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Cardio-Pulmonary Exercise Testing. Dr Simon Donoghue Product Support Manager VIASYS Healthcare. Schedule. 9.30- 10.30        Methodology in CPET 10.30 – 11.00    Coffee 11.00-12.00       Useful Parameters Defined 12.00-13.00       Lunch 13.00-14.00       Basic Interpretation

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dr simon donoghue product support manager viasys healthcare

Cardio-PulmonaryExercise Testing

Dr Simon Donoghue

Product Support Manager

VIASYS Healthcare

schedule
Schedule
  • 9.30- 10.30        Methodology in CPET
  • 10.30 – 11.00    Coffee
  • 11.00-12.00       Useful Parameters Defined
  • 12.00-13.00       Lunch
  • 13.00-14.00       Basic Interpretation
  • 14.00-14.30       Coffee
  • 14.30-15.30       Case Examples, flow limitation
  • 15.30-16.00       Additional Value of CPET
slide8
CPET

Bike or Treadmill

Diffusion & C.O.

Psys, Pdia

ECG

P0.1

Analog channels

Cardiac Output

SpO2

Calorimetry

Mixing chamber

Compliance

Hypoxia/Hypercapnia

(resp. Drive)

slide10

25 Watt

50 Watt

slow walking

VE  18 l/min

VO2 750 ml/min

quick walking

slow step climbing

VE  25 l/min

VO2 1000 ml/min

slide11

75 Watt

100 Watt

quick step climbing (2 steps)

VE  42 l/min

VO2 1500 ml/min

quick step climbing

VE  32 l/min

VO2 1250 ml/min

slide12

150 Watt

200 Watt

swimming (50 m/min)

running (15 km/h)

VE  84 l/min

VO2 2500 ml/min

cross-country run

bicycling (20 km/h)

VE  63 l/min

VO2 2000 ml/min

slide13

WASSERMAN

METABILOSM

CIRCULATION

VENTILATION

PERIPHERAL GAS EXCHANGE

PULMONARY GAS EXCHANGE

indications for cpet
Indications for CPET

I: Provide support in differential diagnosis.

(Cardiac, Pulmonary, Peripheral)

II: Determine performance limitations.

(Chronic lung disease, workplace, pre-operative, insurance)

III: Assess therapeutic interventions.

(Pulmonary rehab, transplant)

contra indications for cpet
Contra-indications for CPET

Absolute Relative

Acute myocardial infarction (3-5 days) Left main coronary stenosis

Unstable angina Moderate stenotic vascular heart disease

Uncontrolled arrhythmia causing symptoms Electrolyte abnormalities

Active endocarditis Severe untreated hypertension (>200mmHg

Active myocarditis or pericarditis systolic, >120 mmHg diastolic)

Symptomatic severe aortic stenosis Significant pulmonary hypertension

Uncontrolled heart failure Tachyarrhythmias or bradyarrhythmas

Acute pulmonary embolus or pulmonary infarction Hypertrophic cardiomyopathy

Acute noncardiac disorder that may affect exercise Mental impairment leading to inability to

performance or be aggravated by exercise . cooperate

Thrombosis of lower extremities High-degree of atrioventricular block

‘Relative’ contra-indications can be over-ruled if the benefits outweigh the risks of exercise

what protocol
What Protocol???

Maximal?

Bicycle?

Steps?

Ramp?

Warm-up?

Workload?

Endpoint?

Sub-maximal?

slide17

What Protocol ???

Max or Sub-max?

Bike or Treadmill?

Exercise Duration?

Ramp or Steps?

Workload?

max or submax
MAX or SUBMAX
  • For cardio-pulmonary diagnostic purposes, MAXIMAL tests are performed.
  • We aim to stress the cardio-resp system until we identify the factor which limits exercise capacity
  • Sub max test are more common in athletics training, rehabilitation etc.
treadmill vs cycle
Treadmill vs Cycle

FEATURE TREADMILL CYCLE

Higher Peak VO2 +

Similar Max HR and Max VE + +

Familiarity of exercise ++ +

Quantitation of external work - - +

Freedom from artifact (ECG, BP) - - + +

Ease of obtaining blood gases - - + +

Safe (less musculoskeletal injuries) +

Useful in supine position +

Less vertical/horizontal space +

Less noise, Less Expensive +

Portable - +

Wasserman et al. Principles of Exercise Testing and Interpretation. Lea & febiger, 1987.

ideal testing duration
Ideal Testing Duration
  • Exercise portion of test lasts 8-12minutes.
selecting the work rate
Selecting the Work Rate

What is the appropriate work rate

increment for each patient?

calculating the work rate
Calculating the Work Rate
  • 1. Approximate VO2 for Unloaded Pedaling:
  • 150+(6 x Weight)
  • 2. Estimate VO2 max
  • Height (cm) - Age(yrs) x 20 (Males)
  • Height (cm) - Age (yrs) x 14 (Females)
  • Work Rate Increment
  • VO2 max pred - VO2 Unloaded /100

Example: 50 yr old male, 100 kg and 180 cm

1. VO2 unloaded = [150+(6x100) = 750 ml/min

2. VO2 Pred max = [(180-50) x 20 = 2600 ml/min

3. Work = [2600 - 750] / 100 = 18.5 (round to 20)

Wasserman, et al. Principles of Exercise Testing and Interpretation. Lea & Febiger, 1987.

selecting the work rate1
Selecting the Work Rate

5 Watts/min Severe impairment(e.g. patient who is

confined to home or walks only short distances)

10 Watts/min Moderate impairment(e.g. patient who

walks one or two city blocks before symptoms)

15 Watts/min Mild impairment or sedentary older

patient

20 Watts/min Sedentary younger patient

25 Watts/min Active younger patient(regular sports,

physical exercise)

30 Watts/min Athletic and fit(competitive sports)

40 Watts/min Extremely fit(highly competitive)

Chris Cooper, MD.. Harbor UCLA Medical

maximal stop 1
Maximal - Stop (1)

Exercise criteria for exhaustion (1):

1. Cardial

  • HR: 220 - age (athlets)
  • HR: 200 - age (patients)
  • (HR = 210 - 0.65 * age)

2. Ventilation

  • no breathing reserve (see below)
  • F/V - limitation
maximal stop 2
Maximal - Stop (2)

Exercise criteria for exhaustion (2):

3. Gas exchange

  • RER > 1.1 - 1.2
  • Breathing equivalent EQO2 > 35
  • VO2-plateau

4. Metabolic

  • Lactate: 6 - 12 mmol/l
  • pH-value < 7.2 (< 7.0)
stop criterias 1
Stop Criterias (1)

Indications for load-stop:

Angina Pectoris

ST-decrease more than 0.25 mV(horizontal or descending)

Dysrhythmia according to Lown IIIa or IV(polytop extrasystols or volleys)

AV block of degree II or III

Decrease of O2-uptake, HR, and/or

O2-pulse during exercise

stop criterias 2
Stop Criterias (2)

Psys:

> 250 mmHg

and / or

Pdia:

> 120 mmHg

slide35

Parameters

  • Breathing Pattern
  • O2 and CO2
  • Heart Rate and ECG
  • Blood Pressure
  • SpO2
  • Also ABGs, Lactate, Indirect Cardiac Output, Flow Volume loops, indirect calorimetry, P0.100, high FIO2
breathing parameters
Breathing Parameters
  • Ventilation VE(L/min)
  • Tidal Volume VT(L)
  • Respiratory RateRR(Breaths/min)
  • Breathing ReserveBR(% Max Pred)
  • Others include Ti, Ttot,
breathing reserve
Breathing Reserve
  • How much Ventilation we have in reserve
  • Percent of PREDICTED MAX

eg Predicted Max Ve = 125 L/min

Current Ve = 100 L/min

25 L/min reserve = 20%

predicted max ventilation
Predicted Max Ventilation

We need to know if patients reached

THEIR ACHIEVABLE MAX VE,

not the Ve predicted for a healthy individual.

  • Should not use prediction from age height etc.
  • Can measure Max Voluntary Ventilation (MVV)
  • Best Prediction for Max VE during exercise=

35 x FEV1

normal ventilatory response
Normal Ventilatory Response

160

-

Predicted Maximum Ventilation

}

BR = 20-40%

.

VE

(l/min)

10

|

0

Max

Predicted

Work

slide41

Ventilatory Limitation

160

-

BR = 50 %

.

Individuals Predicted Maximum Ventilation

BR = 0 %

VE

(l/min)

10

|

0

Max

Predicted

Work

slide42

Breathing Pattern

5

-

Normal

Restrictive

Obstructive

VT

(L)

0

|

0

120

VE

heart rate reserve
Heart Rate Reserve
  • How much heart rate capacity we have in reserve, expressed as number of beats.
  • maximum predicted HR is 180 bpm
  • current HR is 160 bpm
  • HRR of 20 beats.
heart rate and load

VO2

HR =

SV * ( Ca - Cv ) O2

According to Fick

Heart Rate and Load
normal heart rate response
Normal Heart Rate Response

200

-

Predicted Maximum Heart Rate

HRR = 0

HR

(b/min)

0

|

0

Work

Max

Predicted

cardiac limitation
Cardiac Limitation

200

-

Predicted Maximum Heart Rate

HRR = 0

HR

(b/min)

0

|

0

Work

Max

Predicted

normal
Normal

HRR = 0

BR = 20-40%

Predicted Max

Predicted Max

.

HR

b/min

VE

l/min

Work

Predicted

Max

Work

Predicted

Max

ventilatory limitation
Ventilatory Limitation

HRR = ++

BR = 0 %

Predicted Max

.

HR

b/min

VE

l/min

Predicted Max

Work

Predicted

Max

Work

Predicted

Max

cardiac limitation1
Cardiac Limitation

HRR = 0

BR = ++

Predicted Max

Predicted Max

.

HR

b/min

VE

l/min

Work

Predicted

Max

Work

Predicted

Max

slide53
VO2
  • How much oxygen we uptake.
  • Not how much oxygen we breathe in!
slide54
Breath in 10 litres air min

20% O2

2.0 litres of O2 per min.

Breath out 10 litres gas min

15% O2 per min 1.5 litres O2 of per min

VO2 = 500ml/min

vo 2 max or peak
VO2 MAX or PEAK??
  • VO2 MAX is only achieved if VO2 plateaus.
  • Peak VO2 is the highest VO2 achieved without the plateau. Not stated as MAX because the subject ‘could have done better’.
vo 2 responses
VO2 RESPONSES

The slope and linearity of the VO2 response is indicative of the O2 uptake.

Position Displacement: Depends on body weight

Slope Differences: Identifies Aerobic Efficiency, slope for aerobic exercise is 10.2 (+/- 1.0) mlO2/min/Watt. If O2 is not available to muscles, slope will be reduced.

Linearity Differences: Achieving VO2 Max and/or being limited by CV system results in reduced slope.Very fit subjects can show increased slope.

hr and vo 2
HR and VO2

Normal Response:

Linear, max pred VO2 and HR.

COPD:

Linear, reduced max VO2 and HR.

HD:

Non-linear, red VO2, Max HR.

slide65

O2 Pulse

  • VO2 / HR
  • The ammount of O2 uptaken during each stroke of the heart
  • dependant on stroke volume and O2 uptake.

(SV x arterial-mixed venous O2 difference)

cardiac limitation2
Cardiac Limitation

HR increases rapidly,

Little increase in VO2

o2 pulse can increase during recovery
O2 Pulse Can Increase During Recovery
  • The normal response is for O2 pulse to fall after exercise, as heart rate, stroke volume and VO2 fall
  • In patients with significant Heart Disease, during recovery from exercise there is a significant decrease in afterload, this results in increasing SV in hearts that struggle with increased AL.
o2 pulse response in copd
O2 Pulse Response in COPD

HR is normal

Low O2 uptake causes reduced O2 Pulse

vco 2
VCO2
  • How much carbon dioxide we produce.

ml/min

respiratory exchange ratio
Respiratory Exchange Ratio

How much CO2 is exchanged for O2

RER = VCO2 / VO2

RER= 400 / 500 = 0.8

RQ sometimes used, but RQ true measure of exchange in tissues, not at mouth.

aerobic metabolism
AEROBIC METABOLISM

1.0O2

1.0O2

1.0 CO2

0.7 CO2

1.0O2

1.0O2

FAT

FAT

CDH

1.0

0.7

substrate utilisation
Substrate Utilisation
  • Carbohydrate RER = 1.0
  • Fat RER = 0.7
mixture of chd and fat
Mixture of CHD and FAT

1.0O2

1.0 CO2

0.7 CO2

1.0O2

1.7 / 2 = 0.85

substrate utilisation1
Substrate Utilisation
  • Carbohydrate RER = 1.0
  • Fat RER = 0.7

RER between 0.7 and 1.0 tells us what proportion of Fat and CHD we are utilising. Useful in calorimetric studies

when we have incremental exercise
When We Have Incremental Exercise……..
  • Muscles need fast supply of energy
  • Although we get more CALs per gram than CHD,

CHD releases more CALs per litre of O2

  • RER increases close to 1.0
  • Muscles demand more energy than being supplied through AEROBIC METABOLISM.
  • Body also uses internal stores of energy ANAEROBICALLY.
anaerobic threshold defined
Anaerobic Threshold Defined

The highest level of oxygen consumption that can be sustained without developing metabolic acidosis.

The point at which anaerobic metabolism starts to contribute.

slide82
Working beyond the AT can be for a very limited time.
  • The AT defines when the body starts to struggle to cope with the workload
  • Important for assessing work capacity but also pre-operatively
anaerobic metabolism produces
Anaerobic Metabolism Produces…

Energy and Lactic Acid

In the blood, acidity is regulated by buffering and CO2 retention / release. This is a well balanced equilibrium.

CO2 + H2O = H2CO3 = HCO3- + H+

H+

CO2

substrate utilisation2
Substrate Utilisation
  • Carbohydrate RER = 1.0
  • Fat RER = 0.7
  • Fat + CHD RER = 0.7 - 1.0

Because the CO2 production now exceeds O2 consumption, RER above 1 tells us there is some anaerobic contribution

(or hyperventilation)

v slope method of at
V-Slope Method of AT

4

VCO2

L/min

AT: Change in slope

4

VO2 L/min

at v slope 1
AT: V-slope (1)

Slope:

VCO2 against VO2

anaerobic threshold at
Anaerobic Threshold (AT)

Predicted Max VO2

(AT => 40% Pred VO2)

.

VCO2

.

VO2

normal ventilatory response1
Normal Ventilatory Response

CO2 DRIVES VENTILATION

(Disproportionately to the increase in VO2)

160

-

.

VE

(l/min)

10

.

-

|

0

VO2

(l/min)

4.0

ventilatory equivalents
Ventilatory Equivalents
  • How many litres of air we need to breathe to exchange 1 litre of gas.
  • eg an EQO2 of 50 means need to breathe 50 litres to extract 1 litre of oxygen
  • an EQCO2 of 30 means need to breathe 30 litres to expel 1 litre of CO2.
slide93

VE/VO2 improves during exercise

  • REST: VO2 = 250 ml /min

VE = 10 L/min

Would need 4 mins and 40 L ventilation

  • Exercise:VO2 = 3000 ml / min

VE = 75 L/min

Would need 20 seconds and 25 L ventilation

change in vd vt
Change in Vd\Vt
  • With Vt of 600ml, 300ml is deadspace

300ml is alveoloar (gas exch)

  • Increase Vt to 900ml, 300ml is deadspace

600ml is alveoloar (gas exch)

  • Increase ventilation by 50%
  • Increase alveolar ventilation by 100%

BECOME MORE EFFICIENT!

ventilatory equivalents1
Ventilatory Equivalents

(Efficiency of ventilation)

40

VE/VO2

20

AT

0

WORK

Normal values at AT: VE/VO2: 25 (22-27)

at eqo 2 1

VE

EQO2

VO2

VE - VDs * BF

EQO2 =

VO2

AT: EQO2 (1)
respiratory compensation
Respiratory Compensation
  • When isocapnic buffering cannot cope with the increase in CO2 and H+,

CO2 + H2O = H2CO3 =

  • Develop metabolic Acidosis
  • Respiratory system tries to compensate by blowing off CO2.

HCO3- +

H+

ventilatory equivalents2
Ventilatory Equivalents

(Efficiency of ventilation)

40

VE/VCO2

VE/VO2

20

RC

AT

0

Normal values at AT: VE/VO2: 25 (22-27) VE/VCO2: 28 (26-30)

normal ventilatory equivalents
Normal Ventilatory Equivalents
  • Suggest normal VD/VT

Dead Space to Tidal Volume Ratio

  • Matching of VA to Q

Alveolar Ventilation to Perfusion

  • Normal Chemoresponses
slide103
In Healthy Patients: Lowest VE/VO2 at AT

Lowest VE/VCO2 at RC

  • In COPD Patients: Poor VD/VT

Poor VA/Q

Mechanical Limitation

  • In Restrictive Patients: Poor VD/VT
end tidal gases
End-Tidal Gases

40

CO2

(mmHg)

0

40

CO2

(mmHg)

0

vd vt calculation
VD/VT Calculation
  • Look at the difference between:

Mixed expired CO2 / ETCO2

Estimate how much of the gas was involved in gas exchange, compared to how much was not.

Therefore estimate VD/Vt

poor vd vt or va q mismatch
Poor VD/VT or Va/Q mismatch

Much of the air we breathe out has low amount of CO2.

Little gas exchange has occurred.

The End-Tidal CO2 will we be relatively high, compared to the mixed expired gas

Therefore the proprtion of Tidal Volume that is Dead Space will be large.

good vd vt and va q
Good VD/VT and Va/Q

Much of the air we breathe out has high amount of CO2.

Lots of gas exchange has occurred.

The End-Tidal CO2 will not be exceptionally high, compared to the mixed expired gas

Therefore the proprtion of Tidal Volume that is Dead Space will be small

vd vt
VD/VT

VA/Q mismatch

0.4

0.3

0.2

0.1

Normal

Work

slide112

Vd/Vt = (Pet CO2 - PECO2)/PetCO2

Vd/Vt high if Ve/VCO2 if > 45

slide114
Looking at the difference between gas in the alveoli and gas in the blood can tell us about gas exchange
  • Obstructive patients have poor gas exchange. As Vt increases VD/Vt worsens
  • Restricitive patients have reduced pulm vascular bed, so perfusion is limited
dynamic changes
Dynamic Changes

maximal

150 Watt

100 Watt

50 Watt

various methods
Various Methods
  • Fick Principle: rebreathing CO2
  • Acetylene: single breath
  • Wasserman: retro-analysis
cardiac output
Cardiac Output
  • Calculate Arterial-Mixed venous O2 difference

Mixed venous-arterial CO2 difference

This is how many mls of gas difference per litre of blood.

eg CaO2 – CvO2 = 194 -101 = 93ml O2 / L

If we know how much O2 uptake or CO2 expel, ie how many litres of gas per minute, eg VO2 = 1190 ml/min.

Cardiac Output is the volume of blood needed to achieve this VO2 or VCO2

eg 1190 / 93 = 12.8 L/min

acetylene uptake
Acetylene Uptake
  • Acetylene is very soluble
  • Passes from lungs into blood very rapidly
  • Irrespective of Hb, O2 etc
  • Therefore its uptake is only dependant on blood flow
  • If QPulm = CO we can estimate CO and SV
wassermans formula for cardiac output
Wassermans Formula for Cardiac Output
  • Wasserman developed a formula for use in healthy and diseased patients.
  • AFTER study is complete it looks at Peak VO2 and Heart Rate and retro-calculates the Stroke Volume.
  • No special measurements or gases needed.
physiological predictors

Physiological Predictors

  • 1790s Antione Laurent Lavoisier, noted increase in oxygen consumption with exercise…
  • 1960 Clowes and Del Guercio demonstrated perioperative mortality related to poor ventricular function.
  • 1970s Shoemaker et al, Goldman et al assessed physiological variables and cardiac risks in surgical patients (elderly, existing disease, major surgery)
  • 1980 Del Guercio and Cohn implemented pulmonary artery catheters for pre-op risk assessment.
  • 1987 Confidential Enquiry into Perioperative Deaths (CEPOD), looked at 500,000 pts. Found predominately elderly, existing disease, major surgery
hypothesis
Hypothesis…..
  • Mortality is associated with the inability of the cardio-respiratory system to increase output to match the demands mandated by major surgery and post surgical period.
  • Myocardial ischemia and cardiac failure.
slide147

Age is not a predictor of individual risk.

Physiological not chronological!

surgical specific risk
Surgical Specific Risk
  • Low Risk VO2 <120 mL/M2
  • Intermediate Risk VO2 120 – 150 mL/M2
  • High Risk VO2 >150 mL/M2
  • VO2 post major abdominal surgery= 170mL/M2 ie Hypermetabolic State
classification of cardiac failure by cardiopulmonary exercise testing
Classification of Cardiac Failure by Cardiopulmonary Exercise Testing

Weber KT, Janicki JS. Am J of Cardiol 1985; 55:22A-31A

cpet implemented

CPET Implemented

  • 1988 Older and Hall used CPET to screen ALL elderly pts scheduled for major surgery
  • Aimed to identify OCCULT cardiac/respiratory disease.
  • Recognised peak VO2 would be good indicator of Cardiac/Resp function.
  • Recognised that AT is the marker for sustainable aerobic function
mortality rates associated with at
Mortality Rates Associated with AT

There was an 18 percent mortality rate for those with an AT less than 11 ml/min/kg, (three times the basal metabolic VO2rate).

But a 0.8 percent mortality rate for those with an AT greater than 11 ml/min/kg

McGrath BP, Newman R, Older P.

Hemodynamic study of short- and long- term Isradapine treatment in patients with chronic ischemic congestive cardiac failure.

Am J Med 1989;86 (suppl 4A):75-80

mortality rates associated with ischaemia and at
Mortality Rates Associated with Ischaemia and AT

McGrath BP, Newman R, Older P.

Am J Med 1989;86 (suppl 4A):75-80

perioperative cardiac failure
Perioperative Cardiac Failure

The entity could be termed perioperative cardiac failure (PCF); it may only be apparent postoperatively when oxygen demand is increased. It may occur independently of both CCF and MI though all three may coexist. However in our studies only 35% of patients with cardiac failure additionally had demonstrable myocardial ischaemia….. . in other words, postoperative mortality is a function of preoperative cardiopulmonary failure rather than myocardial ischaemia

vo 2 predicting survival in chf
VO2 Predicting Survival in CHF
  • Szlachcic et al 1985 described:
  • 77% 1-year mortality in CHF patients with VO2<10mL/Kg/min
  • 21% 1-year mortality in CHF patients with VO210-18 mL/Kg/min
  • Likoff et al 1987 described:
  • 36% mortality in CHF patients with VO2<13mL/Kg/min
  • 15% mortality in CHF patients with VO2>13 mL/Kg/min
prognosis for cardiac transplant
Prognosis for cardiac transplant
  • n= 116
  • Group 1 VO2 < 14 mL/Kg/min accepted for TP (n=35)
  • Group 2 VO2 > 14 mL/Kg/min (n=52)
  • Group 3 VO2 < 14 mL/Kg/min comorbidity (n=27)
v e vco 2 predicting chf mortality
VE/VCO2 predicting CHF mortality
  • Coats review stated:

An increased ventilatory response to CO2 has been repeatedly demonstrated to relate to all cause mortality in CHF. Although its precise physiological cause remains complicated and uncertain, these findings stress the valuble information that can be obtained by analysis of the cardiopulmonary exercise test responses in CHF patients.

a k gitt et al 2001
A.K. Gitt et al 2001

AT>11 Ve/VCO2<34

AT<11 Ve/VCO2>34