BY
BY
• CPET is a diagnostic procedure that
analyzes the responses and cooperation of
the heart, circulation, respiration, and
metabolism during continuously increase
muscular stress.
ObesityPoor effortMusckluscletal diseases
Heart disease - coronary -ValvularAnemia
ObstructionRestrictionChestwall
• According to place
a) Field tests (e.g. 6MWT, ISWT).
b) Laboratory tests (treadmill and cycle
ergometry).
• According to applied load a) Maximal (incremental tests).
b) Sub-maximal (usually constant workload).
c) Supra-maximal.
A. Field tests
Advantages:
• Safe Easy Cheap
• Identical movement stereotype
Disadvantages:
- Relatively inaccurate determination of power& measurements.
B. Laboratory tests
Advantages:• Accurate determination of work load.
• Standard laboratory conditions.
Disadvantages:
• Different movement stereotype worsen achievement.
• Less safe Expensive Need exprience
Maximal testsAdvantages:• Direct assessment of maximal capacity
Disadvantages:• Dependence on will and motivation
• Risk factor
Sub-maximal tests
Advantages:• Safer • Lower dependence on tested person (more comfortable)
Disadvantages:• Often based on estimation (presumption) of HR max, etc.
worse accuracy
ParameterscycleTreadmill
VO2 maxlowerHigherBlood pressure
assessmentEasy-
Work load measurement
YesNo
ABG collectionYesNoNoiseLessHigherSaftySaferLess Safer
Wt bearing in obese
LessMore
Leg ms trainingLessMore
1. Diagnostic:
– Unexplained dyspnea
– Exercise limitation
– Documenting exercise-induced hypoxemia,
titrating O2 prescription
– Exercise-induced asthma
2. Assessment of functional exercise capacity
– Impairment or disability evaluation
– Selection of patients for cardiac
transplantation
– Prognosis: CF, heart or pulmonary
vascular disease
Routine spirometry and DLCO most useful in evaluating
physiologic operability in low-risk patients
In high-risk/borderline patients, CPET may have a role
along with split-lung function studies
Peak VO2 < 50-60% predicted was associated with
higher morbidity and mortality after lung resection
surgery
-pulmonary or cardiac rehabilitation - health maintenance or athletic training
• Acute myocardial
infarction (3–5 days)
• Unstable angina
• Uncontrolled arrhythmias
causing symptoms or
hemodynamic compromis
• Active endocarditis
• Acute myocarditis or
pericarditis
• Symptomatic severe aortic
stenosis
• Uncontrolled heart failure
• Acute pulmonary embolus
or pulmonary infarction
• Left main coronary stenosis or its equivalent.
• Moderate stenotic valvular heart disease.
• Severe untreated arterial hypertension at rest
( 200 mm Hg systolic, 120 mm Hg diastolic).
• Tachyarrhythmias or bradyarrhythmias.
• Hypertrophic cardiomyopathy.
• Significant pulmonary hypertension.
• Electrolyte abnormalities.
CPET Protocol
Constant work rate5-10 minutes Incremental
Multistage Every 2-3 minutes
Progressive incrementalEvery one minute
Incremental
ConstantB
Exercise portion of test lasts 8-12 minutes .
Ideal Testing Duration
Wasserman, et al. Principles of Exercise Testing and Interpretation. Lea & Febiger, 1987.
1 .Approximate VO2 for Unloaded Pedaling:150(+6 x Weight)
2 .Estimate VO2 maxHeight (cm) - Age(yrs) x 20 (Males)
Height (cm) - Age (yrs) x 14 (Females).3Work 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/min2 .VO2 Pred max = [(180-50) x 20 = 2600
ml/min3 .Work = [2600 - 750] / 100 = 18.5 (round to
20)
Selecting the Work Rate
For patients with reduced MVV, FEV1, DLCO (<80% predicted) we reduced expected peak VO2 proportionally
W = [S*BW *(2, 05 + 0.29*I) – 0, 6 * BW –151] Where W = watt, S = speed, I = inclination,
and BW = body weight.According to recommendation of Wassermann we had change percent of inclination with fixation of speed.
Calculating speed and inclination
VO2 running (ml kg-1min-1) = 0.2 (speed m min-1) + 0.9 (speed m min-1)(grade %) + 3.5 (ml kg-1 min-1) (ACSM 2009). The grade of the treadmill was set at 1%, and the speed converted to km h-1.1 kilometer per hour (km/h) = 16.67 meters per minute (m/min)
Indication for termination of CPET
Maximal exercise testing
Measurements Noninvasive Invasive (ABGs) Metabolic gas exchange VO2, VCO2, RER, AT Lactate
Ventilatory BR,VE, VT, RR,VD/VT
Cardiovascular HR, HRR, ECG, BP, O2 pulse,QT
Pulmonary gas exchange SpO2, VE/VCO2, VE/VO2, PETO2,
PETCO2
PaO2, P(A-a)O2
Acid-base pH, PaCO2, HCO3-
SymptomsDyspnea, fatigue, chest pain
• This is the highest attainable oxygen consumption
achieved during an incremental exercise test
• VO2 is defined by the Fick equation:
VO2 = CO* C (a – v)O2
where CO is cardiac output and C (a – v)O2 is the
arterio-venous O2 content difference.
►the response is linear►slope (DV’O2/change in work rate (DWR)) approximately 10 mL·min1·W-1
Anaerobic threshold (AT or LT)
• Occurs at approximately 40-50% VO2max in normal individuals.
• Indicates test is at least close to maximal exercise.
• Not under voluntary control, not affected by psychological factors
• Direct measurement requires measuring lactate levels in blood (requires frequent blood sampling; impractical)
• Noninvasive assessment using gas exchange parameters
• Buffering of lactate by bicarbonate produces disproportionate increase in VCO2 “V-slope
method”.
Anaerobic threshold
• The ratio of carbon dioxide output and oxygen
consumption (VCO2/VO2) is called the
respiratory exchange ratio (RER).
• Can be used as a rough index of metabolic
activity, this parameter is ~0.85 on a western
diet as this incorporates fat, protein and
carbohydrate.
• RER greater than 1.0 could also be caused by
CO2 derived from lactic acid or by
hyperventilation because of the 20-fold or
more higher tissue solubility of CO2 compared
with O2.
• In health, increases in tidal volume are
primarily responsible for increases in
ventilation during low levels of exercise.
• As exercise progresses, both VT and fr
increase until 70 to 80% of peak exercise;
thereafter fr predominates. VT usually
plateaus at 50 to 60% of vital capacity (VC).
• In health, the increase in VT is due to both a decrease in end-expiratory lung volume (EELV) through encroachment on the expiratory reserve volume but predominantly to an increase in end-inspiratory lung volume (EILV).
• In normal subjects, EELV typically decreases with increasing work rate by as much as 0.5–1.0 L below functional residual capacity, with a consequent increase in inspiratory capacity (IC).
• the ratio of VE at peak exercise to the estimated maximal voluntary ventilation (MVV) represents the assessment of the ventilatory limitation or of the prevailing ventilatory constraints. Ventilatory limitation is judged to occur when VE /MVV exceeds 85%.
• In lung diseases, the increase in VE /MVV may reflect either the reduction in ventilatory capacity (reduction in MVV), the increase in ventilatory demand (increase in VE ), or both.
Recalling that the anatomic dead space volume is about 150 in an average-sized subject at rest, with a tidal volume of 500 ml, VD/ VT would be about 0.30.
The minimal value (which occurs near maximal exercise) should be less than 0.20 in younger individuals, less than 0.28 in individuals less than 40 years of age, and 0.30 for those older than 40 years; higher values are seen in many forms of lung disease.
The difference between total Ventilation (VE) and effective alveolar ventilation (VA) is
wasted or dead space ventilation (Vd)• A high Vd/Vt indicates wasted or inefficient
ventilation, often indicates pulmonary or pulmonary vascular disease
Vd/Vt(Efficiency of gas-exchange(
.4 -
.2-
.1-
.3-
Work Rate
Normal
VA/Q mismatch. .
VD/VT
Achievement of age-predicted maximal HR during exercise is often used as a reflecion of maximal or near maximal effort and presumably signals the
achievement of VO2max.
The difference between the age maximal HR and the maximal HR achieved during exercise is referred to as the HR reserve (HRR). Normally, at maximal exercise, there is little or no HRR.
Predicted HRmax = 220-age
Abnormal HR response may reflect disease of either the left or right heart
Affected by other factors, including drugs, anxiety, anemia
Resting HR: high - suggests anxiety or disease, low - suggests good conditioning or conduction problems
O2 pulse = VO2/HR
ml O2 consumed per beat
taken to reflect stroke volume
assuming PaO2 and C(a-v)O2 respond
normally
O2 pulse < 80% predicted is abnormal
Normal: HR increases fairly linearly with VO2 until max HR
reached; O2 pulse increases linearly until a plateau occurs.
Blood pressure is related to both cardiac output and peripheral vascular resistance.
The usual increase in cardiac output with exercise is thought to result in an increase in systolic blood pressure.
Also in working muscle, there are local mediators that cause intense vasodilatation that increases blood flow to support metabolic demands.
In addition, nonworking muscles are vasoconstricted from reflex increases in sympathetic nerve activity.
The net result is a fall in systemic vascular resistance, but systolic blood pressure typically rises progressively with an increase in VO2.
Diastolic blood pressure typically remains constant or
may decline slightly.
Po2 of respired gas, determined at the end
of an exhalation.
End tidal O2 normaly at rest 90mmHg or greater and
increases with exercise 10-30 mmHg for exercise
above the anaerobic threshold because of metabolic
acidosis induced hyperventilation and rising R
(respiratory exchange ratio) at maximal exercise.
Pco2 of respired gas, determined at the end of
an exhalation.
This is commonly the highest Pco2 measured
during the alveolar phase of the exhalation.
It is expressed in units of millimeters of
mercury (or kilopascals).
Normal resting end tidal CO2 ranges between 36 – 44
mmHg, approximating arterial PaCO2.
With exercise end tidal CO2 should increase 3 -8
mmHg from rest to AT and then slightly decline at
maximal exercise secondary to the anaerobically
induced increase in VE (minute ventilation).
Ratio of the subject’s minute ventilation
(BTPS) to O2 uptake (STPD).
It is a dimensionless quantity.
This ratio indicates how many liters of air
are being breathed for each liter of O2
uptake.
Ratio of the subject’s minute ventilation (BTPS)toCO2 output (STPD).
It is a dimensionless quantity.
This ratio indicates how many liters of air are being breathed to eliminate 1 liter of CO2.
It is used as a noninvasive estimator of appropriateness of ventilation.
VE/VO2VE/VO2
VE/VCO250-
0-
ATRC AT RC
Normal Obstructive Restrictive/PVD(Efficiency of ventilation)
Normal values at AT: VE/VO2: 25 (22-27) VE/VCO2: 28 (26-30)
Ventilatory Equivalents
ATS/ACCP, 2003 reported that
the ventilatory equivalents for
O2and CO2 are both related to
VD/VT, being higher as VD/VT
increases which the case in
patients with pulmonary diseases.
Pulse oximetery provide reasonably accurate measures of O2 saturation, with errors in the
range of ± 2% - 3% when compared with direct arterial blood samples.
Measurement of SpO2 allows assessment of
exercise induced desaturation with a fall in SpO2of >4% considered clinically significant
100-
80-
60-
40-
20-
PO2
Work Rate
Alvart
Diff
Alv
art
Diff
Alv
art
Diff
)Normal) (Obst) (Restr(
Gas-Exchange: P(A-a)O2
Normal VO2max
ECGABG
O2 pulse at VO2 max
Normal Abnormal
ObeseVD/VT
P(A-a)O2
P(a-ET)CO2
NoNormal
YesBR low
NormalCVD
AbnormalPulmonary disease
Low VO2max Normal LT%
BR
Low normal
Lung disHigh VD/VT, P(A-
a)O2, HRR
RF
<50 ILDs
>50 OAD
ECG
Normal (poor effort or muscle)
Abnormal (myocardial ischaemia)
Low VO2 max And LT
BR
low N or H
VD/VT
N Chronic metabolic acidosis
H Lung disease
VE/VCO2 at LT
N Anaemia, HD, or PAD H
N (VC) PVD L (VC) LVF