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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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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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Components of Dialysis Prescription1. Choosing the type of dialyzer2. Establishing blood & dialysate flow3. Prescribing the time for dialysis procedure4. Prescribing the dialysate composition5. Determining the frequency of the dialysis

procedure6. Determining the intensity of

anticoagulation of the extracorporeal circuit

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Comparison of Dialyzers

Dialyzer KoAurea (ml/min) Ultrafiltration coefficient

Conventional <450 <10 ml/mmHg/hr

High-efficiency >450 10 - 19 ml/mmHg/hr

High-flux >450 >15 ml/mmHg/hr

KoAurea = Urea mass transfer coefficient

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Reasons to Use High-Efficiency Dialyzers

LMW clearance Ensure adequate dialysis in large patients

HMW clearance Clearance of HMW substances such as ß2-MG

Biocompatibility

Reduce complement activation, less morbidity & mortality

Short dialysis Improved lifestyle while receiving adequate therapy

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Lack of complement activation and early neutropenia during

hemodialysis should serve as useful indices of biocompatible membrane .

Cuprophan < Cellulose acetate < Hemophan < Polysulfone

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The apparent advantage of biocompatible dialysis

membranes has led to our using them routinely in patients

with ARF.

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Components of Dialysis Prescription

1. Choosing the type of dialyzer2. Establishing blood & dialysate flow3. Prescribing the time for dialysis procedure4. Prescribing the dialysate composition5. Determining the frequency of the dialysis

procedure6. Determining the intensity of anticoagulation

of the extracorporeal circuit

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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

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Prescribing the time for dialysis procedure

2 hours for the first session 3 hours for the second session, if predialysis

SUN is less than 100 mg/dl

Third & subsequent dialysis sessions can often be up to 6 hours in length

Disequilibrium syndrome: Nausea, vomiting, restlessness, headache,

seizures, obtundation, coma

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Composition of HD concentrate

solute Acetate dialysis

Bicarbonate dialysis

Na (mEq/L)K (mEq/L)

Chloride (mEq/L)Mg (mEq/L)

Acetate(mEq/L)Bicarbonate(mEq/L)Glucose(g/100mL)

130-1450-4.0

96-111.50-4.033-42

00-0.25

137-1430-4.0

100-1110-2.52-4.530-350-0.25

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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)

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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)

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Dialysate Buffer Acetate: in the early 1960s became the

standard dialysate buffer used to1. correct uremic acidosis 2. offset the diffusive losses of bicarbonate during

HDIn the mid 1980s some reported the linking between

acetate and cardiovascular instability and hypotension during HD

Bicarbonate: emerged the buffer of choice

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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

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Bicarbonate bufferPotential complications:

Microbial contamination (decreases by short storage time, filtration,..)

Hypoxemia (high concentration of bicarbonate)

Acute metabolic alkalosis (mental confusion, lethargy, weakness and cramps)

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Dialysis Solution Bicarbonate Concentration

Excessive correction of severe metabolic acidosis (HCO3 <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 HCO3 level. ( postdialysis HCO3 = 15 - 20 )

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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., 20 - 28 meq/l, depending on the degree of alkalosis).

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Concentration of Dialysate Components Used in HD

Sodium (meq/l) 135 -145

Potassium (meq/l) 0 - 4

Calcium (meq/l) 2.5 – 3.5

Magnesium (meq/l) 0 – 1.5

Chloride (meq/l) 98 - 124

Bicarbonate (meq/l) 25 - 40

Glucose (mg/dl) 200

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Dialysis Solution Sodium Level

Predialysis serum sodium >=130 meq/l: Dialysis Solution Sodium Level =

140 + (140 - Predialysis serum sodium value)

140 + (140 - 130) = 140 +10 = 150 Predialysis serum sodium <130 meq/l:

Dialysis Solution Sodium Level no higher than 15 - 20 meq/l above the plasma level

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Dialysis Solution Sodium Level

Hypernatremia Whenever dialysis Solution Sodium Level is

more than 3 - 5 meq/l lower than the plasma value, three complications of dialysis occur with increased frequency: 1. Hypotension2. Muscle cramps3. Cerebral edema & exacerbating the

disequilibrium syndrome

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Dialysis Solution Potassium Level

Predialysis serum K level Dialysate K level *

< 4 mEq/l >= 4

3 (in our country)

> 5.5 2 in stable patients

2.5 – 3 in high risk patients

> 7 < 2

*Dialysate K level in our country = 1 , 2 , 3

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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.

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Dialysis potassium

The most efficient way to remove excess K stores:

2 - 3 hr periods of dialysis separated by several hours

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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.

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..

http://utdol.com/application/topic.asp?file=drug_a_k/131665&drug=true

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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.

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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

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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.

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Dialysate Advantage Disadvantage

Na: Increased

Decreased

Ca: Increased

Decreased

K: Increased

Decreased

HCO3: Increased

Decreased

Mg: Increased

Decreased

More hemodynamic stability ,less crampingLess interdialytic weight gain Suppression of PTH, promotes hemodynamic stabilityPermits greater use of VitD & Caco3

Less arrhythmias in setting of digoxin & CAD, improved hemodynemic stabilityGreater dietary intake of K improvement in myocardial contractility?

Correct chronic acidosisLess metabolic alkalosis

Less arrhythmia? hemodynamic benefit?Permits use of Mg-phosphate binder

Dipsogenic effect, increased interdialytic weight gainhypotension and cramping more commonHypercalcemia with Vit D & high-dose Caco3

Negative Ca balance, stimulate PTH

Limited by hyperkalemia

Increased arrhythmia, may exacerbate autonomic insufficiency

Postdialysis metabolic alkalosisPotential for chronic acidosis

Potential for hypermagnesemia

Symptomatic hypomagnesemia

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HD in ARF More intense delivered doses of dialysis

appears to principally benefit patients with ARF and illnesses of intermediate severity.

Patients at either extremes of illness (severely ill or not very ill) have much less survival benefit with intense intermittent hemodialysis regimens.

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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.

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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

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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.

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Dry Weight The lowest weight a patient can tolerate

without the development of signs or symptoms of intravascular hypovolemia.

Estimating dry Weight:Liters of actual body water = 142 × liters of NTBW = 142 × (60% × 60) = 38.72

Predialysis serum sodium 132

38.72 – 36 = 2.72 lit NTBW= Normal Total Body Water

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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 .

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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

به نام خداوند جان و خرد

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