cpx presntation

Dr. Nermine Mounir
Assistant prof. of chest
CPET is aimed at assessing the ability of
the body organ systems to respond
normally during exercise.
In exercise testing, where subjects are
encouraged to achieve their maximum
exercise capacity, the aim to achieve 2
goals: detecting any exercise limitation
and identifying the organ systems
responsible for that limitation.
CPET provide answers
to important
questions related to
exercise intolerance,
exercise limitation,
and patient
General indications:
 assessment of general fitness( exercise
 evaluation of dyspnea (both with and
without related chest pain and fatigue)
Evaluation of certain pulmonary
 chronic obstructive pulmonary disorders
including exercise –induced asthma.
Evaluation of certain cardiovascular
 Pulmonary vascular disorders
 coronary artery disease
 other vascular disorders
General disorders:
 neuromuscular disorders
 Obesity
 anxiety-induced hyperventilation
Allows differential diagnosis according
to different limitations:
1- ventilatory limitation
2- gas exchange limitations
3- cardio-vascular limitations
4- circulatory limitations
5- no limitations
 limiting neurologic disorders
 limiting neuromuscular disorders
 limiting orthopedic disorders
Pulmonary contraindications:
 FEV1 <30% of predicted value.
 Pao2 <40 mmHg at RA.
 Paco2 >70 mmHg.
 severe pulmonary HTN
Cardiovascular contra indications:
acute pericarditis
 congestive heart failure
 recent MI (within last 4 weeks)
2nd or 3rd degree heart block
 significant atrial and ventricular
 uncontrolled HTN
 unstable angina
 recent systemic or pulmonary embolism
 severe aortic stenosis
 thrombophlebitis or intracardiac thrombi
Active cardiac disease
Active pulmonary disease
Hemodynamic instability or acute
noncardiopulmonary disease affecting
exercise performance.
For 2 purposes:
1- identify any potential contraindications to the test.
2- to add to the body of knowledge to evaluate the
subject s response to exercise.
The evaluation minimally include:
history taking : tobacco use, medications, tolerance
to normal physical activity , any distress symptoms
and contraindication illness.
physical examination : height, weight and
assessment of the subjects heart, lung , peripheral
pulses and blood pressure.
Routine pulmonary function tests.( lung volumes,
simple spirometry, diffusing capacity and arterial
blood gases ).
Prior the day of the test:
 Should prepare to wear loose- fitting
clothing and low –heeled or athletic- style
 Abstain from coffee and cigarettes for at
least 2 hours before the test.
 Should continue on any medications for
routine use.
 It is acceptable to eat a light meal prior to
the test and meal should be eaten at least 2
hrs before the test.
On the day of the test:
 All of the test equipments should be
explained and demonstrated to the
 The patient should be instructed that the
maximum work effort by the subject ll be
necessary for the test to be successful.
Should be air – conditioned and temp.
regulated to be comfortable for an
exercising subject.
the subjects view should not be full of
medical equipments esp. the invasive one.
The equipments should be organized and
laid out in preparation.
Resuscitation equipments should be
available and on hands.
the responsible personnel should be tested
and certified for performing CPR
Monitoring system failure
Exhaustion or fatigue
Severe dyspnea or fatigue at peak exercise
Based on clinical signs and symptoms of physiologic stress:
-Dizziness or faintness
-Mental confusion, loss of coordination or headache
-Muscle cramping
-Nausea and /or vomiting
-Onset of sweating and pallor
-Severe claudication or other pain
- Unusual or severe fatigue
- Cyanosis
-Severe dyspnea
-Chest pain
Based on signs of significant hypoxemia:
decrease in SaO2 > 5%
decrease in SaO2< 85%
decrease in PaO2 < 55mmHg
Based on ECG signs of physiologic distress:
atrial arrhythmias
ventricular arrhythmia
2nd or 3rd degree heart block
left or right bundle branch block
ST segment changes
T wave changes
Based on blood pressure signs of physiologic distress:
systolic blood pressure changes, increases to greater than 250
mmHg or failure of systolic pressure to increase with exercise or
a decrease by more than 10 mmHg.
diastolic bl.pr changes , increase to greater than 120mmHg
Pulmonary parameters:
 RR – minute ventilation- end –tidal
oxygen and carbon dioxide- Oxygen
consumption and Co2 production
Cardiovascular parameters:
 Heart rate, blood pressure, ECG
Metabolism parameters:
1-oxygen consumption:
-Normally at rest average 250 ml/min (3.5-4
ml/min/kg), with exercise it will increase
directly with the level of muscular work, VO2
increase until exhaustion occurs and
maximum level of O2consumption(VO2max)
is reached.
- VO2 max is a reproducible , well defined
physiologic end point so it is used as a
definitive indicator of an individual s
muscular work capacity. Normally range
from 1700-5800 ml/ min
Is the amount of o2 in liters that the
body consumes per minute.
 Represents the internal metabolic work
and is directly proportional to the
external WR.
 Maximum VO2:
Is the maximum achievable VO2, can be
detected when VO2 plateaus in relation to
the external workload.(indication for
exercise termination)
Measured peak VO2:
Is the highest VO2 that a subject actually
achieves during CPET.
 Predicted peak VO2:
Is the highest VO2 that a subject is
expected to achieve.
2- CO2 production:
 Normally 200ml/min (2.8 ml/min/kg)
 During the initial phase of exercise it
increase at a rate similar to VO2, once
the anaerobic threshold has been
reached , VCO2 increases at a faster rate
than VO2. the faster rate is the result of
additional CO2 production from
HCO3/CO2 buffering mechanism.
3-Anaerobic threshold:
 In normal individuals occurs at
approximately 60% ± 10% of the
persons VO2 max.
 At the onset of the AT , there is marked
increase in CO2 production because of
lactic acid buffering and a compensatory
increase in ventilation.
 After the onset of the AT, a
breathlessness develops and a burning
sensations begins in working muscles.
4-Respiratory Quotient:
 CO2 production ↑ during exercise esp. after
the AT has been achieved →↑RQ from
resting levels of 0.8 to beyond 1.0
 The subject will be able to continue exercise
for a short period of time as much as 1.5
5-Blood PH:
 Remains relatively unchanged till the onset
of AT → the blood gradually becomes more
acidotic as the body is less able to buffer the
excessive acid (H)produced by anaerobic
1-Minute Ventilation:
 Normally = 5-6 l/min,100l/min in maximal exercise.
 At the very start of an exercise → vent. ↑(d.t. resp.
centers stimulation by the brain motor cortex and
joint proprioceptors)
 Humeral factors (chemoreceptors) do the fine tuning
of vent.
 The level of vent. Continue increasing
correspondingly with the increase of the workload till
AT reached → vent. ↑ in a rate greater than the rate
of workload ↑to compensate for the additional C02
produced during anaerobic metabolism.
 VE max: is the max VE that the patient achieves
during CPET.
Is the maximum minute ventilation that a
subject can achieve.(pred. VE max)
 Calculated MVV: FEV1x 40
 Predicted MVV: Pred. FEV1x 40
Therefore, in respiratory disease, the
calculated MVV will often be less than the
patient s predicted MVV.
Ventilatory reserve= predictedmeasured VE max (MVV-VE max)
Breathing reserve= measured/ predicted
VE max (VEmax/MVV)
2-Tidal volume:
 Normally = 500 ml, 2.3-3 L during
 Increase early in exercise and are initially
responsible for the increase in vent.
3-Breathing Rate:
 Normally = 12-16bpm, up to 40-50 bpm
 Responsible for the increase in minute
ventilation that occur late in maximal
exercise, esp. after AT reached
4-Dead space/ Tidal volume Ratio:
 Normally= 0.20-0.40, ↓ during exercise
 ↓significantly during exercise d.t ↑in tidal
volume with constant dead space
5-Pulmonary capillary blood transit time:
 Normally= 0.75 second, ↓ 0.38 second
d.t ↑ C.O.
6-Alveolar-Arterial Oxygen Difference:
 Normally= 10 mmHg changes little until
a heavy workload is achieved . However,
it can increase to 20-30 mmHg.
7-Oxygen Transport:
 Local conditions of increased temp.,
PCO2 and a relative acidosis in the
muscle tissues → greater release of
oxygen by the blood for use by the
tissues for metabolism.
1-Cardiac Output:
 Normally = 4-6L/min up to 20L/min
 Increase linearly with increases in the
workload during exercise till the point of
 At work levels of up 50%of an individuals
exercise capacity, the ↑ in C.O is d.t ↑ in
heart rate and stroke volume together.
After this point, it ll be d.t. in ↑ heart
2-Stroke Volume:
 Normally = 50-80 ml can double during
 Increase linearly with increase in
workload until a maximum value is
achieved, ≈ 50% of an individuals
capacity for exercise.
 After a HR of about 120bpm , there is
little additional increase in SV → CO
increase based in HR.
3-Heart Rate:
 Can increase as much as 2.5-4 times the
resting HR.
 HR max is achieved just prior of total
exhaustion, considered as physiologic
end point for each individual.
 HRmax (±10bpm)= 210-(0.65X age)
 HRmax (±10bpm)=220- age
 HR reserve= pred. HR max- achieved HR
at peak VO2.
4-Oxygen pulse:
The O2 uptake or consumption for each
cardiac cycle.
 In order to meet the demands of
increasing muscle work during exercise,
each heart contraction must deliver a
greater quantity of oxygen out to the
 O2 pulse= VO2/HR
 Normally = 2.5-4 ml o2/ heart beat up to
10-15 ml in exercise.
The O2 pulse is equivalent to SV.
It is a more qualitative assessment of SV.
If it fail to increase appropriately with
exercise it may indicate cardiac disease.
The body will compensate by increasing
HR to maintain an appropriate increase
C.O. which required to continue
exercising. Reach max HR much earlier
than expected.
5-Blood pressure:
 During exercise→↑systolic blood pressure (up to
200mmHg) while diastolic blood pressure remains
relatively stable( may ↑up to 90mmHg)
 Pulse pressure (difference between systolic and
diastolic pressure) ↑ during exercise.
6-Arterial- Venous Oxygen Content Difference:
 During maximal exercise the difference ↑2.5-3 times
the resting value. (N. 5 vol%)
 The ↑ is due to the greater amounts of O2 that are
extracted by the working muscle tissue during exercise.
7-Distribution of circulation:
 Circulation to the skeletal muscles
increases which in turn increase the
cardiac output.
 Circulation to the heart ↑.
 Skin perfusion ↑ as cooling mechanism for the
body but can ↓ at extreme exercise levels (as the
muscles demand ↑)
CPX is an incremental work rate test.
Fit individuals start with workload of 15
Subjects with pulmonary and
cardiovascular disorders start with 5
watts.(e.g. of increments 5,10,15,20
watts depends on the subject fitness).
Each workload level is maintained for a
time interval 1-3 min.
This procedure is continued until a
workload level is reached where one of
the 2 following events occurs:
1- exhaustion of the patient (muscle fatigue
and possibly breathing fatigue)
2-Demonstration of some adverse reaction
to the exercise.
The subjects normally experience
exhaustion soon after having passed the
AT as a result of:
-Rapid consumption and depletion of
glucose needed for muscle-cell
-An extremely elevated need for ventilation
to eliminate CO2 produced by lactic acid
VO2 max ≥ 85% of predicted or a
plateau is observed in VO2 vs WR curve
VE max ≥ 70% of MVV
HRmax > 90% of predicted
Blood lactate > 8mM
RER ≥1.15
The test considered normal if the subject
achieves a :
-VO2max (within 95% of the predicted).
-VEmax within 70% of the measured MVV
-Oxygen saturation within normal range.
-HRmax approach the predicted HRmax.
- O2 pulse normal increase which occurs with
- VD/VT normal decrease which occurs with
Low VO2max value indicate that some
factor is responsible for limiting the
subjects ability to perform exercise.
Three basic factors can produce
1- poor conditioning
2- pulmonary disorders
3- cardiovascular disorders
The key factor of limitation is that the
cardiovascular system is less capable than
normal of being able to supply oxygenated
blood to the working muscles.
HRmax is achieved at a lower than normal
workload level.
VO2 is low as the cardiovascular system
reaching its maximum level of performance
earlier and at a lower workload.
VE max/MVV is low as the patient becoming
fatigued early before the challenging
ventilation need reached.
VO2 max is low.
VEmax/MVV is elevated which indicates a
ventilatory limitation (occurs primarily in
obstructive disorders) .
It means that there is little or no
ventilatory reserve as the VEmax
approaches the predicted MVV.
SaO2 and PaO2 values reduced.
Mostly patients will reach their maximum tolerated
exercise level before the AT is reached .
VO2 max is low.
VE max/ MVV is reduced as the exercise become
limited before any physiologic need to increase level
of ventilation is required.
HR max reaches the maximum level more quickly and at
lower workloads than normal.
O2 Pulse is reduced as the HR increases to compensate the
lowered SV, the low O2pulse value is an indication that the
subjects stroke volume is limited during exercise.
Exertional hypotension or marked increase in diastolic
ECG changes
A male patient 68 years old. complain of
shortness of breath with limited exertion.
ABG at RA before the test: PH 7.42,
PaCO2 41, PaO2 69, SaO2 92.3%.
PFTS: FVC 55% of predicted, FEV1 23%
of predicted and FEF25-75 7%of
predicted, based on FEV1 the subjects
MVV is 28L/min.
The test was ended when the subject
experienced shortness of breath.
At peak
Pred. max
% pred.
VO2ml/min/ 3.7
Respiratory response:
Spirometry shows severe obstructive
ABGs shows moderate hypoxemia
without hypercapnia.
During exercise desaturation occurred
with development of dyspnea.
VE/MVV reached 83% at the peak of
exercise level.
Cardiovascular response:
 VO2 max less than normal
 HR increase was reasonable
 ECG during exercise was normal
 O2 pulse did not increase significantly
during the test, but this was probably
due to the low maximum workload that
was achieved before the test was ended.
Severe exercise limitation that is due to a
respiratory impairment. This is indicated
by several factors:
 A less than predicted VO2 max.
 Desaturation and greater than normal increase in the
 No evidence of cardiovascular limitation to exercise.
Thank you

similar documents