Guide to the interpretation of Cardiopulmonary Exercise ...

Guide to the interpretation of

Cardiopulmonary Exercise Testing

Dr. Ines Frederix December 2014

Copyright: Ines Frederix


1 Ergospirometry: parameter description .............................................................................. 5

1.1 Cardiovascular parameters .......................................................................................... 5

1.1.1 Heart rate (HR) ..................................................................................................... 5

1.1.2 Blood pressure (BP) ............................................................................................. 5

1.1.3 Oxygen consumption (VO2) ................................................................................. 5

1.1.4 Oxygen pulse (π O2) ............................................................................................. 5

1.2 Metabolic parameters .................................................................................................. 6

1.2.1 Respiratory exchange ratio (RER) ....................................................................... 6

1.2.2 (First) Anaerobic threshold (AT1, VT1) .............................................................. 6

1.2.3 (Second) Anaerobic threshold (AT2, VT2, RCP) ................................................ 6

1.3 Ventilatory and pulmonary gas exchange parameters ................................................. 6

1.3.1 Minute ventilation (VE) ....................................................................................... 6

1.3.2 Carbon dioxide output (VCO2) ............................................................................ 6

1.3.3 Tidal volume (VT) and breathing frequency (fR) ................................................ 7

1.3.4 VD/VT .................................................................................................................. 7

1.3.5 Oxygen saturation (SaO2) .................................................................................... 7

1.3.6 Carbon dioxide respiratory equivalent (VE/VCO2) ............................................. 7

1.3.7 Oxygen respiratory equivalent (VE/VO2) ........................................................... 7

1.3.8 PET O2 and PET CO2 ......................................................................................... 7

1.3.9 VE/VCO2 slope .................................................................................................... 7

1.3.10 1.3.10 Ventilatory reserve (VR) ........................................................................... 7

2 Typical ergospirometry patterns, associated with specific pathologies/conditions ........... 9

2.1 Cardiovascular pathologies .......................................................................................... 9

2.1.1 Heart failure (HF), diagnostic evaluation ............................................................. 9

2.1.2 Heart Failure (HF), prognostic evaluation ........................................................... 9

2.1.3 Coronary artery disease ...................................................................................... 10

2.2 Respiratory pathologies ............................................................................................. 10

2.2.1 Chronic Obstructive Pulmonary Disease (COPD) ............................................. 10

2.2.2 Interstitial Lung Disease (ILD) .......................................................................... 11

2.2.3 Pulmonary Vascular Disease (PVD) .................................................................. 11

2.3 Neuromuscular pathologies ....................................................................................... 13

2.3.1 Mitochondrial myopathy .................................................................................... 13

2.4 Other pathologies/conditions ..................................................................................... 13

2.4.1 Deconditioning ................................................................................................... 13

2.4.2 Hyperventilation syndrome/Anxiety .................................................................. 13

2.4.3 Obesity ............................................................................................................... 14

2.4.4 Poor effort and malingering ............................................................................... 14


2.5 Summary of pathology specific ergosprimetry patterns ............................................ 15

3 Algorithm for ergospirometry analysis ............................................................................ 16

3.1 What is the indication for the ergospirometry? ......................................................... 16

3.2 Assess patient’s history, clinical examination, other examinations (RxTx, ECG,

PFTs, etc.) ............................................................................................................................ 16

3.3 Was the ergospirometry maximal? ............................................................................ 16

3.4 Is aerobic capacity (VO2 max) normal? .................................................................... 16

3.5 Does cardiovascular function contribute to exercise limitation? ............................... 16

3.6 Does ventilatory function (respiratory mechanics) contribute to exercise limitation?

16

3.7 Does pulmonary gas exchange (hypoxemia, inefficient ventilation, increased dead

space ventilation) contribute to exercise limitation? ............................................................ 17

3.8 Integrate all results in final conclusion(s) .................................................................. 17

4 Reference values .............................................................................................................. 19

5 Graphic representation of cardiopulmonary exercise response in healthy person ........... 20

6 References ........................................................................................................................ 21

Ines Frederix 5

1 Ergospirometry: parameter description

1.1 Cardiovascular parameters

1.1.1 Heart rate (HR)

In healthy subjects, HR increases nearly linearly with increasing VO2; initially due to vagal

withdrawal and subsequently due to increased sympathetic activity. Achievement of age-

predicted values for maximal HR during exercise is often used as one of the markers to define

a maximal ergospirometry test (and hence VO2 max). The most widely used reference value

equation for maximal HR is: HR max predicted = 220-age (years). The difference between the

age-predicted maximal HR and the maximal HR achieved during ergospirometry is called the

Heart Rate Reserve (HRR). Normally HRR < 15 beats/min; in case of a maximal exercise

test. When the HRR is zero, there is cardiovascular limitation to exercise (in healthy subjects

cardiovascular, rather than ventilatory limitation is mostly observed). When the HR max <

85% HR max predicted; there is chronotropic incompetence.

Note: the effect of beta-blockers on HR.

1.1.2 Blood pressure (BP)

Systolic BP typically rises progressively during incremental exercise, diastolic BP remains

constant or slightly declines. If systolic BP does not increase with exercise, or in fact declines;

the exercise test should be terminated since this could indicate a serious abnormality such as

HF, ischemia, aortic stenosis, … . Maximal BP’s during exercise testing are 220/90 mmHg.

1.1.3 Oxygen consumption (VO2)

VO2 is defined as the volume of O2 extracted from inspired air in a given period of time. It

can be expressed by the Fick equation, that is: VO2= Qc x C(a-v)O2. This VO2 max is

defined during incremental exercise testing, as the VO2 attained during the VO2 plateau

phase; when the VO2 plateaus despite work rate continuing to increase. The VO2 max is the

gold standard to define a patient’s aerobic capacity. It is influenced by cardiovascular

(central), pulmonary (central) and muscular (peripheral) function.

To calculate VO2 for a maximal incremental cycle exercise test, we use the following

formula:

Male: W (predicted weight ie. 0,79xH – 60,7) x [50,75-0,372 (A)]

Female: (W (predicted weight ie. 0,65xH -42,8) + 43) x [22,78 – 0,17 (A)]

W(eight) in kg, H(eight) in centimeters, A(ge) in years

Normal value for VO2 max: VO2 max > 84% predicted (Ref. 1), > 100% predicted (Ref. 2).

1.1.4 Oxygen pulse (π O2)

The π O2 is defined as: π O2= VO2/HR=SV x C (a-v)O2. The basic profile for the π O2 is to

initially increase in a hyperbolically fashion, followed by a slow approach to an asymptotic

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value. A low, unchanging or flat π O2; with increasing work rate may be interpreted as

resulting from a reduced SV. The normal absolute value of π O2 is > 80%.

1.2 Metabolic parameters

1.2.1 Respiratory exchange ratio (RER)

The RER is defined as : RER= VCO2/VO2. The RER is determined by the fuels used for

metabolism. RER is 1 for carbohydrates; RER is 0,7 for lipids and RER is 0,85 for

carbohydrates and lipids. A RER > 1,1 is one of the criteria to define a maximal exercise test.

1.2.2 (First) Anaerobic threshold (AT1, VT1)

The AT1 is defined as the moment when there is a transition between no or little lactate

accumulation; to a sustained increase in lactate accumulation. It corresponds to the VO2

above which anaerobic energy production substantially supplements aerobic energy

production. It is valuable in setting the intensity for exercise prescription in a highly

individualized manner. Normally AT1 equals > 40% VO2 max predicted (wide range of

normal 40-80%).

AT1 can be determined in different ways:

1. V-slope method: AT1 is identified as the VO2 at which the change in slope of the

relationship of VO2 to VCO2 occurs.

2. Respiratory equivalent method: AT1 is defined as the VO2 at which there is

significant increase in the VO2 respiratory equivalent, without concomitant increase in

the VCO2 respiratory equivalent.

3. PET method: AT1 corresponds to the increase in PET O2 (because of

hyperventilation) with no simultaneous decrease in PET CO2.

1.2.3 (Second) Anaerobic threshold (AT2, VT2, RCP)

AT2 is defined as the VO2 (% VO2 max) at which the carbon dioxide respiratory equivalent

starts to increase (after an initial decrease). AT2 marks the onset of hyperventilation

(“respiratory compensation”) during incremental exercise. It physiologically reflects the

failing of the body’s buffering mechanisms; which leads to metabolic (lactic) acidosis.

Normally AT2 is 60-90% VO2 max predicted.

1.3 Ventilatory and pulmonary gas exchange parameters

1.3.1 Minute ventilation (VE)

VE is the volume of expired air exhaled from the lungs in 1 minute . The VE is calculated as:

VE = VT x fB. With incremental exercise testing; VE increases progressively. The rise in VE

with exercise is primarily associated with an increase in VT during low levels of exercise. As

exercise progresses, both VT and fB increase until 70-80% of peak exercise; thereafter fB

predominates.

1.3.2 Carbon dioxide output (VCO2)

VCO2 is defined as the amount of CO2 exhaled from the body per unit of time.

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1.3.3 Tidal volume (VT) and breathing frequency (fB)

See I.3.1. Normally the maximal fB is <60 breaths/min.

1.3.4 VD/VT

The VD/VT ratio is an index of gas exchange efficiency. An increase in VD/VT reflects an

increased inefficiency of ventilation; due to V/Q mismatching or a right-to-left shunt.

Normally VD/VT is 0,30-0,40 in rest. The ratio typically decreases initially with increasing

exercise intensity due to increasing VT. Patients with respiratory disease may have at rest

either normal or elevated values that fail to decrease normally or may even increase during

exercise.

1.3.5 Oxygen saturation (SaO2)

SaO2 is the actual amount of O2 bound to hemoglobin in a given volume of arterial blood.

1.3.6 Carbon dioxide respiratory equivalent (VE/VCO2)

VE/VCO2 corresponds to the number of liters of air that are being breathed to eliminate 1

liter of CO2. Normally minimal VE/VCO2 equals < 30.

1.3.7 Oxygen respiratory equivalent (VE/VO2)

VE/VO2 corresponds to the number of liters of air that are being breathed for each liter of O2

uptake.

Note: The normal pattern of change in VE/VO2 is a drop early in exercise to its nadir near the

AT1, and then an increase as maximal exercise capacity is approached. The VE/VCO2 also

decreases hyperbolically as work rate increases. For incremental tests, the increase in

VE/VO2, that typically occurs in concert with the development of metabolic acidemia (AT1)

occurs at a time when VE/VCO2 has not yet increased. It is this profile that separates this

response from the onset of hyperventilation from other causes (e.g. anxiety), in which case

both VE/O2 and VE/VCO2 would increase in concert. The normal subsequent increase in

VE/VCO2 reflects the onset of frank compensatory hyperventilation for metabolic acidosis,

with concomitant reduction in PET CO2.

1.3.8 PET O2 and PET CO2

End-tidal PO2 and PCO2.

1.3.9 VE/VCO2 slope

During normal incremental exercise testing; VE correlates closely with VCO2 in a linear

fashion. The slope of this relationship in normal subjects is 23-25 (Ref. 1), < 30 (Ref. 2).

1.3.10 Ventilatory reserve (VR)

The VR is the difference between the ventilatory capacity and the ventilatory demand. The

ventilatory capacity is defined by the MVV (Maximal Voluntary Ventilation). MVV is

calculated as: MVV= FEV1 x 35-40. The ventilatory demand is defined by the VE max. To

calculate the VR; we use the following formula: VR= VEmax/MVV. Normally during

maximal exercise testing; the VE/MVV ratio is 72 ± 15% (Ref. 1), ≤ 80% (Ref. 2). Patients

with pulmonary disease characteristically have reduced VR; in contrary to healthy people

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where the exercise test is usually ended by cardiovascular limitation. Thus, VE/MVV has

diagnostic utility in determining if unexplained exertional dyspnea is related to a pulmonary

mechanism.

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2 Typical ergospirometry patterns, associated with specific

pathologies/conditions

2.1 Cardiovascular pathologies

2.1.1 Heart failure (HF), diagnostic evaluation

For the cardiovascular parameters:

VO2 max: The VO2 max is reduced, reflecting an insufficient increase in cardiac output

during exercise.

∆VO2/∆W slope: In heart failure this slope is typically decreased due to circulatory

insufficiency.

πO2: Flattening of the πO2 during incremental exercise, reflects the fall in SV.

For the ventilatory parameters:

VE/MVV: In general, for patients with heart failure, the cardiopulmonary exercise tests

usually are not ventilatory limited. The presence of VE/MVV approaching or exceeding

100% of predicted (reduced VR), signals the presence of combined cardiovascular and

respiratory limitation and may suggest concurrent pulmonary disease.

VD/VT: The VD/VT is increased due to reduced cardiac output for the metabolic rate; and

hence V/Q mismatching.

VE/VCO2: The VE/VCO2 is increased due to abnormal V/Q relationships due to low

cardiac output for the metabolic rate, subclinical interstitial pulmonary edema,….. .

VE/VCO2 slope > 30 suggests increased filling pressures. Specifically for patients with

heart failure with a preserved EF (HFpEF), exercise-induced pulmonary hypertension is

characterized by high VE/VCO2’s.

For the metabolic parameters

AT1: The AT1 is usually decreased; reflecting the circulatory insufficiency and early onset

of lactic acid metabolism.

2.1.2 Heart Failure (HF), prognostic evaluation

Prognostic markers in patients with HF

VO2 max: The VO2 max is considered one of the most robust prognostic markers in

chronic heart failure. A VO2 max of 11 mL/min/kg seems to be the lower threshold for an

unfavorable prognosis.

VE/VCO2 slope: The VE/VCO2 slope provides additional prognostic information in

chronic heart failure patients; The higher the slope, the worse the prognosis.

Respiratory oscillations: The presence of respiratory oscillations is a negative prognostic

marker. It reflects advanced disease severity and poor prognosis in patients with heart

failure.

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Table 1: Indicates the prognostic and diagnostic stratification for patients with heart

failure.

Heart Failure

VE/VCO2 slope Peak VO2

(mL/kg x min)

Respiratory

oscillations

Blood pressure

< 30:

Ventilatory Class I

>20:

Weber Class A

Not present

Rise in systolic BP

during CPET

30-36:

Ventilatory Class II

16-20:

Weber Class B

Not present

Flat systolic BP response

during CPET

36-45:

Ventilatory Class III

10-16:

Weber Class C

Present

Flat systolic BP response

during CPET

≥ 45:

Ventilatory Class IV

< 10:

Weber Class D

Present

Drop in systolic BP

during CPET

2.1.3 Coronary artery disease

During exercise testing; the onset of myocardial ischemia impairs ventricular contraction and

relaxation functions, thereby reducing the increase in cardiac output during exercise and

raising filling pressures.


∆VO2/∆W slope: The ∆VO2/∆W slope typically starts to flatten and/or decline in case of

myocardial ischemia. The normal average slope is 10 mL/min x W.

πO2: Flattening of the πO2 during exercise, reflects the inability to adequately increase SV

due to myocardial ischemia. Concurrent compensatory more rapid increase in heart rate with

respect to work load is often noted.


VE/VCO2: An increased VE/VCO2 reflects increased filling pressures with exercise.

2.2 Respiratory pathologies

2.2.1 Chronic Obstructive Pulmonary Disease (COPD)


VO2 max: The VO2 max is reduced in case of severe COPD, and is normal in mild

COPD.

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∆VO2/∆W slope: This slope is usually normal, in contrary to cardiovascular pathologies

(HF, coronary artery disease).

HRR: There is usually a significant HRR, a reflection that the cardiovascular system has

been relatively unstressed.


VE/MVV: One of the distinguishing features of many patients with moderate to severe

COPD is a reduced VR (VE/VMM approaching or exceeding 100%), signaling a

significant ventilatory contribution to exercise limitation.

VD/VT and VE/VCO2: Both are abnormal reflecting ventilatory inefficiency, due to

increased dead space ventilation.

PaO2: Patients with COPD usually have low PaO2 values at rest. During exercise PaO2

may increase, decrease or remain the same; but is more likely to be reduced in patients

with moderate to severe COPD.

For the metabolic parameter:

AT1: The AT1 response may be normal, low or indeterminate. A low AT1 may reflect

deconditioning due to physical inactivity and/or skeletal muscle dysfunction.

2.2.2 Interstitial Lung Disease (ILD), Restrictive Lung Disease


VO2 max: The VO2 max is typically reduced.

HRR: The HRR may be increased or normal, since exercise shows ventilatory limitation.


VE/MVV: A reduced VR (high VE/MVV) and ventilatory limitation to exercise are often

seen; primarily reflecting deranged pulmonary mechanics.

VD/VT and VE/VCO2: Inefficient ventilation (increased VE/VCO2 responses) due

primarily to increased VD/VT and also hyperventilation due to hypoxemia and

mechanoreceptor stimulation are usually observed throughout exercise.

PaO2: During exercise, in most patients with significant ILD, impressive arterial

desaturation and abnormal increases in P(A-a)O2 are observed.


AT1: The AT1 response can be normal, although a low AT1 commonly occurs and may be

due to pulmonary circulatory and/or RV dysfunction (O2 delivery) and/or skeletal muscle

dysfunction and deconditioning (O2 utilization).

2.2.3 Pulmonary Vascular Disease (PVD)


VO2 max: The O2 max is usually reduced. These patients’ their exercise tests are usually

cardiovascular limited.

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πO2: The πO2 is often reduced, reflecting the heart’s inability to maintain adequate

cardiac output (CO=SV x HR), in the face of increased pulmonary vascular resistance and

consequent RV afterload.


VE/MVV: As stated above, in PVD patients the exercise test is usually cardiovascular

limited. Hence, there is usually VR at peak exercise.

VD/VT: The VD/VT is usually increased.

VE/VCO2: The VE/VCO2 is typically increased, reflecting inefficient ventilation.


AT1: There is usually an early-onset metabolic acidosis (analogous to heart failure and

circulatory insufficiency).

Table 2: depicts the diagnostic and prognostic stratification of patients with PVD.

Pulmonary Vascular Disease

VE/VCO2 slope

Peak VO2

(mL/kg x min)

PET CO2

apex during

exercise

Blood pressure

SaO2

< 30:

Ventilatory Class I

>20:

Weber Class A

> 37 mmHg

Rise in systolic BP

during CPET

No ∆SaO2

30-36:

Ventilatory Class II

16-20:

Weber Class B

36-30 mmHg

Flat systolic BP

response during CPET

> 5% ↓ from

baseline

36-45:

Ventilatory Class III

10-16:

Weber Class C

29-20 mmHg

Flat systolic BP

response during CPET

> 5% ↓ from

baseline

≥ 45:

Ventilatory Class IV

< 10:

Weber Class D

< 20 mmHg

Drop in systolic BP

during CPET

> 5% ↓ from

baseline

(PET CO2 apex achieved at submaximal levels, typically immediately proceeds ventilatory

threshold)

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2.3 Neuromuscular pathologies

2.3.1 Mitochondrial myopathy

In mitochondrial myopathy, a number of genetic mutations can lead to inefficient oxygen

utilization by muscle tissue. If mitochondrial myopathy is suspected, a muscle biopsy would

be warranted to confirm the diagnosis.


VO2 max: The degree of impairment in VO2 max appears to correlate to the severity of

genetic mutation.

∆VO2/∆W slope: This slope is typically reduced, reflecting the inefficient use of oxygen

by the muscle tissue.

∆Q/∆VO2: In normal circumstances, where oxygen utilization and delivery are well

matched, the ∆Q/∆VO2 slope is 5 L/min. In subjects with mitochondrial myopathies, this

slope is much higher (≥ 7) as oxygen delivery far exceeds the capacity for utilization.


VE/VO2: The VE/VO2 at peak exercise is typically increased, as the ventilatory cost of

VO2 dramatically rises due to aerobic inefficiency by affected skeletal muscle.


RER: High RER’s during cardiopulmonary exercise testing are seen in case of

mitochondrial myopathy.

2.4 Other pathologies/conditions

2.4.1 Deconditioning


VO2 max: The VO2 max is usually normal. However it can be low or at the lower limit of

normal in subjects who are very deconditioned.

πO2: πO2 is typically decreased.


VE/MVV: There is usually a significant ventilatory reserve.

VD/VT and VE/VCO2: The ventilatory response to low levels of exercise is usually

normal. However, increased submaximal VE is observed at any level of VO2 above the

AT1 as a reflection of increased metabolic acidosis, compared with normal subjects.

VD/VT responses are normal, as is the VE/VCO2 slope.


AT1: Typically there is early onset of AT1, due to rapid activation of anaerobic

metabolism.

2.4.2 Hyperventilation syndrome/Anxiety


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VO2 max: These patients have a normal VO2 max.


VE/VCO2: The basic mechanism is increased ventilation as evidenced by abnormal

increases in VE, VE/VCO2, respiratory frequency and respiratory alkalosis (evidenced by

decreased PET CO2 and PaCO2). As an increased VE/VCO2 may reflect inappropriate

ventilation and/or dead space ventilation; arterial PCO2 sampling is recommended. In

contrast to the usual gradual increase in respiratory frequency seen during progressive

exercise, subjects with psychogenic disorders may have an abrupt “turned on” onset of

regular, rapid and shallow breathing disproportionate to the metabolic stress. Also, at the

start of exercise testing, these patients often show an increased breathing frequency (> 20

breaths/min), when compared to normal patients (±10 breaths/min).

2.4.3 Obesity


VO2 max: VO2 max may be decreased when expressed per kilogram of actual body

weight; or normal when expressed per kilogram of ideal body weight.

πO2: The πO2 is usually normal.

VO2/W slope: in severe obesity, the VO2/W slope is typically increased due to increased

oxygen consumption for a given work load, reflecting the increased metabolic need to

move the bulky legs.


VE/MVV: VE/MVV is usually normal, but may be increased in extreme obesity.

VD/VT and VE/VCO2: These parameters are usually normal in obesity.

Note: in severe obesity, initial pulmonary function tests can show a restrictive pattern.

During exercise testing relatively small tidal volumes (reflecting rapid and superficial

breathing) can be noted.


AT1: The AT1 is usually normal.

2.4.4 Poor effort and malingering

This should be suspected in case of early cessation of exercise and a reduced VO2 peak; a

normal or unattained AT1, a low RER value at exercise cessation and a substantial HRR and

VR with no readily apparent peripheral abnormality.

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2.5 Summary of pathology specific ergosprimetry patterns

Table 3: summarizes the most important ergospirometric findings for each of the pathologies discussed in chapter II “Typical ergospirometry

patterns, associated with specific pathologies/conditions”. NA: Not available.

Cardiovascular

Ventilatory

Metabolic

VO2 max or

VO2 peak Peak HR πO2

(VE/MVV)

x100= VR VD/VT

VE/VCO2

(at AT1) PaO2 AT1

Pathology

Cardiovascular

Heart Failure Decreased Variable Decreased Normal or

decreased Increased Increased Normal Decreased

Coronary artery

disease Decreased NA Decreased NA NA Normal/increas

ed

Normal Normal/decreased

Respiratory

COPD Decreased Decreased, normal

in mild

Normal (or decreased) Increased Increased Increased Variable Normal

(decreased/intermediat

e)

ILD Decreased Decreased Normal (or decreased) Normal or

increased

Increased Increased Decreased Normal (or decreased)

PVD Decreased Normal or slightly

decreased (Normal) or

decreased

Normal Increased Increased Decreased Decreased

Neuromuscular

Other

Deconditioning Decreased Normal or slightly

decreased Decreased Normal Normal Normal Normal Normal or decreased

HV Normal Normal Normal NA NA Increased Normal Normal

Obesity Decreased for

actual (normal

for ideal weight)

Normal or slightly

decreased

Normal Normal (or

increased)

Normal Normal Normal Normal (or decreased)

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3 Algorithm for ergospirometry analysis

3.1 What is the indication for the ergospirometry?

Before starting the interpretation of the cardiopulmonary exercise test; it is of primordial

importance to know the exact indication for the test. The main indications for

cardiopulmonary exercise testing are the following:

1. Evaluation of exercise intolerance

- Determination of functional impairment or capacity (VO2 peak)

- Determination of exercise-limiting factors and pathophysiologic mechanisms

2. Evaluation of patients with cardiovascular disease

- Functional evaluation and prognosis in patients with heart failure

- Selection for cardiac transplantation

- Exercise prescription and monitoring response to exercise training for cardiac

rehabilitation

3. Evaluation of patients with respiratory disease

4. Specific clinical applications

3.2 Assess patient’s history, clinical examination, other examinations

(RxTx, ECG, PFTs, etc.)

3.3 Was the ergospirometry maximal?

Patient effort during cardiovascular exercise testing can be considered to be maximal if one or

more of the following occur:

1. The patient achieves predicted peak VO2 and/or a plateau on the VO2 curve is

observed

2. The predicted maximal work rate is achieved

3. The achieved HR is > 85% HR max predicted (cardiovascular limitation)

4. The VE max approaches or exceeds MVV (ventilatory limitation)

5. RER achieved is > 1,1

6. Patient exhaustion/Borg scale rating of 9-10 on a 0-10 scale

3.4 Is aerobic capacity (VO2 max) normal?

Normally, the observed VO2max > 84% VO2 max predicted (Ref. 1), >100% VO2 max

predicted (Ref. 2). The distinction between (ab)normal VO2 max guides the clinician in a first

direction regarding possible underlying pathology (ies).

3.5 Does cardiovascular function contribute to exercise limitation?

The cardiopulmonary exercise test is considered cardiovascular limited in case of reduced

HRR with normal or increased VR. In healthy people, cardiopulmonary exercise test are

usually cardiovascular limited.

3.6 Does ventilatory function (respiratory mechanics) contribute to exercise

limitation?

Ines Frederix 17

The cardiopulmonary exercise test is considered ventilatory limited, in case the VE max

approaches or exceeds VMM in the presence of increased HRR.

3.7 Does pulmonary gas exchange (hypoxemia, inefficient ventilation,

increased dead space ventilation) contribute to exercise limitation?

Exercise hypoxemia most often reflects intrinsic pulmonary gas exchange limitation. A fall in

SaO2 (∆SaO2) of ≥ 4%, SaO2 ≤ 88%, or PaO2 ≤ 55 mmHg during cardiopulmonary exercise

testing is usually considered clinically significant.

3.8 Integrate all results in final conclusion(s)

The observed ergospirometric patterns can help guide the clinician in his

diagnostic/therapeutic thinking. However, frequently different pathophysiologic mechanisms

contribute concomitantly to the patient’s symptoms/exercise intolerance. Therefore, an

integrative approach considering all ergospirometric parameters and also the patient’s history,

clinical examination and static examinations is highly encouraged.

Figure 1: depicts the basic strategy for the interpretation of peak cardiopulmonary exercise

test results.

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4 Reference values Table 4: depicts the formula and reference values for the most important cardiovascular,

ventilatory and metabolic parameters; given a maximal cardiopulmonary exercise test (as

defined in section 3.3).

Parameter Formula (max ErgoSx) Reference values

Cardiovascular

Heart rate HR max= 220 -age > 85% age predicted

HRR HRR= HR pred - HR max < 15 beats/min

VO2 max VO2 max= Qc x c(a-v)max > 84% (Ref. 1), > 100% (Ref. 2) predicted

πO2 πO2= SV x C(a-v)O2 > 80%

∆VO2/∆W / Normal average slope is 10

Ventilatory

VE VE= VT x fB /

fB fB= VE/VT < 60 breaths/min

VD/VT /

< 0,28 for age < 40 years; < 0,30 for age >

40 years

VE/VCO2 slope ∆VE/∆VCO2 23-25 (Ref 1.), < 30 (Ref. 2)

VE/VCO2 (at

AT1) / < 34

∆SaO2 / < 4% (Ref. 1), < 5% (Ref. 2)

Minimal SaO2 / Should be ≥ 95% throughout exercise

VR VR= VEmax/VMM 72 ± 15% (Ref. 1), ≤ 80% (Ref. 2)

Metabolic

RER RER= VCO2/VO2 > 1,1

AT1 /

40-80% VO2 max predicted (Ref. 1); 40-

60% VO2 max predicted (Ref. 2)

AT2 (RCP) / 60-90 % VO2 max predicted (Ref. 2)

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5 Graphic representation of cardiopulmonary exercise response

in healthy person

Figure 2: depicts a graphic representation of the maximal, incremental cardiopulmonary

exercise response of a healthy aged person.

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6 References ATS/ACCP Statement on Cardiopulmonary Exercise Testing. Am J Respir Crit Care Med

2003; 167: 211-277.

Milani R, Lavie C, Mehra M, et al. Understanding the Basics of Cardiopulmonary Exercise

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exercise testing for the functional evaluation of cardiac patients: a report from the Exercise

Physiology Section of the European Association for Cardiovascular Prevention and

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Guazzi M, Adams V, Conraads V, et al. Clinical recommendations for cardiopulmonary

exercise testing data assessment in specific patient populations. Eur Heart J 2012; 1-22.

Dubowy K, Baden W, Bernitzki S, et al. A practical and transferable new protocol for

treadmill testing of children and adults. Cardiol Young 2008; 18: 615-623.

Gläser S, Friedrich N, Koch B, et al. Exercise Blood Pressure and Heart Rate Reference

Values. Heart, Lung and Circulation 2013; 22: 661-667.

Paap D, Takken T. Reference values for cardiopulmonary exercise testing in heathy adults: a

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