Cardiopulmonary Exercise Testing (CPET)

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Cardiopulmonary Exercise Testing (CPET)

• Pathophysiologic Limitations and Exercise
  Prescription
• Dr. Scotty Butcher, PhD, BSc(PT), CSCS, RCEP
• University of Saskatchewan
• scotty.butcher_at_usask.ca
• No conflicts of interest

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Overview

• Overview of exercise limitations
• Cardiovascular limitations
• Metabolic limitations
• Ventilatory limitations
• Clinical exercise prescription

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CPET Interpretation

• Was the test maximal?
• Was RER 1.1?
• HR gt 90 predicted max?
• Patient exhaustion?
• Was there a plateau in VO2?
• Dyspnea score gt5?
• Was there evidence of a ventilatory limitation
• (i.e. Max exercise VE Predicted MVV)?

STEP 1.
What was the exercise limitation(s)?
STEP 2.
Other 1. Leg/Back Pain 2. Cardiac Concern
(i.e. ST depression etc) 3. HR lt max predicted
4. RQ lt 1.1 5. Dyspnea score lt5

• Cardiovascular
• HR max predicted
• RQ 1.1
• Exhaustion
• Max VE lt Pred MVV
• Dyspnea score gt5
• O2pulse lt90 pred

• Pulmonary
• Max VE Pred MVV
• Exp flow limitation
• Hyperinflation
• SpO2 lt 88
• HR lt max predicted
• RQ lt 1.1
• Dyspnea score gt5

STEP 3.
Pathological or Physiological?
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PHYSIOLOGIC EXERCISE AND ACTIVITY LIMITATIONS

• Cardiac/Cardiovascular
• Metabolic and/or muscle
• Fatigue
• Strength/Power/Endurance
• Ventilation
• ? Ventilatory Requirement /or
• ? Ventilatory Capacity
• Tidal volume /or flow constraint

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Cardiovascular Limitations

• May be normal
• Heart rate gt 90 of predicted maximum
• O2pulse indirect marker of SV
• will vary with varying fitness
• Associated with
• Metabolic Limitations
• (Near) Maximal patient effort

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Metabolic Limitations

• Respiratory exchange ratio (RER) VCO2/VO2
• RER gt 1.10
• Indication of impending muscle fatigue
• VO2 and work rate should NOT be used to determine
  a maximal response
• will vary with varying fitness

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Respiratory Limitations

• Gas exchange limitations
• Exercise-induced hypoxemia
• Ventilation limitations

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Exercise-induced hypoxemia

• Decrease in SPO2 gt 4 considered clinically
  significant
• Most testing centers will allow a decrease to 80
  86 before stopping testing
• Decrease in SPO2 contributes to exercise
  intolerance, but is not by itself usually a
  limiting factor

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Respiratory Limitations

• Gas exchange limitations
• Exercise induced hypoxemia
• Ventilation limitations
• Ventilatory requirements approach capacity
• Reduced capacity?
• Increased requirements?

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Ventilatory Reserve in Lung/Airways Disease
Predicted Maximum Ventilation (MVV) (35 x FEV1)
FEV1 1s forced expired volume
Should be 30 VE reserve
.
.
VE
.
VCO2
Exercise Intensity
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EXERCISE FLOW-VOLUME IN COPD
Limitation on ventilation (tidal volume and flow
constraint)
Healthy
COPD
Flow
Volume
Why is breathing at high lung volumes such a
problem?
? work of breathing
EELV
Dynamic Hyperinflation
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Ventilatory Reserve in Athletes
Predicted Maximum Ventilation (MVV) (35 x FEV1)
FEV1 1s forced expired volume
Should be 30 VE reserve
.
.
VE
.
VCO2
Exercise Intensity
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WHEN DEMAND EXCEEDS CAPACITY
Limitation on ventilation (tidal volume and flow
constraint)
Flow
Volume
Why is breathing at high lung volumes such a
problem?
? work of breathing
EELV
EILV
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Elite Male Athlete
Johnson et al. 1991
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AGE
Johnson et al. 1991
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Female subjects
x 48 ml/kg/min lt 56 ml/kg/min
x 63 ml/kg/min gt 57 ml/kg/min
McClaran et al. JAP. 1998841872-1881
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Case

• 22 yr old female
• BMI 26 (but muscular with low body fat)
• Severe dyspnea on exertion diagnosed with
  exercise-induced asthma
• Currently taking salbutamol before and after
  exercise. She says it doesnt help
• FEV1 106 pred.
• FVC 102 pred.
• Very active elite cross country skier
• No CV history or significant family history

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Peak Exercise Data
Measured Predicted
VO2peak 53 ml/kg/min 125
RER / RQ 1.24 gt1.1
Max HR 199 bpm 102
Max VE 122 L 156 L
Breathing Reserve 23 15-30
Arterial Sat. 96 gt88
Anaerobic Thres 86 40-60
.
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Elite Female X-Country Skier
100 VO2max (53 ml/kg/min)
50 VO2max
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CPET Interpretation

• Was the test maximal?
• Was RER 1.1?
• HR gt 90 predicted max?
• Patient exhaustion?
• Was there a plateau in VO2?
• Dyspnea score gt5?
• Was there evidence of a ventilatory limitation
• (i.e. Max exercise VE Predicted MVV)?

STEP 1.
What was the exercise limitation(s)?
STEP 2.
Other 1. Leg/Back Pain 2. Cardiac Concern
(i.e. ST depression etc) 3. HR lt max predicted
4. RQ lt 1.1 5. Dyspnea score lt5

• Cardiovascular
• RQ 1.1
• HR max predicted
• Exhaustion
• Dyspnea score gt5
• Max VE lt Pred MVV

• Pulmonary
• Max VE Pred MVV
• Exp flow limitation
• Hyperinflation
• SpO2 lt 88
• HR lt max predicted
• RQ lt 1.1
• Dyspnea score gt5

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Exercise Prescription from CPET

• Based on CPET results, exercise rehabilitation
  can be more efficient
• Three example methods
• Anaerobic Threshold (AT) Continuous
• AT intervals
• High Intensity Intervals (peak power)

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Anaerobic Threshold

• Definition
• Anaerobic energy production accelerates to
  supplement aerobic energy production
• H production exceeds the rate of removal (and
  consequently, H buffering begins)
• Why is it important?
• Good predictor of aerobic or endurance capacity
• Usually an optimal training intensity for
  cardiovascular adaptation

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Anaerobic Threshold

• Measurement
• Common method is V-slope method
• V-slope graphs VCO2 vs VO2

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VCO2 plotted against VO2 (V-slope method)
VCO2 (L/min)
VO2 (L/min)
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Anaerobic Threshold

• Measurement
• Common method is V-slope method
• V-slope graphs VCO2 vs VO2
• Commercial software often underestimates AT
• Not unusual to see automatic selection of AT at
  an RER 0.85 or less
• Better method dual criteria or ventilatory
  equivalent methods

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Anaerobic Threshold

• Criteria for determining AT using dual criteria
• A nadir in VE/VO2 followed by an incremental
  increase
• A plateau in VE/VCO2
• A respiratory exchange ratio around 1.0 (0.98
  1.02)

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Anaerobic Threshold
Plateau in VE/VCO2
Nadir
RER 1.0
40 60
Exercise Intensity
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Why train at AT and not a of max?
IT individualized at AT ST standard training
at 50
Measure Group Change
VO2max IT ? 20
ST ? 10
AT IT ? 22
ST ? 8
O2pulse IT ? 17
ST ? 9
Vallet 1997 Eur Respir J 10114-122 (COPD
patients)
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Exercise prescription from CPET

• Frequency 3 5 times per week
• Intensity (examples of methods)
• Continuous at, or slightly below, AT
• AT Intervals alternating 10 above 10 below
  AT for 2-5 minutes on 2-5 minutes off
• Peak Power intervals alternating at 100 peak
  work rate for 1-2 minutes and at 20 for 1-2
  minutes
• Time 20 30 minutes
• Type large muscle mass activity
  (walking/running, swimming, cycling)

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SUMMARY

• Comprehensive CPET can be used diagnostically to
  determine functional physiological limitations
• Individualized exercise rehabilitation intensity
  to optimize outcomes

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Acknowledgements

• ICEP Lab
• Dr. Darcy Marciniuk
• Robyn Chura
• Ron Clemens
• Madison Yurach
• Brendan Pikaluk

• Collaborators
• Dr. Don Cockcroft
• Dr. Jon Farthing
• Dr. Phil Chilibeck

• Clinicians
• Trent Litzenberger
• Wendy Verity
• Catherine Baule

• Funding Sources

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Thank you