What is sodium modeling in hemodialysis patients?

What is sodium modeling in hemodialysis patients?

Causes of Intradialytic hypotension(IDH)

Intradialytic Hypotension

Reduced ECVImpaired Vaso-

constriction

Heart problems

Myocardial Infarction

Structural heart dis.

Arrythmias

Pericardial tamponadeDialyzer Rxn Air embolism

Hemolysis

Hemorrhage

Reduced plasma refill-

ing rate

Excessive fluid removal

Ultrafiltration rate > 0.35 ml/min/kg

Decrease in plasma vol. > 20%

Patient-related factors

Autonomic neuropathy (e.g. DM, Uremia)Antihypertensive medications

Sympathetic failure ( 적절한 plasma NE↑ 가 無 )RAS and arginine-vasopressin syst. sensitivity↓

Food ingestion(splanchnic vasodilation)Tissue ischemia(adenosine mediated)

Bacterial sepsisIntradialytic venous pooling

Core body temp↑.Anemia.

Dialysis-related factors

Acetate dalysate (adenosine-mediated)Low dialysate Na &/or ionized Ca conc.

Complemant activation (C3a and C5a-mediated)Cytokine generation(IL-1 and NO-mediated)

Water movement during standard hemodialysis

Water movement

Intracellular fluid Extracellular fluid Dialyzer

Osmolality320 mosm/kg

Osmolality320 mosm/kg

Loss of urea and water

step1

step2

step3

280

Osmolality320 mosm/kg

Falling to 290mosm/kg

as diffusion occurs

Compensatory refilling

Fluid removal

Plasma refilling

Low Na 130-135 meq/l

Na

Fluid removal Fluid removal

Na

Increased risk of hypotension

Historically the dialysate Na was maintained at hyponatremic level, 130-135:

Historically the dialysate Na wasmaintained at hyponatremic level, 130-135:

To prevent: Intradialytic hypertension Thirsty Interdialytic weight gain

To prevent: Intradialytic hypertension Thirsty Interdialytic weight gain

Disadvantages of dialysates with low sodium concentration:

Disadvantages of dialysates with lowsodium concentration:

Increased risk of hypotension Increased risk of intradialytic cramps Increased risk of dialysis disequilibrium

syndrome

Increased risk of hypotension Increased risk of intradialytic cramps Increased risk of dialysis disequilibrium

syndrome

urea removed by dialyzer

Effluent Dialysate

Inffluent Dialysate

urea sequestration in tissue

Increased intracellular osmolarity

fluid

Na

fluid

High dialysate sodium:High dialysate sodium:

Advantages:

Decreased risk of hypotension

Decreased risk of intradialytic cramps

Decreased risk of dialysis disequilibrium syndrome

Advantages:

Decreased risk of hypotension

Decreased risk of intradialytic cramps

Decreased risk of dialysis disequilibrium syndrome

Disadvantages:

Increased rate of hypertension

Interdialytic weight gain

Polydipsia

Disadvantages:

Increased rate of hypertension

Interdialytic weight gain

Polydipsia

Low Na >145 meq/l

Na

Fluid removal Plasma refilling

Na

Different patterns of sodium modeling Different patterns of sodium modeling

Na concentration

Hours after dialysis initiation

145-155 meq/lit

135-140 meq/lit

Dialysate Na should be regulated based on serum Na:

Dialysate Na should be regulated based onserum Na:

hyponatremia:

If Na > 130: Dialysate Na: 140-(140-predialysis Na)

If Na<130: Dialysate Na: Predialysis Na + 15-20

Hypernatremia:

Dialysate Na: Predialysis Na-2 mmol

hyponatremia:

If Na > 130: Dialysate Na: 140-(140-predialysis Na)

If Na<130: Dialysate Na: Predialysis Na + 15-20

Hypernatremia:

Dialysate Na: Predialysis Na-2 mmol

Goals of UF Profiling Provide adequate ultrafiltration (UF)

Minimize symptoms related to hypovolemia

Enhance plasma refill

Allow the patient to reach estimated dry weight (EDW)

Hypovolemia: Decreased blood volume leads to decreased cardiac output which can cause hypotension

Plasma refill: Refilling of the blood compartment, or vascular space from the surrounding tissue spaces

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Fluid Spaces in the Body

BONE, MUSCLE, FAT

VASCULAR SPACE4 LITERS WATER, 5%

INTERSTITIAL SPACE11 LITERS WATER, 15%

INTRACELLULARSPACE

27 LITERS WATER

40%

60% of Total Body Weight

is 42 liters

ofwater

70 kg or 154 lbs.

Extr

acellu

lar

Average weight Male

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The loss of circulating volume in the vascular space The loss of osmolarity as the urea is removed during

dialysis

Only fluid in the vascular space is available during dialysis for ultrafiltration. This amounts to less than 4L in the average patient

Two Basic Reasons That Patients End up With Dialysis Symptoms During Treatment

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Symptom EtiologyWith Constant Ultrafiltration

Ultrafiltration (UF) removes water volume from the blood into the dialysate, causing hypovolemia

Symptoms of Volume loss:• Hypotension

• Cramping

• Dizziness

• Nausea

• Vomiting

• Shock

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Profiling Ultrafiltration: Allows the patient to reach their estimated dry weight (EDW)

Helps prevent symptoms

Allows refilling of vascular fluid volume from the interstitial space (plasma refill)

Allows higher volume fluid removal at times when fluid is more readily available

Prevents hypotension

24

How to Do UF Profiling

Identify patients with dialysis related symptoms

Analyze patient’s treatment records

Decide if the patient will benefit from a profile

Choose a profile that matches your analysis

25

Things to Consider for Ultrafiltration Profiling

Does the patient have difficulty with fluid removal?

Have the MD answer these questions:◦ What UF rates can the patient tolerate?◦ Will the patient require periods of minimum UF? ◦ How will patient co-morbidities affect fluid removal?◦ What type of profile would be best suited for the

patient?

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Individualize the Prescription Based Upon the Patient’s Treatment History

Determine when the patient typically demonstrates symptoms. Beginning – mid – end of treatment?

Does the patient need minimum UF to complete the treatment?

Evaluate the pre treatment systolic blood pressure (SBP)

Evaluate the patient’s weight gains between treatments

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Choosing the Right UF Profiles

A profile that begins with the highest UF that can be tolerated by the patient which then decreases to a minimum will work for patients:

With large weight gains between treatments Who become hypotensive late in treatment Who cramp late or at the end of treatment With large weight gains between treatments and present with an elevated BP

Linear Progressive

Step Step

28

Choosing the Right UF Profiles Consider a profile with varying steps for patients who:

Need a gradual increase in UF at the beginning of the treatment to support low BP or cardiac output

Need short intervals of minimum UF to allow for plasma refill

Have difficulty shifting fluid into the vascular space (elderly, diabetic or unstable)

Cramp or are hypotensive randomly during treatment

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Case Studies

How to select a UF profile for a patient

30

A patient weight gains typically of 3-4 kg and

experiences moderate to severe leg cramps during

the last 30 minutes of treatment

31

220

200

180

160

140

120

100

80

60

40 30

60 90 120 150 180 210 240

Patient tolerates fluid removal (higher UF) at the beginning of

treatment

Symptoms are relieved at the

end of treatment with a lower UF

UF Profile

Systolic B

P

Time in Minutes

32 S

ystolic BP

220

200

180

160

140

120

100

80

60

40 30 60 90 120 150 180 210 240

1.8 Kg/h

1.0 0.7

0.3

Step profiles allow for dramatic decreases in UF.

Lower UF at the middle and end of treatment will reduce

the patient’s symptoms

Fluid overloaded patients benefit from

aggressive UF at the beginning of the

treatment

UF Profile

Time in Minutes

33

Second patient arrives with a systolic blood pressure of 85 and a weight gain of 3 Kg. If her SBP

falls below 75 she becomes symptomatic

34

220

200

180

160

140

120

100

80

60

40 30 60 90 120 150 180 210 240

Time in Minutes

Systolic B

P

Less UF should be used at the beginning of

treatment while the SBP is low. Increase the UF during periods when the

SBP is higher Decrease the UF toward the end of treatment as the

patient approaches her

dry weight to prevent symptoms

35

220

200

180

160

140

120

100

80

60

40 30 60 90 120

150 180 210 240

Time in Minutes

Systolic B

P

Using a Step Profile, you can create multiple minimum UF

periods which will allow plasma refill to occur.

Decrease the UF toward the end of treatment as the patient approaches her dry weight to

prevent symptoms

36

A woman patient is hypertensive and diabetic. She has large fluid gains of 4-6 Kg between treatments and has symptoms of hypotension about 45 minutes into the treatment as well as mid and late treatment

37

Assessment and Plan Assessment:

◦ Large fluid gains◦ Severe hypotensive episodes◦ Poor plasma refill

Plan◦ Support plasma refill, especially during the first part

of the treatment ◦ Prevent hypovolemia ◦ Consider conductivity profiling in addition to UF

profiling

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220

200

180

160

140

120

100

80

60

40 30 60 90 120 150 180 210 240

Time in Minutes

Sys

tolic

BP

Arrows indicate

plasma refill times

Utilize a Conductivity

profile to support solute removal

39

220

200

180

160

140

120

100

80

60

40 30 60 90 120 150 180 210 240

Sys

tolic

BP

Time in Minutes

UF and Conductivity Profiling can be used simultaneously

with similar step curves

40

220

200

180

160

140

120

100

80

60

40 30 60 90 120 150 180 210 240

UF and Conductivity Profiling can be used simultaneously

with similar progressive curves

Time in Minutes

Systolic B

P

41

Summary of UF Profiling Allows unlimited variation of ultrafiltration rates so that fluid can be removed from the vascular space while preventing symptoms

Allows periods of automatic plasma refilling to allow adequate fluid removal

Decreases the patient’s symptoms May be used simultaneously with conductivity profiling

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References

Heinrich, W.L. & Victor, R.G., “Autonomic Neuropathy and Hemodynamic Stability in End-Stage Renal Disease Patients”, Principles and Practice in Dialysis, Williams and Wilkins, Baltimore, 1994.

Wilson, S., Alvarez, D., A Primer on Ultrafiltration Profiling and Sodium Modeling for Dialysis Patients, Contemporary Dialysis and Nephrology, April 2000, pp 34-36.

Bonomini, V., Coli, L., Scolari, M.P., Profiling Dialysis: A New Approach to Dialysis Intolerance, Nephron 1997; 75:1-6

Leunissen, K.M.L., Kooman, J.P., van der Sande, F.M., van Kuijk, W.H.M., Hypotension and Ultrafiltration Physiology in Dialysis, Blood Purif 2000; 18:251-254

Oliver, M.J., Edwards, L.J., Churchill, Impact of Sodium and Ultrafiltration Profiling on Hemodialysis Related Symptoms, J Am Soc Nephrol 12: 151-156 2000

Jensen, B.M., Dobbe, S. A., Squillace, D.P., McCarthy, J.T., (April 1994) Clinical Benefits of High and Variable Sodium Concentration Dialysate in Hemodialysis Patients, ANNA Journal, Vol. 21, No. 2.

43

References

Gambro Basics 1 Gambro Education 1994

Petitclerc, T. and Jacobs, C. Dialysis sodium concentration: what is optimal and can it be individualized? , Nephrol Dial Transplant Editorial Comments1995, 596-599.

Coli, L., Ursino, M., Dalmastri, V., Volpe, F., LaManna, G., Avanzolini, G., Stefoni, S., Bonomini, V., A simple mathematical model applied to selection of the sodium profile during profiled haemdialysis, Nephrol Dial Transplant (1998) 13:404-416

Donauer,J., Kolblin, D., Bek, M., Krause, A., Bohler, J., Ultrafiltration Profiling and Measurement of Reletive Blood Volume as Strategies to Reduce Hemodialysis-Related Side Effects, AJKD, Vol 36, No 1 (July), 2000:pp115-123

Stiller, S., Bonnie-Schorn, E., Grassmann, A., Uhlenbusch-Korwer, Mann, A Critical Review of Sodium Profiling for Hemodialysis, Seminars in Dialysis, Vol 14, No 5 (September-October) 2001 pp. 337-347

Locatelli, F., DiFilippo, S., Manzoni, C., Corti, M., Andrulli, S., Pontoriero, G., Monitoring sodium removal and delivered dialysis by conductivity, The International Journal of Artificial Organs/Vol. 18/no. 11, 1995/pp716-721