Title: Mitchell HOROWitz
1Cardiopulmonary Exercise Testing
2Outline
- Description of CPET
- Who should and who should not get CPET
- When to terminate CPET
- Exercise physiology
- Define terms respiratory exchange ratio,
ventilatory equivalent, heart rate reserve,
breathing reserve, oxygen pulse - Pattern of CPET results COPD vs CHF
3Rationale for Exercise Testing
- Cardiopulmonary measurements obtained at rest may
not estimate functional capacity reliably
4Clinical Exercise Tests
- 6-min walk test
- Submaximal
- Shuttle walk test
- Incremental, maximal, symptom-limited
- Exercise bronchoprovocation
- Exertional oximetry
- Cardiac stress test
- CPET
5Karlman Wasserman
6Coupling of External Ventilation and Cellular
Metabolism
7Adaptations of Wassermans Gears
8General Mechanisms of Exercise Limitation
- Pulmonary
- Ventilatory
- Respiratory muscle dysfunction
- Impaired gas exchange
- Cardiovascular
- Reduced stroke volume
- Abnormal HR response
- Circulatory abnormality
- Blood abnormality
- Peripheral
- Inactivity
- Atrophy
- Neuromuscular dysfunction
- Reduced oxidative capacity of skeletal muscle
- Malnutrition
- Perceptual
- Motivational
- Environmental
9What is CPET?
- Symptom-limited exercise test
- Measure airflow, SpO2, and expired oxygen and
carbon dioxide - Allows calculation of peak oxygen consumption,
anaerobic threshold
10Components of Integrated CPET
- Symptom-limited
- ECG
- HR
- Measure expired gas
- Oxygen consumption
- CO2 production
- Minute ventilation
- SpO2 or PO2
- Perceptual responses
- Breathlessness
- Leg discomfort
11Modified Borg CR-10 Scale
12Indications for CPET
- Evaluation of dyspnea
- Distinguish cardiac vs pulmonary vs peripheral
limitation vs other - Detection of exercise-induced bronchoconstriction
- Detection of exertional desaturation
- Pulmonary rehabilitation
- Exercise intensity/prescription
- Response to participation
- Pre-op evaluation and risk stratification
- Prognostication of life expectancy
- Disability determination
- Fitness evaluation
- Diagnosis
- Assess response to therapy
13Mortality in CF Patients
- Nixon et al NEJM 327 1785 1992.
- Followed 109 patients with CF for 8 yrs from CPET
- Peak VO2 gt81 predicted 83 survival
- Peak VO2 59-81 predicted 51 survival
- Peak VO2 lt59 predicted 28 survival
14Mortality in CHF Patients
- Mancini et al Circulation 83 778 1991.
- Peak VO2 gt14 ml/kg/min
- 1-yr survival 94
- 2-yr survival 84
- Peak VO2 14 ml/kg/min
- 1-yr survival 47
- 2-yr survival 32
15CPET to Predict Risk of Lung Resection in Lung
Cancer
- Lim et al Thorax 65iii1, 2010
- Alberts et al Chest 1321s, 2007
- Balady et al Circulation 122191, 2010
- Peak VO2 gt15 ml/kg/min
- No significant increased risk of complications or
death - Peak VO2 lt15 ml/kg/min
- Increased risk of complications and death
- Peak VO2 lt10 ml/kg/min
- 40-50 mortality
- Consider non-surgical management
-
16Absolute Contraindications to CPET
- Acute MI
- Unstable angina
- Unstable arrhythmia
- Acute endocarditis, myocarditis, pericarditis
- Syncope
- Severe, symptomatic AS
- Uncontrolled CHF
- Acute PE, DVT
- Respiratory failure
- Uncontrolled asthma
- SpO2 lt88 on RA
- Acute significant non-cardiopulmonary disorder
that may affect or be adversely affected by
exercise - Significant psychiatric/cognitive impairment
limiting cooperation
17Relative Contraindications to CPET
- Left main or 3-V CAD
- Severe arterial HTN (gt200/120)
- Significant pulmonary HTN
- Tachyarrhythmia, bradyarrhythmia
- High degree AV block
- Hypertrophic cardiomyopathy
- Electrolyte abnormality
- Moderate stenotic valvular heart disease
- Advanced or complicated pregnancy
- Orthopedic impairment
18Indications for Early Exercise Termination
- Patient request
- Ischemic ECG changes
- 2 mm ST depression
- Chest pain suggestive of ischemia
- Significant ectopy
- 2nd or 3rd degree heart block
- Bpsys gt240-250, Bpdias gt110-120
- Fall in BPsys gt20 mmHg
- SpO2 lt81-85
- Dizziness, faintness
- Onset confusion
- Onset pallor
19CPET Measurements
- Work
- VO2
- VCO2
- AT
- HR
- ECG
- BP
- R
- SpO2
- ABG
- Lactate
- CP
- Dyspnea
- Leg fatigue
20Exercise Modality
- Advantages of cycle ergometer
- Cheaper
- Safer
- Less danger of fall/injury
- Can stop anytime
- Direct power calculation
- Independent of weight
- Holding bars has no effect
- Little training needed
- Easier BP recording, blood draw
- Requires less space
- Less noise
- Advantages of treadmill
- Attain higher VO2
- More functional
21Incremental vs Ramp Exercise Test Protocol
WORK
WORK
TIME
TIME
22Physiology and Chemistry
- Slow vs fast twitch fibers
- Buffering of lactic acid by bicarbonate
- CO2 production from carbonic acid
- Respiratory exchange ratio
- Ventilatory equivalent of oxygen
- Ventilatory equivalent of carbon dioxide
- Graphical determination of AT
- Fick Equation
- Oxygen pulse
23Properties of Skeletal Muscle Fibers
- Red Slow twitch Type I
- Sustained activity
- High mitochondrial density
- Metabolize glucose aerobically
- 1 glucose yields 36 ATP
- Rapid recovery
- White Fast twitch Type II
- Rapid burst exercise
- Few mitochondria
- Metabolize glucose anaerobically
- 1 glucose yields
- 2 ATP and 2 lactic acid
- Slow recovery
24Lactic Acid is Buffered by Bicarbonate
- Lactic acid HCO3 ? H2CO3 Lactate
- ?
- H2O CO2
25Respiratory Exchange Ratio
- RER CO2 produced / O2 consumed
- VCO2 / VO2
-
26Ventilatory Equivalents
- Ventilatory equivalent for carbon dioxide
Minute ventilation / VCO2 - Efficiency of ventilation
- Liters of ventilation to eliminate 1 L of CO2
- Ventilatory equivalent for oxygen
Minute ventilation / VO2 - Liters of ventilation per L of oxygen uptake
27Relationship of AT to RER and Ventilatory Equiv
for O2
- Below the anaerobic threshold, with carbohydrate
metabolism, RER1 (CO2 production O2
consumption). - Above the anaerobic threshold, lactic acid is
generated. - Lactic acid is buffered by bicarbonate to produce
lactate, water, and carbon dioxide. - Above the anaerobic threshold, RER gt1 (CO2
production gt O2 consumption). - Carbon dioxide regulates ventilation.
- Ventilation will disproportionately increase at
lactate threshold to eliminate excess CO2. - Increase in ventilatory equivalent for oxygen
demarcates the anaerobic threshold.
28Lactate Threshold
29Determination of AT from RER Plot (V Slope Method)
30Determination of AT from Ventilatory Equivalent
Plot
31Wasserman 9-Panel Plot
32Oxygen Consumption Fick Equation
- Fick Equation
- Q VO2 / C(a-v)O2
- VO2 Q x C(a-v)O2
- VO2 SV x HR x C(a-v)O2
Arterial oxygen content (1.34)(SaO2)(Hgb) V
enous oxygen content (1.34)(SvO2)(Hgb)
Heart disease Lung disease Muscle
disease Deconditioning
Anemia Lung disease (low SaO2)
Heart disease
33Oxygen Pulse
- Oxygen Pulse
- . . .the amount of oxygen consumed by the body
from the blood of one systolic discharge of the
heart. - Henderson and Prince
- Am J Physiol 35106, 1914
- Oxygen Pulse VO2 / HR
- Fick Equation
- VO2 SV x HR x C(a-v)O2
- VO2/HR SV x C(a-v)O2
- Oxygen Pulse SV
34Interpretation of CPET
- Peak oxygen consumption
- Peak HR
- Peak work
- Peak ventilation
- Anaerobic threshold
- Heart rate reserve
- Breathing reserve
35Heart Rate Reserve
- Comparison of actual peak HR and predicted peak
HR - (1 Actual/Predicted) x 100
- Normal lt15
36Estimation of Predicted Peak HR
- 220 age
- For age 40 220 - 40 180
- For age 70 220 - 70 150
- 210 (age x 0.65)
- For age 40 210 - (40 x 0.65) 184
- For age 70 210 - (70 x 0.65) 164
37Breathing Reserve
- Comparison of actual peak ventilation and
predicted peak ventilation - Predicted peak ventilation MVV, or FEV1 x 35
- (1 Actual/Predicted) x 100
- Normal gt30
38Comparison CPET results
- Normal CHF COPD
- Predicted Peak HR 150 150 150
- Peak HR 150 140 120
- MVV 100 100 50
- Peak VO2 2.0 1.2 1.2
- AT 1.0 0.6 1.0
- Peak VE 60 40 49
- Breathing Reserve 40 60 2
- HR Reserve 0 7 20
- Borg Breathlessness 5 4 8
- Borg Leg Discomfort 8 8 5
39Cardiac vs Pulmonary Limitation
- Heart Disease
- Breathing reserve gt30
- Heart rate reserve lt15
- Pulmonary Disease
- Breathing reserve lt30
- Heart rate reserve gt15
40CPET Interpretation
- Peak VO2 HRR BR AT/VO2max
A-a - Normal gt80 lt15 gt30 gt40 normal
- Heart disease lt80 lt15 gt30 lt40
normal - Pulm vasc dis lt80 lt15 gt30 lt40
increased - Pulm mech dis lt80 gt15 lt30 gt40
increased - Deconditioning lt80 gt15 gt30 gt40
normal
41SUMMARY
- Cardiopulmonary measurements obtained at rest may
not estimate functional capacity reliably. - CPET includes the measurement of expired oxygen
and carbon dioxide. - The Borg scale is a validated instrument for
measurement of perceptual responses. - CPET may assist in pre-op evaluation and risk
stratification, prognostication of life
expectancy, and disability determination.
42SUMMARY
- Cycle ergometer permits direct power calculation.
- Peak VO2 is higher on treadmill than cycle
ergometer. - Peak VO2 may be lower than VO2max.
- Absolute contraindications to CPET include
unstable cardiac disease and SpO2 lt88 on RA. - Fall in BPsys gt20 mmHg is an indication to
terminate CPET. - 1 glucose yields 36 ATP in slow twitch fiber, and
2 ATP 2 lactic acid in fast twitch fiber. - RER CO2 produced / O2 consumed
43SUMMARY
- Above the anaerobic threshold, CO2 production
exceeds O2 consumption. - Ventilation will disproportionately increase at
lactate threshold to eliminate excess CO2. - AT may be determined graphically from V slope
method or from ventilatory equivalent for CO2. - Derived from the Fick equation, Oxygen Pulse
VO2 / HR, and is proportional to stroke volume. - In pure heart disease, BR is gt30 and HRR lt15.
- In pure pulmonary disease, BR is lt30 and HRR
gt15.