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2 History Dialysis is a Greek word meaning "loosening from something else". Dialysis is referred to as "selective diffusion”. Diffusion is the movement of material from higher concentration to lower concentration through a given membrane Thomas Graham, Chairman of Chemistry at University College, London, first discovered this idea of selective diffusion

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4 Dialysate A chemical bath used in dialysis to draw fluids and toxins out of the bloodstream and supply electrolytes and other chemicals to the bloodstream.

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11 Components of Dialysis Prescription 1. Choosing the type of dialyzer 2. Establishing blood & dialysate flow 3. Prescribing the time for dialysis procedure 4. Prescribing the dialysate composition 5. Determining the frequency of the dialysis procedure 6. Determining the intensity of anticoagulation of the extracorporeal circuit

12 Comparison of Dialyzers DialyzerKoA urea (ml/min) Ultrafiltration coefficient Conventional <450<10 ml/mmHg/hr High-efficiency > ml/mmHg/hr High-flux >450>15 ml/mmHg/hr KoA urea = Urea mass transfer coefficient

13 Reasons to Use High-Efficiency Dialyzers LMW clearanceEnsure adequate dialysis in large patients HMW clearanceClearance of HMW substances such as ß 2 -MG BiocompatibilityReduce complement activation, less morbidity & mortality Short dialysisImproved lifestyle while receiving adequate therapy

14 Lack of complement activation and early neutropenia during hemodialysis should serve as useful indices of biocompatible membrane. Cuprophan < Cellulose acetate < Hemophan < Polysulfone

15 The apparent advantage of biocompatible dialysis membranes has led to our using them routinely in patients with ARF.

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18 Components of Dialysis Prescription 1. Choosing the type of dialyzer 2. Establishing blood & dialysate flow 3. Prescribing the time for dialysis procedure 4. Prescribing the dialysate composition 5. Determining the frequency of the dialysis procedure 6. Determining the intensity of anticoagulation of the extracorporeal circuit

19 Establishing blood & dialysate flow  Blood flow: ~ 3 × weight for the initial treatment, especially when the predialysis SUN>130 mg/dl In chronic dialysis patients minimum blood flow is ~ 4 × weight,range 300 – 500 ml/min  Dialysate flow: 500 – 800 ml/min

20 Components of Dialysis Prescription 1. Choosing the type of dialyzer 2. Establishing blood & dialysate flow 3. Prescribing the time for dialysis procedure 4. Prescribing the dialysate composition 5. Determining the frequency of the dialysis procedure 6. Determining the intensity of anticoagulation of the extracorporeal circuit

21 Prescribing the time for dialysis procedure 22 hours for the first session 33 hours for the second session, if predialysis SUN is less than 100 mg/dl TThird & subsequent dialysis sessions can often be up to 6 hours in length DDisequilibrium syndrome: Nausea, vomiting, restlessness, headache, seizures, obtundation, coma

22 Components of Dialysis Prescription 1. Choosing the type of dialyzer 2. Establishing blood & dialysate flow 3. Prescribing the time for dialysis procedure 4. Prescribing the dialysate composition 5. Determining the frequency of the dialysis procedure 6. Determining the intensity of anticoagulation of the extracorporeal circuit

23 Composition of HD concentrate soluteAcetate dialysis Bicarbonate dialysis Na (mEq/L) K (mEq/L) Chloride (mEq/L) Mg (mEq/L) Acetate(mEq/L) Bicarbonate(mEq/L) Glucose(g/100mL)

24 Dialysate Sodium  Low Na dialysate  High Na dialysate - Stability of plasma osmolality - Improve tolerance to HD Increasing Na from 130 to 136 mEq/L : reducing cramps during dialysis Dialysate Na between 139 to 144 mEq/L: fewer headaches,less cramping,nausea and vomiting - Weight gain and poor blood control - ( Henrich et al: modest weigh gain were not associated with increases in BP or sign of volume overload)

25 Dialysate Sodium  Na Modeling A high dialysate Na concentration is used initially with a progressive reduction toward isotonic or even hypotonic levels by the end of HD (Dumler et al,1979: 50% decrease in cramping episodes) (Raja et al,1983 :no difference in hypotensive episodes) (Daugirdas et al,1985: no difference in hypotensive episodes or cramps) (Acchiardo et al,1991: 50% decrease in hypotensive and cramping episodes) (Sang et al,1997: Decrease in hypotensive and cramping episodes but only in 22% of patients)

26 Dialysate Buffer  Acetate: in the early 1960s became the standard dialysate buffer used to 1. correct uremic acidosis 2. offset the diffusive losses of bicarbonate during HD In the mid 1980s some reported the linking between acetate and cardiovascular instability and hypotension during HD  Bicarbonate: emerged the buffer of choice

27 Bicarbonate buffer  Has become the standard base in most chronic dialysis center  Require a specifically designed system that mixes a bicarbonate and an acid (lactic or acetic acid) and all the Ca and Mg  PH of the final solution 7.0 to 7.4 and the final concentration of bicarbonate is 33 to 38mmol/L

28 Bicarbonate buffer Potential complications:  Microbial contamination (decreases by short storage time, filtration,..)  Hypoxemia (high concentration of bicarbonate)  Acute metabolic alkalosis (mental confusion, lethargy, weakness and cramps)

29 Dialysis Solution Bicarbonate Concentration  Excessive correction of severe metabolic acidosis (HCO 3 <10 meq/l) can have adverse consequences, including paradoxical acidification of the CSF & an increase in the tissue production rate of lactic acid.  Initial therapy should aim for only partial correction of the plasma HCO 3 level. ( postdialysis HCO 3 = )

30 Dialysis Solution Bicarbonate Concentration  If the predialysis plasma bicarbonate level is >= 28 meq/l or if the patient has respiratory alkalosis dialysis solution with lower bicarbonate level should be used (e.g., meq/l, depending on the degree of alkalosis).

31 Concentration of Dialysate Components Used in HD Sodium (meq/l) Potassium (meq/l) Calcium (meq/l) 2.5 – 3.5 Magnesium (meq/l) 0 – 1.5 Chloride (meq/l) Bicarbonate (meq/l) Glucose (mg/dl) 200

32 Dialysis Solution Sodium Level Predialysis serum sodium >=130 meq/l : Dialysis Solution Sodium Level = (140 - Predialysis serum sodium value) ( ) = = 150 Predialysis serum sodium <130 meq/l : Dialysis Solution Sodium Level no higher than meq/l above the plasma level

33 Dialysis Solution Sodium Level Hypernatremia Whenever dialysis Solution Sodium Level is more than meq/l lower than the plasma value, three complications of dialysis occur with increased frequency: 1.Hypotension 2.Muscle cramps 3.Cerebral edema & exacerbating the disequilibrium syndrome

34 Dialysis Solution Potassium Level Predialysis serum K levelDialysate K level * < 4 mEq/l>= 4 3 (in our country) > 5.52 in stable patients 2.5 – 3 in high risk patients > 7< 2 *Dialysate K level in our country = 1, 2, 3

35 Dialysis Solution Potassium Level Potassium rebound: marked rebound increase in the serum K level within1 - 5 hours after dialysis. (approximately 30%) Hemodialysis can remove 25 to 50 mEq of K per hour, with variability based upon the initial serum: K concentration Dialyzer Blood flood rate K concentration of the dialysate.

36 Dialysis potassium The most efficient way to remove excess K stores: hr periods of dialysis separated by several hours

37 Prevention of Hyperkalemia  Minimizing episodes of fasting which, in part via the reduction in endogenous insulin release, results in potassium movement out of the cells.insulin  In one report, fasting for 18 hours led to a mean 0.58 meq/L raise in the plasma potassium concentration.  Thus, patients with ESRD undergoing elective surgery should receive parenteral glucose containing solutions when fasting overnight..

38 Calcium Calcium plays a role both in myocardial contractility and in peripheral vascular resistance. Therefore, an increase in dialysate calcium concentration may be useful in cardiac compromised hypotension- prone patients.

39 Dialysate Calcium Aim: net flux of Ca into the patient Dialysate Ca concentration of 3.5mEq/L(1.75mmol/L) is widely used The dialysate Ca concentration should be individualized Patients treated with the dialysate Ca concentration <1.5 mmol/L the iPTH levels must be remain in acceptable range

40 Dialysis Solution Calcium Levels Routine use of 2.5 meq/l calcium dialysate is conceptually inappropriate in the acute setting, where a decline in the ionized calcium concentration is usually undesirable.

41 DialysateAdvantageDisadvantage Na : Increased Decreased Ca : Increased Decreased K: Increased Decreased HCO3: Increased Decreased Mg: Increased Decreased More hemodynamic stability,less cramping Less interdialytic weight gain Suppression of PTH, promotes hemodynamic stability Permits greater use of VitD & Caco 3 Less arrhythmias in setting of digoxin & CAD, improved hemodynemic stability Greater dietary intake of K improvement in myocardial contractility? Correct chronic acidosis Less metabolic alkalosis Less arrhythmia? hemodynamic benefit? Permits use of Mg-phosphate binder Dipsogenic effect, increased interdialytic weight gain hypotension and cramping more common Hypercalcemia with Vit D & high- dose Caco 3 Negative Ca balance, stimulate PTH Limited by hyperkalemia Increased arrhythmia, may exacerbate autonomic insufficiency Postdialysis metabolic alkalosis Potential for chronic acidosis Potential for hypermagnesemia Symptomatic hypomagnesemia

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43 Components of Dialysis Prescription 1. Choosing the type of dialyzer 2. Establishing blood & dialysate flow 3. Prescribing the time for dialysis procedure 4. Prescribing the dialysate composition 5. Determining the frequency of the dialysis procedure 6. Determining the intensity of anticoagulation of the extracorporeal circuit

44 HD in ARF MMore intense delivered doses of dialysis appears to principally benefit patients with ARF and illnesses of intermediate severity. PPatients at either extremes of illness (severely ill or not very ill) have much less survival benefit with intense intermittent hemodialysis regimens.

45 HD in ARF CAN DIALYSIS DELAY RECOVERY OF RENAL FUNCTION?  There is at least theoretical concern that dialysis might have detrimental effects on renal function. Three factors may be important in this regard: a reduction in urine output induction of hypotension complement activation resulting from a blood- dialysis membrane interaction.

46 Components of Dialysis Prescription 1. Choosing the type of dialyzer 2. Establishing blood & dialysate flow 3. Prescribing the time for dialysis procedure 4. Prescribing the dialysate composition 5. Determining the frequency of the dialysis procedure 6. Determining the intensity of anticoagulation of the extracorporeal circuit

47 Indications For Heparin-Free dialysis Pericaditis (tight heparin acceptable if bleeding risk deemed low) Recent surgery, with bleeding complications or risk. Especially:  Vascular & cardiac surgery ( within 7 days)  Eye surgery (retinal & cataract)  Renal transplant  Brain surgery (within 14 days) Coagulopathy Thrombocytopenia ICH Active bleeding Routine use for dialysis of acutely ill patients by many centers

48 Ultrafiltration Orders In ARF even patients who are quite edematous & in pulmonary edema, rarely need removal of more than 4 L of fluid during initial session.

49 Dry Weight  The lowest weight a patient can tolerate without the development of signs or symptoms of intravascular hypovolemia.  Estimating d ry Weight: Liters of actual body water = 142 × liters of NTBW = 142 × (60% × 60) = Predialysis serum sodium – 36 = 2.72 lit NTBW= Normal Total Body Water

50 Indications include the following : 1. Refractory fluid overload 2. Hyperkalemia (plasma potassium concentration >6.5 meq/L) or rapidly rising potassium levels 3. Metabolic acidosis (pH < 7.1) 4. Azotemia (BUN > 80 to 100 mg/ dl ) No consensus exists concerning the optimal timing for the initiation of dialysis in patients with ARF.

51 5. Signs of uremia, such as pericarditis, or an otherwise unexplained decline in mental status 6. Severe dysnatremias (sodium concentration greater than 155 or less than 120 meq/L ) 7. Hyperthermia 8. Overdose with a dialyzable drug/toxin

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