascular disease is accompanied by hypoalbuminemia, it is advisable to use 25% albumin or concentrated plasma to adjust the plasma protein concentration, and then use mannitol as appropriate
.

■3 After the application of mannitol, transient hypervolemia occurs first, thereby increasing blood pressure
.
Therefore, for patients with concurrent hypertension, before using mannitol, furosemide can be used to adjust the blood volume before using mannitol to avoid adverse reactions
.

■4 Mannitol allergic reactions are rare, occasionally causing asthma, skin rashes, and even death; when the administration rate is too fast, some patients may experience headaches, dizziness, arrhythmia, chills, blurred vision, acute pulmonary edema and other adverse reactions; If the dose is too large, convulsions may occasionally occur; avoid local swelling and pain caused by drug extravasation, and even tissue necrosis
.

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