2. Moderators:
Professors:
Prof. Dr. G. Sivasankar, M.S., M.Ch.,
Prof. Dr. A. Senthilvel, M.S., M.Ch.,
Asst Professors:
Dr. J. Sivabalan, M.S., M.Ch.,
Dr. R. Bhargavi, M.S., M.Ch.,
Dr. S. Raju, M.S., M.Ch.,
Dr. K. Muthurathinam, M.S., M.Ch.,
Dr. D. Tamilselvan, M.S., M.Ch.,
Dr. K. Senthilkumar, M.S., M.Ch.
Dept Of Urology, KMC and GRH, Chennai 2
3. Definition
Renal replacement therapy is a term used to
encompass life-supporting treatments for renal failure
Treatment modalities: Dialysis and Transplantation
First hemodialysis in human being was done by Dr.
HASS in 1924
First to construct a working dialyzer was Dr .
WILLIAM KOLFF in 1943.
Dept Of Urology, KMC and GRH, Chennai 3
4. INDICATIONS FOR RRT
Biochemical indications
Refractory hyperkalemia> 6.5 mmol/L
Serum urea > 50 mmol/L not due to hypovolemia
Refractory metabolic acidosis pH ≤ 7.1
Clinical indications
End-organ damage: pericarditis, encephalopathy,
neuropathy, myopathy, uremic bleeding, weight loss
Refractory volume overload
Dept Of Urology, KMC and GRH, Chennai 4
5. PRINCIPLES
Whatever be the technique of RRT, the fundamental
principle is the removal of unwanted SOLUTES &
WATER through a semipermeable membrane and
maintain hemostasis
WATER : Removal of water occurs through a process of
ULTRAFILTRATION
Dept Of Urology, KMC and GRH, Chennai 5
6. It is achieved by generating a TRANS MEMBRANE
PRESSURE , which is greater than the plasma oncotic
pressure ( HF, IHD)
By increasing the osmolarity of the dialysate ( PD)
Dept Of Urology, KMC and GRH, Chennai 6
7. SOLUTE REMOVAL
It occurs by either DIFFUSION or by CONVECTION (
SOLVENT DRAG ).
In diffusion an electro-chemical gradient is created
across the membrane with a dialysate solution.
Dept Of Urology, KMC and GRH, Chennai 7
9. Dialysis is any process that changes the concentration of
solutes in the plasma by exposure to a second solution
( the dialysis solution ) across a semipermeable membrane
.
Definition
Dept Of Urology, KMC and GRH, Chennai 9
10. Hemo dialysis
The 3 essential components of HD are :
Dialyzer
Composition of dialysate
Blood delivery system
Dept Of Urology, KMC and GRH, Chennai 10
11. DIALYZER
Hollow-fiber dialyzer, the most commonly used type
of dialyzer
composed of bundles of capillary tubes through which
blood circulates and the dialysate travels on the
outside of the fiber bundles.
The blood and the dialysate may circulate in the same
or in opposite directions in co-current and
countercurrent techniques, respectively
Dept Of Urology, KMC and GRH, Chennai 11
12. Dialysis membrane
It can be synthetic or biological.
Cellulose :
Has low flux
poor in removing middle MW molecules.
More complement and leucocyte activation.
Not desirable in ICU patients.
Worsening of the organ damage.
Dialysis membrane :
•
Dept Of Urology, KMC and GRH, Chennai 12
13. SYNTHETIC
High flux membranes.
Made up of PMMA, PAN, Polyamide, Polysulphone
(PS).
Allows convective therapy and removal of middle MW
substances.
Better biocompatibility, less leucocyte/complement
activation and end organ dysfunction
Dept Of Urology, KMC and GRH, Chennai 13
15. When to start dialysis
To treat or to prevent life - threatening
hyperkalemia, acidosis, or hypervolemic pulmonary
edema,
or
To treat complications of chronic renal failure
such as pericarditis, neuropathy, seizures, and
coma.
Modern renal replacement uses dialysis to
remove unwanted solutes by diffusion and
hemofiltration to remove water, which carries
with it unwanted soluble substances.
Dept Of Urology, KMC and GRH, Chennai 15
17. Clinical indications to start dialysis
in CKD
Pericarditis or pleuritis
Progressive uremic encephalopathy or neuropathy
A clinically significant bleeding diathesis attributable to
uremia
Fluid overload refractory to diuretics
Persistent metabolic disturbances that are refractory to
medical therapy; these include hyperkalemia, metabolic
acidosis, hypercalcemia, and hyperphosphatemia
Persistent nausea and vomiting
Hypertension poorly responsive to antihypertensive
medications
Weight loss or signs of malnutrition
Dept Of Urology, KMC and GRH, Chennai 17
18. When not to dialyse?
Dementia
Severe peripheral arterial disease
Hypotensive heart failure
Severe mental illness
Malignant disease with poor prognosis
Dept Of Urology, KMC and GRH, Chennai 18
19. MODES OF RRT
INTRACORPOREAL : Peritoneal dialysis
EXTRACORPOREAL :
Intermittent Hemodialysis
Slow low efficiency dialysis (SLED)
Continuous Hemo-filtration
CAVH
CVVH
CAVHDF
CVVHDF
Dept Of Urology, KMC and GRH, Chennai 19
21. Peritoneal dialysis
Principle
Solute and fluid exchange occur between
peritoneal capillary blood and dialysis solution in the
peritoneal cavity
Dept Of Urology, KMC and GRH, Chennai 21
22. Anatomy
Largest serosal surface
Surface area is approximately equal to body surface
area 1-2sq.m in an adult
Can hold appreciable quantity of fluid without overt
physiological alterations
Parietal: more important in PD-blood supply from
the lumbar, intercostal and epigastric arteries and
drains into the IVC
Blood flow 50-100ml/min
Dept Of Urology, KMC and GRH, Chennai 22
23. Fluid and molecules transfer
Diffusion
Osmosis
Dept Of Urology, KMC and GRH, Chennai 23
24. Three pore model
Ultrasmall pores (3–5 Å; water-selective pore), allowing
the transport of water but not solutes. About 50 per cent
of transcapillary UF occurs through these pores, inspite
of the surface area being only 1–2 per cent.
Small pores (40–50 Å; interendothelial clefts have been
considered the equivalent of small pores)—colloid
osmosis occurs at this level. (urea, creatinine, sodium,
potassium)
Large pores (>150 Å; probably less than 0.1 per cent of total
pore count), which are involved in macromolecular
transport
Dept Of Urology, KMC and GRH, Chennai 24
26. In peritoneal dialysis, 1.5 – 3 L of peritoneal dialyzate
solution is infused into the peritoneal cavity and allowed to
dwell for a set period of time, usually 2 to 4 hours.
The rate of diffusion diminishes with time and eventually
stops when equilibration between plasma and dialyzate is
reached
Lactate is the preferred buffer
Icodextrin, has been found to be associated with more
efficient ultrafiltration than dextrose-containing solutions.
It may be associated with the complication of
ENCAPSULATING PERITONEAL SCLEROSIS.
Dept Of Urology, KMC and GRH, Chennai 26
27. Contraindications
Absolute:-
Loss of peritoneal function producing inadequate
clearance
Adhesions blocking flow
Abdominal hernia
Stoma
Diaphragmatic fluid leak
Dept Of Urology, KMC and GRH, Chennai 27
28. Contraindications
Relative:-
Fresh foreign body
Large polycystic kidneys
VP shunt
Morbid obesity
Severe malnutrition
Bowel disease
S.aureus carrier
Skin infections
Dept Of Urology, KMC and GRH, Chennai 28
31. Modes of PD
Intermittent peritoneal dialysis
Continuous Ambulatory (CAPD)
– 3 exchanges during waking hours
Automated or Alternative (APD)
Nocturnal Intermittent (NIPD)
- No exchange during day, 6-8 at night via cycling machine
Nocturnal Tidal (NTPD)
No exchange during day, 6-8 at night each hour with a constant
volume of ≈ 1,500 mL in peritoneal cavity
Continuous Cyclic (CCPD)
Dialysate instilled in AM, dwells during day, removed prior to bed
Hybrid devices :Night exchange device
PD plus
Dept Of Urology, KMC and GRH, Chennai 31
34. Mechanical
Kinking of catheter
Early catheter malfunction
Late catheter malfunction
Migration
Blood
Fibrin
Peritonitis
Dept Of Urology, KMC and GRH, Chennai 34
35. Medical
Glucose overload
Malnutrition – protein loss
Hypo / hypercalcemia
Idiopathic ascites
Haemoperitoneum
Eosinophilic peritonitis
Dept Of Urology, KMC and GRH, Chennai 35
36. Medical
Glucose overload
Malnutrition – protein loss
Hypo / hypercalcemia
Idiopathic ascites
Haemoperitoneum
Eosinophilic peritonitis
Dept Of Urology, KMC and GRH, Chennai 36
37. Other complications
Hernias (15-20%); any existing hernia should be
repaired pre PD
Fluid leaks
Prolapse
Back pain
Dept Of Urology, KMC and GRH, Chennai 37
39. Principle
The use of a semipermeable membrane that will
allow the passage of water and small molecular weight
(MW) solutes, but not large molecules (e.g. proteins)
MW of urea = 60, creatinine = 113, vitamin B12 =
1355, albumin = 60 000, IgG = 140 000 Da
Dept Of Urology, KMC and GRH, Chennai 39
40. Mechanisms of solute clearance
Diffusive transport
Along concentration gradient
Small solutes
Convective transport
Smaller and larger solutes are effectively dragged along
with fluid
Depends on pore size
Ultrafiltration
Pressure gradient
Fluid and small molecules
Dept Of Urology, KMC and GRH, Chennai 40
41. Types of vascular access
AV fistula
AV graft
Central venous catheters
Dept Of Urology, KMC and GRH, Chennai 41
42. AV fistula
Constructed in subcutaneous
plane between an artery and
vein (side of artery to side or
end of vein)
Advantages
Excellent patency
Lower rates of complications
(infection, steal, stenosis)
Disadvantages
Long maturation time
Occasional failure to
develop
Dept Of Urology, KMC and GRH, Chennai 42
43. AV graft
Synthetic conduit, usually polytetrafluoroethylene (PTFE, also known
as Gortex), between an artery and vein
Advantages
Short maturation time
Easy cannulation and large surface area
Easier surgical handling
Disadvantages
Inferior long term patency
High infection rate than native AVF
Good alternative in patients in whom adequate AVF cannot be created
Dept Of Urology, KMC and GRH, Chennai 43
45. Central venous catheters
Temporary catheters
(Vascath)
ARF requiring dialysis
ESRD but without
alternative access
Tunneled cuffed catheters
Alternative form of long
term vascular access for
patients in whom AV
access cannot readily be
created
Dept Of Urology, KMC and GRH, Chennai 45
49. Water
Dialysate diluted in sterile water
Ratio of 1:34
Standard 4 hour session, flow rate 500ml/min – 120 L
of water
Dept Of Urology, KMC and GRH, Chennai 49
50. Contraindications
Absolute
No vascular access possible
Relative
Difficult access
Needle phobia
Cardiac failure
Coagulopathy
Dept Of Urology, KMC and GRH, Chennai 50
51. ANTI-COAGULANTS IN DIALYSIS
Interacting of blood with dialyzing membrane causes
activation of clotting cascade – thrombosis-dysfunction.
Commonly used anti-coagulant is HEPARIN .
SYSTEMIC ANTICOAGULATION :
Administered in doses of 50-100u/kg at the initiation
followed by a bolus of 100u/hr
REGIONAL ANTICOAGULATION :
circuit alone is anti-coagulated by administering 500-750
u/hr intothe arterial line and by parallel administration of
protamine 1mg/100u of heparin.
Dept Of Urology, KMC and GRH, Chennai 51
52. VARIANT OF REGIONAL ANTI-COAGULANT :
uses sodium citrate with dialysate containing no
calcium, Used for patients with high risk of bleeding.
DIALYSIS WITHOUT ANTI-COAGULANTS :
Uses the saline flush technique
HD is initiated at a higher rate to reduce the
thrombogenicity and dialyzer is flushed every 15-
20min with 50ml of saline.
DIRECT THROMBIN INHIBITORS :
Hirudin, lepirudin, Argatroban
Dept Of Urology, KMC and GRH, Chennai 52
53. Complications
Dialysis reactions
Cardiovascular
Neuromuscular
Haematologic
Pulmonary
Technical
Dept Of Urology, KMC and GRH, Chennai 53
55. Hypotension
10-30%
Asymptomatic to organ hypoperfusion
Trendelenburg position
Stop dialysis
Normal saline
Cool dialysate
Dept Of Urology, KMC and GRH, Chennai 55
58. Dialysis disequilibrium syndrome
Neurologic symptoms of varying severity that are thought
to be due primarily to cerebral edema
Reverse osmotic shift
Intracerebral acidosis
Early findings
Headache, nausea, disorientation, restlessness, blurred vision
Late findings
Confusion, seizures, coma, and even death
Prevention
The initial dialysis should be gentle, but repeated frequently
The aim is a gradual reduction in BUN
Dept Of Urology, KMC and GRH, Chennai 58
60. Pulmonary
Dialysis-Associated hypoxemia
PaO2 decreases by 5-20mmHg
Clinically not significant
Important in patients with respiratory compromise
Dept Of Urology, KMC and GRH, Chennai 60
61. Technical
Air embolism
Altered dialysate composition
Line disconnection
Dept Of Urology, KMC and GRH, Chennai 61
65. Advantages Disadvantages
Haemodialysis Short treatment
Efficient removal
Specialised staff
and equipment
Heparinisation
Protein loss
Peritoneal
dialysis
Can be
performed
manually
No heparinisation
Longer treatment
period
Continuous
Risk of peritonitis
May cause
respiratory
compromise
Dept Of Urology, KMC and GRH, Chennai 65
66. Goals of dialysis
Achieve desired dry weight
Adequate removal of waste products
Prevent sequelae of electrolyte disturbances
Reduce morbidity and mortality
Dept Of Urology, KMC and GRH, Chennai 66
67. SLOW LOW- EFFICIENCY DIALYSIS
Conventional dialysis treatment .
Uses dialysate flow rates of 300 ml/min & low blood
flow pump speeds of 200ml/min for 6 – 12 hrs a day.
Excellent small molecule detoxification.
Reduced anticoagulant requirement.
11 hrs SLED is comparable to 24 hrs of CHD .
Dept Of Urology, KMC and GRH, Chennai 67
68. Haemofiltration
Solute clearance purely by convection – dragged along
with water
Large volumes removed – replace
Replacement fluid directly administered to patient
Highly permeable large membranes
High flow rate
Dept Of Urology, KMC and GRH, Chennai 68
71. CONTINUOUS VENO-VENOUS HEMOFILTRATION
Solute clearance occurs by convection.
No dialysate , 1-2 l/hr of ultrafiltration rates used.
Replacement fluid provided to replace the excess
volume that is being removed and replenish desired
solutes
Effective method of solute removal
Major advantage is that solute can be removed in large
quantities ,maintaining a net zero or even a positive
fluid balance
Dept Of Urology, KMC and GRH, Chennai 71
72. CONTINUOUS VENO-VENOUS HEMODIAFILTRATION
Involves the ultrafiltration of fluid across a high-flux
dialyzer with compensatory reinfusion of ultrapure
dialysate
increases middle-sized molecule clearances
Benefits of both diffusion and convection for solute
removal
Use of replacement fluid allows for adequate removal
of solutes with zero or positive net fluid balance
Dept Of Urology, KMC and GRH, Chennai 72
73. SLOW CONTINUOUS ULTRAFILTRATION
Ultrafiltration at a rate of 100-300ml/hr is performed
to maintain fluid balance.
No fluids are administered either as dialysate or
replacement fluids.
Indicated in CCF refractory to diuretics and in volume
overload
Dept Of Urology, KMC and GRH, Chennai 73
74. Advanatges
Better removal of large substances
Improved clearance of uremic toxins
Better cardiovascular stability
Less inflammatory reactions
Suitable for patients planned for long term dialysis
Dept Of Urology, KMC and GRH, Chennai 74
