Why does Dialysis cause low Blood Pressure?

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Dialysis is a life-saving medical treatment used primarily for patients suffering from end-stage renal disease (ESRD) or severe kidney dysfunction. When the kidneys cannot perform their crucial function of filtering toxins and waste products from the blood, dialysis steps in to do this job. However, as beneficial as it is, dialysis can lead to complications, one of which is low blood pressure, also known as hypotension.

Mechanism of Dialysis-Induced Hypotension

  1. Fluid Removal (Ultrafiltration):
    • One of the main functions of dialysis is to remove excess fluid from the body. This process, known as ultrafiltration, involves using a dialyzer to filter out excess fluids. Rapid fluid removal over a short period can reduce blood volume, causing a drop in blood pressure.
  2. Imbalance of Electrolytes:
    • Dialysis also balances electrolytes like sodium, potassium, and calcium. If there is an imbalance between the patient’s blood composition and the dialysate (fluid used in dialysis), it can cause a rapid shift of fluids between the blood and cells, resulting in hypotension.
  3. Temperature and Osmolarity Changes:
    • Variations in the temperature or osmolarity (concentration of dissolved particles) of the dialysate can affect blood vessel behaviour and cause them to dilate or constrict inappropriately, resulting in a sudden drop in blood pressure.
  4. Autonomic Dysfunction:
    • Patients with ESRD often have issues with their autonomic nervous system, which regulates involuntary body functions, including blood pressure. During dialysis, this autonomic dysfunction can exacerbate blood pressure instability.
  5. Medications:
    • Many patients undergoing dialysis are on medications to manage their conditions. Certain antihypertensive medications, particularly if taken too close to dialysis, can amplify the hypotensive effect.

Clinical Manifestations of Dialysis-Induced Hypotension

Symptoms include:

  • Dizziness
  • Nausea and vomiting
  • Cramps
  • Fatigue
  • Blurred vision
  • Loss of consciousness

Risk Factors for Dialysis-Related Hypotension

  1. Patient-Specific Factors:
    • Age and gender
    • Diabetic status
    • Pre-existing cardiovascular conditions
    • Level of fluid overload before the session
  2. Dialysis-Specific Factors:
    • High ultrafiltration rate
    • Low sodium content in the dialysate
    • Use of warm dialysate

Preventive Strategies

  1. Individualized Ultrafiltration:
    • Personalizing the ultrafiltration rate to a patient’s tolerance level is crucial. Slow and steady fluid removal often results in fewer blood pressure drops.
  2. Dialysate Optimization:
    • Adjusting the temperature or composition of the dialysate (like sodium profiling) can help maintain hemodynamic stability.
  3. Medication Review:
    • Avoiding certain antihypertensives or diuretics immediately before dialysis can prevent hypotensive episodes.
  4. Dietary Management:
    • Encouraging patients to adhere to low-sodium diets helps manage fluid retention and reduces the amount of fluid that needs to be removed during dialysis.
  5. Patient Positioning:
    • Supine or semi-supine positions can sometimes aid in stabilizing blood pressure during dialysis sessions.
  6. Biofeedback Monitoring:
    • Implementing technology that monitors real-time blood pressure fluctuations can be beneficial in providing early intervention.
  7. Fluid Management Counseling:
    • Educating patients on controlling their fluid intake between sessions is crucial to minimize the risk.

Treatment of Dialysis-Induced Hypotension

  1. Immediate Measures:
    • Lowering the patient’s head and elevating their legs can help return blood flow to the brain and core.
    • Reducing the ultrafiltration rate immediately.
    • Administering intravenous fluids, such as saline or hypertonic glucose, to restore blood volume.
  2. Medication Adjustments:
    • Midodrine, an alpha-adrenergic agonist, is often prescribed to increase vascular tone and support blood pressure.
  3. Long-term Management:
    • Implementing changes in the dialysis regimen, like increasing frequency but reducing the duration of sessions.


Dialysis remains a cornerstone therapy for patients with ESRD, but it comes with risks such as hypotension, which can significantly impact the patient’s quality of life. Understanding the underlying mechanisms and risk factors allows clinicians to develop tailored preventive and therapeutic strategies that prioritize the patient’s safety and treatment efficacy.

In Kenya, where advanced dialysis facilities are becoming increasingly accessible, selecting the best hospital for dialysis care can make a significant difference. The best hospital in Kenya will not only offer cutting-edge technology but also comprehensive care teams, personalized treatment protocols, and patient education programs. Combining expertise with compassionate care ensures that the complications like hypotension are minimized, and patients receive optimal treatment outcomes.

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