Dry Weight 2018

Establishing and maintaining normal extracellular volume (ECV) is required to achieve normotension. The achievement of an optimal fluid status, as expressed by "dry weight" (DW), should allow for controlling blood pressure (BP) in the large majority of HD patients

1. Fluid Balance, DryWeight and
Intradialytic Hypotension
.
Dr Rodriguez Jose
Dr. Faroeuk
Consultant Nephrologist
CNN 1. Paramaribo. Suriname .

2. INTRODUCTION
Cardiovascular(CV)
disease is the
primary cause of
mortality in Maintenance
hemodialysis (HD)
patients.

3. INTRODUCTION
•Poor control of hypertension is, in
great part, responsible for this
situation.
•Several factors are involved in the
pathogenesis of hypertension, but the
main one is extracellular volume (ECV)
overload.

4. INTRODUCTION
Establishing and maintaining normal
extracellular volume (ECV) is required to
achieve normotension.
The achievement of an optimal fluid status,
as expressed by "dry weight" (DW), should
allow for controlling blood pressure (BP) in the
large majority of HD patients.

WE MUST FOCUS ON THE DRY WEIGHT

5. BODY WATER
INTRACELLULAR
FLUID
INTRA
VASCULAR
FLUID
INTERSTITIAL
FLUID
EXTRACELLULAR
FLUID

6. BODY WATER
INTRACELLULAR
FLUID
2/3 TBW
28 LINTRAVASCULAR
FLUID
3.5 L
70kg manTOTAL BODY WATER:42 L
INTERSTITIAL FLUID
10.5 L

7. WHAT
IS
DRY WEIGHT?

8. Dry weight
Ideal postdialysis weight that allows a
constantly normal blood pressure to be
maintained without using antihypertensive
medications.
"that body weight at the end of dialysis at
which the patient can remain normotensive
until the next dialysis without
antihypertensive medication"
Dry weight is not the actual postdialysis weight.
It is the ideal postdialysis weight allowing for a
normal BP.

9. Evaluation of fluid status
(extracellular volume)

10. DW : Clinical evaluation
Overload symptoms:
– Hypertension
– Peripheral edema
– Pulmonary edema (Dry
cough, exercise dyspnea,
orthopnea, crackling rattles)
– Effusions (hypoventilation /
pulmonary dullness, ascites)

11. DW : Clinical evaluation
Hypovolaemia symptoms:
– Hypotension, tachycardia,
polypnoea.
– Vasoconstriction with
peripheral and / or central
hypoxemia signs (dry, cold and
white skin; cramps
and angina; confusion, coma;
…).
– Skin dryness and xerostomia.
 Applicable to each dialysis
session

12. Dry weight Assessment: Clinical
Blood pressure
JVP
Oedema/ascites
Lungs examinations
Weighing scale.
Advantages
–Cheap
–Immediate
–universally
available at the
patient's
bedside.
Disadvantages:
–Unreliable
–Insensitive
–inaccurate.

13. Dry weight Assessment: non-clinical
inferior vena cava diameter,
atrial natriuretic peptide (ANP)
Bioimpedance
blood volume monitoring

14. Pathophysiology
of
dry weight

15. Pathophysiology of dry weight
Normal kidney functions 24 hrs/day
HD is discontinuous, a few hours every 2
or 3 days: to a peak-and-valley situation.
The patient gains one to several liters of
ECV during the interdialytic period.

16. Daily weight and DW
variations
24h physiological weight variations :
– Food time & rythm of the appetite.
– Physical activity.
– Bladder content.
– Constipation.
– …etc…
• Extracorporal weight variation factors : Clothes &
shoes,
prostheses, diaper and urine bag, scales, weighing
errors, …
 DW is highly variable
 “Moving dry weight” concept

17. Pathophysiology of dry weight
At the initiation of each
HD session:
the patient is saline
overloaded, or "wet.“??
He needs to lose the
weight gained during
the interdialytic
period to return to the
last postdialysis weight.
Wt : 62 kg
Wt 58 kg

18. Pathophysiology of dry weight
If this weight has
been found to be too
high, the planned
ultrafiltration (UF)
must be increased.
IDWG = 3 kg
Set UF = 3.2 kg
–allow about 200 ml
extra for blood
return + fluid & food
taken during HD
If it has been found
to be too low, the
planned UF must be
decreased.
IDWG = 1kg
Set UF =1.2 kg

19. Pathophysiology of dry weight
The water and salt subtraction from the plasma
volume creates a disequilibrium situation
between the plasma and interstitial spaces.
Water & salt removal
from plasma/
intravascular space

20. Pathophysiology of dry weight
Refilling from interstitial (and intracellular)
spaces has started but is not yet completed
(it takes about 4 hours).

21. Pathophysiology of dry weight
At the end of the HD session, plasma
volume reaches a nadir(the lowest point )
At disconnection the patient is
hypovolemic, or "dry," and may have a
postural BP drop that will disappear
within a few hours.

22. Pathophysiology of dry weight
Plasma volume preservation during UF is
linked to the initial interstitial volume
status.
–The higher it is, the faster the
refilling
–During the session, as the patient gets
less and less volume overloaded, his
refilling capacity decreases and the
hazard of hypotension increases.

23. Pathophysiology of dry weight
Blood pressure usually remains stable
during the first two thirds of the
session.
In some patients, hypotension, rather
than being compensated by an adequate
hemodynamic response, may be
complicated by a vasovagal syncope

24. Pathophysiology of dry weight
 In fact, several factors modulate
cardiovascular compensation:
–extracorporeal temperature
–dialysate buffer
–calcium concentration.

25. Pathophysiology of dry weight
The heart's ability to compensate for an acute
volume change is:
–most important.
–impaired by reduced left ventricular
compliance, which is very common in HD
patients.
Poor LV compliance or LV function leads to poor
cardiac output thus causing hypotension

26. Assessment
of
Dry Weight

27. Assessment
Setting of accurate dry weight
Usually determined by trial and error.
The only way to clinically know:
Symptomatic development: Cramps,
hypotension, nausea.
Other measures, Blood Volume Monitoring,
bioimpedance, inferior vena cava ultrasound of
uncertain value. More studies are needed.
If the patient’s weight is below the dry weight,
need to inform the physicians to adjust the dry
weight or assess for acute/unresolved illnesses.
Any new reasons for volume depletion?

28. Assessing Dry Weight
If BP is elevated even slightly, DW is reduced
by a few hundred grams.
If, on the other hand, the patient experiences
an orthostatic hypotension that persists more
than a few hours after disconnection, then post-
dialysis weight is increased.
The trial-and-error process can be alleviated by
ambulatory BP measurement, which gives a more
objective view of the real BP than intermittent
measurements.

29. “Failure” of Dry Weight
Clinical Scenario
antihypertensive
treatment is a major
source of failure to
achieve DW .
low BP artificially
maintained by the
medication, even if
the patient is not
really "dry“.

30. “Failure” of Dry Weight
Clinical Scenario
One of the main potential problems in
achieving DW is insufficient dialysis time:
insufficient time allocated for UF.
A shorter HD session leads to more
hypertension, and at the same time
hypotension
When session time is shortened, UF rate
is increased and hypotension occur.

31. “Failure” of Dry Weight
Clinical Scenario
This has several bad effects:
The patient has a poor perception and
acceptance of HD and asks for a shorter
session.
The nurse has to cut down the UF rate or give
saline, so prescribed DW is not achieved.
The physician wrongly re-evaluates DW. Often
he prescribes a higher dialysate sodium (Na
profiling).
This, reduces the diffusive sodium drag from
the patient and leads to increased osmolality,
thirst, and interdialytic weight gain.
Consequence: the patient does not achieve DW


32. “Failure” of Dry Weight
Clinical Scenario
Another potential factor in achieving an
adequate ECV is the existence of so-
called hypotension-prone patients
Risk factors:
–left ventricular hypertrophy (LVH) and
impaired diastolic relaxation
–Poor LV function impaired cardiac
output

33. Management
of
Dry Weight

34. Which is more important?
restricting fluid
Versus
restricting sodium
on weight gain
between dialyses

35. Management of Dry Weight
Sodium intake must
be reduced to the
lowest level .
Hamburger
Ikan masin/pekasam
Belacan
Cincaluk
Budu
Chicken nuggets
Kwan Tai Restaurant

36. Management of Dry Weight
A multidisciplinary approach is needed to
educate the patient and caregivers
A low sodium diet of 2-3 gm. ,
daily fluid restriction
(30-40 oz/day or 1000 to 1200 cc/day)
is needed for the average 60 Kg patient

37. Intradialytic
Hypotension

38. Intradialytic Hypotension
Standard Definition (NKF K-DOQI)
–Decrease in SBP by ≥20mmHg or
decrease in MAP by 10mmHg
•Associated with symptoms or clinical
events to require intervention.
–Potential symptoms: Abdominal
discomfort, yawning, sighing, nausea,
vomiting, cramps, restlessness,
dizziness, anxiety.

39. Subclinical Negative Impact
Brain Ischemia: MRI have shown pathologic changes
with dialysis, worse with intradialytic hypotension
(IDH)
–Brain white matter ischemic injury from loss of
axons and myelin (McIntyre, Seminars in Dialysis,
2010)
Cardiac Stunning: Echo during dialysis confirms the
presence of LV regional wall motion abnormality
(Chesterton, Hemodialysis International, 2010)
–Episodic IDH is thought to exacerbate evolving
myocardial injury.
–Cardiac muscles receive coronary flow during
diastole and most HD patients have a widened
pulse pressure.

40. Predicting Intradialytic
Hypotension
The first line of defense against IDH:
–Pausing of ultrafiltration
–Placing the patient in a reclined
position
–Possible administration of Saline IV
Patients have individual MAP values
which remain constant when well.
–MAP=SBPx0.33+DBPx0.66
–BP1: 110/70=MAP 82;
BP2:110/45=MAP 66

41. Predicting Intradialytic
Hypotension
Decreasing MAP can precede IDH
–MAP <70mmHg or decrease by
30mmHg from pre-dialysis value
–Preventive pause in Uf for 10 minutes;
Uf resumed if MAP improved to
70mmHg or if MAP returned “close to
starting MAP.”
–This preventive maneuver reduced the
risk of IDH by 61%.

42. Prevention of Recurrent Episodes
Reassessing Dry Weight
–Trial and error
–Blood volume monitoring
–Bioimpedance spectroscopy
–Avoiding Food: Peripheral vascular
resistance drops, up to 2 hrs following
the ingestion
–BP medication adjustments

43. Acute Management
Decrease or stop the Uf rate
Patient position: Trendelenburg
with leg raised by 15-30°
Saline Bolus IV: 200-500ml usually
adequate
Oxygen to maintain end-organ
perfusion

44. As the immediate measures are taken,
evaluate for other acute problems.
Sepsis? Fever, chills, new coughs, wounds
Hemolysis? Acute back/chest/abdominal pain,
Pericardial effusion? Distant heart sounds,
pericardial rubs ,
Worsened cardiac function? Recent MI, chest
pains,
Severe AS Bleeding? Melena, CGE, BRBPR ,
Air Emboli? Dialyzer reaction? ,
Medication overdose?
Acute Management

45. Summary
Safe Uf rate is <13 ml/kg/hr.
–Remind patients to drink less liquids.
–Discuss with the patient/physician to
increase dialysis time.
Low dialysate temperature in place?
Monitor for changes in MAP.
–Pre-emptive holding of Uf for 10
minutes until MAP better?
–Saline, hypertonic saline, 20% dextrose,
albumin as per local procedures and
physician orders.

46. Summary
Na profiling: Pros vs. Cons
Uf profile review
Holding BP medications pre-
dialysis
Discuss with physicians re:
midodrine, caffeine, Zoloft
Role of Blood Volume Monitoring?
Always think of acute issues
Is Peritoneal Dialysis an option?

47. Thank you