Prescription Rates Dose Fluids - Pediatric Continuous Renal
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Transcript Prescription Rates Dose Fluids - Pediatric Continuous Renal
PEDIATRIC CRRT
THE PRESCRIPTION:
RATES, DOSE, FLUIDS
Michael Zappitelli, MD, MSc
Montreal Children's Hospital
McGill University Health Centre
OVERVIEW
Rates & Dose
Blood flow
Dialysis fluid
Replacement fluid
Ultrafiltration rate
Fluids
Suggested
Not necessarily a recipe
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 (?)
BLOOD FLOW RATE
No set “perfect rates”
From 3 to ~10 ml/kg/min, depending on age:
Examples:
0-10 kg:
25-50ml/min
11-20kg:
80-100ml/min
21-50kg:
100-150ml/min
>50kg:
150-180ml/min
Based on
previously most
commonly used
machine
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
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
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).
IDEAL SOLUTIONS
Physiological/
compatible
Composition:
Peritoneal dialysis fluid?
Hyperglycemia, metab acidosis
Sodium: ~ 130 to 140
Soysal et al, Ped Neph, 2007
Reliable
Chloride: ~105 to 120 dependent on other anions (HCO3)
Pre-made
IV solutions:
Potassium: MOST Zero – need
to add (some
have)
Inexpensive
Magnesium: 1 to 1.5 mEq/L Saline, Lactated Ringers
Glucose/Dextrose: 0 to 110 mg/dL
Easy
to prepare
Multi-bag
systems:
why?
Lactate:
Most 0 to 3 mEq/L (35-40
mEq/L
if lactate
buffer)
Custom-made solutions:
Simple to storeBicarbonate:
Local pharmacy; outsource
Most 30-35 mEq/L
Quick to the bedside
Few ZERO Commercially available solutions:
As low as 22 to 25
mEq/L
Ready-bags (compartments)
Widely available
Concentrate added to bag
Calcium:
0 to 3.5 mEq/L
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....)
Accusol
Prismasate
Some solutions
are more flexible than others
Normocarb
Duosol
Prismasol
Hemosol BO
...........
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 1.2-1.5 mmol/L
Pharmacy versus nurse-based addition?
ADDING PHOSPHATE
Troyanov et al, Intens Care Med, 2004
Experiment
Added 1.2 mmol/L PO4to calciumet
– rich
Santiago
al, solutions
Therap Apher & Dialysis, 2010
5 hours: no effect on calcium,Consideration:
bicarb, pH, pCO2
No visual precipitation Experiment
Added
NaPO4
to dialysis/replacement fluid bags (12)
With and
without
filtering
Most
dialysis
or
replacement
fluid
containing calcium and magnesium
2 days: to precipitation
bags will not need to0.8
bemmol/L
hung for
mmol/L
Retrospective
clinical
Santiago more
et
al, KI,
2009
than
a1.5
day
2.5 mmol/L
14 adults CVVHDF
Experiment
KPO4
addedevaluation
when <1.5ofmmol/L
(protocolized)
Pre-post
adding
NaPO4
to
dial & replace
solution
No
change
inbicarb,
calcium,
magnesium,
sodium, gluc, pH
No negative
effects
caused
on
calcium,
pH
0.8 mmol/L, 47 children, solutions contained
Ca++
&
Mg++
2, 24 and 48 hours
No precipitation seen
Less IV PO4 needed
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
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
SOLUTIONS: WATCH FOR ERRORS!
Barletta et al, Pediatr Nephrol, 2006
Soysal et al, Pediatr Nephrol, 2007
Survey: ICU, Nephrology, CRRT
Country where resources dictate need to use PD solution for dialysis
16/31
programs
reported
solution compounding
errors
and NS
+ additives
for replacement
fluid
2 deaths
Many
electrolyte
1 non reported
lethal cardiac
arrest complications: glucose, sodium, acidosis
6 seizures (hypo/hypernatremia)
7 without complications
DIALYSIS AND REPLACEMENT FLUID
RATES: CLEARANCE & DOSE
Clearance mostly a function of:
Dialysis fluid flow rate (Qd)
Replacement fluid flow rate (Qr)
Qd + Qr (CVVHDF)
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
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 ~ 20-40 ml/kg/hour
OR 2 to 2.5 liters/hr/1.73msq.
Urea clearance
~ 30-40 ml/min/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
1 0 KG C H I L D : 3 0 M L / KG / H R “ C L E A R A N C E ”
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
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
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
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
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