Cardiopulmonary Exercise Testing

Question 1

CPET definition

Answer 1

-Non-invasive, simultaneous measurement of the cardiovascular and respiratory system
-during exercise to assess a patient’s exercise capacity

Question 2

Rationale for CPET

Answer 2

-Exercise intolerance is the hallmark of pulmonary and cardiac diseases
-Measurements at rest are poorly predictive of the degree of exercise intolerance
-Necessary to directly assess an individual’s exercise intolerance and where possible, establish its causes

Question 3

Coupling of external ventilation and cellular metabolism

Answer 3

Question 4

Mechanisms of exercise limitation

Answer 4

Pulmonary
-ventilatory
-respiratory muscle dysfunction
-impaired gas exchange

Cardiovascular
-Reduced SV
-Abnormal HR response
-Circulatory abnormality

Peripheral
-Inactivity
-Atrophy
-Neuromuscular dysfunction

-Perceptual
-Motivational
-Environmental

Question 5

What is CPET?

Answer 5

-Symptom-limited exercise test
-Measure airflow, SpO2, expired oxygen and CO2
-Allows calculation of peak oxygen consumption, anaerobic threshold

Question 6

ETT vs CPET

Answer 6

-ETT uses non-uniform increments (Bruce) which are too difficult for pulmonary patients
-ETT terminated at arbitrary end point (85% predicted max heart rate) does not provide peak VO2 or reserve capacities
-Gas exchange provides additional cardiac/circulatory information non-invasively

Question 7

Advantages of bike over treadmill

Answer 7

-cheaper
-safer
-direct power calculation
-little training needed
-easier bp recording
-less space/noise

Question 8

Advantages of treadmill over bike

Answer 8

-Attain higher VO2
-More functional

Question 9

What is the modified Borg scale?

Answer 9

-Measure of exertion
1 - nothing
10 - maximal

Question 10

Indications for CPET

Answer 10

-Pre-op evaluation
-Assess response to therapy
-Prognosis of life expectancy
-Disability determination
-Pulmonary rehabilitation - response to participation
-Evaluation of dyspnoea - cardiac vs pulmonary vs peripheral limitation

Question 11

Absolute contraindications of CPET

Answer 11

-Acute MI
-Unstable angina
-Uncontrolled arrhythmias causing symptoms
-Syncope
-Active endocarditis/myocarditis/pericarditis

Question 12

Relative contraindications of CPET

Answer 12

-Left main coronary stenosis
-Moderate stenotic valvular heart disease
-Severe arterial hypertension at rest (200/120)
-Tachyarrhythmias/Bradyarrhythmias
-High degree AV block

Question 13

Steps before carrying out CPET

Answer 13

-Ensure all equipment is serviceable and calibrated
-Take history, cardiac medication (beta blockers?)
-Gain verbal/written consent
-Take height and weight
-12 lead ECG - abrade and alcohol
-Perform spirometry - patient sat down
-Remind patient of end-point criteria

Question 14

Increment vs Ramp protocol

Answer 14

-Ramp is better
-8-12 minute duration
-Long enough to see peak VO2
-Not so long that it demotivates

Question 15

How to calculate work rate?

Answer 15

Question 16

Selecting work rate for different levels of fitness

Answer 16

Question 17

Indications for exercise termination

Answer 17

-Patient request
-Dizziness/faintness/confusion
-Ischemic ECG changes (>2mm ST)
-2nd or 3rd degree heart block
-Fall in BP >20mmHg

Question 18

Slow twitch vs Fast twitch muscle fibres

Answer 18

Red/slow twitch/type 1
-sustained activity
-high mitochondrial density
-metabolise glucose aerobically
-rapid recovery

White/fast twitch/type 2
-rapid burst exercise
-few mitochondria
-metabolise glucose anaerobically
slow recovery

Question 19

Lactic acid

Answer 19

-Product of anaerobic respiration
-Build up of hydrogen ions causes muscle fatigue
Resting blood lactate = 1mM
AT = 4mM
VO2 max = 8mM
Top athletes = 25mM

Question 20

What is RER?

Answer 20

Respiratory Exchange Ratio
RER=CO2 produced/O2 consumed
RER closer to 0.7 - fats being used
RER closer to 1.0 - carbs being used

Question 21

What are ventilatory equivalents?

Answer 21

-Litres of ventilation to eliminate 1 litre of CO2
-Litres of ventilation to uptake 1 litre of O2
-Ratio between these

Question 22

Ventilatory equivalents at rest and exercise

Answer 22

Rest: 6-10 litres/min
Exercise: 100-170 litres/min

Question 23

How does VE increase with VO2?

Answer 23

-Increases linearly with VO2 and workload until 60% of maximum
-Beyond this, it increases at a faster rate due to AT: more CO2, blood is more acidic, breathing rate increases

Question 24

What is average anaerobic threshold?

Answer 24

50-60% of VO2 max
-AT can be estimated using ventilatory response to exercise

Question 25

Relationship of AT to RER

Answer 25

Question 26

Method 1 of determining AT

Answer 26

V slope method

Question 27

Method 2 of determining AT

Answer 27

Ventilatory equivalent plot
-At AT, VE increases at a higher rate than O2 consumption, so VE/VO2 begins to increase
-Point at which VE/VO2 and VE/VCO2 lines cross

Question 28

VO2 max definition

Answer 28

-Maximum ability of cardiovascular system to deliver oxygen to exercising skeletal muscle
-and exercising skeletal muscle to extract oxygen from the blood

Question 29

Fick equation for VO2

Answer 29

HR x SV x A-VO2 difference
Average of 3.5ml/kg/min at rest

Question 30

VO2 max vs VO2 peak

Answer 30

VO2 max = max in theory
VO2 peak = max in reality

Question 31

Formula for maximum HR

Answer 31

220-age

Question 32

What is heart rate reserve?

Answer 32

(1-actual/predicted) x 100
Normal < 15%
Low HRR = Heart disease
High HRR = Lung disease

Question 33

What is breathing reserve

Answer 33

(1-actual/predicted) x 100
Normal = 10-40%
Low BR = Lung disease
High BR = Heart disease

Question 34

Cardiac vs Pulmonary limitation

Answer 34

Heart disease
BR > 40%
HRR < 15%

Lung disease
BR < 40%
HRR >15%