Complications of Pediatric Complications of Pediatric CRRTCRRT

Theresa A. Mottes RNTheresa A. Mottes RN

Pediatric Dialysis/Research Pediatric Dialysis/Research NurseNurse

C.S. Mott Children’s HospitalC.S. Mott Children’s Hospital

University of Michigan University of Michigan

Complications of Pediatric Complications of Pediatric CRRTCRRT

Temperature instabilityTemperature instability

Hemodynamic instability Hemodynamic instability

Anticoagulation RiskAnticoagulation Risk

Circuit/Access ComplicationsCircuit/Access Complications

Factors effecting Factors effecting hemodynamicshemodynamics

Patient Volume StatusPatient Volume Status• Ultrafiltration RateUltrafiltration Rate

– patients hemodynamicpatients hemodynamic– typically vasopressor dependenttypically vasopressor dependent

– patients intravascular volume patients intravascular volume

• Ultrafiltration RateUltrafiltration Rate– 1-2ml/kg/hour net ultrafiltration1-2ml/kg/hour net ultrafiltration– absolute necessity to control ultrafiltrationabsolute necessity to control ultrafiltration– error of accurate ultrafiltration monitoring error of accurate ultrafiltration monitoring

RESULTSRESULTS(Smoyer et al, CRRT 1997)(Smoyer et al, CRRT 1997)

0 100 200 300 400 500 600 700 800 900 1000-4

-3

-2

-1

0

1

2

3

4

0 100 200 300 400 500 600 700 800 900 1000

Dialysate

Ultrafiltrate

IV Pump Flow Rate (ml/hr)

% E

rror

Trilogy Pump: Accuracy over Range of Flow Rates

Ultrafiltration accuracyUltrafiltration accuracy2.8 kg infant on PRISMA2.8 kg infant on PRISMA

0102030405060708090

100

1 2 3 4 avg/4hrs

Prescribed net U/FActual net U/F

Ccs

/hr

Hour of Therapy

PrescriptionBFR 30 mls/minDx FR 300 mls/hr

Factors effecting Factors effecting hemodynamicshemodynamics

What now?What now?• Hourly assessment of Intake and Hourly assessment of Intake and

Output Output • Hourly Ultrafiltration calculationsHourly Ultrafiltration calculations

– adjusting for pump erroradjusting for pump error

• Accurate measuring of UltrafiltrationAccurate measuring of Ultrafiltration• Close monitoring of hemodynamicsClose monitoring of hemodynamics• Accurate daily weightAccurate daily weight

Factors effecting Factors effecting hemodynamicshemodynamics

Calculation for Pump ErrorCalculation for Pump Error

Factors effecting Factors effecting hemodynamicshemodynamics

Vasopressor clearance Vasopressor clearance • Vasopressor agents all have in Vasopressor agents all have in

common a small molecular weight common a small molecular weight and minimal protein bindingand minimal protein binding– EpinephrineEpinephrine– NorepinephrineNorepinephrine– DopamineDopamine– DobutamineDobutamine

Factors effecting Factors effecting hemodynamicshemodynamics

Vasopressors Vasopressors • Due to proximity of infusionDue to proximity of infusion

– be aware of infusing vasopressor agents be aware of infusing vasopressor agents in immediate proximity to the “arterial” in immediate proximity to the “arterial” port of the hemofiltration machineport of the hemofiltration machine

– potential for recirculation potential for recirculation – effects delivery and clearanceeffects delivery and clearance

Intravascular Blood Intravascular Blood VolumeVolume

<< 10 kg 80 ml/kg 10 kg 80 ml/kg• e.g. 8 kg infant = 640 ml intravascular e.g. 8 kg infant = 640 ml intravascular

volumevolume > 10 kg 70 ml/kg> 10 kg 70 ml/kg

• e.g. 20 kg child has 1.4 liter intravascular e.g. 20 kg child has 1.4 liter intravascular volumeBloodvolumeBlood

Priming Hemofiltration CircuitPriming Hemofiltration Circuit• Recommended when circuit volume > 10 Recommended when circuit volume > 10

% of patients intravascular blood volume% of patients intravascular blood volume

AnticoagulationAnticoagulation

HeparinHeparin

CitrateCitrate

NoneNone

Circuit ComplicationsCircuit Complications

Circuit ClottingCircuit Clotting• Inability to ultrafiltrate desired Inability to ultrafiltrate desired

amountamount• Increasing Access/Return PressureIncreasing Access/Return Pressure• Inadequate clearancesInadequate clearances• Observe clotting in filter/ tubingObserve clotting in filter/ tubing

RRT PreHFHCT

Post HFHCT

Delta Hctchange

CVVHPre-filterReplacement

27% 44% 62%

CVVHPost-filterReplacement

36% 46% 27%

CVVHD 32% 34% 6%

Clotting with CVVH vs Clotting with CVVH vs CVVHDCVVHD(Mottes et al, CRRT 1999)(Mottes et al, CRRT 1999)

Flow RatesFlow Rates

BloodBlood• 5-10 ml/kg/min keeping venous 5-10 ml/kg/min keeping venous

pressure under 200 mm Hgpressure under 200 mm Hg Dialysate/Replacement fluidDialysate/Replacement fluid

• 2 liters/1.73 m2 liters/1.73 m22/hr/hr– (extrapolation of adult data)(extrapolation of adult data)

Access ComplicationsAccess Complications

What is the correct access?What is the correct access?• One that worksOne that works

In Flow DifficultiesIn Flow Difficulties

Obstruction or clot on the return lineObstruction or clot on the return line• high intrathoracic pressure with HIFIhigh intrathoracic pressure with HIFI• up against the vessel wallup against the vessel wall

Clamp on inflowClamp on inflow Access kinked at skin siteAccess kinked at skin site Consider reversing or changing Consider reversing or changing

accessaccess

Out Flow DifficultiesOut Flow Difficulties

Clamp on access/”arterial” lineClamp on access/”arterial” line Inflow port up against vessel wallInflow port up against vessel wall Patient “dry” eg with femoral sitePatient “dry” eg with femoral site High of blood flow requirements High of blood flow requirements

based upon flow ability of access based upon flow ability of access Consider Consider

• reverse flow, change access, decrease reverse flow, change access, decrease blood flow ratesblood flow rates