What Is Dialysis Disequilibrium Syndrome?
Hemodialysis can result in a serious but rare complication known as dialysis disequilibrium syndrome (DDS). The majority of its symptoms are neurological. In most cases, the symptoms are brief, self-limiting, and rarely fatal. Patients with very high plasma urea concentrations, those with chronic kidney disease (CKD), and starting hemodialysis with aggressive urea removal are more likely to experience symptoms. Although the exact frequency of dialysis disequilibrium is unknown, it appears to be declining since the beginning of hemodialysis, most likely because patients today are starting dialysis at considerably lower urea concentrations than in the past.
Who Gets Dialysis Disequilibrium Syndrome?
The common predisposing factors that put a patient at risk of developing dialysis dysequilibrium syndrome (DDS) are stated as follows -
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First hemodialysis treatment.
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High blood urea nitrogen (BUN) (above 175 milligrams per deciliter) before starting the dialysis treatment.
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Extremes of age, children, and elderly.
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Abrupt adjustment to the dialysis regimen.
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Pre-existing neurological diseases such as stroke (blocked or damaged blood vessels of the brain), malignant hypertension (sudden spike in blood pressure risking organ damage), head trauma, or seizure disorder (sudden uncontrolled electrical disturbance in the brain).
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Presence of other conditions causing cerebral edema, such as hyponatremia (abnormally low sodium concentration) and hepatic encephalopathy (nervous system disorder due to severe liver disease).
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Conditions causing increased permeability of the blood-brain barrier, such as sepsis (extreme response to an infection), meningitis (inflammation of the brain and spinal cord covering), encephalitis (brain inflammation), hemolytic uremic syndrome (blood clot formation due to inflamed and damaged small kidney blood vessels), and vasculitis (inflammation of the blood vessels).
What Causes Dialysis Disequilibrium Syndrome?
The exact pathophysiology has yet to be well known. However, the development of DDS may be associated with cerebral edema caused due to water movement into the brain. There are two main theories proposed -
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First, during a dialysis session, the concentration of urea in the blood decreases more quickly than it does in the brain, which is the cause of DDS. A net water shift from the blood into the brain is facilitated by this lag, which results in cerebral edema and elevated intracranial pressure (ICP).
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Second, dialysis may result in a lower pH in the cerebrospinal fluid (CSF) and brain tissue due to a carbon dioxide gradient between plasma and CSF. Due to the increase in hydrogen ion concentration and the in-situ generation of osmols (acid radicals from protein metabolism), this change may lead to brain edema and increased brain cell osmolality. Osmolality is the test measuring the concentration of chemical particles in the fluid part of the blood.
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The primary causes of dialysis disequilibrium syndrome are cerebral edema and elevated ICP, which are the targets of treatment.
What Are the Signs and Symptoms of Dialysis Disequilibrium Syndrome?
The majority of cases of DDS can be mild and self-limiting, with patients reporting some common symptoms such as :
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Headache.
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Nausea.
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Other central nervous system symptoms such as restlessness and confusion.
Most of the time, these symptoms disappear within a few hours of starting dialysis.
Some symptoms that occur towards the latter part of dialysis and are also considered to be part of DDS include -
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Dizziness.
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Muscle cramps.
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Rarely, DDS can present as increased intraocular pressure (fluid pressure of the eye).
In severe cases, symptoms can progress to -
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Seizure (sudden, uncontrolled electrical disturbance in the brain).
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Somnolence (strong desire for sleep or drowsiness).
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Stupor (near unconsciousness).
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Coma leading to death.
How Is Dialysis Disequilibrium Syndrome Diagnosed?
DDS is diagnosed based on the signs and symptoms, medical history, and physical examination of the patient. There are no specific imaging or laboratory tests. In suspected patients who develop symptoms after starting dialysis or returning to it after a period of non-compliance, it remains an exclusion diagnosis. The differential diagnosis should include clinical conditions with similar manifestations.
How Is Dialysis Disequilibrium Syndrome Treated?
Since the development of an osmotic gradient that causes water to move into the brain is the main factor that causes dialysis disequilibrium syndrome, preventing this gradient would help prevent the syndrome. As a result, the management should focus primarily on preventative measures to prevent cerebral edema, especially when starting new patients on hemodialysis. However, the following measures should be taken once a patient exhibits symptoms:
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Initiate Sodium Remodeling - Modifying the dialysis prescription is the initial treatment for DDS, regardless of its severity. This is done by changing the sodium dialysate bath or drawing in the changed prescription on the dialysis machine. The symptoms ought to go away in as little as 30 minutes. As a result, dialysis can continue unabated. Lingering side effects (nausea, vomiting) after the prescription change and sodium rebuilding can be dealt with through symptomatic treatment. However, if the symptoms do not improve with treatment, dialysis may need to be stopped occasionally to look for other underlying causes.
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Sodium Remodeling Failure - In patients with extreme side effects of DDS despite sodium remodeling, a preliminary to diminish intracerebral tension could be taken. Although based on anecdotal evidence (individual experiences or observations) and limited data, some experts recommend increasing the plasma osmolarity while simultaneously reducing further osmotic shift by administering five milliliters of 23 percent saline or 12.5 milligrams of intravenous mannitol. It has also been reported that adding urea to the dialysate prevents potential neurological issues by allowing repeated and intense dialysis sessions.
Conclusion:
Dialysis disequilibrium syndrome is a group of symptoms that can occur during dialysis, especially in patients who are starting dialysis for the first time or who miss a lot of sessions. It is thought to occur as a result of the rapid clearance of accumulated substances like urea that get accumulated in the blood. This can result in an imbalance in the amount of fluid in the brain cells, resulting in swelling and symptoms like headache, nausea, restlessness, confusion, and, in more severe cases, seizures, coma, and death. Patients can experience discomfort and distress from dialysis disequilibrium syndrome, which is now becoming less common with increased awareness. In order to take preventative measures, patients should be advised to report any symptoms once dialysis is started. In order to help reduce the risk of DDS, it is also essential to educate patients and their families about the importance of maintaining regular dialysis sessions.
