1. Basics Concepts Of Dialysis
Naveed Aslam, MD
Consultant & clinical tutor
Department of Nephrology
PSMMC

2. Outline Introduction Indications Modalities Access Apparatus
Complications of dialysis access
Acute complications of dialysis

3. Functions of Kidneys
Excretory
Homeostatic
Endocrine
Metabolic

4. Functions of Kidneys Fluid Balance Electrolyte Balance---Na—K---H
Acid base Balance
Excretion of waste products of Metabolism and Drugs
Hormonal Secretion
Epo—Renin—Active
Vit D---D3

5. Indications to initiate dialysis
Diabetics: Creatinine clearance is < 15 mL/min
Non-diabetics: creatinine clearance < 10 ml/min

6. Additional Indications
Symptoms
Pericarditis
Uncontrollable fluid overload
Pulmonary edema
Uncontrollable and repeated hyperkalemia
Coma
Lethargy
Less Severe Symptoms
Azotemia
Nausea
Vomiting

7. Dialysis
Definition
Artificial process that partially replaces renal function
Removes waste products from blood by diffusion (toxin clearance)
Removes excess water by ultrafiltration (maintenance of fluid balance)
Wastes and water pass into a special liquid – dialysis fluid or dialysate

8. Main Goals of Dialysis Fluid Fluid Waste Products Electrolyte
Remove
Fluid
Waste Products
Urea
Creatinine
Potassium
Phosphorous
Sodium
Maintain
Fluid
Electrolyte
Acid-base balance

9. Therapeutic Modalities
Hemodialysis
In center dialysis
Home hemodialysis
In center nocturnal dialysis
Peritoneal Dialysis
Continuous ambulatory peritoneal dialysis
Continuous cycling peritoneal dialysis

10. Selection for HD/PD Clinical condition Lifestyle
Patient competence/hygiene (PD - high risk of infection)
Affordability / Availability

11. What we need for hemodialysis
Access
- Arteriovenous Fistula
- Arteriovenous Graft
- Central Venous Catheter
Membane
Dialysis Machine
Dialysate 11

12. Dialysis Health Care Team
Patient
Dialysis Nurse
Dialysis Technician
Nephrologist
Nephrology Social Worker
Renal Dietitian

13. 13

14. Arteriovenous Fistula
Venous Needle
Arterial Needle
Radial artery to cephalic vein
4-6 weeks to become fully functional
Subclavian route can be used temporarily
Vein
AV Fistula
Artery
In the forearm: subcutaneous joining of radial artery and cephalic vein. Essentially asking vein to function like an artery.
Preferred method- less long-term complications.
Takes 4-6 weeks to become fully functional.

15. AV Fistula

16. Internal Arteriovenous Graft (AVG)
Primary used in CRF & elderly
Synthetic graft which provides a bridge between the artery and vein
Needs 3-6 weeks to heal prior to use
Advantages:
Decreased risk of bleeding
Can be used indefinitely
No dressing
Allows freedom of movement 16

17. Arteriovenous Graft Used when veins are not adequate
Artery
Vein
Used when veins are not adequate
Polytetrafluroethylene (teflon) tube
Needles placed in graft
Graft Connection
Graft
Venous Needle
An arteriovenous graft or 'graft' is similar to a fistula except the artery is not connected directly to a vein. Instead, a surgeon uses short piece of plastic like tubing to connect the artery and vein together. Once the connection between the artery and vein is created the large amount of blood needed for dialysis is able to flow directly from the artery into the vein through the graft. During dialysis sessions two needles are placed into the graft, one to take blood to the dialysis machine and one to inject the cleaned, dialyzed blood back into the body.
Arterial Needle

18. 18

19. 19

20. Vascular Access Sites Temporary Vascular Access
Percutaneous cannulation of the internal jugular, femoral vein, or subclavian
Can stay in place for 1-6 weeks (newer ones can stay in longer)
Used mainly in acute renal failure
Problems:
Assess for hematoma, bleeding, dislodging, infections
Maintain occlusive dressing
Do not use catheter for any other reason other than dialysis
Femoral: do not sit up more than 45 degrees or lean forward
Since the lumens of these devices are considerably smaller than the permanent: duration of dialysis usually longer (4-8hrs)
External AV shunt: not used a much d/t complications
two silastic cannulas put in forearm or leg (forms external blood path)
Advantages: can be used immediately, no venipuncture necessary
Disadvantages: disconnect or dislodge, hemorrhage , infection, clotting, skin erosion 20

21. Vascular Access Double lumen catheter Catheter able to provide
sufficient blood flow
11 French and greater
Avoid kinking
Secure connections, make them visible
Right size at the right place
length requirement
Jugular and subclavien left side insertion19,(obese as well)
Jug, and Suclavien Right insertion,15
Femoral 25 cm
Cephalic position for return side (blue) 21

22. 22

23. Access(PermCath) Use immediately No needle sticks High infection rate
jjjj 23

24. Central Venous Catheter
Blood to dialysis machine
Blood from dialysis machine

25. Recirculation Femoral 13.5 cm - 22.8% Femoral 19.5 cm - 12.6%
Access recirculation may limit clearances
IJC= 1-2%
Subclavian 4.1%
Femoral 13.5 cm %
Femoral 19.5 cm %
flow 300 ml/min)
More problematic in IHD than CRRT
Kelber J et al. Am J Kidney Dis 1993; 22:
Leblanc M et al. J Am Soc Nephrol 1995; 5: 496. 25

26. Hemodialysis
Waste products filtered from blood by a semipermeable membrane and removed by the dialysis fluid, or dialysate.
In-center: 4 hours, 3 days a week
Home: may be daily
Nocturnal In-center: 6-8 hours, 3 nights/week
Dialysis fluid- “dialysate”- fluid used by dialysis procedure to assist in removal of metabolic byproducts wastes and toxins composition is determined by individual patient requirements.

27. Hemodialysis
The dialyzer, or artificial kidney, contains numerous small cellophane-like tubes with microscopic holes through which your blood passes as it is cleansed.
Your blood cells are too large to pass through these microscopic holes, but the waste products (sodium, potassium, creatinine, urea) can pass through. The fluid containing the waste products is discarded and the cycle begins again.
The diffusion process is sometimes compared to what happens when you make a cup of tea. Think of the tea bag as a filtering membrane, similar to the dialyzer. The tea leaves are like red blood cells and waste products, and the water is like clean dialysate solution. When you dip the tea bag into the hot water, the flavoring and color inside the leaves pass through the tea bag into the water, but the tealeaves can't pass through because they are larger than the holes in the bag.

28. Acute Complications of Dialysis
Hypotension (25-55%)
Cramps (5-20%)
Nausea and vomiting (5-15%)
Headache (5%)
Chest pain (2-5%)
Back pain (2-5%)
Itching (5%)
Fever and chills (<1%)

29. Effects of HD on Lifestyle
Flexibility:
Difficult to fit in with school, work esp if unit is far from home. Home HD offers more flexibility
Travel:
Necessity to book in advance with HD unit of places of travel
Responsibility & Independence:
Home HD allows the greatest degree of independence
Sexual Activity:
Anxiety of living with renal failure affects relationship with partner
Sport & Exercise:
Can exercise and participate in most sports
Body Image:
Esp with fistula; patient can be very self conscious about it

30. Problems with HD Rapid changes in BP Fluid overload
fainting, vomiting, cramps, chest pain, irritability, fatigue, temporary loss of vision
Fluid overload
esp in between sessions
Fluid restrictions
more stringent with HD than PD
Hyperkalaemia
Loss of independence
Problems with access
poor quality, blockage etc. Infection (vascular access catheters)
Pain with needles
Bleeding
from the fistula during or after dialysis
Infections
during sessions; exit site infections; blood-borne viruses e.g. Hepatitis, HIV

31. Removal of Toxins: Diffusion Depends on
Concentration gradient across the membrane

32. The use of diffusion (dialysis fluid) to achieve clearance

33. Thomas Graham ( )

34. Blood: Urea
Dialysate: HCO3

35. Diffusion
Blood: Urea
Dialysate: HCO3

36. Dialysis: General Principles
Ultrafiltration (water & fluid removal)
Movement of fluid across a semipermeable membrane as a result of an artificially created pressure gradient.

37. Convection
Membrane
Blood

40. Convective solute removal
Replacement fluid
SCUF
CVVH
Coffee maker analogy of hemofiltration
Removal of large volumes of solute and fluid via convection
Replacement of excess UF with sterile replacement fluid

41. Hemodialysis: Diffusion

42. Hemofiltration: Convection
Membrane
Blood

43. Hemodialfiltration
Membrane
Blood
Dialysate

44. SCUF: Isolated UF
Blood Inflow
Ultrafiltration
No Dialysate

45. SCUF Slow Continuous Ultrafiltration
Access
Return
Effluent
Fluid removal
Minimal solute clearance
CVVHDF, or Continous Veno-venous hemofiltration, provides solute removal by diffusion and convection simultanously, and patient fluid removal if desired.
It offers hight volume ultrafiltration using replacement fluid which can be given pre-filter (pre-dilution) or post filtre (post-dilution). Simultaneously dialysate is pumped at counter flow to blood

49. What we need for dialysis
Access
- Arteriovenous Fistula
- Arteriovenous Graft
- Central Venous Catheter
Membane
Dialysis Machine
Dialysate

50. Recirculation Femoral 13.5 cm - 22.8% Femoral 19.5 cm - 12.6%
Access recirculation may limit clearances
IJC= 1-2%
Subclavian 4.1%
Femoral 13.5 cm %
Femoral 19.5 cm %
flow 300 ml/min)
More problematic in IHD than CRRT
Kelber J et al. Am J Kidney Dis 1993; 22:
Leblanc M et al. J Am Soc Nephrol 1995; 5: 496.

51. 1913:The First Hemodialysis Experiment
Abel and Roundtree used a collodion hollow fiber tube arrangement, Dialysate, and Hirudin for anticoagulation. experiments used live dogs.

52. 1926:The First Human Experiment
George Haas used a collodion tube arrangement to successfully dialyze human subjects
Allergic reactions to impurities in Hirudin led him to abandon his experiments

53. Dialyzer used by Kolf: 1943

55. 1937:Nils Alwall used the Alwall Kidney to perform the first ever hemodialysis treatment at the university of Lund, Sweden

57. Today's Filters

58. Hemodialysis Filter

59. Hollow fiber structure

60. Hollow fiber structure
Blood inlet
Hollow Fiber
Housing material Polycarbonate
Blood inlet
Potting material Polyurethane
Filtrate Dialysate outlet
Filtrate compartment

61. This is what we have made !
Dialysate
Blood
Diffusion
Convection
Dialysate
Blood

63. Membranes Can be Low Flux Low efficiency High Efficiency
Can be High Flux

64. Biocompatibility Blood comes in contact with foreign membrane
A patient dialyzed for 15 yrs will be in contact with 4000 m2 of foreign surface
Biocompatibility:
“Ability of a material to perform with an appropriate host response in a specific application”

65. Bio-Incompatibilty Involves 4 primary immune systems
Interaction of the blood elements with the membrane [Leukocytes, Red Cells ]
The complement system (C3a et C5a).
The coagulation system (platelets and proteins).
The immune system (cytokines).

66. Clinical Consequences
Hypersensitivity reactions
Infections
Β-2 Microglobulin[ Dialysis Related Amyloidosis]
Malnutrition
Renal Reserve decline

67. Synthetic Polysulfone [PS] PS + Polyvinylpyrrolidine [PS]
Polyarlyethersulfone [PES]
Polymethylmetacrylate [PMMA]
Polyacrylonitrile [PAN]
Polycarbonate [PC]
Polycarbonate Polyether [Gambrane]
Helixone –PS using nanotechnology

68. Replacement Fluid/Dialysate
Must contain:
Sodium
Calcium (except with citrate)
Base (bicarbonate, lactate or citrate)
May contain:
Potassium
Phosphate
Magnesium

69. Dialysate Na 135-145 Meq/L K 0- 4.0 Ca 2.5- 3.5 Mg 0.5-0.75
Chloride
Bicarbonate 30-40
Dextrose 11 pH

70. Dialysate Ca and Mg precipitate with HCO3 Dialysate:
Acid Bath Bicarbonate bath
Acetic Acid HCO3
Ca, Mg, K, Cl Na
Na, Dextrose

72. Dialysate Mixing by the machine at the time of dialysis
[1:34, Dialysate: Water]
H+ + HCO3  H2CO3  pH 7-7.4
No ppt of Ca & Mg

73. Factors Influencing Solute Removal
Molecular weight of the solute
Dialyzer
Access BF
Dialysate
Time on dialysis
Machine
MODALITY
ACCSES RECIRCULATION

74. CVVHD Continuous Veno-Venous Hemodialysis Fluid removal Solute removal
Access
Return
Effluent
Dialysate
Fluid removal
Solute removal
(small molecules)
Counter-current dialysis flow
Diffusion
Back filtration

75. CVVHDF Continuous Veno-Venous Hemodiafiltration
Dialysate
Access
Fluid removal
Solute removal
(small and larger solutes)
Diffusion
Convection
Return
Replacement S
Effluent

76. Why CRRT?
Reduces hemodynamic instability preventing secondary ischemia
Precise Volume control/immediately adaptable
Uremic toxin removal
Effective control of uremia, hypophosphatemia, hyperkalemia
Acid base balance
Rapid control of metabolic acidosis
Electrolyte management
Control of electrolyte imbalances
Allows for improved provision of nutritional support
Management of sepsis/plasma cytokine filter
Safer for patients with head injuries
Probable advantage in terms of renal recovery

77. WHAT IS IN CURRENT PRACTICE
DAILY DIALYSIS
ON LINE HDF
HOME HD
TIDAL HD
AFB
CITRASATE

78. Peritoneal Dialysis The process takes place inside the body.
A tube (Tenckhoff catheter) is inserted into the abdominal cavity.
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.

79. Peritoneal Dialysis Infusion Drain Dialysis Solution Peritoneum
Abdominal Cavity
Catheter

80. PD as a Three-step process:
The ‘used’ dialysis fluid, containing water and waste is drained out of the body.
1.5 to 3 liters of ‘New’ dialysis fluid is then fill into abdomen. The amount will vary according to individual’s size.
The Dialysis fluid is then left inside peritoneum for 1-8 hrs.

81.  Peritoneal Dialysis Peritoneal cavity: reservoir for dialysate
Peritoneum: semipermeable membrane across which excess body fluid and solutes are removed
Polyurethane or silicone catheter
These two compartments are (a) the blood in the peritoneal capillaries, which in renal failure contains an excess of urea, creatinine, potassium, and so forth, and (b) the dialysis solution in the peritoneal cavity, which typically contains sodium, chloride, and lactate and is rendered hyperosmolar by the inclusion of a high concentration of glucose. The peritoneal membrane that acts as a “dialyzer” is actually a heteroporous, heterogeneous, semipermeable membrane with a relatively complex anatomy and physiology.
Peritoneal Capillaries
Fluid
Urea
Creatinine
Potassium
Peritoneal Cavity
Sodium
Chloride
Lactate
Glucose 

82. Peritoneal Dialysis Continuous Ambulatory PD Automated PD
3-10 dwells nightly
Continuous Cycling PD– 1 dwell during the day
Nocturnal Intermittment PD- dry during day
L dwells
4-8 hours
4 times/day

83. CAPD Dialysis takes place 24hrs a day, 7 days a week
Patient is not attached to a machine for treatment
Exchanges are usually carried out by patient after training by a CAPD nurse
Most patients need 3-5 exchanges a day i.e.
4-6 hour intervals (Dwell time) 30 mins per exchange
May use 2-3 litres of fluid in abdomen
No needles are used
Less dietary and fluid restriction

84. CAPD Exchange

85. APD Uses a home based machine to perform exchanges
Overnight treatment whilst patient sleeps
The APD machine controls the timing of exchanges, drains the used solution and fills the peritoneal cavity with new solution
Simple procedure for the patient to perform
Requires about 8-10 hrs
Machines are portable, with in-built safety features and requires electricity to operate

86. PD Access
Done under
LA or GA

87. APD

88. PD Transport Diffusion Ultrafiltration Absorption
Uremic solutes and potassium
Peritoneal capillary ➔ dialysis solution
Glucose, lactate, and calcium
Dialysis solution ➔ peritoneal capillary
Ultrafiltration
Water and associated solutes
Absorption
Water and solute
Peritoneal cavity ➔ lymphatic system
A.Diffusion. Uremic solutes and potassium diffuse from the peritoneal capillary blood down the concentration gradient into the peritoneal dialysis solution, whereas glucose, lactate, and, to a lesser extent, calcium diffuse in the opposite direction.B.Ultrafiltration. Simultaneously, the relative hyperosmolarity of the peritoneal dialysis solution leads to ultrafiltration of water and associated solutes across the membrane.C.Absorption. Also simultaneously, there is constant absorption of water and solute from the peritoneal cavity both directly and indirectly into the lymphatic system.
Amount of fluid and solute removal affected by dwell time
Ultrafiltration can remove kg fluid/day

89. Lifestyle Changes with PD
Flexibility
Can be performed almost anywhere
Least impact on work / school life (esp APD)
Travel
Dialysis supplies can be delivered to most parts of the world; travel more flexible. APD machines are portable; will fit into a car boot, can be carried by train/air
Responsibility
Requires more responsibility from patient but more independence

90. Problems with Treatment
Poor drainage
Common problem esp with new patients
Fibrin plug
Catheter displacement
Leakage
Fluid may leak around catheter exit site. (May leak into scrotum)
Stop PD temporarily
Resite catheter (use new one)
Infections
Exit site infections
Tunnel infection
peritonitis

91. Problems with Treatment
Hernia
Aggravation of pre-existing herniae (repair)
Evolution of new herniae
Declining effectiveness of the peritoneum
e.g. repeated infection
Effect of glucose in the dialysis fluid

92. Comparison of Dialysis Treatment OptionsPD
Unit HD
Home HD
Home Dialysis √ ×
Convenient Sessions
Socializn with other CRF pats
Home Equipment/Supplies
Special diet/fluid allowance
Sports/exercises participation
Most
Full day activity -work/school
Not alwys
Direct assist–partner/family
Travel
√ Delivery of supplies to most destins easy. Some notice req
√ Prior arrangements must be made well in advance
× Prior arrangements must be made well in advance

93. THANKS