Hemodialysis is an artificial kidney therapy that filters waste products and excess water from the blood through semi-permeable membrane principles. It is primarily used as a replacement therapy for patients with renal failure. This treatment mimics the metabolic regulatory functions of the kidneys, maintains electrolyte balance, and prevents uremia from becoming life-threatening. Suitable candidates include patients with stage 5 chronic kidney disease or those experiencing internal environment imbalance due to acute kidney injury.
The procedure must be performed under the supervision of a professional medical team, typically 2-3 times per week, each session lasting 3-5 hours. This therapy can effectively delay and control complications of end-stage renal disease but requires dietary control and medication management for optimal results.
Hemodialysis mainly divides into conventional in-center dialysis and home dialysis. Conventional treatment requires the use of a dialysis machine at a medical facility, where the patient's blood is routed through a vascular access into the dialyzer. Waste products such as urea and creatinine are removed via diffusion across the dialysis membrane and dialysate. The pore size of the dialysis membrane is designed to filter molecules based on size, retaining essential proteins and cellular components.
The mechanisms include diffusion, convection, and adsorption: diffusion removes small molecules, convection clears middle molecules via pressure gradients, and adsorption utilizes the surface of the dialysis membrane to bind excess substances. These three processes simulate glomerular filtration and tubular reabsorption functions but cannot fully replace the endocrine functions of the kidneys.
Main indications include:
In special cases:
The treatment usually involves central venous access, including arteriovenous fistula or central venous catheter. Anticoagulants (such as heparin) are injected into the blood circuit to prevent clotting, with doses adjusted based on body weight (typically 0.5-1.5 IU/kg/h).
Dialysis duration and frequency vary:
The main effects include:
Long-term benefits include:
Common immediate side effects include:
Long-term risks include:
Absolute contraindications include uncontrolled bleeding tendencies, severe shock, or aortic aneurysm compressing the vascular access. Relative contraindications include untreated infection sites or severe cardiopulmonary dysfunction.
Before treatment, attention should be paid to:
When combined with anticoagulants (such as warfarin), dosage adjustments are necessary because dialysis may reduce circulating anticoagulant levels. The clearance rates of iron preparations or erythropoietin should also be considered.
Interactions with cardiovascular drugs:
Clinical studies show that regular dialysis can improve 5-year survival rates of end-stage renal disease patients to 30-50%. Adequacy of dialysis (Kt/V >1.2) can reduce cardiovascular events by up to 40%. The urea reduction ratio (URR) after dialysis should exceed 70% to ensure efficacy.
Long-term follow-up data indicate:
The main alternative is peritoneal dialysis, which uses the peritoneum as a semi-permeable membrane for continuous outpatient dialysis. This method offers flexibility for home treatment but carries a higher risk of infection. Kidney transplantation is the only curative option but requires donor matching and carries rejection risks.
Special scenarios include:
Before hemodialysis, patients should follow medical advice to adjust their diet, avoid high-potassium foods, and stop medications that may affect coagulation. Additionally, ensuring the patency of vascular access (such as fistula) and conducting blood pressure, weight, and blood tests to evaluate the parameters for the session are essential. Healthcare staff will also check the operation of the dialysis machine to ensure safety.
What should be done if muscle cramps occur during hemodialysis?Cramps may result from fluid loss or electrolyte imbalance. Patients should pause dialysis and notify medical staff, who may adjust the dialysis rate or supplement fluids and electrolytes. Regular exercise and dietary adherence can help prevent recurrence.
Can I adjust my eating schedule during hemodialysis?The timing of meals on dialysis days should coordinate with treatment sessions. It is generally recommended to eat 2 hours before dialysis to prevent hypotension during treatment. If additional snacks are needed, choose low-potassium and low-phosphorus small portions and discuss dietary adjustments with your nephrologist.
How can patients safely exercise during hemodialysis?Patients can perform low-intensity exercises such as walking or yoga but should avoid vigorous activity to prevent vascular access damage. Exercise is best scheduled 2 hours after dialysis, and carrying identification is advised in case of hypotension or dizziness.
When should the frequency or duration of hemodialysis be adjusted?If patients experience excessive weight gain, abnormal blood urea nitrogen levels, or symptoms like palpitations or difficulty breathing, dialysis frequency or session length may need adjustment. The physician will reassess the suitability of the dialysis plan based on blood test results and overall health status.
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