‫به نام خدا‬
‫دكتر محمد امامي‬
‫فوق تخصص ريه‬
‫عضوهيات علمي دانشگاه علوم‬
‫پزشكي اصفهان‬
Cardiopulmonary
Exercise Testing
JOSEPH PRIESTLY (1733-1804)
Discovers Oxygen
Exercise requires the coordinated
function of several integrated systems:
1-Heart
2-Lung
3-Blood
4-Muscle

Oxygen content
The arterial oxygen content (CaO2) is
the amount of oxygen bound to
hemoglobin plus the amount of oxygen
dissolved in arterial blood
 CaO2 (mL O2/dL) = (1.34 x hemoglobin
concentration x SaO2) + (0.0031 x PaO2)
 Normal CaO2 is approximately 20 mL
O2/dL.

the mixed venous blood oxygen content
(CvO2) is the amount of oxygen bound
to hemoglobin plus the amount of oxygen
dissolved in mixed venous blood
 CvO2 (mL O2/dL) = (1.34 x hemoglobin
concentration x SvO2) + (0.0031 x PvO2)
 Normal CvO2 is approximately 15 mL
O2/dL

Oxygen delivery
Oxygen delivery (DO2) is the rate at
which oxygen is transported from the
lungs to the microcirculation
 DO2 (mL/min) = Q x CaO2
 Normal DO2 is approximately 1000
mL/min
 AV oxygen difference (mL O2/dL) =
CaO2 - CvO2

Oxygen consumption (VO2)
Oxygen consumption (VO2) is the rate at
which oxygen is removed from the blood
for use by the tissues
 Normal VO2 in a conscious, resting
person is approximately 250 mL O2/min
 VO2 (mL O2/min) = Q x (CaO2 - CvO2)

Oxygen extraction
Oxygen extraction is the slope of the
relationship between oxygen delivery
(DO2) and oxygen consumption (VO2)
 O2 Extraction Ratio = (CaO2 CvO2)/CaO2
 Normal O2 extraction ratios range from
0.25 to 0.30

NORMAL PHYSIOLOGY
Oxygen consumption (VO2) is
proportional to oxygen delivery (DO2)
and oxygen extraction
 DO2 and oxygen extraction are inversely
proportional to one another
 At rest,VO2 remains constant over a
wide range of oxygen delivery (DO2)
because changes in DO2 are balanced by
reciprocal changes in oxygen extraction

VO2 decreases if DO2 declines to such a
degree that it cannot be balanced by
increasing oxygen extraction
 The threshold value of DO2 below which
VO2 will fall is called the "critical DO2"

PATHOPHYSIOLOGY

Decreased oxygen delivery or increased
metabolic demand are common sequelae
of medical illness
Decreased oxygen delivery



Oxygen delivery (DO2) will decrease if
cardiac output falls or arterial oxygen
content (CaO2) declines
Cardiac output can decrease due to cardiac
disease or hypovolemia
CaO2 can decrease due to anemia or poor
oxygenation. The latter can be caused by
lung disease (eg, ventilation-perfusion
mismatch, diffusion limitation), a right-to-left
shunt, diminished inspired oxygen, or
hypoventilation
Increased metabolic demand

Metabolic demand is elevated in critically
ill patients (eg, acute respiratory distress
syndrome, sepsis, or septic shock)
Cardiac Pump
CO=HRxSV
 The predicted maximum HR is 220 minus
age in years (alternate: 210 - [0.65 x age
in years])
O2 Pulse

O2 pulse is Vo2/HR, obtained by dividing
these two simultaneous measurements
taken during exercise
AT
Most of the metabolic work performed
by the muscles during exercise is done via
aerobic mechanisms
 There is workload above which a given
person his or her or her physiologic
capability to do most of the work
aerobically, and incremental work rates
result in progressive lactic acidosis in the
blood due to anaerobic metabolism in
muscle

The Ventilatory Pump
VE=TVxRR
 Early in exercise,VE increases mostly due
to increases in TV
 As TV reaches approximately 50 to 60%
of vital capacity (VC), it begins to plateau,
and further increases in VE are mostly due
to increases in RR
Gas Exchange in the Lung
Total VE=VA+VD
 VD/VT Ratio=0.3 at rest
 VD/VT Ratio=0.18 during maximum
exercise
 VD/VT=Paco2-pEco2/Paco2

O2 Transfer

During exercise, P(A-a)O2 increases due
V/Q mismatching, O2 diffusion limitation,
and low Svo2
Exercise physiology
Skeletal muscle metabolism can rise quickly
to fifty times its resting rate during heavy
exercise.
 VO2 increases linearly versus work rate with
a slope of approximately 10 mL/min per watt
in normal subjects
 A true maximal VO2, identified by a plateau
of VO2 versus work, occurs only in a small
subset of normal subjects and patients
 normal VO2max is greater than 20 mL/kg
per min, and can be predicted from age,
gender, height, and lean body weight.

The VO2max increases as a function of
training and decreases with age
 A young, world-class endurance athlete
may have a VO2max greater than 80
mL/kg per minute


Minute ventilation (VE) normally rises
during incremental exercise as a result of
a linear increase in breathing frequency
(up to about 50 breaths/minute in normal
adults) and a hyperbolic increase in tidal
volume (Vt)

During exercise, the partial pressure of
oxygen in arterial blood (PaO2) remains
near resting values despite marked
reductions in mixed venous oxygen
tension (PvO2) and an abbreviated red
cell transit time through the pulmonary
capillaries
External and Internal Measurements
of Work
During an incremental exercise test, there
is a steady, linear increase in external
work rate performed by the patient. This
is expressed in watts.
 Internal metabolic work performed by
the muscles is generally represented by
the linear increase in Vo2 with increasing
work


The shift into increasing anaerobic
metabolism is a reflection of limitations in
O2 delivery or in muscle oxidative
capacity, or both
Equipment
Bicycle
 treadmill

Patient Safety
a relatively safe procedure
 The risk of complications is related to the
underlying disease
 Rate of death is between 2 and 5 per
100,000 tests

Primary Measurements
ECG:The ECG is used for heart rate (HR),
Stsegment depression, and arrhythmia
detection
 Collection of Expired Gases
 Pulse Oximetry
 Arterial Catheterization
 BP

Indications for CPET
Unexplained Exertional Intolerance: Dyspnea
or Fatigue
 Objective Assessment of Capacity/Impairment
 Establish Organ System-Limiting
ExerciseWhen Multiple Diagnoses Are
Present
 Preoperative Assessment Before Lung
Resection
 Diagnose Exercise-Induced Asthma

Identify Gas Exchange Abnormalities
 Titrate O2 Flow During Exercise
 Pulmonary Rehabilitation Prescription and
Assessment of Response
 Transplant Referral and Prognosis
 Assess Response to Therapy

Absolute Contraindications to CPETs
1-acute myocardial infarction (prior 3 to 5
days)
 2-unstable angina
 3-uncontrolled, symptomatic arrhythmias
 4-syncope
 5-active endocarditis; acute myocarditis or
pericarditis
 6-symptomatic severe aortic stenosis
 7-uncontrolled heart failure

8-thrombosis of lower extremities
 9-suspected dissecting aneurysm
 10-uncontrolled asthma
 11-pulmonary edema
 12-room air saturation ,85% (can exercise
with supplemental O2);
 13-respiratory failure
 14-mental impairment leading to inability
to cooperate

Relative Contraindications to CPETs










left main coronary stenosis or equivalent
moderate stenotic valvular heart disease
severe untreated arterial hypertension at rest (.200
mm Hg systolic, .120 mm Hg diastolic)
tachyarrhythmias or bradyarrhythmias
high-degree atrioventricular block
Hypertrophic cardiomyopathy
significant pulmonary hypertension (although this can
be done safely)
advanced or complicated pregnancy
electrolyte abnormalities
orthopedic impairment that compromises exercise
performance
Indications for Exercise Termination











chest pain suggestive of ischemia
ischemic ECG changes
complex ectopy
Second or third-degree heart block
fall in systolic BP> 20 mm Hg
hypertension (>250 mm Hg systolic, >120 mm Hg diastolic)
desaturation (Spo2<80% when accompanied by symptoms
and signs of severe hypoxemia)
sudden pallor
loss of coordination
mental confusion; dizziness or faintness
signs of respiratory failure