GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
TARGET AUDIENCE
ICU Nursing Staff
ICU Medical Staff
PURPOSE
This guideline describes the medical & nursing management of patients receiving renal replacement
therapy as a patient in the Intensive Care Unit (ICU).
If the patient is simultaneously receiving ECMO, the ECMO guideline should also be consulted.
This guideline does NOT describe the management of patient receiving:
Hepatic Support using the MARS therapy, OR
Plasma Exchange using the Prismaflex TPE therapy, OR
Charcoal Filtration using the Prismaflex.
GUIDELINE
This guideline should be read in conjunction with the
Bayside Clinical Care Standards Policy
Mutual Obligations for Patient Safety & Quality of Services at Bayside Health
[ICU] CRRT Initial Settings CRRT Initial settings.pdf
[ICU] Anticoagulation in CRRT (Heparin) CRRT Anticoagulation (Heparin).pdf
[ICU] Anticoagulation in CRRT (Citrate) CRRT Regional Anticoagulation (Citrate).pdf
[Drug Guideline] LEPIRUDIN INFUSION Lepirudin.pdf
[ICU] Recirculation procedure on the Prismaflex CRRT Recirculation on the PrismaFlex.pdf
REFERENCES (In APA citation style - for style see:
http://www2.liu.edu/cwis/cwp/library/workshop/citapa.htm)
Need to add references
KEYWORDS
Continuous Renal Replacement Therapy (CRRT)
CVVHDF
CVVH
CVVHD
AUTHOR / CONTRIBUTORS
* denotes key contact
Name
*Nat Adams
Geik Lim
Bianca Levkovich
Dr Owen Roodenburg
Dr Ashley Crosswell
ICU Nurses
Position
ICU Clinical Nurse Educator
ICU Clinical Nurse Specialist
Clinical Pharmacist
ICU Consultant
ICU Registrar
ICU Renal Special Interest Group
Service / Program
Need to populate footer
Endorsed by:
Name/Title:
Date:
Approved by:
Name/Title:
Date:
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
Disclaimer: This guideline has been developed within the context of Alfred Health service delivery. Alfred Health shall not be responsible
for the use of any information contained in this document by another organisation outside of Alfred Health.
CONTENTS
1.
Indications for Continuous Renal Replacement Therapy (CRRT)..……………………..
3
2.
Establishing Vascular Access for CRRT ......................................................................
4
3.
“Heparin-lock” for Vascular Access …................................................................. …….
5
4.
Commencing CRRT using Prismaflex… ............................................................. …….
6
4.1
Priming Equipment........................................................................................................
6
4.2
Priming Fluid ................................................................................................................
6
4.3
Priming Machine ..........................................................................................................
6
4.4
Attaching Machine to the Patient (via vascath) ............................................................
7
4.5
Settings for CRRT using Prismaflex (non-citrate)........................................................
9
4.6
Disconnecting from Prismaflex .....................................................................................
10
4.7
Recirculation on Prismaflex………………………………………………………………….
12
5.
Anticoagulation for CRRT..............................................................................................
12
5.1
General Anticoagulation Rules .....................................................................................
12
5.2
Monitoring and Adjusting Anticoagulation in CRRT……………………………………….
14
6.
Nursing Management of Patient on CRRT using Prismaflex……….……………………
15
6.1
Nursing Management - Cannula (vascath)…………………………………………………
15
6.2
Nursing Management - Machine (Prismaflex)……………………………………………..
15
6.3
Nursing Management - Circuit………............................................................................
15
6.4
Nursing Management - Patient…………………………………………………………..….
16
6.5
Nursing Management - Documentation ……………………………………………………
16
6.6
Nursing Management - Troubleshooting ………………………………………….………
16
6.7
Nursing Management - Waste management & safety……………………………………
16
7.0
Management of Renal Replacement Therapy (CRRT)................................................
17
7.1
Management of Patient‟s Electrolytes..........................................................................
17
7.1.1 Calculating potassium chloride concentration in CRRT 5L fluid bags………………….
17
7.2
Management of Patient‟s Fluid Balance.......................................................................
18
7.3
Management of Patient‟s Acid-Base Balance..............................................................
18
7.4
Management of Patient‟s Toxin Removal.....................................................................
19
Appendix 1: Glossary of Terms Used with CRRT ...............................................................
20
Appendix 2: Prismaflex Controls...........................................................................................
25
Appendix 3: Molecular Weights ...........................................................................................
26
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
1. Indications for Continuous Renal Replacement Therapy
1.1 Primary goal of CRRT
To compensate for loss of renal function, & correct its associated sequelae, including:




Accumulation of nitrogenous waste products
Electrolyte disturbance
Metabolic acidosis
Volume overload
1.2 Indications for commencing CRRT
Currently there is no measurable parameter, or marker of renal function that mandates
commencement of CRRT. Instead, CRRT may be initiated to treat the adverse sequelae
mentioned above. A reasonable, but by no means exclusive approach would be:





Development of uraemic signs or symptoms
Management of fluid overload
Electrolyte disturbance
o Hyperkalaemia not responding to pharmacological therapy, or causing physiologic
disturbance
o Other less common - Na+, Ca2+, PO43-,Mg2+, & uric acid
Metabolic acidosis
Dialyzable or filterable toxins (aspirin, lithium, methanol, ethylene glycol, methotrexate, &
theophylline, myoglobin metabolites etc)
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
2. Establishing Vascular Access for CRRT
2.1 Equipment
Standard tray
Antiseptic solution (e.g. chlorhexidine) / * betadine only for ECMO circuits
Local anaesthetic (e.g. lignocaine)
Sterile gown & gloves
Mask & protective goggles
Cannula (e.g. vascath )
10 ml ampoule of 0.9% sodium chloride (x2)
Syringes - 5 ml & 10 ml
Needles - 19 g & 21 or 25 g
Leur-lock IV caps (x2)
Transparent film dressing (e.g. Tegaderm)
Suture material (2/0 silk)
Scalpel blade
Biopatch
+/- Heparin 5000 units in 5ml (x1) [if heparin-lock required]
2.2 Procedure
Refer to insertion guidelines within the ICU Central Venous Catheter Guideline
Central Line Catheter (CVC) in ICU.pdf
2.3 Site
Site of vascath cannulation may affect filter performance, it is preferable to gain access via either
Femoral vein > R) Internal Jugular > Subclavian >L) Internal jugular.
Note: If long-term haemodialysis is likely, subclavian vascath access should be avoided due to the
risk of subclavian vein stenosis.
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
3. “Heparin-lock” for Vascular Access
When vascath lumens are not being used, each lumen should be “heparin-locked” with undiluted
heparin (ampoule 5000 units in 5 ml) to the volume of the lumen.
The volume of the lumen is specified on each of the 2 lumens on the vascath (e.g. red lumen
1.7ml, blue lumen 1.8ml)
This remains in situ until the vascath is next used for CRRT or for other IV access
Heparin-lock must be aspirated before vascath is used
For patients with a heparin sensitivity (i.e. HITS), six hourly 0.9% sodium chloride 10 ml flush
should be used instead.
3.1 Equipment
Dressing pack
Sterile huck towel
Antiseptic solution (e.g. chlorhexidine) / * betadine only for ECMO circuits
Sterile gloves & protective goggles
Syringe - 10 ml (x4), to aspirate & then flush each lumen
0.9% sodium chloride 10ml (x2)
Syringe - 2 ml (x2)
Needle - 19 g (x2)
Heparin 5000 units in 5ml (x1)
Leur-lock IV caps (x2) or Positive Pressure Valves (PPV) if 0.9% sodium chloride flushes to be
used.
3.2 Procedure
1. Apply goggles, perform hand hygiene, open & add equipment to sterile field
2. Perform hand hygiene & apply sterile gloves
3. Draw up 2 x 10ml 0.9% sodium chloride
4. Using 2ml syringes & needles, draw up Heparin to the specified volume printed on each
vascath lumen
5. Place sterile drape from dressing pack underneath vascath
6. Remove leur-lock caps (or PPV‟s if in situ)
7. “Scrub the hub” of each lumen with antiseptic solution & allow to dry
8. Place sterile huck towel underneath newly cleaned vascath
9. Aspirate 10ml blood from each lumen, then flush with 10ml 0.9% sodium chloride to ensure that
vascath lumen is clear of blood
10. Instil heparin (gently) according to volume specified on vascath
11. Attach leur-lock caps or PPV (as above) and apply lumen clamp.
12. Label vascath with heparin stickers & drug label to indicate “heparin-lock” in situ. Sign drug
order.
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
4. Commencing CRRT using Prismaflex
4.1 Priming Equipment
Prismaflex machine
Prismaflex Set (standard set ST 100), (need to add section on ST 150 sets)
Wide-bore, thermal blood warmer tubing
50 ml leur-lock syringe + 50mls of 0.9% sodium chloride
Priming solutions:
o 0.9% sodium chloride 1L bag (x2)
o Heparin 5000units in 5mls (x2)
Dialysate, PBP & Replacement fluids (refer to guideline below)
o
CRRT Initial settings.pdf
Additives for CRRT 5L fluid bags if required (e.g. potassium chloride)
If using anticoagulation, collect chosen drugs & delivery devices
ICU Renal Replacement Record (CRRT Orders) MR M31
4.2 Priming Fluid
The Prismaflex CRRT circuit is primed twice. The first facilitates heparin bonding to the filter
membrane, while the second removes excess heparin from the priming solution.
Do not use heparin in patients diagnosed with HITS. (Prime once with sodium chloride)
Priming solutions:
1st Prime: 0.9% sodium chloride 1000ml with heparin 10,000units (unless HITS)
2nd Prime: 0.9% sodium chloride 1000ml
Note: if machine is to be idle for > 30 minutes, leave 2 nd prime until about to connect to patient,
otherwise a 3rd prime will be required prior to connecting to patient.
4.3 Priming Machine
1. Follow instructions on screen CLOSELY (read the screen)
2. Choose CVVHDF mode (this ensures all other modes are available)
3. Enable syringe, add 50mL syringe primed with 0.9% sodium chloride
4. Add warming coil to blood circuit (via blue leur-lock connections, post filter), wrap coil around
blood warmer
5. Check all connections are secure
6. Prime TWICE, (1st heparin, 2nd 0.9% sodium chloride)
7. Perform Prime Test
8. Accept patient fluid gain/loss 400 mls / 3 hours; unless patient is 30kg or less (consider
decreasing accepted value in lighter patients)
9. If machine idle for > 30 minutes prior to attaching to patient – perform another prime.
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GUIDELINE
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
4.4 Attaching Machine to the Patient (via vascath)
4.4.1 Equipment
2 people
Dressing pack
Sterile huck towel
Antiseptic solution (e.g. chlorhexidine) / * betadine only for ECMO circuits
Sterile gloves & protective goggles
Syringes, 10ml (x 4)
10ml 0.9% sodium chloride (x 2)
Leur-lock IV cap
4.4.2 Preparation
This procedure requires 2 people
o Person 1 (sterile) - accessing vascath
o Person 2 (scout) - managing lines, machine & patient
Explain procedure to patient & provide reassurance
Position of comfort, preferably supine to monitor patient‟s haemodynamic status
Consider potential for hypotension on commencement of CRRT. Assess patient‟s
haemodynamic status PRIOR to attachment to Prismaflex.
Ensure ICU registrar present or readily available when connecting patient
Discuss options for management of haemodynamic instability with ICU registrar prior to
connecting the patient.
o Consider fluid loading & availability of vasopressors (e.g. noradrenaline, metaraminol)
o Consider increasing inotropes prior to connecting patient
Position patient supine if possible to facilitate monitoring & management of haemodynamics
prior to, & during commencement of CRRT.
Ensure continuous & accurate blood pressure monitoring
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
4.4.3 Procedure
Person 1(Using aseptic technique & holding non-sterile lines with antiseptic soaked gauze,
ascertain patency of both access (red) & return (blue) lumens of vascath):
o Apply goggles, perform hand hygiene, open & add equipment to sterile field
o Perform hand hygiene & apply sterile gloves
o Draw up 2 x 10ml 0.9% sodium chloride
o Place sterile drape from dressing pack underneath vascath
o Remove leur-lock caps (or PPV‟s if in situ)
o “Scrub the hub” of each lumen with antiseptic solution & allow to dry
o Place sterile huck towel underneath newly cleaned vascath
o Aspirate 10 mls of blood from each vascath lumen & discard – address any patency /
flow issues, (see 6.1 Nursing Management of Cannula)
o Flush each vascath lumen with 10mls of 0.9% sodium chloride – address any patency /
flow issues, (see 6.1 Nursing Management of Cannula)
o Clamp both lumens
Person 2 –
(Pass lines to person 1, ensuring they are clamped, not tangled or contaminated & attend
to Prismaflex flow rates)
o Hand Access line (red) to Person 1, who takes hold of it with sterile antiseptic soaked
gauze & connects it directly to the access lumen (red) of vascath.
o Swap Effluent line (yellow) & Return line (blue), so that effluent line (yellow) is now
directly connected to effluent bag & return line (blue) is connected to one lumen of the
“Y” connector (still attached to the priming bag).
o If spare limb of “Y” connector is not being used (e.g. for protamine or calcium), clamp
spare limb closest to bifurcation, to minimise blood backflow into lumen during treatment
& add leur-lock IV cap
o Detach “Y” connector from priming bag & hand to Person 1, who takes hold of it with
sterile antiseptic soaked gauze & connects it directly to vascath return lumen (blue).
Persons 1 & 2
o
Ensure that all lines are unclamped.
Person 2
o
o
o
o
o
Start blood flow rate at 50ml/min & assess patient for any compromise in haemodynamic
status.
Increase blood flow rate to target rate, (see section 4.5) ideally within 5 minutes.
Do not start PBP, Dialysate or Fluid Removal until CRRT blood flow has been safely
increased to target; patient is haemodynamically stable and anticoagulation has been
commenced.
Once blood flow target rate is reached & patient is stable, enter dialysate, PBP,
replacement & fluid removal rates (see section 4.5)
Ensure that de-aeration chamber level is adequate (blood–fluid interface)
4.4.4 Post procedure
Ensure current, signed, valid IV orders for all priming & treatment fluids (MR M31)
Continue to observe for & address any haemodynamic instability
Secure all lines, ensuring tension relieving secondary anchor dressing in situ
Ensure blood warmer turned on
Ensure emergency blood return pack available at back of Prismaflex machine
Need to add link to photos of line securing
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
4.5 Settings for CRRT using Prismaflex (non-citrate)
Note: For patients being treated using citrate anticoagulation, see Citrate/Calcium guideline
CRRT Regional Anticoagulation (Citrate).pdf
For all other anticoagulation (e.g. Heparin), or no anticoagulation – the set up is as follows:
4.5.1 CVVHDF (Pre Dilution) on Prismaflex
Provides solute removal by both convection & diffusion.
Allows patient fluid removal if required.
Parameter
Blood Flow
Dialysate Flow
Initial Setting
50mls/min
0 ml/hr until Blood flow at target
0 ml/hr until Blood flow at target
Target Setting
250ml/min
30x Patient Weight (in kg) to
maximum 3000mls or (100kgs)
200 ml/hr (to reduce clotting in deaeration chamber)
1250 ml/hr
Replacement Flow
(Post)
PBP Flow (used for fluid
replacement as
Pre-Dilution)
Fluid Removal Rate
Anticoagulation
0 ml/hr until Blood flow at target
0 ml/hr until Blood flow at target
as per Protocol (if used)
as per ICU Medical Orders
as per Protocol (if used)
4.5.2 CVVHDF (Post Dilution) on Prismaflex
Provides solute removal by both convection & diffusion.
Allows patient fluid removal if required.
Parameter
Blood Flow
Dialysate Flow
Initial Setting
50ml/min
0 ml/hr until Blood flow at target
Replacement Flow
(Post)
PBP Flow
Fluid Removal Rate
Anticoagulation
0 ml/hr until Blood flow at target
(not used)
0 ml/hr until Blood flow at target
as per Protocol (if used)
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Target Setting
250ml/min
30x Patient Weight (in kg) to
maximum 3000mls or (100kgs)
1250 ml/hr (used for fluid replacement
as Post-Dilution)
(not used)
as per ICU Medical Orders
as per Protocol (if used)
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
4.5.3 CVVHD on Prismaflex
Provides solute clearance by diffusion.
Allows patient fluid removal if required.
Parameter
Blood Flow
Dialysate Flow
Initial Setting
50mls/min
0 ml/hr until Blood flow at target
Replacement Flow
(Post)
PBP Flow
Fluid Removal Rate
Anticoagulation
0 ml/hr until Blood flow at target
(not used)
0 ml/hr until Blood flow at target
as per Protocol (if used)
Target Setting
250ml/min
30x Patient Weight (in kg) to
maximum 3000mls or (100kgs)
200 ml/hr (to reduce clotting in deaeration chamber)
(not used)
as per ICU Medical Orders
as per Protocol (if used)
4.5.4 CVVH on Prismaflex
Provides solute removal by convection.
Allows patient fluid removal if required.
Note: CVVH is not routinely used in Alfred ICU
4.5.5 SCUF on Prismaflex
Provides fluid removed by ultrafiltration.
Note: SCUF is not routinely used in Alfred ICU
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
4.6 Disconnecting from Prismaflex (either cessation of treatment or for recirculation)
4.6.1 Equipment
2 people
Dressing pack
Sterile huck towel
Antiseptic solution (e.g. chlorhexidine) / * betadine only for ECMO circuits
Sterile gloves & protective goggles
500mls 0.9% sodium chloride
Bag spike x1 for cessation, x 2 for recirculation
[for lumen aspiration, flush & heparin-lock]
o Syringe - 10 ml (x4), to aspirate & then flush each lumen
o 0.9% sodium chloride 10ml (x2)
o Syringe - 2 ml (x2)
o Needle - 19 g (x2)
o Heparin 5000 units in 5ml (x1)
o Leur-lock IV caps (x2) or Positive Pressure Valves (PPV) if 0.9% sodium chloride flushes
to be used.
Consider adding extra gauze pieces to aid sterility when accessing multiple lumens
Note: The above equipment is available in a pre-made pack (located in ICU equipment store) & should
be available at the back of the Prismaflex at all times.
This ensures equipment is readily available if blood needs to be returned urgently
4.6.2 Preparation
This procedure requires 2 people
o Person 1 (sterile) - accessing vascath,
o Person 2 (scout) - managing lines, machine & patient
Explain procedure to patient & provide reassurance
Position of comfort, preferably supine to monitor patient‟s haemodynamic status
Turn off anticoagulant infusions (if applicable)
4.6.3 Procedure
Person 1
o
o
o
o
o
Place sterile huck towel underneath vascath
“Scrub the hub” of each lumen & allow to dry
Ask 2nd person to press “Stop” via Prismaflex screen
Using sterile antiseptic soaked gauze - clamp access (red) lumen & limb of access (red)
circuit.
Disconnect access (red) limb of circuit & add spike, then pass to person 2 who:
 will connect to 0.9% sodium chloride 500ml
 unclamp access (red) circuit limb
 choose „End Treatment‟ or „Change Circuit‟ via Prismaflex screen
 follow instructions on Prismaflex screen to return blood, (if not clotted)
 if filter clotted, disconnect without returning blood
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
Person 1 (continued)
o
o
o
o
o
o
o
Aspirate access (red) lumen to remove remnant clots, then flush lumen with 10ml of 0.9%
sodium chloride
Wait until blood in circuit has been returned via return (blue) lumen, then
Using sterile chlorhexidine soaked gauze - clamp return (blue) lumen & limb of return
(blue) circuit
Disconnect & pass to 2nd person to discard in yellow clinical waste bin
Aspirate return (blue) lumen to remove remnant clots, then flush lumen with 10ml of 0.9%
sodium chloride
Heparin lock vascath lumens (see section 3 “Heparin-lock”).
Label vascath with heparin stickers & drug label to indicate “heparin-lock” in situ. Sign
drug order
Either person
o
o
o
Ensure all blood circuit lines are clamped before unloading
Unload circuit from Prismaflex & discard in yellow clinical waste bin
Discard effluent bag fluid into pan room sluice & other remaining fluids into sink
NOTE:
If treatment ceased due to any Prismaflex malfunction; clearly describe incident & all alarms
preceding, providing as much information as possible to help Equipment Nurse / Gambro mechanics
to troubleshoot issues.
4.7 Recirculation on Prismaflex
Utilised when patient requires temporary disconnection (< 120 mins) from CRRT (e.g.
troubleshooting of access issues, transport, short procedure, physiotherapy), to preserve circuit &
prolong filtration time.
For procedure see “CRRT Recirculation”
CRRT Recirculation on the Prismaflex.pdf
For Prismaflex screen prints demonstrating the recirculation procedure, see
Prismaflex Recirculation Slides.pdf
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
5. Anticoagulation for CRRT
5.1 General Anticoagulation Rules
Anticoagulation is required to prevent clotting of the extracorporeal circuit during CRRT, with the aim
being to anticoagulate the circuit, but not necessarily the patient.
This anticoagulation can be achieved in a number of ways depending on which is most appropriate
for the patient, & preference of the treating team.
NOTE:
Unless contraindicated or choosing non-standard anticoagulation, most patients should
default to having low dose heparin added to the CRRT circuit.
CRRT Anticoagulation (Heparin).pdf
Other options:
No anticoagulation
Heparin low dose (circuit)
Heparin / Protamine (circuit)
Systemic therapeutic anticoagulation
o Heparin
o Lepirudin
o Bivalirudin
Citrate / Calcium (circuit)
Other anticoagulation (please discuss with ICU pharmacist prior to commencement):
o Epoprostenol (circuit)
In most cases, anticoagulation infusions should be attached to the filter syringe line.
If anticoagulant reversal is used (e.g. Protamine, Calcium), it should be connected via a 'Yconnector‟ at the return cannula of the vascath.
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
5.2 Monitoring and Adjusting Anticoagulation in CRRT
Check anticoagulation as per specific protocol. Monitoring times vary, dependant on type of
anticoagulation being utilised.
Options for Patient sample:
o
o
o
Arterial line (preferable)
CVC lumen (this sample must be labelled clearly).
First sample port of (red) component of circuit, between the vascath access lumen &
the PBP fluid entering the circuit (for patients without alternate access as per above)
The Circuit sample to be taken from the (red) pre-filter sample port.
o
o
o
o
o
“Scrub the hub” of pre filter port with alcohol swab
Use a 5ml syringe (with 21g or smaller needle) or ABG syringe (for citrate) & insert
into the rubber port of sample site
Aspirate blood slowly to avoid disrupting pressure pod membranes:
 2.7mls for APTT
 0.5 -1ml in ABG syringe for ionized calcium
Pull back on syringe plunger when pulling out needle as there will be pressure behind
it & it may spray blood
Inject blood into appropriate blood tube
Adjust dosage of anticoagulation according to relevant ICU protocol.
o CRRT Anticoagulation (Heparin).pdf
o CRRT Regional Anticoagulation (Citrate).pdf
If restarting treatment after filter has clotted (< 24 hrs), refer to protocols above for
anticoagulation dose guidance.
If restarting CRRT after more than 24 hours since last filter, start anticoagulation as for new
filter circuit.
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Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
6. Nursing Management of Patient on CRRT using Prismaflex
6.1 Cannula
Access site:
o Monitor for signs of bleeding or disconnection
o Monitor for signs & symptoms of infection
Dressing:
o Maintain dressing integrity, ensure Biopatch correctly placed
o Ensure tension relieving secondary anchor dressing in situ
o Change dressing weekly / prn & document on ICU Active.
Limb observations:
o 8/24 + prn (if femoral approach)
o Colour, warmth, movement, sensation & pedal pulses present
Assessing patency
o Assess patency of cannula lumens prior to attaching to circuit
o Removal of blood or return of sodium chloride (10 mls in 3 secs) suggests good access.
o If removal or return is difficult or sluggish, don‟t connect to circuit until these access
issues are resolved – this may result in a new vascath.
6.2 Machine (Prismaflex)
Don‟t prime CRRT circuit until vascath is in situ & patent
Consider position of machine before connecting circuit to patient:
o Ensure safe access around room
o Adequate circuit line length available to reach patient‟s vascath
o No fluid bags resting on any equipment or patient‟s bed (as this will affect the
machine‟s weight system to adjust fluids)
Plug into blue UPS power point (if possible)
Lock brake
Unless attaching immediately, label circuit with date & time of priming.
6.3 CRRT circuit:
Circuit
o
o
o
o
Ensure blood warmer turned on
Ensure all connections are tight
If primed circuit idle > 30mins (&<24hours) reprime with 1L 0.9% sodium chloride prior to
attachment to patient.
If primed circuit idle > 24 hours – discard (or keep for teaching)
Returning blood
o
o
o
Ensure emergency equipment for return of blood available at back of Prismaflex
machine (see 4.6 Disconnecting from Prismaflex)
Consider elective return of blood & change of circuit when TMP rises significantly over a
period of time. Note: sudden rises are likely to be access-related issues which may be
resolved with troubleshooting.
Prismaflex machine will prompt user to change the circuit after 72 hours of use or 780L
of blood exchange - whichever occurs first. This is a company recommendation & they
will not guarantee the integrity of the membrane fibres after this time. This alarm can be
overridden, but a yellow alarm will remain present on the machine. Please discuss with
medical staff if you are considering leaving the same circuit running after this alert.
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6.4 Patient:
Monitor total patient input & output to assess fluid status, (See 7.2 Management of Patient’s Fluid
Balance)
Ideally, avoid hip flexion > 30° if femoral cannula in situ
check if possible to go higher
Ensure lines are secured & tension relieving anchor dressing in situ
Monitor coagulation & adjust as per anticoagulation protocols
o CRRT Anticoagulation (Heparin).pdf
o CRRT Regional Anticoagulation (Citrate).pdf
add single link to stickers
Monitor patient's core body temperature add further warming options as required.
(Note: May mask septic febrile event),
6.5 Documentation:
Ensure ALL CRRT fluids are documented & signed on MR M31
Hourly documentation on ICU chart as per stickers:
o CRRT Sticker 2012 (non-Citrate).pdf
o CRRT Sticker 2012 (Citrate).pdf
Document any interruption or cessation of treatment, including a reason, on the bottom of the
ICU chart
6.6 Troubleshooting:
Have a 2nd person (line manager) present for patient turns to prevent movement of cannula &
reduce potential for “access” alarm issues
If trouble with “access” alarms, consider:
o Using “change bags” option just prior to moves / turns
o Rotating cannula at the hub to move it off the wall of the vessel (if appropriate vascath)
o Adding 1-2mls 0.9% sodium chloride into circuit via an access pod, to make circuit less
negative & allow blood pump to recommence
6.7 Waste management & safety
Ideally have only 2 bags of 5L CRRT fluid made up at any one time
Ensure cytotoxic stickers on both circuit & effluent bags if patient in cytotoxic precautions. If
discarding cytotoxic effluent in sluice, nurse is responsible for removal of emptied bags.
Maximum of 2 effluent bags to be left in a cubicle at a time. Don‟t pile effluent bags on top of
each other as this may lead to leakage.
Adhere to “Safemove”, back smart principles when moving, attaching & disconnecting any
CRRT fluid bags.
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GUIDELINE
Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
7. Management of Renal Replacement Therapy (CRRT)
The primary role of the kidneys is to maintain the composition & volume of the extra cellular fluid,
thereby ensuring a constant environment in which normal cellular functions can take place. The
kidneys accomplish this by:
Regulating plasma composition with regard to electrolytes & osmolality
Regulating fluid balance to maintain circulating volume & total body water
Maintaining the acid-base balance by excreting hydrogen ions & conserving HCO3Excreting the toxic waste products of metabolism while conserving substances needed by the
body
During CRRT, these renal functions are managed by the ICU medical & nursing staff.
Note that CRRT can also mask signs of other organ systems in failure (e.g. the temperature in a
febrile patient, or the serum lactate in patients with an ischaemic bowel).
7.1 Management of Patient‟s Electrolytes
The healthy kidney regulates serum electrolyte concentrations. CRRT principally regulates
electrolytes by establishing a diffusion gradient across the semi-permeable membrane. The dialysis
solutions contain many electrolytes at concentrations (mmol/L) equivalent / close to the desired
plasma concentration (mmol/L). Solutions may or may not contain potassium,
As the patient‟s blood passes along the membrane, electrolytes diffuse down the concentration
gradient across the semi-permeable membrane until the levels equilibrate on each side.
However, other processes in the body may also be increasing or reducing the serum level of these
electrolytes, (e.g. vomiting, diarrhoea, multiple blood transfusions, bleeding, severe acidosis,
endocrine dysfunction, TPN)
Plasma electrolytes must be regularly monitored whilst patient is receiving CRRT
7.1.1 Calculating potassium chloride concentration in CRRT 5L fluid bags
Note: ALWAYS check whether there is potassium preloaded into bag (e.g.: PrismOcal)
Final 5L bag potassium chloride concentration = added potassium chloride (mmols/L) / 5L
For example, if you add:
o 20 mmol/L potassium chloride to 5 L bag = (20 mmol/L / 5 Litres) = 4 mmol/L
o 10 mmol/L potassium chloride to 5 L bag = (10 mmol/L / 5 Litres) = 2 mmol/L
Note:
Add the same potassium chloride amount to both the dialysate & PBP 5L bags (unless using
PrismOcal which already contains potassium)
Serum potassium level may fall quite rapidly if no potassium is added to CRRT fluid bags
Take into account patient‟s clinical condition when considering what potassium amount to add to
CRRT fluid bags
o Patient may have large amounts of potassium loss, e.g. Diarrhoea
o Patient may have alternate sources of potassium delivery, e.g. TPN
o Patient may require higher serum potassium level; e.g. Cardiac issues
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
7.2 Management of Patient‟s Fluid Balance
During CRRT, the patient‟s fluid balance is determined by the net effect of fluids prescribed to the
patient, & fluid removed by the machine. The daily fluid balance is prescribed during the ICU medical
rounds. This balanced is achieved by altering the hourly fluid removal by the CRRT machine.
When setting the hourly fluid removal it is important to consider:
the prescribed 24 hour fluid balance goal
the obligatory fluid inputs including nutrition (TPN, oral & enteral), infusions, drug
administration
additional occasional fluid inputs including blood products
fluid losses including urine, faecal, wounds, drains & insensible losses
Total fluid balance should be calculated & assessed at least 4 hourly, to ensure hourly
CRRT fluid removal rate will support 24 hour fluid removal goal
E.g.
Target Daily Fluid Balance = minus 2000mL
Hourly Fluid Balance = minus 2000/24 = minus 83mL
Hourly Fluid Removal = hourly input + 83mL
The patient's haemodynamic stability (BP, CVP, etc) should be assessed prior to altering CRRT fluid
removal rate.
7.3 Management of Patient‟s Acid-Base Balance
In acute kidney injury (AKI), organic & inorganic acids are retained leading to metabolic acidosis.
During a polyuric phase of AKI, the renal tubules fail to reclaim the bicarbonate (HCO3-) from
glomerular filtrate. Thus, a patient with AKI may have either an excess of acids or a deficit of total
body HCO3-. Additionally, the patient‟s primary pathology may increase circulating acids including
lactic or ketotic acids.
During CRRT, HCO3- diffuses into the patient‟s blood across the filter membrane, while acids are
removed through convection & diffusion.
Severely acidotic patients with AKI may require urgent filtration to assist with management of an
acute metabolic acidosis.
Caution should be used when the patient‟s primary pathology is being monitored via plasma acid
levels (e.g. Lactic acid to monitor bowel ischaemia). CRRT will lower serum acid levels & may falsely
imply an improvement in the underlying pathology.
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Title
CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
7.4 Management of Patient‟s Toxin Removal
Provided their molecular weight is small enough to pass through the pores of the filter membrane,
toxins will be removed through CRRT. The rate at which toxins are removed is affected by their
protein binding; the CRRT flow rates & the amount of clotting that has occurred within the filter.
Daily monitoring of serum urea & creatinine levels provides a method of measuring the effectiveness
of the CRRT. Consider a filter circuit change if urea & creatinine have increased during the previous
24 hour period.
Other agents that may be removed during CRRT:
Inotropes:
o inotropes are usually titrated to effect, the inotropic effect should be closely monitored
when starting or ending CRRT; as serum levels may be affected by inotrope loss
through the filter or sudden cessation of CRRT
Antibiotics:
o consideration should be given to antibiotic loss through the filter
o alert pharmacist when CRRT is commenced or to be ceased
Drugs:
o close monitoring of therapeutic drugs should be maintained, dosing may need to
increase whilst on the filter, but also importantly dose reduction may be required if
CRRT is ceased for extended periods without return of native kidney function
Electrolytes:
o see above for potassium management, however CRRT will influence total body gains
or losses of other electrolytes
o phosphate supplementation will usually be required after the first few hours of CRRT
Nutrition:
o water soluble vitamins & smaller amino acids can be lost during CRRT
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
Appendix 1: Glossary of Terms Used with CRRT
Access Pressure
The pressure measured by the blood circuit‟s Access Pressure Pod just after the blood flow
exits from the patient, but before the blood pump & haemofilter.
Convection
The movement of solutes during ultrafiltration (UF), in the direction of the flow of the water.
Convection rates are greatly increased when replacement fluid is used due to the increased
flow across the filter membrane.
Also called “solvent-drag”.
Counter-Current
The process by which two fluids flow in opposite direction, on either side of a semi-permeable
membrane. During CRRT the blood flow & dialysate flow run as counter-currents.
This means that the differing solute concentrations are maintained for the length of the
haemofilter, optimising solute exchange across the membrane.
CVVH (Continuous Veno-Venous Haemofiltration)
Continuous haemofiltration with the aid of a blood
pump provides solute removal by convection. It
offers high volume ultrafiltration using replacement
fluid, which can be administered pre-filter or postfilter.
The pump guarantees adequate blood flow to
maintain required UF rates.
CVVHD (Continuous Veno-Venous Haemodialysis)
Continuous haemodialysis with the aid of a blood
pump, using venous access via dual lumen vascath.
It provides solute removal by diffusion, & fluid removal
by osmosis.
Dialysate is pumped in counter-current flow to the
blood. As the blood progresses along the semipermeable membrane, the composition of the plasma
approaches that of the dialysate.
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
CVVHDF (Continuous Veno-Venous Haemo-Diafiltration)
Continuous haemodiafiltration with the aid of a blood
pump provides solute removal by diffusion &
convection simultaneously. It offers high volume
ultrafiltration using replacement fluid, which can be
administered pre-filter or post-filter. Simultaneously,
dialysate is pumped in counter-current flow to the
blood.
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Diffusion
Movement of solutes from an area of high concentration to
an area of low concentration.
In CRRT, solutes will only diffuse across the semipermeable membrane if they are smaller than the size of the
filter pores. (see Molecular Weights Table below)
Filter Gradient (ΔP) (also called „Pressure Drop‟)
Pressure used to determine micro-clotting in the hollow fibres of the filter. As resistance
within the filter increases so too does the pressure gradient required to maintain the same
flow. Measures the pressure difference between blood at the top & bottom of the filter to
determine micro-clotting within the filter.
ΔP = Filter Pressure – Return pressure
Filter Pressure
The highest pressure in the blood flow. It is measured after the blood pump & prior to the
filter. Thus, it reflects the force required to pump the blood through the filter.
Filtration / Ultrafiltration
In ultrafiltration, plasma water with solutes is pulled from the
patient‟s blood across the semi-permeable membrane in the
filter.
The effluent pump automatically controls the ultrafiltration
rate by adjusting the hydrostatic pressure gradient (TMP)
across the filter membrane.
Only solutes that are smaller than the pore size of the filter
will pass through the membrane.
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
Osmosis / Oncotic Attraction
Movement of water from an area of low solute concentration
to an area of high solute concentration.
In CRRT, different blood & dialysate solute volumes are
maintained by the semi-permeable membrane. Plasma
proteins, being larger than the filter pore size, remain on the
blood side of the membrane.
PBP (Pre Blood Pump)
If required, the PBP infuses sterile replacement solution into the blood circuit, at the
beginning of the Access Line.
Post-Dilution
Haemofiltration circuit where replacement is
added after the blood has passed through the
filter. The blood becomes highly concentrated
due to fluid removal through the filter membrane.
Pre-Dilution
Haemofiltration circuit where replacement is
added prior to the blood entering the filter. The
bloods solutes, clotting factors, & osmotic pull are
diluted prior to entering the filter.
Return Pressure
Pressure measured in blood circuit just prior to return to patient. Provides information about
the patency of the blood return line & cannula.
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SCUF (Slow Continuous Ultrafiltration)
Continuous process of fluid removal across a semipermeable membrane, providing patient fluid
removal by ultrafiltration. No substitution fluid or
dialysate is used.
TMP
Pressure exerted across the filter membrane during operation.
Pressure difference between the blood & fluid compartments.
Predicts the risk of haemolysis within the filter.
TMP = Filter Pressure + Return Pressure - Effluent Pressure
2
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CONTINUOUS RENAL REPLACEMENT THERAPY (CRRT) IN ICU (DRAFT ONLY)
Appendix 2: Prismaflex Controls
Appendix 3: Molecular Weights
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