1. Hemodialysis involves removing fluid and solutes from the body through diffusion and convection to achieve "dry weight." Careful fluid removal is needed to minimize hypotension risks. 2. Blood pressure fluctuates significantly during hemodialysis due to changes in vascular volume, cardiac output, and systemic vascular resistance. Both hypotension and hypertension are common complications. 3. Preventing intradialytic blood pressure issues involves accurate dry weight determination and gradual, steady ultrafiltration. Treatment of issues focuses on fluid balance, vasoactive medications, and optimizing dialysis prescription elements like sodium and temperature.

1. CHANGES IN BLOOD
PRESSURE AFTER
HEMODIALYSIS
Magdy El-Masry
Prof. of Cardiology
Tanta University

2. Hemodialysis
Removal of Fluid and Solutes with the Goal to Achieve
“Dry Weight”
What the cardiologist should know ?

4. Hemodialysis Basics

8. Diffusion

9. Convection

10. Goals of Dialysis
–Solute clearance
• Diffusive transport (based on countercurrent
flow of blood and dialysate)
• Convective transport (solvent drag with
ultrafiltration)
–Fluid removal

11. 11

12. Body Fluid Compartments
Figure 3-2

13. Extravascular
Fluid Removal by Ultrafiltration (UFR)
illicits compensatory mechanisms, termed
plasma or intravascular refill, aimed at
minimizing this reduction
Appropriate Removal Rate
setting the fluid removal rate to not exceed
the plasma refill rate (PRR) will minimize
risk of hypovolemia, hypotension
“Never too fast, never too much”
UFR ≤ PRR
Plasma
Refill
Rate
Intravascular
Vascular
Space
Hemodialysis
UF rate

14. Dialysate Buffer
•
•
Acetate: in the early 1960s became the
standard dialysate buffer used to correct
uremic acidosis
In the mid 1980s some reported the linking
between acetate and cardiovascular
instability and hypotension during HD
Bicarbonate: emerged the buffer of choice

15. Dialysis Solution Sodium Level
Plus
Minus
Low
dialysate
sodium
Less weight-gain,
thirst
&hypertension
More hypotension,
cramps
High
dialysate
sodium
Less hypotension, More weight gain,
cramps
thirst
& hypertension

16. CONCEPT of DRY WEIGHT
EXCESS FLUID WEIGHT
Body weight at which composition of
body fluid compartments is normal.
DRY WEIGHT
(euvolemia)
At higher weights there is expansion
of compartments
At lower weights there is depletion
of compartments.
Both these states have adverse
clincal consequences.

17. In short, among all these elements, the 2 essential
clues are the BP and the weight

19. Intradialytic Hypotension

20. Acute complications of dialysis
HHCCBNF
•
•
•
•
•
•
•
•
Hypotension — 25 to 55 %
Cramps — 5 to 20 %
Nausea and vomiting — 5 to 15 %
Headache — 5%
Chest pain — 2 to 5 %
Back pain — 2 to 5 %
Itching — 5 %
Fever and chills — Less than 1 %

21. Intradialytic
Hypotension
K/DOQI
• ↓SBP≥20mmHg or ↓MAP 10mmHg
with symptoms:
abdominal discomfort,
yawning, sighing, N/V, cramps,
restlessness, anxiety, fainting

22. Arterial Blood Pressure
Cardiac output
Heart rate / rhythm
Diastolic filling
Atrial kick
Systemic vascular resistance
Stroke volume
preload
afterload
contractility

23. PATHOGENESIS
Ultrafiltration
Osmolality
Fall
Warm
Dialysate
Bio-incompatibility
Endotoxin
Acetate
Infusion
MEDIATORS
Volume
PATHOPHYSIOLOGY
CARDIAC
OUTPUT
PATIENT
Heart Disease
Vasopressors
Vascular
Disease
Vasodilatator
Autonomic
Dysfunction
PERIPHERAL
RESISTANCE
Cell
Dysfunction
Hormonal
Dysfunction
Medications
Complement
Activation,
Sepsis
Infection
Cytokine release
HYPOTENSION
Hypoxemia
Vasovagal
stim.

24. Acute management of low blood pressure
associated with hemodialysis
 Ultrafiltration should either be stopped or the
rate decreased.
 The patient should be placed in the
Trendelenburg position.
 The blood flow rate should be reduced.
 Intravascular volume may be replaced with
mannitol or saline. Currently the use of an
intravenous bolus of saline is the first-line
therapy for hypotension.

25. PREVENTION
• Accurate setting of the "dry weight"
• Steady, constant ultrafiltration
• Increased dialysate sodium concentration and
sodium modeling
• Bicarbonate dialysate buffer
• Decrease dialysate temperature from 37C to
34-35C

26. Prevention – Con’t
 Improvement in cardiovascular Performance in
cardiac patients.
 Midodrine (the selective alpha-1 adrenergic
agonist) in patients with autonomic neuropathy and
perhaps others with severe hemodialysis
hypotension not responsive to the above measures.
 Avoidance of food.
 Avoid large interdialytic weight gain
 No antihypertensive before dialysis

27. Intradialytic Hypertension
The growing problem of
intradialytic hypertension
(5 – 15 % of HD patients )

28. Intradialytic Hypertension
Clinical Definitions
• ↑MAP of ≥ 15 mmHg during or
immediately post dialysis
• Hypertension during 2nd or 3rd hr
of HD after significant UF removed
• ↑BP that is resistant to UF

29. The Etiopathogenesis of Intradialytic Hypertension
Hypervolemia
Sodium balance positive and extracellular volume expand
Increased systemic vascular resistance
Increased sympathetic activity
Renin-angiotensin system hyperactivity
Endothelial cell dysfunction
Elevated concentration of endothelin 1
Nitric oxide deficiency
Increased vascular stiffness
Calcification of the arterial tree
Increased hematocrit
Erythropoietin Therapy

30. Hypertension in dialysis
(Another World
• There are limited studies on controlling blood
pressure in patients on dialysis.
• No consistent guidelines available due to the
fact that no one knows what blood pressure to
target.
– Pre, Post, intradialytic, non-dialysis day.

31. Blood pressure measurement
in dialysis patients
 Majority of Uremic patients lack diurnal variation in BP
 Immediate pre‐dialysis and post‐dialysis are misleading and not
reflective of true interdialytic BP
However, a post dialytic BP is more reflective of interdialytic BP
*Continuous monitoring is warranted in poor control patients
(those with large interdialytic weight gain)
*“Systolic load “ ‐‐ > amount of time SBP exceeds 140 mmHg per
day as correlates to incidence of LVH

32. K/DOQI
Blood Pressure Goals in Hypertensive ESRD Patients
• Target BP ≤ 140/90 mmHg (predialysis)
• ≤ 130/80 mmHg (postdialysis)

33. Treatment of hypertension in
patients on hemodialysis
Treatment of hypertension is often a multiple-step,
multidisciplinary process to reach KDOQI guidelines
of predialysis BP values of <140/90 mm Hg.
The key to successful treatment is patience; it often
takes 4-6 weeks to achieve results.
(This represents the lag phenomenon )

34. Lag period between normalisation of
ECF and optimal control of BP
DLIS etc
Chronic
volume
expansion
LAG
BP
ADMA
Vascular Na/K
ATPase
NO Synthetase
iCa++
NO
DLIS etc
ADMA
ECV
Vasoconstriction
Sustained UF & Na restriction
DLIS:digoxin-like immunoreactive substance
ADMA:asymmetric-dimethyl arginine

35. Treatment of Intradialytic Hypertension
The step-by-step approach

38. Choice of antihypertensive drugs
All classes of antihypertensive drugs can be used
in dialysis patients, with the sole exception of
diuretics, which are not commonly used because
of their lack of efficacy.
Therefore, with the exceptions of diuretics, the
criteria for drug selection are quite similar to
those used in non-dialysis patients.

39. Dialysis Clearance of Drugs
In general, removal of drugs on HD has NOT
been tested and is based on theoretical
considerations of molecular size and chemical
makeup of the drug
Drugs with low MW, limited volume of
distribution (Vd) , and that are water-soluble are
most likely to be removed by HD and will require
extra dosing

40. Postdialysis dosing or extra doses after HD may
be necessary for certain antihypertensive agents:
•Angiotensin converting enzyme inhibitors (ACE-I): all are
dialyzable except fosinopril
•Angiotensin receptor blockers (ARB): none are dialyzed
•B-blockers: atenolol and metoprolol are dialyzable but
labetolol and carvedilol are not
•Calcium channel blocker: amlodipine is not dialyzable

41. Conclusions
The fluctuations in BP
with every dialysis is
complex
“We can do better”

42. Intradialytic Blood Pressure Fluctuations
• Current State
Clinically significant alteration in blood pressures
is one of the biggest challenges encountered in
the dialysis unit
• Ideal State
Clinicians understand the physiological changes
in blood pressures during hemodialysis and
prevent and manage these changes effectively to
ensure patient’s safety

43. Thank you for your attention
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