Dialysis is a medical treatment that takes over the function of the kidneys for people with end-stage kidney failure. This life-sustaining process cleans the blood by removing waste products and excess fluid. While dialysis is necessary, nausea is a common symptom many patients experience during or immediately following treatment. Understanding the specific causes of this discomfort is the first step toward effective management.
How Common is Nausea During Dialysis
Nausea and vomiting are frequent complications reported during hemodialysis (HD), the type of dialysis that filters blood outside the body. The incidence of nausea during HD varies, but it affects a significant portion of patients, sometimes occurring in over 25%. In routine cases, the prevalence of nausea and vomiting together is often cited in the 5% to 15% range. Symptoms usually arise during the treatment (intra-dialytic) or shortly after the session concludes (post-dialytic).
Although less common, patients undergoing peritoneal dialysis (PD) may also experience gastrointestinal issues. For PD, symptoms are typically less acute and often relate to a feeling of fullness or early satiety due to the presence of fluid in the abdominal cavity.
Primary Causes Related to the Dialysis Procedure
The primary drivers of nausea during dialysis relate to the rapid physiological changes the body undergoes as blood is filtered. One significant cause is the rapid removal of excess fluid, a process called ultrafiltration. If the ultrafiltration rate is too aggressive, it can lead to a sudden drop in blood pressure, known as intradialytic hypotension.
This sudden decrease in blood pressure reduces blood flow to the gastrointestinal tract and the brain, triggering the nausea response. Patients experiencing hypotension during a session often report dizziness alongside the feeling of sickness.
Another contributing factor is the rapid shift in the concentration of solutes, which can lead to a condition called Dialysis Disequilibrium Syndrome (DDS). This occurs when the urea and other waste products are cleared from the blood faster than they are removed from the brain tissue. The temporary imbalance creates an osmotic gradient, causing water to shift into the brain cells, leading to mild cerebral edema and a range of symptoms, including headache, restlessness, and nausea.
The temperature of the dialysate, the fluid used by the machine to filter the blood, can also play a role in patient discomfort. Standard dialysate temperatures sometimes contribute to the dilation of blood vessels, which can exacerbate the tendency toward low blood pressure. Using a cooler dialysate has been shown to help stabilize blood pressure and reduce the incidence of associated symptoms like nausea. Furthermore, imbalances in electrolytes, such as sodium or calcium in the dialysate, can disrupt the body’s equilibrium and lead to feelings of sickness.
Strategies for Managing and Preventing Nausea
Effective management of dialysis-related nausea involves both procedural adjustments and patient-driven lifestyle changes. Dietary adjustments are a simple yet effective first line of defense against discomfort. Patients should consider consuming only small, light meals before a dialysis session.
It is beneficial to avoid foods that are heavy, greasy, spicy, or excessively sweet in the hours leading up to treatment, as these items are more likely to upset the stomach. Some patients find relief with bland, cold foods or by incorporating natural antiemetics, such as ginger products, into their diet. Managing fluid intake between sessions is also helpful, as excessive fluid gain increases the amount that must be removed during treatment, heightening the risk of hypotension.
Clinicians can modify the dialysis prescription to mitigate the risk of nausea. One common procedural adjustment involves slowing down the ultrafiltration rate to ensure a more gradual removal of fluid, which helps prevent a sudden drop in blood pressure. The dialysis team may also adjust the composition of the dialysate, such as changing the sodium or bicarbonate concentration, to better maintain the patient’s physiological stability. The use of cooler dialysate is a specific intervention that can be employed to minimize the risk of hypotension and related nausea.
For persistent or severe symptoms, medical professionals may recommend antiemetic medications. Drugs like Ondansetron or Metoclopramide can be prescribed to help control the feeling of sickness. Any use of medication must be carefully managed by the healthcare team, as certain drugs require dose adjustments for people with kidney disease.