1. Pediatric CRRT The Prescription: Rates, Dose, Fluids
Michael Zappitelli, MD, MSc
Montreal Children's Hospital
McGill University Health Centre

2. Not necessarily a recipe
Overview
Rates & Dose
Blood flow
Dialysis fluid
Replacement fluid
Ultrafiltration rate
Fluids
Suggested
Not necessarily a recipe

3. Blood flow rate Qb Age & weight – based
Promote circuit lifespan patient stability: clots vs alarms
Highly access-dependent
Aim return access pressures ~ < 200 mmHg, no alarms
May be machine – dependent
Prisma: 180 ml/min
Prismaflex & Aquarius: 450 ml/min
Start lower and increase by about 10 minutes (?)

4. Blood flow rate No set “perfect rates”
From 3 to ~10 ml/kg/min, depending on age:
Examples:
0-10 kg: ml/min
11-20kg: ml/min
21-50kg: ml/min
>50kg: ml/min
Neonates 8 to 12 ml/kg/min
Children 4 to 8 ml/kg/min
Older 2 to 4 ml/kg/min.
Most not > 200 ml/min: not dangerous just not necessary
Based on
previously most
commonly used
machine

5. Blood flow rate May need to modify:
Be aware of access and return pressure
Visually inspect filter for clots
Transmembrane pressure – may need to increase blood flow
Filtration fraction

6. Solutions Slow continuous ultrafiltration – none
CCVHD – dialysis fluid for diffusive clearance
CVVH – replacement fluid:
replacing fluid you are removing to achieve solute
clearance by convection
CVVHDF – both
Using these to correct metabolic abnormalities (remove) and
prevent treatment-related metabolic abnormalities (replace).

7. Ideal solutions Composition: Bicarbonate: Calcium:
Physiological/ compatible
Reliable
Inexpensive
Easy to prepare
Simple to store
Quick to the bedside
Widely available
Composition:
Sodium: ~ 130 to 140
Chloride: ~105 to dependent on other anions (HCO3)
Potassium: MOST Zero – need to add (some have)
Magnesium: 1 to 1.5 mEq/L
Glucose/Dextrose: 0 to 110 mg/dL
Lactate: Most 0 to 3 mEq/L (35-40 mEq/L if lactate buffer)
Peritoneal dialysis fluid?
Hyperglycemia, metab acidosis
Soysal et al, Ped Neph, 2007
Pre-made IV solutions:
Saline, Lactated Ringers
Multi-bag systems: why?
Custom-made solutions:
Local pharmacy; outsource
Commercially available solutions:
Ready-bags (compartments)
Concentrate added to bag
Bicarbonate:
Most mEq/L
Few ZERO
As low as 22 to 25 mEq/L
Calcium:
0 to 3.5 mEq/L

8. Some solutions are more flexible than others
Choosing solutions
Cost (Storing, frequency of use)
Anticoagulation: +/- calcium with citrate anticoagulation
There are citrate based solutions and data
Patient safety – patient volume?
Does everyone prescribing really understand?
Regulatory issues (dialysis versus replacement fluid....)
Some solutions are more flexible than others
Accusol Prismasate
Normocarb
Hemosol BO
Duosol Prismasol

9. Phosphate They WILL develop hypophosphatemia
Can replace: IV boluses, TPN
MANY add it to solutions – but no good data
Worry about precipitation, calcium-magnesium binding
How much too much? No good answer. Many mmol/L
Pharmacy versus nurse-based addition?

10. Troyanov et al, Intens Care Med, 2004 Retrospective clinical
Adding Phosphate
Troyanov et al, Intens Care Med, 2004
Experiment
Added 1.2 mmol/L PO4- to calcium – rich solutions
5 hours: no effect on calcium, bicarb, pH, pCO2
No visual precipitation
With and without filtering
2 days: to precipitation
Retrospective clinical
14 adults CVVHDF
KPO4 added when <1.5 mmol/L (protocolized)
No negative effects caused on calcium, bicarb, pH
Santiago et al, Therap Apher & Dialysis, 2010
Experiment
Added NaPO4 to dialysis/replacement fluid bags (12)
containing calcium and magnesium
0.8 mmol/L
1.5 mmol/L
2.5 mmol/L
No change in calcium, magnesium, sodium, gluc, pH
2, 24 and 48 hours
Consideration:
Most dialysis or replacement fluid bags will not need to be hung for more than a day
Santiago et al, KI, 2009
Experiment
Pre-post evaluation of adding NaPO4 to dial & replace solution
0.8 mmol/L, 47 children, solutions contained Ca++ & Mg++
No precipitation seen
Less IV PO4 needed

11. Dialysis fluid? Replacement fluid?
Personal suggestion: use the same solution
If needed (e.g. alkalosis) can modify the replacement solution
Regulatory issues may hinder:
Replacement solution – saline, with additives

12. Albumin dialysis Removes protein bound small substances:
e.g. copper/Wilson's, drugs, toxins of liver failure
Albumin live a scavenger
Dialysis:
albumin-containing solution across highly permeable membrane
25% albumin “added” to dialysis fluid bag: 2-5% albumin solution
it's “single pass” - bags are changed
Shouldn't affect sodium – may affect (reduce) other electrolytes
Theoretically may affect citrate anticoagg rates
Allergic reaction
Collins et al, Pediatr Nephrol, 2008
Askenazi et al, Pediatrics, 2004
Ringe, Pediatr Crit Care Med, 2011

13. Solutions: watch for errors!
Barletta et al, Pediatr Nephrol, 2006
Survey: ICU, Nephrology, CRRT
16/31 programs reported solution compounding errors
2 deaths
1 non lethal cardiac arrest
6 seizures (hypo/hypernatremia)
7 without complications
Soysal et al, Pediatr Nephrol, 2007
Country where resources dictate need to use PD solution for dialysis
and NS + additives for replacement fluid
Many reported electrolyte complications: glucose, sodium, acidosis

14. Dialysis and Replacement Fluid Rates: Clearance & Dose
Clearance mostly a function of:
Dialysis fluid flow rate (Qd)
Replacement fluid flow rate (Qr)
Higher rates
= higher clearance for IEM, drug removal, severe high K
= more middle molecule clearance (CVVH/CVVHDF)
= more hypophosphatemia, kalemia, magnesemia
= more amino acid losses
= more drug clearance
= more CITRATE clearance
= more work to change bags, give electrolyte infusions
Lower rates simplify electrolyte balance and limit protein loss
Qd + Qr (CVVHDF)

15. Dialysis and Replacement Fluid Rates: Clearance & Dose
No well-defined right “dose” of clearance.
For CRRT:mostly expressed in terms of effluent (ml/kg) per hour
“Standard” suggestion:
Qd or Qr or Qd+Qr ~ ml/kg/hour
OR 2 to 2.5 liters/hr/1.73msq.
Some do much higher: some machines as high as 8L/hour
REALIZE:
What you prescribe is not necessarily what the patient gets!!
Time off circuit, microclots in filter over time, predilution
Urea clearance
~ ml/min/1.73msq

16. 10 kg child: 30 ml/kg/hr “clearance” OR ~ 0. 26 msq: 2L/1
10 kg child: 30 ml/kg/hr “clearance” OR ~ 0.26 msq: 2L/1.73msq/hour = 300 ml/hour
CVVH
Qr = 300 ml/hour
CVVHDF
Qd = 150ml/hour
Qr = 150 ml/hour
CVVHD
Qd = 300 ml/hour

17. Ultrafiltration/fluid removal Rates
1717
Ultrafiltration/fluid removal Rates
No Study has identified effective, safe UF rates in Children.
General acceptance that 1-2ml/kg/hr is often safe (stable patient)
Choose UF rate to:
balance input (e.g. boluses, citrate, calcium, etc)
remove excess fluid over time
“make room” for IV fluids and nutrition
Also provides solute clearance by convection

18. Ultrafiltration/fluid removal Rates
Fluid removal should be safe AND effective – no need to sacrifice one for other:
Frequent communication
Frequent reassessment (MD), Hourly reassessment (RN)
Know what the “usual hourly input is”:
IV fluids
Citrate & calcium
Nutrition (give!!)
Meds/infusions
Provide “rules” for removing “intermittent fluids”
Be aware of the “outs”
(tubes, urine, diarrhea) – account for

19. Ultrafiltration/fluid removal Rates
Decide desired DAILY fluid removal, after understanding TOTAL severity of Fluid Overload
Assure safety of this desired daily fluid removal
Decide desired hourly “negative balance”
Even balance?: Simply remove hourly ins – significant outs
Negative balance?: Same + remove desired negative balance
Think about filtration fraction – make sure not too high
UFR/Plasma flow rate --- UFR/Qb
<20-25% CVVHD or post-filter CVVH
<30-35% pre-filter CVVH

20. Summary Blood flow: balance access/circuit life with tolerability
Solutions: Many choices
Know their content, regional rules, CRRT type used
Decide on desired flexibility
Decide what's best for your institution (volume, expertise)
Bicarbonate and calcium are most substantial differences
Be aware of errors
Dialysis/replacement fluid rates: ie clearance dose
Balance desired clearance with undesired losses
2-2.5 L/hour/1.73msq – suggested only
Ultrafiltration rate:
Frequent reassessment, team + targeted fluid removal decisions
Safety AND efficacy are feasible