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what happens during dialysis

During dialysis, your blood is gently cleaned by a machine (or by fluid in your abdomen) to remove waste, extra water, and balance salts when your kidneys can’t do this well enough.

Quick Scoop

1. Big picture: what dialysis actually does

  • Dialysis acts like an artificial kidney , helping remove waste products, extra fluid, and keeping minerals like potassium and sodium in safe ranges when kidneys fail.
  • It also helps control blood pressure by managing how much fluid is in your body.
  • You usually need it regularly (often several times a week) for as long as your kidneys are not working well enough or until transplant.

2. Two main types: what happens in each

There are 2 main ways dialysis works.

Haemodialysis (blood-cleaning machine)

  • Your blood is taken from a blood vessel, run through a filter in a dialysis machine, and returned to you cleansed.
  • Blood flows through many tiny hollow fibers in the filter while a special dialysis fluid (dialysate) flows in the opposite direction outside those fibers.
  • Waste and extra salts move from your blood into this fluid, while the cleaned blood stays inside the fibers and goes back into your body.
  • The machine constantly checks your blood pressure and controls how fast blood flows and how much fluid is taken off during treatment.

To make this possible, most people have a special access created in advance (often an arteriovenous fistula in the arm).

Peritoneal dialysis (using your tummy lining)

  • Here your blood stays inside your body, and a soft tube (catheter) in your abdomen lets a dialysis fluid fill your tummy space (peritoneal cavity).
  • The lining of your abdomen (peritoneum) acts as a natural filter, letting waste and extra fluid move from your blood into the dialysis fluid.
  • After a few hours, that used fluid is drained out and replaced with fresh fluid, repeating this “fill, dwell, drain” cycle.
  • The catheter is placed with a small operation usually about 2 weeks before starting treatment.

3. Step‑by‑step: what happens during a hemodialysis session

A typical in‑center hemodialysis session often lasts around 4 hours.

  1. Arrival and check‑in
    • Staff check your weight, blood pressure, and general well‑being.
  1. Connecting to the machine
    • Needles are placed into your access (often an arm fistula) or a line is connected, and tubes link you to the dialysis machine.
  1. Blood cleaning phase
    • Your blood circulates through the dialyzer (filter) repeatedly; in a 4‑hour session, it may pass through the filter 15–20 times, but only about 1–1.5 cups of blood are outside your body at any moment.
 * The machine removes waste, extra fluid, and helps balance minerals using the dialysate solution tailored by your kidney doctor.
  1. Monitoring during treatment
    • The machine continuously monitors pressures and flow, and staff watch your blood pressure and symptoms.
  1. Finishing up
    • The blood in the tubing is returned to you, needles are removed, and your access is bandaged.
 * Your weight and blood pressure are checked again to see how much fluid was removed and how you tolerated treatment.

Many people use this time to read, nap, watch TV, or listen to music while the machine quietly does the work in the background.

4. What dialysis feels like for many people

Experiences vary, but common themes:

  • The first session can feel strange: new environment, sounds of the machine, and the needle sticks can be uncomfortable or anxiety‑provoking.
  • As treatment goes on, many people describe a rhythm or routine, sometimes feeling more clear‑headed and “lighter” after fluid and toxins are removed.
  • Some experience tiredness after sessions, especially early on, as the body adjusts.

One description compares dialysis to sitting beside a steady, mechanical “breath” that moves your blood through filters while you slowly relax into the routine.

5. What your blood is actually doing

While you sit or lie back:

  • Blood is drawn from your access into the machine, through tubing, and into the dialyzer (filter).
  • Inside the filter, blood moves through hollow fibers, while dialysate moves in the opposite direction outside those fibers.
  • Wastes like urea and extra salts diffuse across the thin membrane into the dialysate; extra water is pulled off according to your prescription.
  • Cleaned blood returns to your body through the tubing and access, over and over until the treatment ends.

The dialysate itself contains water and carefully adjusted chemicals so that it can safely pull out what you have too much of and avoid taking away what you need.

6. Possible side effects during dialysis

Not everyone has side effects, but common ones with hemodialysis include:

  • Low blood pressure (feeling dizzy, faint, or nauseated).
  • Muscle cramps, especially if fluid is removed quickly.
  • Headache, tiredness, or weakness after a session.
  • Problems with the access site like blockage or infection over time.

With peritoneal dialysis, people may notice bloating or fullness in the abdomen during fluid “dwell” times, or risk of infection around the catheter or inside the tummy (peritonitis).

Healthcare teams adjust how fast fluid is removed, dialysate composition, and session length to reduce these problems.

7. Day‑to‑day life and the “bigger story”

Dialysis is more than just a machine session; it becomes part of a weekly routine:

  • Scheduling life around treatments : in‑center hemodialysis is often three times per week, while peritoneal dialysis can be done multiple times daily or overnight using a machine.
  • Diet and fluid : many people need to track fluid intake and limit certain foods (for example, very salty or high‑potassium foods), because kidneys and dialysis share the job of keeping balance.
  • Emotional side : people describe dialysis as both demanding and life‑extending, giving them time to work, be with family, or wait for a kidney transplant.

One modern view is that dialysis sessions are not just clinical events but “checkpoints” where patients and care teams adjust the plan so people can keep living, working, and enjoying life despite kidney failure.

8. “Latest news” and evolving care

  • Recent resources emphasize home hemodialysis and peritoneal dialysis options, giving more flexibility and independence to suitable patients.
  • Newer guidelines increasingly focus on tailoring dialysis prescriptions (fluid removal rates, dialysate contents) to improve comfort and reduce long‑term heart and blood pressure complications.
  • Patient stories and clinic blogs in the last few years highlight technology improvements in machines and better education to make first‑time dialysis less frightening.

9. Quick FAQ style answers

  • What happens during dialysis in one line?
    Your blood is cleaned by a filter (or by fluid in your tummy) to remove waste, extra fluid, and balance minerals when your kidneys can’t.
  • Is all my blood outside my body?
    No; only a small amount (around 1–1.5 cups) is in the tubing and machine at any one time during hemodialysis.
  • Does it hurt?
    The main discomfort is usually from needles or the catheter and sometimes cramps or low blood pressure, but staff work to minimize these.
  • Is it permanent?
    Some people are on dialysis long term; others use it while waiting for a transplant or as a bridge through an acute kidney problem.

Information gathered from public forums or data available on the internet and portrayed here.