Clinical Exercise Testing and Interpretation

Question 1

What are the 7 indications for CPET

Answer 1

A) Pre-Operative assessment
B) Evaluation of heart-lung transplantation
C) Prognostic assessment and risk stratification
D) Evaluation of exercise tolerance and functional capacity
E) Evaluation of disease severity and progression
F) Exercise prescription for rehabilitation
G) Determining effectiveness of pharmacological agents/exercise intervention

Question 2

What are the 10 absolute contraindications to to symptom-limited maximal exercise testing?

Answer 2

1) Acute myocardial infarction (within 2 days)
2) Ongoing unstable angina
3) Uncontrolled cardiac arryhythmia with hemodynamic compromise
4) Active endorcaditis
5) Symptomatic severe aortic stenosis
6) Decompensated heat failure
7) Acute pulmonary embolism, pulmonary infarction or DVT
8) Acute myocarditis or Pericarditis
9) Acute aortic dissection
10) Physical disability precluding safe or adequate testing

Question 3

What are the 8 relative contraindications to symptom limited maximal exercise testing?

Answer 3

1) Left main coronary artery stenosis
2) Asymptomatic aortic stenosis
3) Tachyarrhythmia with uncontrolled rate
4) Acquired advanced or complete heart block
5) Recent stroke or TIA
6) Mental impairment with limited cooperation
7) Resting hypertension >200 mmHg or diastolic >110 mmHg
8) Uncontrolled medical conditions such as significant anaemia, important electrolyte imbalance and hyperthyroidism

Question 4

What things should be done prior to testing?

Answer 4

1) Resting ECG
2) Educate patient on test (what they’ll feel/do)
3) Medical history
4) Current medications

Question 5

How does peak oxygen uptake differ between a bike and treadmill and other modalities?

Answer 5

• Roughly 10% lower on a bike due to local muscular fatigue
• Reduced oxygen uptake with smaller muscle mass used

Question 6

What is the basic outline of CPET protocols and what variables might influence the protocol?

Answer 6

1) Duration of 8-12 minutes
2) Individualised based on age, exercise tolerance, and symptoms
3) Low-intensity warm-up followed by by a progressive, continuous exercise in which demand is elevated to individual’s maximum level

Question 7

What are the steps in cardio-pulmonary exercise testing?

Answer 7

1) Informed consent
2) Baseline measures: Weight, height, medication changes adherence to protocol
3) ECG lead set up
4) Spirometry: Nose clips - Breath in - blow in and out as fast as you can fully empty the lung
5) Measure blood pressure, breathing, at rest for 3-5 minutes
6) Warm-up for 3-5 at 1.5-2.0 METs or less in unfit
7) Each stage of Watt protocol is held for 1 minute
8) Increase Watt protocol 10 - 20 Watts per minute depending on fitness
9) Cool-down for 3-5 minutes at 1.5 to 2-minutes
10) Recovery period: 10 minutes

Question 8

What, When, and How are the various variables measured during a cardio-pulmonary exercise test

Answer 8

Electrocardiogram:
- Monitor continuously in supine and position of exercise test
- Record during last 5-10 sec each stage or every 2 minutes (Ramp Protocol)
- Immediately post-exercise - after 60s recovery - every 2 minutes after
Heart rate
- Position of exercise
- Last 5-10 seconds of each minute throughout test
Blood pressure:
- Every 2 minutes or ever 30-60s of each stage
- Immediately post-exercise, after 60s recovery, every 2 minutes
Signs and symptoms (light-headed, dyspnea, angina):
- Monitor continously
Rating of perceived exertion
- Explain scale before
- Last 5-10 seconds each stage or every 2 minutes
- Obtain peak shortly after exercise is terminated
Pulse Oximetry (Pulmonary disease):
- Decrease of SPO2 >5% with exercise is considered a abnormal response

Question 9

What can effect SPO2 reading?

Answer 9

• Low perfusion, Haemoglobin abnormalities, Low oxygen saturation, Very dark skin tone, Nail Polish, Acrylic nails and movement during exercise

Question 10

Outline the 3 scales for determining angina, claudication and dyspnea? What is their significance in CPET?

Answer 10

1) Angina scale: 0 (no pain), 1 (barely noticeable), 2 (bothersome) 3 (very uncomfortable), 4 (Very severe worst pain experienced)
2) Claudication scale: 0 (no pain), 1 (minimal), 2 (painful but can be diverted), 3 Intense pain (cannot be diverted), 4) Unbearable pain
3) Dyspnea scale: (No SOB), 1 (barely noticeable), 2 (Bothersome), 3 (Moderately severe), 4 (Most severe, very uncomfortable)
Scoring 3 out of 4 on any of these measures is indication for stopping the test

Question 11

What did Rochmis and Blackburn find

Answer 11

17 studies showed event rate of 35 per 10,000

Question 12

What are the absolute safety indications for terminating a maximal exercise test?

Answer 12

1) ST elevation (>1.0 mm)
2) Drop in SBP >10 mmHg despite increasing work rate when accompanied by evidence of ischemia
3) Moderate to severe angina
4) CNS symptoms (ataxia, dizziness, or near syncope)
5) Cyanosis or Pallor, (blue/white colour)
6) Sustained ventricular tachycardia or other arrhythmia including second or third degree atrioventricular block that interferes with normal maintenance of cardiac output
7) Technical difficulties monitoring equipment
8) Individual asks to stop

Question 13

What are the relative safety indications for stopping a CPET

Answer 13

1) ST depression >2mm
2) SBP >10 mmHg reduction despite increasing work rate with no evidence of ischemia
3) Increasing chest pain
4) Fatigue, SOB, Wheezing, Claudication
5) Arrhythmias that interfere with hemodynamic instability
6) Exaggerated hypertensive response (>250 mmHg SBP or >115 mmHg DBP)
7) Development of bundle branch block that cannot be distinguished from ventricular tachycardia
8) SPO2 <80%

Question 14

What are the issues with estimating exercise capacity on a treadmill?

Answer 14

1) Confounded by factors such as treadmill experience, walking efficiency, presence of disease, exercise protocol used, used of handrails for support

Question 15

What are the criteria for determining a maximal effort on a exercise test AND WHAT is a test called if these are not achieved?

Answer 15

1) Plateau in VO2 (or failure to increase by 150 ml despite increasing work rate)
2) Failure of heart rate to increase with workload
3) Post exercise lactate concentration of >8.0 mmol
4) RPE >17
5) Peak RER >1.10
VO2 peak if criteria not achieved - no consensus on number of these that should be reached

Question 16

What is the benefit and use of field walking tests?

Answer 16

1) Can be done in a hallway
2) More appropriate to activities of daily living
3) More comfortable for patients

Question 17

What is the most widely used prediction equation for directly measured VO2 peak and what is considered indicative or low physical function? What considerations should be made

Answer 17

1) Hansen, Sue, and Wasserman - previously termed Wasserman equations.
2) <80% of age predicted is indicative of reduced physical function
3) Population on which prediction is made should be as close to individual being tested 4) Circulation journal has simple equation for patients with medical or surgery diagnosis

Question 18

What oxygen consumption at the anaerobic threshold, peak oxygen consumption and ventilatory efficiency slope is determined high and very-high risk for post-operative complications?

Answer 18

VO2 at AT: High risk: <11 ml/kg/min
VO2 at AT: Very high-risk: <9 ml/kg/min
VO2 peak: High risk: 10-14 ml/kg/min
VO2 peak: Very high risk: <10 ml/kg/min
VE/VCO2 slop: High Risk: 34-36
VE/VCO2 slope: Very High Risk: >36
Oxygen pulse: <9-10 ml/beat - impaired cardiovascular function

Question 19

What are the various elements of cardio-pulmonary exercise testing and outline them briefly

Question 20

What is cardio-pulmonary exercise testing?

Answer 20

Maximal or symptom limited progressive exercise with ventilatory expired gas analysis. It is breath-by-breath monitoring of oxygen and carbon dioxide during exercise that enables accurate assessment of a patient’s functional capacity and underlying exercise limitation using a nine panel PLOT

Question 21

What are the pre-test considerations in CPET?

Answer 21

1) Patient consent
2) Protocol explanation and full explanation of test protocol
3) History and clinical examination
4) Compliance with pharmacological treatment
5) Assessment of co-morbidities e.g orthopaedic limitation
6) Anthropometric measures
7) Resting ECG
8) Pre-test spirometry

Question 22

Outline the 4 key parameters for exercise tolerance testing

Answer 22

1) Peak oxygen consumption: Measures the maximum rate at which oxygen consumption during exercise - overall capacity of cardiovascular and pulmonary system to deliver oxygen
2) VE/VCO2 slope: Ventilatory efficiency - increased slope indicates poor gas exchange
3) Anaerobic threshold: The point at which anaerobic metabolism begins to contribute significantly to energy production
4) Oxygen pulse: VO2/HR represents the amount of oxygen pumped per beat

Question 23

What is the physiological mechanism behind which a low anaerobic threshold increases the risk of complications?

Answer 23

• Oxygen increase by approximately 10% to 50% from baseline following non-cardiac surgery.
• Low AT reflects decreased ability to deliver oxygen.
• Impaired tissue perfusion in heart, brain, kidney increasing risk of ischemia and organ dysfunction
• Impairs wound healing
• Increased anaerobic metabolism associated with low AT can produce systemic inflammation and oxidative stress which can exacerbate tissue injury

Question 24

What is the mechanism behind why the VE/VCO2 slope

Answer 24

• Show impaired ventilation perfusion mismatch
• Increased demand on heart to make up poor ventilation
• Metabolic imbalance can lead to metabolic acidosis, cellular dysfunction, and tissue injury, particularly in organs with high metabolic demand such as the heart and brain.
• An elevated VE/VCO2 slope reflects reduced physiological reserve and impaired aerobic capacity, indicating limited ability to tolerate the physiological stress of surgery and anesthesia.
• Anesthesia and sedation medications can depress respiratory drive, reduce tidal volume, and impair gas exchange, leading to hypoventilation and hypoxemia.
• Inadequate oxygenation and ventilation during surgery and post-operative recovery. This can contribute to respiratory complications such as atelectasis (collapsed lung), pneumonia, and respiratory failure.

Question 25

Why is pneumonia more likely to occur post-surgery in those less fit?

Answer 25

• Individuals who are less fit may have reduced lung capacity, impaired gas exchange, and diminished respiratory muscle strength, leading to ineffective ventilation and inadequate oxygenation.
• Compromised respiratory function increases the risk of atelectasis, a common complication following surgery, which predisposes individuals to pneumonia by creating a favorable environment for bacterial growth and colonization in the lungs.