CPEXCPETMetabolic testing Sathish Parasuraman Cardiovascular research fellow University of East Anglia When to do it How to do it How do you interpret it Some examples When to do it ID: 913538
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Slide1
Interpreting the cardiopulmonary exercise test[CPEX/CPET/Metabolic testing]
Sathish Parasuraman
Cardio-vascular research fellow
University of East Anglia
Slide2When to do itHow to do it?How do you interpret it?
Some examples
Slide3When to do it?When you want the whole picture of how a disease is affecting a person Eg. A young sarcoid / young congenital heart disease patient, you want to review annually2. Patient with exercise limitation ?due to lung ?due to heart3. Fitness for surgeryAugust 16, 2016
Slide4Quiz!When the presenting complaint is exercise limitation, what is the best test to do?Exercise test Coronary angiogramContrast CT scan of chestBlood testsAugust 16, 2016
Slide5August 16, 2016
Slide6What can CPEX tell you?Exercise time/ECG/BP/Heart rateOxygen consumption at peak exerciseWhen does the anaerobic metabolism begin?Oxygen saturations at rest and peak exerciseAugust 16, 2016
Slide7Terminologies in CPEXVE – “minute ventilation” (Litres) = Respiratory frequency * Tidal volume VO2 – Oxygen uptake (ml/kg/min)Peak VO2 – Oxygen uptake at peak exercise (ml/kg/min)VCO2 – Carbon dioxide output (ml/kg/min)AT – Anaerobic Threshold, when anaerobic metabolism supplements exerciseR – Gas exchange ration = VCO2/VO2
August 16, 2016
Ignore V prefix
You know most terms
Slide8Determinants of exercise capacityAugust 16, 2016
Slide9Energy supply during exercise Hydrolysis of phosphocreatinineOxidation of glucose and fatty
acids
Anaerobic metabolism
August 16, 2016
1
st
minute
2
nd
to
10
th
minute
7
th
to 10
th
minute
Slide10CO2 Production during exerciseGlucose + 10 O2 10 CO2+ H2O + EnergyPalmitate + 10 O2 7 CO2 + H2O + EnergyAnaerobic Glycolysis Lactate + Energy
CO2
Slide11oxygen and carbon-dioxide kineticsAugust 16, 2016
CO2
O2
Time
O2, CO2
P VO2
Peak VO
2
< 85%
Heart Problem
Lung problem
Blood problem
Muscle problem
Deconditioning
Slide12Respiratory Exchange RatioRER or simply “R”RER or R=VCO2/VO2Climbs steadily after ATAt peak exercise it is >1Anaerobic Threshold or Lactate ThresholdAugust 16, 2016
Slide13Anaerobic thresholdAugust 16, 2016
CO2
O2
Time
O2, CO2
Heart Problem
Lung problem
Blood problem
Muscle problem
Deconditioning
Anaerobic threshold
Slide14VO2 at anaerobic threshold and O2 pulseVO2 at Anaerobic thresholdNormal VO2 @ AT / Predicted PVO2 >40%If VO2@AT/pred PVO2 <40% suggests cardiac limitation O2 pulse = VO2/heart rate
Surrogate for stroke volume
A fall on incremental exercise indicates cardiac pathology
VO2 at AT/
pred
PVO2
=15.69/38.75
=40%
Slide15August 16, 2016So far..Low Peak VO2 indicates a pathologyRespiratory Exchange Ratio (CO2/O2) >1.15 suggests maximal testAnaerobic metabolism sets in early in heart failure (<40% of predicted peak VO2)
Oxygen pulse is a surrogate for stroke volume
Slide16VentilationVentilation is a product of tidal volume and respiratory frequencyVE = tidal volume X resp. freq.During progressive exercise, dead space decreases, tidal volume increasesRespiratory frequency increases, later, but rarely beyond 50 breaths/minuteAugust 16, 2016
Slide17Maximum voluntary ventilation & Breathing reserveMaximum Voluntary Ventilation – The upper limit of body’s ability to ventilate the lungsMaximum Voluntary Ventilation(MVV) = FEV1*40Breathing reserve = MVV - VE (Ventilation) at peak exercise
August 16, 2016
Heart Problem
Lung problem
Blood problem
Muscle problem
Deconditioning
Breathing reserve<11 L
Slide18Desaturation during exercise Desaturation suggests a lung problemOxygen saturations do not fall markedly until the PO2 is <8 kPaIf saturation falls >5%, it suggests abnormal exercise induced hypoxemiaAugust 16, 2016
Slide19Ventilatory efficiencyVentilatory efficiency of elimination CO2Measured from the beginning of exercise to anaerobic thresholdHigh VE/VCO2 slope indicates ventilation-perfusion mismatchAugust 16, 2016Heart ProblemLung problem
Blood problem
Muscle problem
Deconditioning
VE-VCO
2
slope <30
degrees
Slope 63
Slope 34
Slope 23
Slide20So far…Desaturation indicates lung problemLow breathing reserve indicates lung problemHigh VE-VCO2 slope indicates ventilation-perfusion mismatchAugust 16, 2016
Slide21August 16, 2016Truly limitedNot the lungs
V/Q mismatch
and early anaerobic met.
Lung limitation
High VE/VCO2 slope
Slide22General considerationsA protocol is chosen, so patient lasts no more than 8-12 minutesReason for stopping could give a clueLeg fatigue- cardiacLeg pain-peripheral vascular diseaseChest pain-anginaBreathlessness-lung
Slide2364 mRecent diagnosis of prostrate Ca, receiving local radiationFeels tired and breathlessInconclusive treadmill ETT
VO2 at AT/
Pred
PVO2
= 18.27/24.8
= 74%
Slide24August 16, 201664 mRecent diagnosis of prostrate Ca, receiving local radiationFeels tired and breathlessInconclusive treadmill ETTReportNormal PVO2Normal VO2 at ATNormal VE/VCO2 slopeBorderline breathing reserveNo desaturation during exerciseAbrupt flattening of VO2, VO2 pulse towards peak exercise, with unexpected raise on recoveryImpCoronary ischemia
Slide25Coronary ischemiaAugust 16, 2016
Slide26FH of HOCMIVS of 13 mmFit & well man
Slide27FH of HOCMIVS of 12 mmAsymptomaticReportNormal PVO2Normal VO2 at ATNormal spirometry, breathing reserve & saturationsNormal VE-VCO2 slopeImpNo exercise limitation
Slide28A difficult case67 year old man, breathlessX1 yearClubbedCT chest- ground glass opacification, normal LV systolic functionEx- smoker X 40 PYAbnormal spirometry with reduced DLCOAugust 16, 2016
Slide29A difficult caseTreadmill CPEX for 7 minutes, stopped due to breathlessnessPVO2 of 82% of predictedR of 1.29VO2 at AT is 53% of predicted PVO2VE/VCO2 slope is 41 @ RCPBreathing reserve is 6, maximal respiratory frequency was 40
Slide30August 16, 2016Oxygen saturation Increased on exercise!suspect this is primary lung issuecoexisting ischemiaWhy the PaO2 increases on exercise?Potential right to left shunt which decreased during exerciseie-pulmonary shunt
Slide31August 16, 201643 m, BreathlessHT, DM, congenital blindnessMild LV hypertrophy, normal angiogram, Normal spirometry
Slide32Slide33August 16, 2016
10 mins recovery
Ph
7.21
20 mins recovery
7.27
PH 7.19
Report
Likely mitochondrial myopathy
Slide34Another difficult case19 FemaleBeing investigated for breathlessness/tirednessNormal haemoglobin, echocardiogramNormal FEV1, FVC, reduced DLCO (65%)Normal CT (plain) chest
Slide35August 16, 201619 f, breathless. Slightly reduced DLCO, normal echo & plain CT
Low PVO2
Low VO2 at
AT
Normal breathing reserve
Slide36August 16, 2016ReportLow PVO2Low VO2 at ATNormal VE-VCO2Saturations at peak exercise unclearVery high respiratory frequencyImp/DDMitochondrial myopathyLeft to right shunt
Slide37Evidence base for CPEXHeart failure patients with PVO2 < 12 ml/kg/min indicate poor prognosis and are candidates for heart transplantationIn lung cancer- a PVO2 of <15 ml/kg/min predicts high perioperative riskIn major abdominal and vascular surgeries, VO2 at AT of <11ml/kg/min predicts high cardiovascular risk and poor survival
August 16, 2016
Slide38August 16, 2016Thank you!