5. Renal Anatomy & Physiology
overview .
COMPONENTS OF THE KIDNEY:
The cortex (outer layer) contains 80% of the nephrons.
These nephrons filter the blood continuously to maintain
balance.
The medulla(inner layer) contains 20% of the nephrons.
These nephrons also filter the blood, but have the added
responsibility to concentrate urine. This becomes an
important diagnostic tool.
The renal pelvis is the start of the collecting system,
containing the collecting tubules and the ureter.
Additionally,ureters carry urine into the bladder where it
is stored until it is eliminatedfrom the body through the
urethra.
6. Renal Anatomy & Physiology
overview .
KIDNEY FUNCTIONS is A WET BED :
A : Acid Base Balance .
W : water (fluid over load removal).
E : Electrolyte Balance .
T : Toxin Removal (BUN , CREAT).
B : Blood Pressure stabilizing .
E : Erythropoietin production .
D : Vitamin D metabolism .
7. Renal Anatomy & Physiology
overview .
The kidney is capable of maintainingthe body’s
equilibrium until about 50% of the nephrons are
damaged .
After 50% loss of kidney function, the body begins
to make trade-offs to maintain homeostasis. For
example, parathyroid hormone (PTH) increases to
compensate for increased excretion of
phosphorus. The patient will likelyremain
asymptomatic .
After 90% loss of kidney function, some form of
renal replacement therapy is necessary to preserve
life .
10. Renal Anatomy & Physiology
overview .
The glomerulus consists of a
group of cells with selective
permeability. It is a semi-
permeable membrane.
Selectivepermeabilitymeans
that certain substances will cross
the membrane and others will
not be allowedto cross. Through
selectivepermeability, the
kidney regulates fluid and
electrolyte balance. The tea
filter is a sample of a membrane
with selective permeability
11. Renal Anatomy & Physiology
overview .
The kidneys produce approximately 180 liters of filtrate
per day. Only 1.5 - 2 liters are excreted as urine. The
remaining 178 liters remain in the body. This is simply
recycled body water.
The afferent arteriole has a larger lumen than the
efferent arteriole. Therefore, blood flows into the
glomerulus faster than it flows out, which creates by
gravity a pooling of blood in the Bowman’s capsule
which cause a pressure called hydrostatic pressure .
Hydrostatic pressure on the blood will force fluid to cross
the glomerular membrane and enter the tubules. This is
ultrafiltration.
As filtrate flows through the tubular network, special cells
will respond to the need for reabsorption and secretion.
12. Renal Anatomy & Physiology
overview .
The end product of this filtrate is urine. In the
normal kidney, this urine will be the right color,
have the right osmolality and contain the right
substances.
Osmolality is used because it measures
particles independently of their molecular
weight. Substances including urea, creatinine,
phosphorus, potassium acids etc. are cleaned
and filtered to keep the blood values normal.
13. Renal Anatomy & Physiology
overview .
The kidneys also produce
hormones like renin, vitamin D
and erythropoietin. Renin
promotes sodium retention
and it also causes
vasoconstriction. Vitamin D
stimulates calcium and
phosphate absorption.
Erythropoietin promotes
production of red blood cells
in the bone marrow .
15. Continuous Renal Replacement Therapy (CRRT)
CRRT is the blanket term which encompasses all
continuous therapies. It has been defined as , Is an
extracorporeal blood purification therapy intended to
substitute for impaired renal function over an extended
period of time and applied for or aimed at being applied
for 24 hours a day , in the critically ill patient. It allows for
slow and isotonic fluid removal that results in better
hemodynamic tolerance even in unstable patients with
shock and severe fluid overload. This process can be
applied to both adults and children.
16. HISTORY OF CRRT
‘The history of CRRT is relatively short. Its beginning was in 1977 when
Kramer, while introducing a catheter into the femoral veinbefore
hemodialysis, accidentally inserted the catheter into the femoral artery. He
realized the possibility of using the arteriovenous gradient for filtration of
blood and fluid elimination. He replaced the excessivelosses by
continuous infusion of substituting solutions. He used for the method the
term continuous arteriovenous hemofiltration(CAVH). This was the first step
in CRRT.’2 Over the past thirty years CRRT has continuedto develop and
has emerged as a front line therapy for treatment of criticallyill patients
with acute renal failure.
17. CRRT GOALS
The main goals are to:
1. Mimic the functions and physiology of the native kidney .
2. Restore and maintain hemodynamic stability.
3. Avoid complications while achieving good clinical
tolerance.
4. Provide conditions that favor renal recovery.
18. CRRT GOALS
Removal of waste products .
Restoration of acid-base balance .
Correction of electrolyte abnormalities.
Hemodynamic stabilization .
Fluid balance .
Nutritional support .
Removal and/or modulation of septic mediators .
19. Renal indication of CRRT
AKI with oliguria or Anuria .
Azotemia ( medical conditioncharacterized by
abnormal levels of urea , creatinine , various body waste
compounds ,and other nitrogen rich compounds in the
blood as a result of insufficient filteringof the body by the
kidneys ) .
Fluid Overload.
Lysis syndrome .
Sepsis .
Cerebral edema .
21. Role of CRRT in AKI
Removal of toxins ( urea , creatinine ) .
Regulate electrolyte and waterbalance .
Regulate acid base balance .
Prevent further damage to the kidney tissue .
Promotehealing and kidney recovery .
22. Role of CRRT in CHF
Maintain 24/7 fluid balance ( all CRRT therapies )
- reduce ascites and peripheral edema.
- relieve pulmonary edema.
Normalize cardiac filling pressures .
Maintain 24/7 electrolyte and acid/base balance (CVVHD /
CVVHDF).
- dialytic control of electrolyte .
- delivery of lactate and bicarbonate buffer .
23. Role of CRRT in ARDS
Maintain acid base balance .
Fluid control.
Regulate electrolyte balance .
Removal of toxins .
24. Role of CRRT in sepsis
Removal of middle to large septic mediator by convection
and adsorption including TNF-@ , IL-1 , IL-6 , IL-8 though :
I. Removal of excess fluid and waste product .
II. Maintenance of acid base balance .
III. Improve cardiovascularhemodynamic ------ removal of
cardio depressents ( caused by inflammatory mediators)
IV. Thermoregulation.
25. Role of CRRT in
Rhabdomyolysis
Maintenance of acid base balance .
Regulate electrolyte balance .
Prevent further damage to kidney tissues .
Removal of small to middle protein molecules
17000 Daltons through convection .
Example of
reduction of
pigmentation in
ultrafiltration
and
convection
over3 days of
CRRT
28. DIFFUSION
Diffusion is the movementof solutes through a semi-permeable
membrane from an area of higher concentration to an area of
lower concentrationuntil equilibrium has been established.
• Rate of diffusion is dependent on:
surface area of filter
ratio of dialysate flow to blood flow
size of the solute
31. CONVECTION
Convectionis the one-way movement of solutes through a
semi-permeable membrane with a water flow. Sometimes it is
referred to as solvent drag.
Efficient for both larger and smaller molecules.
34. ULTRAFILTRATION
Ultrafiltration is the movementof fluid through a semi-
permeable membrane along a pressure gradient.
The pressure gradient in the extracorporeal circuit is created by
positive,negative,or oncotic pressure from non-permeable
solutes. For our purposes, ultrafiltration results in removal of fluid
(plasma water)from the patient’s blood. The fluid that is
removed is sometimes referred to as “UF”.
37. ADSORPTION
As you can see withour cups in the next slide , a semi
permeable membrane separates a concentrated solution from
a solution with no solute. In this diagram, very little solute
actually passes through the membrane, instead, it adheres to
the membrane. Movement of fluid is required for adsorption to
occur. Not all membranes possess this adsorptivequality and it
is necessary to identify specific properties of the membrane
and target molecules in order to predict whetheradsorption
willplay a role in the clearance of a specific substance.
39. ADSORPTION
Adsorption is the final transport mechanism that we will
have to tackle. With adsorption, molecules are
removed from the blood by adhering to either the
surface of the membrane or become trapped inside of
the membrane.
This mechanism is used in:
• SCUF .
• CVVH .
• CVVHD or CVVHD with ultrafiltration .
• CVVHDF.
44. SLOW CONTINUOUS ULTRAFILTRATION (SCUF)
SCUF (slow continuous ultrafiltration) when using this
therapy, significant amounts of fluid are removed from
the patient. No dialysate or replacement fluid is used
because solute control is not a goal of this therapy.
Ultrafiltration can be adjusted to cause dramatic fluid
shifts. SCUF treatment utilize UFR’s of up to 2L/hr in some
cases. The only pumps needed for this therapy is a blood
pump and an effluent pump.
45. SLOW CONTINUOUS ULTRAFILTRATION (SCUF)
• Primary Goal
Safe management of fluid removal.
Large fluid removal via ultrafiltration.
Transport mechanism: Ultrafiltration.
The pressure gradient in the extracorporeal circuit is created by
positive, negative, or oncotic pressure from non-permeable solutes.
For our purposes, ultrafiltrationresults in removal of fluid(plasma water)
from the patient’s blood. The fluidthat is removedis sometimes
referred to as “Ultrafiltrate or UF”.
46. SLOW CONTINUOUS ULTRAFILTRATION
(SCUF)
High flux membrane .
Blood flow 100-200 ml/min .
No dialysis fluid used .
No replacement solution used .
Can achieve up to 2000ml/hour of
fluid removal .
Maximum remove 10000ml / day .
Can be done up to 24 hours .
typically UF rate 2-8 ml/min.
For volumeand fluid overload
control only .
Access
Return
Effluent
P
R
I
S
M
A
47. CONTINUOUS VENO-VENOUS
HEMOFILTRATION (CVVH)
CVVH (continuous veno-venous hemofiltration) aims for
maximizing convective removal of middle to large
molecules. Replacement solutions are used to drive
convective transport. When performing CVVH the
following pumps are used: The blood pump,
replacement pump and the effluent pump.
Transport Mechanism: Convection
48. CONTINUOUS VENO-VENOUS
HEMOFILTRATION (CVVH)
Transport Mechanism: Convection
• Removal of solutes, especiallymiddle and large molecules, by
convection of relatively large volumes of fluidand simultaneous.
• This transport mechanism is used:
CVVH.
CVVHDF.
Convection is a transport mechanism that we see only in CVVH and CVVHDF. The
replacement solution is infused into the blood.Whether it is infused pre-filter or post-filter
the solution mixes with the blood.The premise is to move solutes with fluid, referred to as
a “solvent drag”. Plasma water and certain solutes depending on the molecular weight
are forced across the membrane.
49. CONTINUOUS VENO-VENOUS
HEMOFILTRATION (CVVH) Access
Return
Effluent
Replacement
P
P
R
I
S
M
A
High flux membrane .
Blood flow 100-200 ml/min .
No dialysis fluid used .
Replacement solution used .
Replacement fluid rate500-2000 ml/hr .
Can achieve up to 4000ml/hour of fluid
removal.
Can be done up to days /weeks .
UF rate 10-60 ml/min .
50. CONTINUOUS VENO-VENOUS
HEMODIALYSIS (CVVHD)
CVVHD (continuous veno-venous hemodialysis) is a
therapy that uses dialysate solution on the fluid side of
the filter to increase solute exchange by diffusion.
Replacement solution is not required for this therapy.
The pumps required for this therapy are as follows:
Blood, dialysate and effluent pump. Plasma water and
solutes are removed by diffusion and ultrafiltration.
51. CONTINUOUS VENO-VENOUS
HEMODIALYSIS (CVVHD)
Transport Mechanisms: Diffusion .
• Removal of small moleculesby diffusion through the addition
of dialysate to the fluidside of the filter.
• Dialysate is used to create a concentration gradient across a
semi permeable membrane
• Dialysis uses a semi permeable membrane for selected
diffusion
• This transport mechanism is used in:
CVVHD
CVVHDF
52. CONTINUOUS VENO-VENOUS
HEMODIALYSIS (CVVHD)
Dialytic therapies use a semi permeable membrane (the
filter) through which solutes diffuse selectively, based on
particle size, as blood passes through the filter. Solutes are
defined as any substance that dissolves in a liquid to form
a solution. Solutes removed by diffusion during CRRT might
be waste products, electrolytes, buffers, etc.
54. CONTINUOUS VENO-VENOUS
HEMODIAFILTRATION (CVVHDF)
CVVHDF (continuous veno-venous hemodiafiltration)
combines the benefits of CVVH and CVVHD using both
convective and diffusive transport mechanisms.
Replacement and dialysate fluids are both employed.
The pumps required for this therapy are as follows: A
blood, dialysate, replacement and effluent pumps.
Transport Mechanisms: Diffusion and Convection .
55. CONTINUOUS VENO-VENOUS
HEMODIAFILTRATION (CVVHDF)
The use of both diffusion and convection transport
mechanism create a therapy called hemodiafiltration.
This specific therapy combines dialysate solution to create
diffusive clearance of small molecules, and replacement
solution to create convective clearance of middle to
large molecules.
• Removal of small molecules by diffusion through the
addition of dialysate solution.
• Removal of middle to large molecules by convection
through the addition of replacement solution.
58. CRRT clearance
CRRT solute clearance is dependent on the following:
The size of the molecule and the pore size of the semi-
permeable membrane. The best way to drive solute
clearance is to increase the ultrafiltration removal /
higher substitution fluid rate ( combination of
replacement solution and patient plasma water).
59. CRRT clearance
Remember the transport of a molecule through a membrane is
governedlargely by its molecular weight. Generally, the more a
moleculeweighs, the larger it is in size and the more resistant it is to
transport.
Molecular weights are measuredin units calledDaltons.
Small molecules <300 Daltons, e.g. urea, creatinine, Na+, electrolytes .
Intermediate or middle molecules 500-5000 Daltons e.g. B12 .
Large molecules 5000-50000 Daltons e.g. LMW proteins, beta 2 micro
globulins, cytokines, myoglobin .
60. CRRT clearance
Molecular size: Both molecule size
and pore size determine the solute
flow through the semi-permeable
membrane. As you can see from
this picture we have a membrane
with small pores. The yellow
moleculerepresent Urea molecules,
which are considered small size
molecules. The blue molecules
represents cytokine molecules,
which are considereda middle size
molecules. The (yellow molecule)
Urea easily passes through the small
pores, but the (blue molecule)
Cytokines are to large to move
across the membrane therefore they
remain in the blood.
61. CRRT clearance
This picture depicts a
membrane that has large
pore size. As you can see
from this picture we have a
membrane with large pores.
Again, we willsay the pink
molecule represent Urea
molecules, and the blue
molecules represent a TNF
molecules. The Urea easily
passes through the large
pores, and the TNF also
move across the membrane
therefore they are removed
from the blood.
62. CRRT clearance
Now that you have an
understanding of
molecular size and
membrane porosity let me
introduce to you sieving
co-efficient. Sieving
coefficient is defined as
the ability of a substance
to pass through a
membrane from the blood
compartment of the
hemofilter to the filter side
of the hemofilter.
63. CRRT clearance
Solutes witha sieving coefficient
of 1 means 100% movement of
that solute moves across the
membrane, but a coefficient of
0 the solute is unable to pass
through the membrane at all.
For example, the sieving
coefficient of potassium is 1,
meaning that 100% of it willcross
the membrane. The sieving
coefficient of Albumin is 0,
meaning it is unable to move
across the membrane because
of its large size.
64. CRRT clearance
A sieving coefficient of 1 will
allow free passage of a
substance; but at a
coefficient of 0, the
substance is unable to pass.
• .94 Na+
• 1.0 K+
• 1.0 Cr
• 0 albumin will not pass
67. Vascular access
A patient will need a veno-
venous double lumen
catheter or two single lumen
venous hemodialysis
catheter. One side of the
lumen will deliver blood from
the patient to the filter, and
the other lumen will return
the blood back from the
filter to the patient.
68. Vascular access(Access Location)
There are three access locations that are
used some may be preferred over others .
• Internal Jugular Vein
Primary site of choice due to lower
associatedrisk of complication and
simplicity of catheter insertion.
• Femoral Vein
Patient immobilized, the femoral vein is
optimal and constitutes the easiest site
for insertion.
• Subclavin Vein
The least preferred site given its higher risk
of pneumo/hemothorax and its
association with central venous stenosis.
70. Choosing the right catheter
Choosing the right catheter is another important
aspect to be considered.. The catheter length will
depend on the site used. Pediatric of course will
need to be assessed for an appropriate size
catheter.
• The following are suggested guidelines for the different
sites:
RIJ= 15 cm French .
LIJ= 20 cm French .
Rt Sub.C 15 cm French.
Lt Sub.C 20 cm French
Both Femoral= 25 cm French .
71. Membrane types and characteristics
Membrane types and characteristics are other
important technical considerations.
Hemofilters are composedof a membrane
that consists of high flux material (porous). The
membrane material is usually synthetic,but
very biocompatible to the patient.
Here are a few examples of high-flux
membrane material:
Polysulfone (PS) , Polyamide (PA)
Polyacrylonitrile ( PAN)
The structural design of a high flux membrane
is characterized by high fluidremoval and
typicallyhas a molecular cut-off weight of
55,000 Daltons.
72. Semi-permeable Membrane
The hemofilter contains a semi-
permeable membrane that provides
an interface between the blood and
dialysate compartment. This
interface creates a barrier so that the
blood and dialysate never come in
contact with each. Biocompatibility
is an important feature, because the
membrane’s chemical properties
minimize blood’s reaction I.e.
thrombocytes and/or complement
activation and immunesystem
response (allergic reaction).
73. Complications During CRRT
A common complicationencountered during CRRT is vascular
access. There are many reasons why a catheter may not be
functioning properly during CRRT treatment. Here are only a few
reasons a catheter may not be functioning:
Vascular spasm caused by initial BFR being too high. The easiest way
to remedy this complication is to decrease the blood flow rate.
Catheter’s proximal or distal port opening move against the vessel
wall impeding blood flow. This can sometimes be alleviated by
repositioning the patient, or having the doctor repositionthe
catheter.
Improper placement, or length of the catheter .
74. Complications During CRRT
Fluid volume deficit may also occur during CRRT if the patient’s I/O
status is not monitoredclosely and regularly. A fluidvolume deficit
may lead to hypotension and compromise patient safety.
Intravascular volume depletion (fluidvolume deficit) can lead to
hypotension. It is important to monitor I/O data to make sure the
patient is hemodynamically stable. If hypotension occurs during
treatment, the patient fluidremoval shouldbe decreased and
sometimes placed at zero. A full assessment of the reasons for the
hypotensionshouldbe addressed: loss of blood, increased urinary
output, or fluid status has normalized.
75. Complications During CRRT
Electrolyte imbalances , Patient electrolytes can become
imbalancedfor many reasons. A goal of CRRT is to balance
electrolytes, however sometimes high ultrafiltration rates can disturb
the delicate balance of electrolytes, therefore it is important to
monitor and replenish electrolytes and bicarbonate. It is
recommended the nurse and MD monitor lab values closely and
regularly, with the MD making adjustments to dialysate or
replacement solution accordingly.
76. Complications During CRRT
Acid/base imbalance (Renal dysfunction ,Respiratory
compromise) : Just as with electrolyte imbalance, acid/base
balance is another aspect to monitor closely. The physician and
the nurse must identify whether acid/base imbalance is due to
renal dysfunction or due to respiratory compromise.
77. Complications During CRRT
Blood loss : during CRRT can and will occur due to ineffective
anticoagulation therapy causing the hemofilterto clot. Once
the filter is clotted the blood is not returned to the patient. Keep
in mind when a system clots the patient can loss anywhere from
93 cc to 189 cc depending on the hemofilter set. Other reasons
for blood loss could be due to over-anticoagulation so clotting
parameters should be monitored closely. Inadvertent
disconnection in the CRRT system could potentially happen if
the connection between the catheter and set is not tight.
78. Complications During CRRT
Air embolus (Leaks or faulty connections in tubing ,Line
separation).
All CRRT monitors on the market have an air detector so if by
chance air enter the circuit the air detectorwould detect the
air causing the treatmentto be suspended. Leaks/faulty
connections, or line separation could potentially happen after
the air detector allowing air to enter the patient. In this case
the nurse would initiate interventions of positioning the patient
on their left side or in Trendelenburg position.
79. Complications During CRRT
• Cardiac arrest (Hypotension/hypertension ,Hemolysis,Air
embolism,Circulatory overload,Arrhythmias).
As we have discussed, CRRT treats a varietyof conditions
from fluid overload to electrolyte imbalance, which could
inadvertently cause cardiac arrhythmias. Monitoring
cardiac status is important at all times to avoidcardiac
arrest. Other reasons for cardiac arrest maybe hemolysis, air
embolism, circulatory overload and arrhythmias.
80. Clinical Conditions to Consider
There are many clinical conditions we see everyday in
practice that perhaps could be considered for CRRT.
The main point of patient consideration is: DON’T WAIT TOO
LONG!! CRRT is indicated for the treatment of Acute Renal
Failure and Fluid Management. Think of your body of patients
that you work with on a daily basis and let’s discuss how those
patients might be considered for CRRT.
81. Clinical Conditions to Consider
Examples: Post cardiovascular Surgery, Pulmonary
Edema/CHF, Organ Transplants, SIRS, Trauma, Burns (Thanks to
improved Emergency Management of fluids, a very small
percentage of these patients actually develop acute renal
failure), or generally, patients that need fluid/electrolyte/acid
base control.
82. Hypothermia in CRRT
The patient’s blood is exposed to room temperature as it
circulates through the extracorporeal circuit. Additionally,fluids
(replacement fluid and/or dialysate) infused at room
temperature may be administered, often in volumes of 2-4 liters
per hour.
As a result, the patient may show signs and symptoms of
decreased body temperature. As you know, this can be
reflected in the patient by hemodynamic instability, chilling
and shaking, as well as skin pallor, coolness, and cyanosis.
83. Hypothermia in CRRT
You can choose to warm the patient eitherwith the use of
warming blankets or the CRRT machine warmer .
The Machine Blood Warmer and have been designed to
replace heat to return blood flow, which was lost to the
atmosphere and effluent flow during a System treatment.
84. Replacement Fluids(substitution
/Dialysate fluid)
Physicians will always prescribe replacement solutionaccording to
patients clinical needs. Along with the replacement solution
prescription the physician will indicate the route of administration
whether it is to be delivered pre blood pump, pre-filter or post-filter.
Replacement solutions are sterile and labeled for IV use.
Replacement solutions usually contain electrolytes and a buffer
similar to plasma values.
• Sterile replacement solutions may be:
Bicarbonate-based or Lactate-based solutions
Electrolyte solutions
Must be sterile and labeled for IV Use
Higher rates increase convective clearances
85. Replacement Fluids(substitution
/Dialysate fluid)
solution is a clear, sterile solution free of bacterial endotoxins.
This solution is used in Continuous Renal Replacement Therapies
(CRRT) as a replacement solution in hemofiltration and
hemodiafiltration.
The physician will also prescribe the dialysatecomposition as
wellas the deliveryflow rates. Dialysate solution usually reflect
normal plasma values. Through diffusion dialysate solution
corrects underlying metabolic problems.
86. Replacement Fluids(substitution
/Dialysate fluid)
Today, there are two main buffers lactate and bicarbonate available
in commercial solutions to administer during CRRT. At one time
lactate-based solutions were predominately used with CRRT, because
of its stability. The lactate in a dialysate or replacement solution must
be metabolized into bicarbonate and this process takes place in the
liver. The liver converts lactate on a 1:1 basis to bicarbonate. This can
sufficiently correct acidemia, but there are clinical conditions that
influence the use of this buffer.
87. Replacement Fluids(substitution
/Dialysate fluid)
Lactate based solution has a pH value of 5.4, which could worsen
acidosis. Lactate is a powerful peripheral vasodilator, that affects
myocardial contractility and inadvertently reduces blood pressure.
Lactate administration can further compromise a patient who is
already experiencing hypoxia, liver impairment, and can cause
lactic acidemia.
Now let’s take a look at a more physiologicbuffer. Bicarbonate
solution is quickly becoming the solution of choice….
88. Replacement Fluids(substitution
/Dialysate fluid)
Bicarbonate Based Solution :As I prefaced, bicarbonate
is fast becoming the buffer of choice, because of its
physiologic nature and the immediate replacement of
lost bicarbonate ions. This solution is a great tool to
correct acidosis within a 24-48 hours, and additionally
improves hemodynamic stability, resulting in fewer
cardiovascular events.
89. Replacement Fluids(substitution
/Dialysate fluid)
Bicarbonate solution is the preferred buffer for
patients with compromised liver function.
Bicarbonate also offers stabilizationin a varietyof
areas. The patient’s mean arterial pressure
remains stable, and bicarbonate normalizes
acidosis without the risk of alkalosis. It also allows
the patient to remain hemodynamically stable
and have fewer cardiovascular events.
91. Replacement Fluids(substitution
/Dialysate fluid)
Replacement Fluid
provides the physician
with a range of choices
in response to each
patient’s specific
condition. Available in
seven formulas varying
in calcium, potassium,
bicarbonate
and dextrose levels.
92. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Sodium
Should be in the physiologic range (140 Meq⁄l ).
CVVHDF is more likely to achieve serum sodium
concentrations within the normal range than CVVH .
Supra physiological sodium concentration in the
dialysate or replacement solutions would improve the
hemodynamic stability or prevent the increase in
intracranial pressure, but there are no conclusive data
concerning this issue.
93. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Potassium
K concentrations between 0 to 4 meq⁄ l are acceptable
and commercially available.
Most patients have a degree of hyperkalemia at
initiation of RRT therapy.
If K free fluid is used, careful monitoring is necessary.
In cases of severe hyperkalemia associated with
arrhythmia and⁄or hemodynamic collapse hemodialysis
should be utilized.
94. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Calcium
About 60% of total plasmacalcium is ultrafilterable,
substitution fluid in CVVH must contain about 3 mEq/l of
calcium.
Patients undergoing an exchange of very large volumes
of ultrafiltrate carry the risk of hypercalcemia, therefore
may require a lower content of calcium in replacement
fluids.
Calcium is always absent from solutions when
phosphate is present .
During citrate anticoagulation, if calcium is present in
the fluidit will neutralize the citrate before it can do its
job of keeping the filter free of clots
95. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Magnesium
Mg in CRRT fluids ranges between 1 and 1.5 meq ⁄
l. This levelis not well studied but has been
clinically successful .
A bolus of 2–4 g should be prescribed when Mg
levels fall below normal range.
96. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Phosphorus
Phosphorus is not a standard component of replacement
or dialysate fluids in CRRT. This is appropriate as CRRT is
commonly employed in the settingof hyperphosphatemia
• Majority of patients on CRRT will require phosphate
supplementation shortly after CRRT initiation.
• Critically illpatients present several conditions predisposing
hypophosphatemia .
Management of hypophosphatemia:
- Ensure proper nutrition.
- Add Po4 to the solutions .
- Use Phosphate-containingready solutions .
97. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Glucose
Physiologic concentrations of glucose in the dialysate and
replacement fluids is advised to compensate
extracorporeal losses .
Glucose-free solutions might be used when an adequate
nutritional regimen has been established .
Lactate
The simplest, most economical solution; no mixing required.
Effectiveness is well-supported in clinical literature.
Many adults are successfully treated with CVVH using
Lactated Ringer's solution as it is:
- convenient .
- cheap.
- eliminates risk of pharmacy error.
98. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Lactate
Patients with severe liver failure, and particularly those with reduced
muscleblood flow, may fail to metaboliselactate and develop a
metabolic acidosis.
In ICU patients suffering from multiple organ dysfunction, the
conversion of lactate to bicarbonate is frequently impaired
Lactic acidosis causes cardiac dysfunction and hypotension
Many fluids contain a small, clinicallyinsignificant amount of lactate
to improve stability
99. Replacement Fluids(substitution
/Dialysate, fluid Composition )
Albumin
Can be added in dialysate to remove protein bound
medications in the setting of intoxication as well as
substances such bilirubin
101. Anticoagulation in CRRT
Why do we change filters? Is everything related
to clotted filters? .
Why do filters/circuitsclot? .
Various Anticoagulants available .
Is there a single best anticoagulant? .
Available evidence .
Anticoagulationin specific circumstances – Liver
patients.
105. Ideal Anticoagulation
Selectively active in the circuit – minimal effects on
patient hemostasis
Readily available
Consistently delivered(protocols)
Safe (?)
Easy, rapid monitoring and reversible
Prolonged filter life
Cost Effective
Uncomplicated ,easy to follow protocols- Staff
training
107. Heparin
Heparin is a sulfatedpolysaccharide with a molecular
weight range of 3000 to 30 000 Da (mean, 15 000 Da).
It produces its major anticoagulant effect by inactivating
thrombin and activatedfactor X (factor Xa) through an
antithrombin (AT)-dependent mechanism.
Antithrombin (AT) is a small protein molecule that
inactivates several enzymes of the coagulation system.
Its activity is increasedmanifoldby
the anticoagulant drug heparin, which enhances the
binding of antithrombinto factor II and factor X.
109. Heparin Protocol
Heparin infusion prior to filter with post filter ACT
measurement and heparin adjustment based upon
parameters .
Bolus with 10-20 units/kg – Not always .
Infuse heparin at 10-20 units/kg/hr .
Adjust post filter ACT 180-200 secs .
Interval of checking is local standard and varies from 1-4
hr increments.
111. Heparin – Side Effects
Lipids: Heparin activates lipoprotein lipase, and in this
way can increase the serum triglyceride concentration.
Lower levels of high-density lipoprotein (HDL) cholesterol
also are associatedwith heparin use. Both lipid
abnormalities are improved when using low molecular
weight heparin.
Pruritus: Heparin can cause local itching when injected
subcutaneously,and may cause itching during dialysis.
There is no evidence that removal of heparin from the
extracorporeal circuit reliably improves uremicpruritus .
112. Heparin – Side Effects
Hyperkalemia: heparin-induced suppression of
aldosterone synthesis from adrenal cortex( act on
kidney to regulate K&Na and water balance),
aldosterone might still aid potassium excretion via
GIT mechanism. LMWH may improve the
aldosterone/ plasma renin activity ratio and result
in slight improvement of hyperkalemia in dialysis
patients.
Osteoporosis : Long-term administrationof heparin
can cause osteoporosis.
113. Heparin – Side Effects
1. Anaphylactic reactions to bolus of LMWH so
called first-use syndrome has been reported
with both UFH& LMWH.
2. Bleeding complications: patients being treated
with LMWH who are also receiving clopidogrel
and aspirin, bleeding complications have been
reported.
114. Clotting tests used to monitor heparin
therapy
1. Activated partial thromboplastin time (APTT).
This is for unfractionatedheparin monitoring only..
2. Whole-blood partial thromboplastin time (WBPTT).
3 . Activated clotting time (ACT) which is the easiest one ,
lees time consumed ,bed side used .
The ACT test is similar to the WBPTT test but uses siliceous
earth to accelerate the clotting process. It is for
unfractionatedheparin monitoring only. ACT post filter
target must be around 180-200 sec .
4. Lee-White clotting time (LWCT).
118. CRRT for Pediatrics
Indications for RRT in children .
Type of RRT – PD vs. HD vs. CRRT .
Prescription of CRRT for pediatric patients
Vascular access (covered).
Priming the machine .
Anticoagulation (Covred) .
Blood flow rates (Covered).
Clearance (Covered).
Net ultrafiltration goals (Covered) .
119. Indications for CRRT in the ICU
A -- Alkalosis or Acidosis ( metabolic)
E -- Electrolyte disturbances
-- Hyperkalemia
-- hypocalcemia
-- Hypernatremia
-- hypercalcemia
-- Hyperphosphatemia
-- hyperuricemia
T -- Intoxication with a drug that can be dialyzed
W -- Overload of Fluids ( H20 retention)
-- Pulmonary edema or hypertension
U -- Uremia - Not azotemia which can be secondary to
steroids, bleeding .
-- CNS encephalopathy, vomiting, pericarditis .
121. Pediatrics AKI
Definition
Stage Serum Creatinine Criteria UOP criteria
1 ↑ SCr of ≥0.3 mg/dl or
↑ SCr to 150-199% of baseline
UOP > 0.5 cc/kg/hr
and
≤ 1 cc/kg/hr
2 ↑ SCr to 200%-299% x baseline UOP > 0.1 cc/kg/hr
and
≤ 0.5 cc/kg/hr
3 ↑ SCr to ≥ 300% of baseline or
SCr ≥ 2.5 mg/dl or Receipt of dialysis
UOP ≤ 0.1 cc/kg/hr
Baseline SCr will be defined as the lowest previous SCr value
No Major Congenital Anomalies of the Kidney and Urinary Tract
127. Vascular Access for CRRT
:
Put in the largest and shortest catheter
when possible .
• The following are suggested guidelines for the
different sites:
RIJ= 15 cm French .
LIJ= 20 cm French .
Rt Sub.C 15 cm French.
Lt Sub.C 20 cm French
Both Femoral= 25 cm French .
A 7 or 8 F catheter may not fit in the femoral
vein for pediatrics .
131. References
Handbook of Dialysis, Fifth edition, John T. Daugirdas, Peter G.
Blake, Todd S. Ing .
Continuous renal replacement therapy in critically ill patients.
Ronco C, Bellomo R, Ricci Z.
THE NATIONAL KIDNEY FOUNDATION KIDNEY DISEASE
OUTCOMES QUALITY INITIATIVE (NKF KDOQI ™
) (2015) .
Renal replacement therapy in the intensive care unit ,Neesh
Pannu and RT Noel Gibney .
Polaschegg, HD. Mechanical Aspects of Dialysis; The
Extracorporeal Circuit. Seminars in Dialysis Vol. 8, No 5 (Sep-Oct)
1996 pp 299-304.
20th International Conference on Advances in Critical Care
Nephrology .
132. Knowledge is having the right
answer . Intelligence is asking
the right question !
133. This presentation prepared by :
Ashraf Z.Qotmosh.
BSN , RN , HN .
Regional InfectionControl Nursing Specialist .
Diaverum AB Branch –Saudi Arabia .
SA Mob : +966546429551
PS Mob : +970598151329
A.Qotmed@outlook.com
Ashraf.Qotmosh@diaverum.com
