Cardiopulmonary Exercise
Testing (CPET, CPX)
Jeff Pretto DocHlthSc, B AppSc, GDBI, CRFS
Scientific Director
Department of Respiratory & Sleep Medicine
John Hunter Hospital, Newcastle, New South Wales, Australia
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CPET – Equipment
•
Ergometer
 Cycle (electronically braked)
 Treadmill (speed & grade adjustment)
•
Metabolic analysis system
•
Pulse oximeter, ECG recorder
•
Emergency Trolley (incl. defibrillator,
emergency drugs)
•
Total ~$ 80-100k
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Cycle or Treadmill?
* Zeballos and Weismann. Clinical exercise testing. WB Saunders,
Karger, USA, 2002. ISBN-10: 3805572980
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CPET - Exercise Format
• Incremental workload
 Bruce / Ellestad / Naughton / Balke / Astrand
protocols (specifically for treadmill)
 Fixed increment per minute (Winc of 5W – 30W)
 Aim to achieve ~10 minute test duration
 Winc can be determined from baseline pulmonary
function*
* Pretto et al. Using baseline respiratory function data to optimise
cycle exercise test duration. Respirology 2001, 6: 287-91
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Metabolic Equivalents
(NSW Department of Health. 2006. NSW Chronic Care Program)
5–10
15–35
40-60
60–80
80–100
100–120
120-150
150–170
Approx. Workload (Watts)
170–190
200+
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CPET Report
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CPET Report
End-of-test symptoms
Reason for test
Maximum values
(compared with predicted)
Efficiency of ventilation
HR / SpO2 responses
Interpretative comment
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Normal response to exercise
• Limited by cardiac, rather than respiratory
factors
- Approach predicted HRmax
- Some ventilatory reserve (~30%)
• Adequate Wmax, VO2peak, oxygenation
• Highly trained athletes:
 May have evidence of respiratory limitation
 May develop hypoxaemia
 Elevated Wmax, VO2peak
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VE – VO2 Graph
Indicates efficiency of O2 extraction
120
VE
(L/min)
Normal range
90
60
Normal
30
Wasted ventilation
1.0
2.0
3.0
VO2 (L/min)
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COPD
•
•
•
Exercise intolerance multi-factorial:
-
Reduced ventilatory capacity
-
Peripheral muscle dysfunction
-
O2 transport abnormalities
-
Exertional symptoms
-
Development of dynamic hyperinflation
Primary findings:
-
Increased ventilatory requirements (wasted ventilation)
-
Reduced Wmax
-
Little ventilatory reserve
Other findings:
- Arterial oxygen desaturation (larger SpO2 observed during walking than
cycling)*
*Turner et al: Physiologic responses to incremental and self-paced
exercise in COPD. Chest, 2004, 126: 766-73
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COPD: Typical end test values
Measured
% Pred Max.
HRmax
128 bpm
65%
VEmax
45 L/min
115% (of 35×FEV1)
VO2max
1.41 L/min
60%
Wmax
70W
54%
Borg scores: Leg fatigue:4, Dyspnoea: 8.5
“Evidence of ventilatory limitation, with some cardiac
reserve. Maximal workload achieved was significantly
reduced below the predicted value.”
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Interstitial Lung Disease
• Increased ventilatory response (wasted ventilation)
• Shallow rapid breathing (low VT, high RR)
• Arterial desaturation
 Correlates with disease severity better than other PFTs
 Provides most useful prognostic indicator
 Predicts survival
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Typical CPX response in ILD*
• Reduced maximal workload (Wmax)
• Increased ventilatory response with
reduced ventilatory reserve (VEmax/MVV)
• Increased breathing frequency
• Fall in PaO2, SpO2
• Typically, elevated HR-VO2 relationship
* Lama et al,Clin Chest Med, 2004, 25:435-53
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Typical CPX response in ILD
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Cardiac Response
Cardiac Output (CO) = Stroke volume (SV) × HR
 if SV cannot , CO can only increase by rises in HR
 HR response is steeper
Normal
Heart disease
200
HR
(beats/min)
150
SV
(ml)
150
100
100
50
50
1.0
2.0
3.0
VO2 (L/min)
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Heart rate response
Athlete
Deconditioned (unfit)
Cardiac disease
HR
(beats/min)
Normal range
200
150
100
50
1.0
2.0
3.0
VO2 (L/min)
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CPET Response – 50yo competitive cyclist
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Oxygen Pulse
= VO2 (ml/min) / HR (bpm)
= mls of O2 taken up per heart beat
= non-invasive estimate of stroke volume
O2 pulse
(ml/beat)
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Normal
Pulm. hypertension
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IHD
1.0
2.0
3.0
VO2 (L/min)
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Mrs PL. 61yo female, asthma, SOBOE
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Mrs PL. 61yo female, asthma, SOBOE
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Mrs PL. 61yo female, asthma, SOBOE
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Mrs PL. 61yo female, asthma, SOBOE
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Mrs PL. 61yo female, asthma, SOBOE
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Mrs PL. 61yo female, asthma, SOBOE
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18yo male, Fontan circulation
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18yo male, Fontan circulation
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52yo female, known airways disease,
disproportionate SOBOE
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47yo male, difficult asthma, SOBOE
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Summary
•
Exercise testing rarely provides a definitive diagnosis
•
Specific patterns of response are characteristic of different disease
states
•
CPET is particularly useful in the following applications:
 Determination and quantification of functional impairment or capacity
 Functional evaluation of unexplained exertional dyspnoea and/or
exercise intolerance
 Differentiation between cardiac, pulmonary or other causes of dyspnoea
and/or exercise limitation
 Functional and prognostic evaluation in known pulmonary disease
 Pre-operative evaluation of cardiopulmonary fitness and suitability for
surgery
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Further reading
•
ERS Task Force: Recommendations on the use of exercise testing
in clinical practice. Eur Respir J 2007, 29: 185-209
- Evidence-based recommendations on the clinical use of
CPET.
•
Wasserman et al. Principles of Exercise Testing and
Interpretation. 4th ed.Lippincott Williams & Wilkins. Philadelphia, 2005
ISBN-10: 0781748763
- Excellent reference for physiology, testing techniques,
interpretation and multiple case studies.
•
Hancox & Whyte. McGraw Hill’s Pocket Guide to Lung Function
Tests. McGraw Hill, Sydney 2001. ISBN-10: 0074715968
- Concise pocketbook guide to lung function tests with good
summary of exercise testing
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Patterns of response in different diseases*
* ERS Taskforce, ERJ, 1997, 10: 2662 - 99
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The Anaerobic Threshold
• At low workloads, energy source is predominantly
aerobic
• As exercise intensity increases, ventilation increases
(linearly) to meet  oxygen demand
• Eventually, a point is reached where anaerobic
metabolism is required to perform extra work
• By-product is lactic acid  acidaemia  offload CO2
to buffer  ventilation relative to oxygen demand
• Results in inflection in the VE/VO2 relationship
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