3. Introduction
The facility to replace some functions of the kidney
artificially by dialysis has been available since the 1960s.
Such treatment is now routine in patients with acute or
chronic renal failure. It does not replace the endocrine
and metabolic function of the kidney, but aim to
maintain the plasma biochemistry at acceptable levels.
Also remove excess fluid and helps maintain euvolemia.
3/15/2023 3
4. CONT;
The original renal replacement therapy was hemodialysis,
and still the most common form of treatment.Avariety of
other types have been developed particularly for unstable
patients with acute renal failure.
Room for conservative management also very important.
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5. EPIDEMIOLOGY
About 3million people worldwide either are treated by
hemodialysis or peritoneal dialysis, or live with a functioning renal
transplant. In the UK,around 53000 people receive treatment for
ESKD;around 50% have been transplanted,42% are on
haemodailysis and 8% are on peritoneal dialysis.
In Nigeria the incidence of CKD has been shown by various
studies to range between 1.6 and 12.4%.
End stage renal disease accounts for 8% of all medical admissions
and 42% of renal admissions in Nigeria.
Age,hypertension,obesity,DM,use of herbal and prolonged use of
NSAID have been identified as risk factors for CKD in Nigeria.
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6. INDICATIONS FOR RRT
CLINICAL INDICATIONS
ARE;
• Uremic encephalopathy
• Refractory pulmonary edema
• Uremic pericarditis
• Refractory edema
• Uncontrolled hypertension
• Bleeding diathesis
• Severe metabolic acidosis
• Uremic myopathy
• Urine output of <200ml/12hrs
or anuria
BIOCHEMICAL
INDICATIONS
• Hyperkalemia >6.0mmol/l or
daily rise>1mmol/l
• Creatinine >600mmol/l or
daily rise >100mmol/l
• Urea >30mmol/l or daily rise
>10mmol/l
• Bicarbonate <12mmol/l
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7. Contd..
● Overdose with a dialyzable drug or toxin .
● drugs are cleared byRRTif they are water-soluble and not highly
protein-bound
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8. contd
Severe sepsis
● patients with ARF have severe sepsis, multiorgan
dysfunction and amajor systemic inflammatoryresponse.
● to remove or adsorb inflammatory mediators which cause
organ dysfunction may represent yet another reason for its
preferential application
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9. Starting and choice of RRT
• Complex decision taking in to consideration of symptoms, patient
preference,biochemistry,fluid overload and EGFR.
• Most people stat dialysis due to symptoms, but evidence suggested that there
was no overall harm of starting at an EGFR of 5-7ml/min/1.73m2 .
• Patients with slowly progressive disease may not report symptoms that
indicate dialysis need ,therefore starting dialysis should be considered on an
individual basis.
• Evidence of pre-emptive timing of transplant at an EGFR <10ml/min/1.73m2
was limited and contradictory,
• The choice of RRT should be based on individual factors as there was no
evidence of differential benefit or harm in any specific group of people.
• Evidence showed that transplantation offers a clear advantage over dialysis in
terms of extending life, reduced hospitalization and better quality of life.
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10. BASIC PRINCIPLES
◈ The basic components of the dialyzer unit:
◈ Dialyzer – cellulose, substituted cellulose, synthetic non cellulose membranes.
◈ Dialysis solution – dialysate : water must remain free of Al, Cu, chloramines,
bacteria and endotoxin.
◈ Tubing for transport of blood and dialysis solution.
◈ Machine to power and mechanically monitor the procedure
◈ Air monitor
◈ Proportioning system
◈ Temperature sensor
◈ Urea sensror to calculate clearance.
◈ The basic components of the dialyzer unit:
◈ Dialyzer – cellulose, substituted cellulose, synthetic non cellulose membranes.
◈ Dialysis solution – dialysate : water must remain free of Al, Cu, chloramines,
bacteria and endotoxin.
◈ Tubing for transport of blood and dialysis solution.
◈ Machine to power and mechanically monitor the procedure
◈ Air monitor
◈ Proportioning system
◈ Temperature sensor
◈ Urea sensror to calculate clearance.
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12. MECHA
NIS
MOFS
OLUTEANDFLUIDREMOVA
L
● Haemofiltration
● involvesblood being pumped
throughan extracorporeal
system that incorporates asemi-
permeable membrane.
● The hydrostatic pressure that is
created on the blood-side of the
filter drives plasma water across
the filter.
● This process is referred to as
“ULTRAFILTRATION”.
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13. ● Moleculesthat are small enoughto passthroughthe
membrane (<50,000 Daltons) are dragged across the
membrane with the water by the process of
CONVECTION.
● The filtered fluid (ultrafiltrate) is discarded and a
replacement fluid isadded in an adjustable fashion according
to the desired fluid balance.
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14. ● Haemodialysis
● involvesblood beingpumped through
an extracorporeal system that
incorporatesadialyzer.
● In the dialyzer, blood is separated
from acrystalloid solution (dialysate)
byasemi-permeable membrane.
● Solutesmove acrossthe membrane
along their concentration gradient
from one compartment to the other
obeying Fick`s laws of diffusion.
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15. ● For example, bicarbonate moves from
dialysate to blood whereasurea and
potassium move from blood to dialysate.
● In order to maintain concentration
gradientsand therefore enhance the
efficiencyofthe systemthe dialysate flows
countercurrent to the flowof blood.
● When removal of water is required the
pressure on the blood-side of the membrane
hasto be increased forcing water molecules
to passinto the dialysate.
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16. ● Haemodiafiltration
● asits name suggests, is acombination of filtration and dialysis.
● It hasthe benefits of both techniques but to alesser extent than
when the individual techniques are used on their own.
● There is no evidence to suggest that CVVDFhasasurvival benefit
when compared to CVVHbut may be auseful wayof increasing
clearance of small solutes.
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23. S
C
U
F
• High flux membranes
• Up to 24 hrs per day
• Objective VOLUME control
• N
No
ot
t suitable for solute clearance
• Blood flow 50-200 ml/min
• UF rate 2-8 ml/min
• High flux membranes
• Up to 24 hrs per day
• Objective VOLUME control
• Not suitable for solute clearance
• Blood flow 50-200 ml/min
• UF rate 2-8 ml/min
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24. CAV
V
H
• Extended duration up to weeks
• High flux membranes
• Mainly c
co
on
nv
ve
ec
ct
tiv
ive
e clearance
• UF > volume control amount
• Excess UF r
r
e
e
p
p
l
a
l
a
c
c
e
e
d
d
• Replacement pre- or post-filter
• Blood flow 50-200 ml/min
• UF rate 10-60 ml/min
• Extended duration up to weeks
• High flux membranes
• Mainly convective clearance
• UF > volume control amount
• Excess UF replaced
• Replacement pre- or post-filter
• Blood flow 50-200 ml/min
• UF rate 10-60 ml/min
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25. CAV
V
H
D
• Mid/high flux membranes
• Extended period up to weeks
• D
Diff
iffu
us
siv
ive
e solute clearance
• Countercurrent dialysate
• UF for volume control
• Blood flow 50-200 ml/min
• UF rate 1-8 ml/min
• Dialysate flow 15-60 ml/min
• Mid/high flux membranes
• Extended period up to weeks
• Diffusive solute clearance
• Countercurrent dialysate
• UF for volume control
• Blood flow 50-200 ml/min
• UF rate 1-8 ml/min
• Dialysate flow 15-60 ml/min
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26. OtherB
en
efitsofCRRT
● Its ability to reduce energy expenditure by cooling the
febrilepatient,
● in the patient with heart failure resistant to diuretics,
continuousultrafiltrationcanproduce arise incardiac
index,whileavoidingafall inarterial pressure.
● Thehaemodynamic improvementismostlyduetoa change
in preload which optimises myocardial contractility onthe
Starlingcurve
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27. S
u
sta
in
edlowefficiencydia
lysis
● aimsto combinethelogistic andcostadvantagesofIHD
withtherelative cardiovascularstabilityofCRRT.
● Treatmentsareintermittentbutusuallydailyandwith
longer sessiondurationsthanconventionalIHD.
● Solute andfluidremoval areslower thanIHD, but faster than
CRRT.
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30. 2. The patient`s cardiovascular status
• CRRTcauses less rapid fluid shifts and is the preferred option if there
is anydegree of cardiovascular instability.
3. The availability of resources
• CRRTis more labour intensive and more expensive than IHD
• Availability of equipment maydictate the form of RRT.
4. The clinician`s experience
• It is wise to use aform of RRTthat is familiar to all the staff involved.
5. Other specific clinical considerations
• Convective modes of RRTmaybe beneficial if the patient hasseptic
shock
• CRRTcan aid feeding regimes byimproving fluid management
• CRRTmaybe associated with better cerebral perfusion in patients
with an acute brain injury or fulminant hepatic failure.
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31. V
ascular accessinHD/CRRT
Type Advantages disadvantages
Fistula Natural vessels; least
likely to clot, longer
Require time to
mature
Graft Second best
ready to use in two
week
Swings in flow as above.
More likely to clot
Risks of pneumothorax
Catheter Usually in settings of
emergency.
Infection rates high.
Can damage blood vessels
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32. DialysateFluid
● Bicarbonate buffer solutions is used in IHD to replenish
serum bicarbonate levelsand neutralise metabolic acids that are
usuallypresent in patients with renal failure.
● Acetate buffer solutions
● In critically ill patients the acetate levels rise due to decreased
skeletal muscle metabolism.
● Increased acetate levels havebeen associated with hypotension
and hypoxia due to its negative inotrope effect and vasodilatation
● Lactate buffer soulutions
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34. Filters
● Filtersare either cellulose-based or synthetic.
● Synthetic filters such as polysulphone and polyamide are
more biocompatible and are higher-flux membranes so seem
more suitable for CRRT
● high-flux membranes with asurface area of 0.6– 1.2m2 and
apore size allowing the passageof molecules up to 50,000
Daltons
3/15/2023 34
35. P
roperties
● Biocompatibility
o The degree to which the membrane will activate the patient`s
inflammatoryand coagulation pathways.
o The greater the biocompatibility of amembrane the less activation
it will cause
● Flux
o The permeability of the filter. High flux membranes are
hydrophobic and mayhavemore or larger pores allowing more
water and solute to move acrossthe membrane.
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36. ● Adsorption
o
o The ability of larger solutes to adhere to the surface of the membrane.
Ahighly adsorptive membrane offers the potential benefit of adsorbing
mid sized molecules including inflammatory mediators but only until it
is saturated with them (usuallyafter the first few hours)
● Thickness
o Thinner membranes allow greater movement of solute by diffusion and
also favour convective movement
● Surfacearea
o The surface area of the membrane determines the available area for
diffusion and ultrafiltration
3/15/2023 36
37. Anticoagulation
● extracorporeal circuit will activate coagulation pathways and the
premature clotting of afilter is acommon problem.
● Even asmall amount of clot formation will reduce filter
performance.
NON-PHARMACOLOGICALMEASURES
1. adequate central venous pressure,
2. optimisingvascular access
3. adding a proportion of the replacement fluid to the patients
blood before it passes through the haemofilter (this is predilution)
3/15/2023 37
38. PHARMACOLOGICAL
MEASURES
3/15/2023 38
● Unfractionated heparin (UFH) [5-30kDa] is the most commonlyused
anticoagulant
● typical regime involves a40-70 IU.kg-1 bolus followed byapre-
filterinfusion at 5-10 IU.kg.-1hr-1
● It isthe most cost effective anticoagulant and is fullyreversible with
protamine.
● TheAPTTshould be monitored to avoid excessive anti- coagulation
but there is no evidence that elevating theAPTTprolongsfilter life.
39. ● Low molecular weight heparins (LMWH) [4.5-6kDa]
● They are dependant on renal elimination so in this setting
their dosingneeds to be guided byanti-factor Xalevels
(aiming for 0.25-0.35 IU.ml-1
● The half life of LMWHsis longer than for UFH(2-6 hrs
versus 1.5-3hrs) and their effect can onlybe partially
reversed with protamine.
● There is not ahuge amount of data on the use of LMWHin
CRRT and there isno evidence to suggest that theyare
superior to UFH.
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40. Prostaglandins
● Prostaglandins (prostacyclin or prostaglandin E2) inhibit platelet
function and can either be used on their own or in combination
with heparin theyhave asynergistic effect.
● short half life (several minutes) so are administered asan infusion
(2.5 – 10 ng/ kg/.min). The
● anticoagulant effect stops within 2 hoursofdiscontinuing the
infusion’
● theyare expensive and so are onlyused as second line therapy
3/15/2023 40
41. Regional citrate anticoagulation
● It isuse asalternative to heparin
● Sodium citrate is infused into the circuit pre-filter which chelates
calcium and inhibits clot formation.
● The calcium citrate complex is freely filtered so acalcium infusion
isrequired post-filter.
● Thisform of anticoagulation is limited bythe metabolic
derangements that it can cause: Hypocalcaemia,
hypomagnesaemia, hypernatraemia, metabolicalkalosis(citrate is
metabolised to bicarbonate), metabolic acidosis (caused bythe
citrate especially if the body`s citrate handling is impaired e.g.
liver failure).
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42. GUIDELINESF
OR NO
ANTICOAGULATION
● There isaalreadyadegree of coagulopathy
● INR> 2-2.5
● APTT> 60 seconds
● platelet count < 60 x 10³.mm3
● There is ahighriskof bleeding
● The patient is receivingactivated protein C.
3/15/2023 42
43. Peritoneal dialysis
• The peritoneum act as semipermeable membrane
• Dextrose containing solution(dialysate)is use abt 1.5-3l
in 2-4hours
• Considered for children <2years
• Mechanism of solute removal is by diffusion and
convection while fluid removal by osmosis
• Infection,drugs,position and exercise affect the rate of
transport
• Drugs additional; antibiotics,heparin,insulin
• Preferred buffer is LACTATE
3/15/2023 43
45. PERITONEAL
EQUILIBRIUM TEST
• Done within two months of initiation
• The test classified patients in to groups as follows;
1. Low transporters (1-5%)
2. Low average (25-30%)
3. High average (50%)
4. High transporters (10-17%)
3/15/2023 45
47. A
dequacyofDialysis
● Precise standards and goals of dialysis adequacy are based on
the clearance of urea.
● The volume of distribution of urea reflects the total body water.
● Mathematical modeling based on the changing blood
concentrations
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48. Dialysisdose
1. Measuring fractional reduction of BUN with each dialysis.
Measured by volume adjusted fractional clearance of urea.
K*t ÷ V urea
Where K – dialyzer urea clearance
t – time on dialysis
V – volume of distribution of urea
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49. Dialysis dose
2. Measurement of urea removed through each dialysis.
% of reduction in urea during single hemodialysis treatment –
Urea reduction ratio
[1-(post dialysis BUN concentration) ] x 100
(pre dialysis BUN concentration)
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50. Care of patients receiving hemodialysis
Variable Goals
Dialysis dose Urea kinetics model
Fluid balance Individualised. Intradialytic weight gain should be less than 5%
of IBW
Quality Measure endotoxin and bacteria in the dialysate water
Anemia Target aHb of 10-12gms%. Avoid high dose erythropoietin
Vascular access Monitoring. To establish AV access rather than
indwelling catheters.
Bone & Mineral Calcium levels between 8.4-9.5 and aPO4 3.5-5.5mg/dl
Blood pressure Optimum targets & strategies not well defined
LDL cholesterol <100mg/dl
Quality of life indices Support from the medical social worker
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51. KIDNEY TRANSPLANTATION
• Most effective treatment of ESRD
• Tend to have better outcome with matched familial donors
than cadaveric donors, 75-90% to 50-60% graft survival rates at
1year respectively.
• After the first year, graft survival curves shows an exponential
decline in functions. T1/2 2yrs since 1980s.
• Mortality rates after transplantation are highest in the first year
and age related.
• Occasionally acute irreversible rejection occurs after many
months of good function .
• Most graft however succumb to a chronic vascular and
interstitial obliterated process termed chronic rejection.
• Overall transplantation returns the majority of patients to an
improved lifestyle and life expectancy.
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52. RECIPIENT SELECTION
• The current standard of care is that the candidate should have a
life expectancy of >5years to be put on cadaver organ wait list.
• Average wait time for a cadaver kidney is now >4years.
• Screening of infections such as HIV,HBV,HCV,TB and neoplasm
should be routine.
• Overt AIDS or active hepatitis are considered absolute
contraindications because of high risk of opportunistic
infection.
• ABO and HLA antibodies screening pre transplant should be
done as mismatch is associated with very early graft rejection.
3/15/2023 52
53. DONOR SELECTION
• ABO/HLA matched donors are selected
• Cadaveric donors should be free of neoplastic disease, hepatitis
and HIV.
• Selective renal arteriography to rule out multiple or abnormal
renal arteries.
• Surgeons are now using a laparoscopic method to isolate and
remove the living donor kidney.
• Elderly donor or donor with renal failure or cadaveric kidney
that has prolonged period of ischemia and storage have high
risk of graft failure.
• Blood transfusion lead to increased risk of early graft rejection
as there is exposure to HLA antigens and sensitization of the
body.
• 10year survival rate with zero mismatched is 65%.
3/15/2023 53
54. Management of recipient after
transplantation
• Adequate dialysis should be performed within 48hours of
surgery
• K+ level should be monitored to avoid cardiac arrhythmias
• Strict input/output for early detection of acute tubular
necrosis or inability of ischemic tubules to regulates
sodium/water excretion.
• Immunosuppressive treatment.
• Fever of unknown origin is common ;blood culture cannot be
over emphasized
• Infections like PCP,CMV,HSV,candida,aspergillos are common
• Malignancy in patients on immunosuppressive therapy is 100x
higher than in the general population.
3/15/2023 54
55. Cont;
• Hypercalcemia; due to failure of hyperplastic parathyroid
glands to regress
• Hypertension; rejection activity in the transplant, native
kidney,,,
• Anemia; usually due to bone marrow suppression by
immunosuppressive effect.
• Chronic hepatitis; especially HBV tends to progress with fatal
outcome.
• Recipient of transplant have higher incidence of coronary and
peripheral vascular disease.
3/15/2023 55
56. Conclusion
• The hospital mortality in patients with AKI requiring RRT is as
high as 60%.
• No specific treatment have been shown to reverse the course
of AKI,so RRT forms the basis of further management.
• Screening for CKD facilitates early detection, evaluation and
best treatment of patients with CKD.
• Access to RRT in Nigeria is limited, and mortality rates are very
high, ranging between 40-60%. Important steps towards
improving the situation are the development of awareness and
prevention programs, increased funding to ensure availability of
RRT.
3/15/2023 56
57. REFRENCES
1. Boon A.N et al, Davidson`s principles &practice of Medicine,
20th edition,London,churchill Livingstone Elsevier;2006:pg 491-
496.
2. M O Odubanjo et al. Int Urol Nephrol. 2011 Sep.
3. Akinsola W, Odesanmi WO, Ogunniyi JO, Ladipo GO.
Disease causing chronic renal failure in Nigerians—a
prospective study of 100 cases. African journal of medicine and
medical sciences. 1989 Jun 1;18(2):131-7.
4. Harrison T.R et al, Harrison`s principles of Internal
Medicine,16th edition, volume 11, New York,McGraw-
Hill;2005:pg 1661.
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