predicting fluid response in the icu
TRANSCRIPT
Predicting fluid responsePredicting fluid responsein the critically illin the critically ill
Dr. Andrew FergusonDr. Andrew Ferguson
Consultant in Anaesthesia & Intensive Care MedicineConsultant in Anaesthesia & Intensive Care Medicine
Craigavon Area HospitalCraigavon Area Hospital
Approach to shockApproach to shock
Fluid challenge central to therapyFluid challenge central to therapy +/- CVP (and/or PA) monitoring+/- CVP (and/or PA) monitoring Repeat if CVP/PAWP still lowRepeat if CVP/PAWP still low Stop if CVP/PAWP goes highStop if CVP/PAWP goes high Surrogate markers for COSurrogate markers for CO
– LactateLactate
– SvOSvO22
So what’s the problem?So what’s the problem?
? validity of CVP as end-point? validity of CVP as end-point ? validity of PAWP as end-point? validity of PAWP as end-point Preload-SV relationship unknownPreload-SV relationship unknown Only 50% of patients fluid-responsiveOnly 50% of patients fluid-responsive Excess fluid problemsExcess fluid problems
– Interstitial fluid excessInterstitial fluid excess– Worsened gas exchangeWorsened gas exchange– Limitation of oxygen diffusionLimitation of oxygen diffusion
Variability of fluid response ratesVariability of fluid response rates
Michard (Chest 2002; 121: 2000-2008)
Preload does Preload does notnot guarantee response guarantee response
To be a fluid responder, To be a fluid responder, bothbothventricles must be on ascendingventricles must be on ascendingportion of Frank-Starling curveportion of Frank-Starling curve
Response depends on contractility and diastolic function as well as load
Common measures used to indicate Common measures used to indicate likelihood of responselikelihood of response
CVPCVP PAWPPAWP RVEDV (thermodilution)RVEDV (thermodilution) LVEDA (echo)LVEDA (echo)
R2 = 0.2
In spontaneous resp. a fall > 1 mmHg in RAP has positive predictivevalue of 77-84% and negative predictive value of 81-93% for response
R2 = 0.33
ROC curve minimal correlation
They don’t workThey don’t work------
what next??what next??
BP change relates to SV changeBP change relates to SV change
Cardio-pulmonary interactionsCardio-pulmonary interactions
Changes in SV, PP, SBP with positive pressure ventilation
Increased pleural pressureIncreased pleural pressure
RV preload fallsRV preload falls LV afterload fallsLV afterload falls
Increased transpulmonary pressureIncreased transpulmonary pressure
RV afterload increasesRV afterload increases LV preload increased byalveolar vessel squeeze
LV preload increased byalveolar vessel squeeze
Decreased RVSV Increased LVSV
Inspiratory decrease in RVSV
Expiratory decrease in LVSV
Expiratory decrease in LV preload
Pulmonary transit time
Stroke volume variation and LVEDPStroke volume variation and LVEDP
Potential toolsPotential tools
Stroke volume variationStroke volume variation Systolic pressure variationSystolic pressure variation Pulse pressure variationPulse pressure variation Peak aortic blood flow velocity variationPeak aortic blood flow velocity variation
Systolic Pressure VariationSystolic Pressure Variation
down is theimportant one forfluid response
Systolic pressure variationSystolic pressure variation
SP as indicator of fluid responseSP as indicator of fluid response
Pulse pressure variationPulse pressure variation
PP as indicator of fluid responsePP as indicator of fluid response
Measures of Measures of response toresponse to
volume volume
Predictive valuesPredictive valuesStudyStudy No. of No. of
patientspatientsMeasureMeasure ThresholdThreshold Positive Positive
pred. val.pred. val.Negative Negative pred. val.pred. val.
MagderMagder 3333 RAPRAP
(SPONT)(SPONT)
1 mmHg1 mmHg 8484 9393
TavernierTavernier 3535 DownDown 5 mmHg5 mmHg 9595 9393
Magder & Magder & LagonidisLagonidis
2929 RAPRAP
(SPONT)(SPONT)
1 mmHg1 mmHg 7777 8181
MichardMichard 4040 PPPP 13%13% 9494 9696
FeisselFeissel 1919 VPeakVPeak 12%12% 9191 100100
Problems withProblems with PP and PP and SVSV
Equipment not universalEquipment not universal Need sinus rhythmNeed sinus rhythm False positive in severe abdominal False positive in severe abdominal
distensiondistension
Normal valuesNormal values
PPPP 13%13% SPV SPV downdown 5%5% Vpeak Vpeak (aortic blood flow velocity)(aortic blood flow velocity) 12%12% SVSV 10%10%
ConclusionsConclusions
Conventional measures often not validConventional measures often not valid New and accurate measures availableNew and accurate measures available Consider passive leg raising!Consider passive leg raising! Know cardio-pulmonary interactionsKnow cardio-pulmonary interactions