A brief description on Haemodialysis for health care providers.

1. BASIC HAEMODIALYSIS
Farah Adibah Kasmin
Nephrology Department
Serdang Hospital, Malaysia

2. 25th report of the Malaysian Dialysis and Transplant
Registry 2017

3. DEFINITION
A filtration therapy
Occurs outside the body in a machine
Require artificial membrane that is called a dialyzer
Aim:
1- Remove accumulated metabolic waste products
2-To correct blood electrolytes composition by means of an
exchange between patient's blood and a dialysate fluid across a
semi-permeable membrane in a countercurrent mechanism.
3-To remove excess fluids by means of ultrafiltration

4. Counter current blood dialysate flow
1. Hemodialysis utilizes counter current flow, where the dialysate is
flowing in the opposite direction to blood flow in the extracorporeal
circuit.
2. Counter-current flow maintains the concentration gradient across the
membrane at a maximum and increases the efficiency of the dialysis.

5. Blood flows into one end of the dialyzer and through
these thousands of tiny hollow-fibers. Dialysate, at
the same time, is pumped into the cylinder and
across the tiny hollow-fibers. This method keeps
fresh dialysate circulating constantly.
The efficiency of hemodialysis is strongly influenced by the following
3 parameters: the blood flow rate (QB), the dialysis fluid flow rate
(QD), and the overall mass transfer area coefficient (K0A), an index of
a dialyzer's performance. The flow ratio (QB : QD) to obtain a well-
balanced dialysis efficiency is generally said to be 1 : 2.
Effects of reduced dialysis fluid flow in hemodialysis:J Nippon Med Sch. 2013;80(2):119-30.

6. BASIC PRINCIPLES
-Solutes removal: Diffusion and convection
-Fluids removal: Ultrafiltration

7. Diffusion
Movement of solute across semipermeable membrane from region of high
concentration to one of low concentration.
Convection
Solutes are swept through the membrane pores along with the water (a
process called “solvent drag”) in response to a transmembrane hydrostatic
pressure gradient.
Ultrafiltration
Made possible by osmosis which is a movement of water across
semipermeable membrane from low osmolality to high osmolality.

8. Renal replacement therapy in critical care: BJA Education, Volume 17, Issue 3,
March 2017

9. Equipment for Haemodialysis National HD and Quality Standards 2018 by KKM and
MSN
Haemodialysis machine
Water treatment system
Dialyzer reprocessing machine
Dialysis consumables National HD and Quality Standards 2018 by KKM and MSN
Dialysis concentrate /Dialysate
Dialyser
Blood lines
Access

10. VASCULAR ACCESS
A fistula should placed at least 6 months before anticipated of HD treatments.
A selection of permanent vascular access and order of preference for AVF:
1. A radial-cephalic primary AVF
2. A brachial-cephalic primary AVF
If not possible,
1. A transposed brachial basilic vein fistula
2. An arteriovenous graft of synthetic material
Access maturation of fistula by the rule of 6s:
- Diameter >6mm
- < 6mm from the surface of the skin
-Flow >600mls per min
-If the fistula fails to mature by 6 weeks, reassessment required.

11. ANTICOAGULANT
Requires to prevent extracorporeal clotting.
Factors favour clotting of the extracorporeal circuit:
- Low blood flow
-High haematocrit
-High ultrafiltration rate
-Dialysis access recirculation
-Intradialytic blood, blood products and lipid transfusion

12. 1. Standard anticoagulation with heparin with normal bleeding risk:
Constant-infusion method
- Bolus dose – 50u/kg
-Start heparin infusion at a rate 10-20u/kg/hour
-Stop the heparin infusion 1 hour before end of dialysis
2. Tight heparin dialysis – Potential risk of bleeding or use of heparin free
dialysis has been unsuccessful due to frequent clotting.
-Bolus dose – 10-25u/kg
-Maintenance dose constant infusion 5-10u/kg/hour with monitoring ACT
every 30minutes where feasible

13. Other forms of anticoagulation:
-LMWH: Enoxaparin, Nadroparin
-Regional citrate anticoagulation
-Thrombin inhibitors - Argatroban

15. INTERMITTENT
HEMODIALYSIS (IHD/IRR
T)
• Threetimesaweek
• 3to4hourspersession,
• Bloodflowrateof200to300mL/min
• Dialysateflowrateof500to800mL/min.
• Principles:Diffusion
• Dialysisdose:Thedegreeofsoluteclearance.Itdepends on rateofblood flow.

16. • Advantages of IHD:
• Rapid solute and
volume removal
• Rapid correction of
electrolyte disturbances,
such as hyperkalemia
• Rapid removal of drugs or
other substances in fatal
intoxications in a matter of
hours.
• Decreased need for
anticoagulation due to
short duration of therapy
and faster blood flow rate.
• Disadvantages of IHD:• Risk of systemic
hypotension(20-30 %
cases)• Cerebral edema and
increased intracranial
pressure due to rapid
solute removal.
limits the efficacy of IHD and
result in
1. Poor solute
clearance,
2. Insufficient acid-
base correction,
and

17. SLEDD
• Use low blood-pump speeds of 200 mL/min and low
dialysate flow rates of 30-60 mL/min for 6 to 12 hours
daily.
• Combine the advantages of CRRT and IHD.
• Removes the need for expensive CRRT
machines, costly customized solutions, and
trained staff.
• Avoids the interruption of therapy for various diagnostic
and therapeutic procedures that may be required in
such patients.
improved hemodynamic stability
through
gradual solute and volume removal
provide high
solute
clearances

18. CRR
T
• Continuous treatment occurring 24 hours a day with a bloodflowof100to 200
mL/min and adialysate flowof15to60mL/minif adiffusiveCRRT modalityis
used.
• Lessincidenceofhypotension;idealinhemodynamicallyunstable
• Lessercomplicationssuchasarrhythmiasandcerebraledema(duetorapidchangesvolume
andion concentrations)
• Slow,continuousfluidremovalwhilemaintainingsteadysoluteconcentrationsandpreventing
peaks oftoxicsubstances.
• Removestoxinswithalargevolumeofdistribution(methotrexateandprocainamide)
• Beneficialinpatientswithsepsisormultiorganfailureasclearlarger-molecular-weight
molecules (upto30,000 d)
Advantages:

19. CONTINUOUS VENOVENOUS
HEMODIALYSIS (CVVHD)
• Dialysate solution runs
countercurrent to the flow
of blood at a rate of 1 to
2.5 L/h
• Solute removal occurs by
diffusion.
• Unlike IHD, the dialysate
flow rate is slower than
the blood flow rate,
allowing small molecules to
equilibrate completely
between the blood and
dialysate.
• As a result, the dialysate
flow rate approximates

20. CONTINUOUS VENO-VENOUS HEMOFILTRATION (CVVH)
Soluteclearanceoccursbyconvection.Solutesare
carriedalongwiththebulkflow offluidina
hydraulic-inducedultrafiltrate ofblood.
Nodialysateisused.
Hourlyultrafiltrationratesof1to2L/h areused.

21. CONTINUOUS VENOVENOUS
HEMODIAFILTRATION
(CVVHDF)
• It combines the
convective solute
removal of CVVH and
the diffusive solute
removal of CVVHD.
• It requires the
administration of
intravenous
replacement fluids.
(like CVVH).

22. SLOW CONTINUOUS ULTRA FILTRATIO
(SCUF)
• Indications:volumeoverloadin
patientswithcongestiveheartfailure
refractoryto diuretics.
• Low-volumeultrafiltrationatarate of
100to300mL/h
• Maintainsfluidbalanceonlyand
doesnotresultinsignificant
convectiveclearanceof solutes.