1 Basics Concepts Of DialysisNaveed Aslam, MD Consultant & clinical tutor Department of Nephrology PSMMC

2 Outline Introduction Indications Modalities Access ApparatusComplications 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---HAcid base Balance Excretion of waste products of Metabolism and Drugs Hormonal Secretion Epo—Renin—Active Vit D---D3

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

6 Additional IndicationsSymptoms 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 ElectrolyteRemove Fluid Waste Products Urea Creatinine Potassium Phosphorous Sodium Maintain Fluid Electrolyte Acid-base balance

9 Therapeutic ModalitiesHemodialysis 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 LifestylePatient competence/hygiene (PD - high risk of infection) Affordability / Availability

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

12 Dialysis Health Care TeamPatient Dialysis Nurse Dialysis Technician Nephrologist Nephrology Social Worker Renal Dietitian

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14 Arteriovenous FistulaVenous 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 adequateArtery 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

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20 Vascular Access Sites Temporary Vascular AccessPercutaneous 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 providesufficient 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

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23 Access(PermCath) Use immediately No needle sticks High infection ratejjjj 23

24 Central Venous CatheterBlood 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 DialysisHypotension (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 LifestyleFlexibility: 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 overloadfainting, 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 onConcentration 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 PrinciplesUltrafiltration (water & fluid removal) Movement of fluid across a semipermeable membrane as a result of an artificially created pressure gradient.

37 Convection Membrane Blood

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40 Convective solute removalReplacement 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: ConvectionMembrane Blood

43 Hemodialfiltration Membrane Blood Dialysate

44 SCUF: Isolated UF Blood Inflow Ultrafiltration No Dialysate

45 SCUF Slow Continuous UltrafiltrationAccess 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

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49 What we need for dialysisAccess - 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 ExperimentAbel and Roundtree used a collodion hollow fiber tube arrangement, Dialysate, and Hirudin for anticoagulation. experiments used live dogs.

52 1926:The First Human ExperimentGeorge 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

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

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57 Today's Filters

58 Hemodialysis Filter

59 Hollow fiber structure

60 Hollow fiber structureBlood 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

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63 Membranes Can be Low Flux Low efficiency High EfficiencyCan be High Flux

64 Biocompatibility Blood comes in contact with foreign membraneA 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 systemsInteraction 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 ConsequencesHypersensitivity 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/DialysateMust 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 0.5-0.75Chloride 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

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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 RemovalMolecular weight of the solute Dialyzer Access BF Dialysate Time on dialysis Machine MODALITY ACCSES RECIRCULATION

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

75 CVVHDF Continuous Veno-Venous HemodiafiltrationDialysate 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 PRACTICEDAILY 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 PeritoneumAbdominal 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 dialysatePeritoneum: 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 PD3-10 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 weekPatient 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 exchangesOvernight 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 AbsorptionUremic 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 PDFlexibility 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 TreatmentPoor 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 TreatmentHernia 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