Hemodialysis is a mechanical process of removing waste products (toxic nitrogenous substances) and replacing essential substances by the process of diffusion and removal of excess water from body by the process of osmosis by means of artificial kidney (made with modified cellulose or synthetic) through semi-permeable membranes.

1. Hemodialysis

2. Introduction
• Hemodialysis is the most common renal
replacement therapy used for ESRD.
• Involves use of an artificial kidney to remove
waste products and excess water from
patient’s blood.
• Doesnot cure renal disease and does not
compensate for the loss of endocrine or
metabolic activities of the kidney.

3. • More than 90% of patients requiring long
term renal replacement therapy are on
maintenance hemodialysis.
• Most patients receive intermittent
hemodialysis that involves treatments three
times a week with the average treatment
duration of 3-4 hours in an outpatient setting.

4. Definition
• Hemodialysis is a mechanical process of
removing waste products (toxic nitrogenous
substances) and replacing essential
substances by the process of diffusion and
removal of excess water from body by the
process of osmosis by means of artificial
kidney (made with modified cellulose or
synthetic) through semi-permeable
membranes.

5. History
• First dialysis machine was
made by Willem Johan Kloff in
1943.
• Made during World War II
which used everyday
materials as sausage skins,
orange juice cans and washing
machines.
• In 1945, treated a 67 year old
woman in uremic coma who
regained consciousness after
11 hours of dialysis.

6. • Professor of medicine at
the University of Washington,
Dr. Belding Scribner came up
with the idea of connecting
the patient to the dialyzer
using plastic tubes, one
inserted into an artery and
one into a vein for circulatory
access.
• In 1962, Scribner started the
world’s first outpatient
dialysis facility.

7. • In Nepal dialysis service was started in Bir
Hospital from 1987.
• Estimated 221 HD machines in Nepal
• 46 dialysis centers provide free hemodialysis
services

8. Principle of haemodialysis
• Diffusion
• Osmosis
• Ultrafiltration

9. Diffusion
• Movement of toxins and wastes (urea,
creatinine, uric acid and electrolytes) from an
area of higher concentration in the blood to
an area of lower concentration in the dialysate
through semi-permeable membrane of
dialyser.

10. Osmosis
• Water moves from an area of low
concentration potential of solutes (the blood)
to an area of high concentration potential (the
dialysate bath).
• It is the spontaneous net movement of solvent
molecules through a semi-permeable
membrane in the direction that tends to
equalize the solute concentrations on the two
sides.

11. Ultrafiltration
• Created by an increased pressure in the blood
compartment. Water moves under high pressure
to an area of lower pressure.
• Accomplished by applying negative pressure or a
suctioning force to the dialysis membrane.
• Because patients with renal disease usually
cannot excrete water, this force is necessary to
remove fluid to achieve fluid balance.
• Usual ultrafiltration goal is total weight gain + 500
ml.

13. HD System
• The Hemodialysis system includes:
Dialyzer
Dialysate
Vascular access routes
HD machine

14. Dialyzer
• Dialyzers are hollow-fiber
devices containing thousands
of tiny cellophane tubules that
act as semipermeable
membranes.
• Blood flows through the
tubules while the dialysate
circulates around the tubule.

16. • The artificial kidney or
dialyzer has 4 parts: a
blood compartment, a
dialysate compartment,
a semi-permeable
membrane and an
enclosed support
structure

17. Dialysate
• Made from water and chemicals and is free of
chemicals and waste products or drugs.
• The dialysate delivery system mixes electrolyte
concentrate (Part A-5lts) with the mixture of purified
water- RO water (9 lts)+ sodium bicarbonate HD
solution (Part B) to approximate the chemical
composition of ECF.
• The composition of dialysis fluid used varies
according to clinical need (can be bicarbonate or
acetate solution)

18. Acid concentrate
NaHCO3 concentrate
Pure H2O
Final Dialysate

19. • Final dialysate composition
 Sodium 137 meq/l
 Chloride 105 meq/l
 Calcium 3 meq/l
 Acetate 4.0 meq/l
 Potassium 2.0 meql/
 Bicarbonate 3.3 meq/l
 Magnesium 0.75 meq/l
 Dextrose 200 mg/dl
• A standard solution aims to allow a net outflow of potassium from
the blood, at a rate below that to create hypokalemia, and a net
inflow of calcium.

20. Vascular access
• Provides location for easy access to patient’s
blood for dialysis
• Normal venous cannulation does not provide
high rate of blood flow.
• Haemodialysis requires the availability of a
large amount of blood flow: at least 250-300
ml/min, usually for a period of 3-4 hours for
vascular access.

21. Types of vascular access
• Permanent
AV fistula
AV graft
• Temporary
Dialysis catheter
Tunnelled catheter

22. AV fistula
• AV fistula are formed by surgically
connecting an artery to a vein.
• Most often used are radial or
brachial artery and cephalic vein of
non dominant hand.
• Fistula increases blood flow to 25-
500 ml/min.
• As AV fistula matures after
anastomosis, the increased
pressure of arterial blood flow to
vein causes the vessel walls to
thicken which increases its strength
and durability for repeated
cannulation.

24. Dialysis catheter
• IJ most common
• Tunnelled under skin to
reduce communication
from skin flora with
blood
• High infectious and high
thrombosis risk

26. AV Graft
• Graft is created
subcutaneously interposing
a biologic, semibiologic or
synthetic material between
an artery and vein.
• Commonly used synthetic
material is
polytetrafluoroethylene.
• Created when patient’s
vessels are not suitable for
creating fistula (as in
patients with vascular
diseases)

27. Care of vascular access
• Check access before each treatment.
• Keep access clean at all times. Do not use cream or
lotion over the site.
• Use access site only for dialysis.
• Be careful not to cut access.
• Don’t put a blood pressure cuff on access arm.
• Remove jewellery or tight clothes over access site.
• Don’t sleep with access arm under head or body.
• Don’t lift heavy objects or put pressure on access arm.
• Check the pulse in access every day.

28. HD machines
This machine has three
main jobs:
• pump blood and
monitor flow for safety
• clean wastes from
blood
• monitor blood pressure
and the rate of fluid
removal from body

29. Consists of 3 sections:
• Monitor section
• Module section- blood
pump (300 ml/min); for
patients with heart
disease and according to
condition of fistula- 200
ml/min
• Hydraulic section-
connected to dialysate
solution (part A and part
B)

31. Anticoagulant
• Because the blood has tendency to clot in the
extracellular circuit, an anticoagulant most commonly
heparin is used.
• However, in patients with decreased hematocrit,
thrombocytopenia or prolonged partial thromboplastin
time (PTT), anticoagulant may not be used.
• Commonly used heparin dose in our dialysis unit- 5000
U in divided doses
• 1000 U – in circulation
• 2000 U- bolus/stat
• 2000 U- continuous

32. Procedure
• When haemodialysis is started, blood and
dialysate (dialysing solution) flow in opposite
directions across an enclosed semipermeable
membrane.
• Dialysate contains a balanced mix of electrolytes
and water that closely resemble human plasma.
• On the other side of the membrane is patient’s
blood, which contains nitrogen waste products,
excess water and excess electrolytes.

33. • During dialysis, the waste products more from
blood into the dialysate because of difference in
concentrations (diffusion)
• Some water is removed into dialysate by osmosis
• Electrolytes can move in either directions as
needed
• Potassium and sodium typically move out of
plasma into dialysate
• Bicarbonate and calcium generally move from
dialysate into plasma

34. Complications
• Disequilibrium syndrome (neurologic signs)
• Muscle cramps and back pain
• Headache
• Itching
• Hypotension
• Cardiac arrhythmias
• Dialyzer hypersensitivity
• Haemorrhage
• Infection