ARTIFICIAL KIDNEY

HAMID NASEEMMD SOHRAB ANSARI

Department of Electrical engineering

Outlines Introduction Function of the Kidney Working of Kidney Bowman’s Capsule Reabsorption by Kidney Dialysis Types of Dialysis How does dialysis work? References

Introduction

Human Possess Two Kidneys

Situated at the back of the abdominal cavity

Each kidney is connected to a tube called the ureter which empties into the urinary bladder

Each kidney is supply by a renal artery which supplies urea and oxygen

Each is also supply with a renal vein that leaves the kidney with the correct levels of urea, salts & water.

Function of the Kidney

Remove undesirable substances from the blood plasma:

• Toxins• Metabolism wastes• Excess of ingested water• Excess of mineral salts

Regulate the Acidity of blood

25% of the blood flows through the kidneys (1,2 l/min)

Terminology

Blood is filtered in the Nephrons

The cortex of kidney contains about 1million Nephrons

Nephron consists of Renal Corpuscle & Renal Tubule

The main filter of the Nephron is Glomerulus which is

located within the Bowman's Capsule

How Kidney Works

Supplied with blood from

Renal Artery

Inside it splits into many

fine Capillaries

Each capillary supplies

blood to hundreds of

thousands of tiny filtration

units called Nephrons

B

RENAL CORPUSCLE: SITE WHERE BLOOD IS FILTERED

B

1. Glomerulus brings a large surface area of blood capillaries in close contact with Bowman’s capsule

2. Liquid filtered from blood under pressure (filtration)

3. Glomerular filtrate produced containing:

- Water- Glucose- Salts- Urea

(Protein molecules and red bloodcells do not pass into tubule asthey are TOO BIG!!!!)

Blood travels through narrow capillary towards renal veinGlomerular

filtrate

Filtration

Blood from renal artery enters wide capillary

Bowman’s Capsule

Reabsorption by Kidney Once the main components of Glomerulur filtrate enter

the bloodstream, they are no longer in bloodstream

If nothing more happened in the Nephron then all the useful stuff would be lost in the urine!

Therefore, Glucose, Water and some Salts need to be reabsorbed!

Dialysis Process of removing waste products and excess fluid

from the body Also controls blood pressure and helps body to keep

proper balance of chemicals such as potassium, sodium, and chlorine.

There are two methods:

Hemodialysis (HD)

Peritoneal dialysis (PD).

How does dialysis work? It uses a membrane as a filter and a solution called

dialysate to regulate the balance of fluid, salts and minerals carried in the bloodstream.

The toxins pass from the blood through the membrane and into the dialysate to be taken away.

These toxins would normally be filtered by the

kidneys and taken away in urine.

Hemodialysis

The process takes place outside the body

A dialysis machine pumps small amounts of blood

out of the body and through a filter called an artificial

kidney or Dialyzer.

The Dialyzer filters extra fluid & wastes from blood.

The Blood is then pumped back into the body.

• Fig. Hemodialysis setup

Dialyzer

Dialyzer contd…

The dialyzer is a large container containing thousands

of small fibers through which blood is passed.

Fluid, called dialysate, is added to the Dialyzer to :

i. Help filter out extra fluid and wastes

ii. Add chemicals that your body uses

The Dialysate is pumped around the fibers. The fibers

allow wastes and extra fluids to pass from blood into the

solution, which carries them away.

Complications of Hemodialysis

Peritoneal Dialysis

The process takes place inside the body.

A tube (catheter) is inserted into the abdomen during

operation.

Special dialysis fluid is drained into the abdomen.

Excess waste and water pass from the blood into the fluid

and after a few hours the fluid is drained out.

PD as a Three-step process:

Types of Peritoneal Dialysis

1) Continuous Ambulatory Peritoneal Dialysis

Involves 3 main steps

FILL

A bag of solution called dialysate is put

into the abdomen through the catheter

The bag holds about 2 quarts of fluid

It takes about 10 to 20 minutes to fill

When the bag is empty, it can be clamped

off

DWELL

The solution stays in the abdomen 4 to 6 hours. While the solution is in the abdomen, extra fluid and wastes

move from the blood and into the solution.

DRAIN

Using gravity, the solution is then drained

out of the body into a drain bag. The drained fluid is much like urine and

will be clear yellow.

2) It takes about 10 to 20 minutes to drain.

2) Continuous Cycling Peritoneal Dialysis

Involves same fill, dwell and drain cycles.

But the dwell time is shorter and a machine does the

exchanges.

The dwell time is about 1½ hours.

The machine is set up and the person is connected to the

machine for 8 to 10 hours during the night.

Hemodialysis Peritoneal Dialysis

Slower

Requires less equipment

Causes fewer physiologic

adverse reactions

Requires professionals

Faster

Requires more equipment

More physiologic adverse

reactions

Can be performed by patient

itself

Hemodialysis v/s Peritoneal Dialysis

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