Clinical Exercise Testing

Dr.Demet Demircioğlu

• Cardiopulmonary exercise testing (CPET) is an exercise test for analyzing both diagnostic and prognostic assessment by evaluating both submaximal and peak exercise response involving the pulmonary, cardiovascular, hematopoietic, neuropsychological, and skeletal muscle systems

• CPET is aimed at the evaluation of exercise performance, functional capacity, and impairment by assessing undiagnosed exercise intolerance and exercise-related symptoms. the patient is performing the exercise (walking and jogging) on a Treadmill or a Bicycle ergometer for a period of time, and exercise grade.

• This exercise test can be used, for patient management with lung and heart surgeries, COPD, Unexplained Dyspnea, cardio and respiratory disease, and also used for training tools in athletes.

• In CPET different patients have different exercise protocols and exercise grades to follow.

Cardiopulmonary exercise testing (CPET) is the study of responses of the cardiovascular and ventilatory systems to known exercise stress. This is because gas exchange at the airway is a consequence of cardiac output and pulmonary blood flow, as well as peripheral O2 extraction coupled to ventilation. Thus, the heart, with the circulation, couples gas exchanges (O2 and CO2) of muscle respiration with that at the lungs.

The adequacy of the cardiovascular transport of O2 for known exercise work rates is described by the lung gas exchange.

• CPET involves mainly the analysis of respiratory gases including.

• Respiratory oxygen uptake (Vo2),

• Carbon dioxide production (Vco2),

• Ventilatory measures during a symptom-limited exercise test.

Purpose

• Diagnostic and prognostic evaluation of cardiovascular and pulmonary diseases.

• Evaluation of the disease severity and functional effects.

• Assessment for suitability of treatment, (i.e. surgery, transplantation, supplemental oxygen therapy)

• Evaluation of efficacy of the therapeutic intervention

• The Outcome variable for clinical trials

• Measurable goals to improve fitness

• To measure exercise rehabilitative training intensity

• Development of knowledge and understanding of the disease.

Technique

• Cardiopulmonary exercise testing (CPET) can be assessed by the

• Laboratory method

• Treadmill

• Bicycle ergometer

Exercise Test Modalities

• The treadmill is the most common exercise testing mode.

• Treadmills in clinical exercise laboratories should be electronically driven, allow for a wide range of speed (1–8 mph or 1.61–12.8 km ∙ h−1) and grade (0%–20%), and be able to support a body weight of at least 350 lb (159.1 kg).

Exercise Test Modalities (cont.)

• The treadmill should have handrails for balance and stability; but given the negative impact tight gripping of the handrails can have on both the accuracy of estimated exercise capacity (estimated VO2peak with handrail gripping is greater than measured VO2peak) and the quality of the ECG recording, handrail use should be discouraged or minimized to the lowest level possible when maintaining balance is a concern.

• An emergency stop button should be readily visible and available to both the subject undergoing testing and supervising staff .

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Exercise Test Modalities (cont.)

• Cycle ergometers are the most common exercise testing modes used in many European countries.

• Cycle ergometry is less expensive and requires less space than treadmill testing and is a viable alternative to treadmill testing in individuals with obesity and those who have orthopedic, peripheral vascular, and/or neurologic limitations.

• The cycle ergometer must include handlebars and an adjustable seat, allowing for the knee to be flexed ~25 degrees of full extension in a given subject.

Exercise Test Modalities (cont.)

• Incremental work rates on an electronically braked cycle ergometer are more sensitive than mechanically braked ergometers because the work rate can be maintained over a wide range of pedal rates.

• Because there is less movement of the patient’s arms and thorax during cycling, it is easier to obtain better quality ECG recordings and blood pressure measurements.

Exercise Test Modalities (cont.)

• However, stationary cycling is an unfamiliar method of exercise for many and is highly dependent on patient motivation.

• The test may end prematurely (i.e., because of localized leg fatigue) before a cardiopulmonary endpoint has been achieved.

• Lower values for maximal oxygen consumption during cycle ergometer testing (vs. treadmill testing) can range from 5% to 25%, depending on the participant’s habitual activity, physical conditioning, leg strength, and familiarity with cycling.

Exercise Test Modalities (cont.)

• Arm ergometry is an alternative method of exercise testing for patients who cannot perform leg exercise.

• Because a smaller muscle mass is used during arm ergometry, maximal oxygen consumption during arm exercise is generally 20%–30% lower than that obtained during treadmill testing.

• Although this test has diagnostic use, it has been largely replaced by the nonexercise pharmacologic stress techniques that are described later in this chapter.

Exercise Test Modalities (cont.)

• Arm ergometer tests can be used for physical activity counseling and exercise prescription for certain disabled populations (e.g., spinal cord injury).

• Arm ergometer test can be used by individuals who perform primarily dynamic upper body work during occupational or leisure time activities.

Exercise Protocols

• The protocol employed during an exercise test should consider

– the purpose of the evaluation,

– the specific outcomes desired, and

– the characteristics of the individual being tested (e.g., age, symptomatology).

Exercise Protocols (cont.)• Most common exercise test protocols

– Bruce

– Ellestad

– Naughton

– Balke-Ware

– Ramp

• Bruce treadmill test is one of the most commonly used in CPET

• Bruce or Ellestad is better suited for screening younger and/or physically active individuals (larger progressive workload)

• Naughton or Balke-Ware is preferable for older or deconditioned individuals and patients with chronic diseases. (smaller progressive workload)

• The Bruce protocol is a diagnostic test used in the evaluation of cardiac function.

• According to the original Bruce protocol, the patient walks on an uphill treadmill in a graded exercise test with electrodes on the chest to monitor the EKG. Every 3 minutes, the speed and incline of the treadmill are increased. There are 7 such stages and only very fit athletes can complete all 7 stages.

• The modified Bruce protocol is an alteration in the protocol so that the treadmill is initially horizontal rather than uphill, with the first few intervals increasing the treadmill slope only.

• The test can detect evidence of angina pectoris (chest pain and discomfort), a previous heart attack, and ventricular aneurysm (bulging in the ventricle of the heart).

• Exercise capacity is reported in terms of estimated metabolic equivalents of task (METs).

• The MET unit reflects the resting volume oxygen consumption per minute (VO2) for a 70-kg, 40-year-old man, with 1 MET equivalent to 3.5 mL/min/kg of body weight.

• In the standard Bruce protocol, the starting point (ie, stage 1) is 1.7 mph at a 10% grade (5 METs). Stage 2 is 2.5 mph at a 12% grade (7 METs). Stage 3 is 3.4 mph at a 14% grade (9 METs). This protocol includes 3-minute periods to allow achievement of a steady state before workload is increased.

• The modified Bruce protocol has 2 warmup stages, each lasting 3 minutes. The first is at 1.7 mph and a 0% grade, and the second is at 1.7 mph and a 5% grade. This protocol it is most often used in older individuals or those whose exercise capacity is limited by cardiac disease.

https://www.youtube.com/watch?v=f_FvOdFZ_g8

Measurements During Exercise Testing

• Common variables assessed during clinical exercise testing include

– heart rate

– ECG changes,

– blood pressure,

– subjective ratings,

– signs and symptoms, and

– expired gases and ventilatory responses.

Heart Rate and Blood Pressure (cont.)

• Heart rate and blood pressure responses should be measured before, during, and after the GXT(Graded Exercise Testing).

• A standardized procedure should be adopted for each laboratory so that baseline measures can be assessed more accurately when repeat testing is performed.

Potential Sources of Error in Blood Pressure Assessment

• Inaccurate sphygmomanometer

• Improper cuff size

• Auditory acuity of technician

• Rate of inflation or deflation of cuff pressure

• Experience of technician

• Reaction time of technician

• Faulty equipment

• Improper stethoscope placement or pressure

• Background noise

• Allowing patient to hold treadmill handrails or flex elbow

• Certain physiologic abnormalities (e.g., damaged brachial artery, subclavian steal syndrome, arteriovenous fistula)

Subjective Ratings and Symptoms

• The measurement of perceptual responses during exercise testing can provide useful clinical information.

• Somatic ratings of perceived exertion (RPE) and/or specific symptomatic complaints include

– degree of chest pain, burning, and discomfort;

– dyspnea;

– light-headedness; and

– leg discomfort/pain.

Borg Rating Of Perceived Exertion

• Borg rating of perceived exertion (RPE) is an outcome measure scale used in knowing exercise intensity prescription. It is use in monitoring progress and mode of exercise in cardiac patients as well as in other patient population undergoing rehabilitation and endurance training.

• Borg RPE scale was developed by Gunnar Borg[1] for rating exertion and breathlessness during physical activity; that is, how hard the activity is as shown by high heart and respiration rate, profuse perspiration and muscle exertion.

• Versions and Scoring

• Borg original version is a scale of 6-20; it has a high correlation to heart rate and multiplying each number by 10 gives the training heart rate as at the time of scoring.

• It was later reconstructed to category (C) ratio (R) scale, termed Borg CR10 Scale or modified Borg Dyspnoea Scale which is mostly used in diagnosis of breathlessness and dyspnea, chest pain and musculo-skeletal pain.

• The CR-10 scale is best used in a specific area of the body sensation such as muscle pain or from pulmonary responses.

Borg RPE Scale Borg CR10 Scale

Scoring Level of Exertion Scoring Level of Exertion

6 No Exertion 0 No Exertion

7 Extremely Light 0.5 Very very Slight

8 1 Very Slight

9 Very Light 2 Slight

10 3 Moderate

11 Light 4 Somewhat Severe

12 5 Severe

13 Somewhat Hard 6

14 7 Very Severe

15 Hard (Heavy) 8

16 9 Very very Severe

17 Very Hard 10 Maximal

18

19 Extremely Hard

20 Maximal Exertion

• In Borg RPE;

• 9 = ‘very light’ exercise which equals walking slowly for few minutes at own pace of a healthy individual..

• 13 = ‘somewhat hard’ but the individual is still able to continue the activity.

• 17 = ‘very hard’. A healthy person can continue but must push themselves beyond their comfort of being very fatigued.

• 19 = extremely strenuous exercise. for most people, the hardest they have ever experienced.

Specific symptomatic complaints includeFrequently used scales for assessing the patient’s level of angina (top), claudication (middle), and dyspnea (bottom).

Gas Exchange and Ventilatory Responses

• Currently, the combination of standard GXT procedures and ventilatory expired gas analysis (cardiopulmonary exercise testing) is the clinical standard for patients with CHF being assessed for transplantation candidacy and individuals with unexplained exertional dyspnea.

• The direct measurement of oxygen uptake is more reliable and reproducible than estimated values from treadmill or cycle ergometer work rates.

• Maximum oxygen uptake or VO2max is considered the recognized standard of cardiovascular, pulmonary, and muscular aerobic fitness.

• VO2max is the maximum oxygen consumption that can be used per minute, representing any individual's upper limit of aerobic metabolism. For example; Raising the VO2max levels of an athlete through systematic training invariably leads to significant gains in distance running performance.

• The Fick Equation is a mathematical estimation of a person’s theoretical VO2max. Understanding the individual components that comprise VO2max can help us determine the specific types of workouts.

The formula for determining VO2max through the Fick Equation is represented as:VO2 max = Q(CaO2-CvO2)Q is cardiac output,CaO2 = arterial oxygen content,CvO2 = venous oxygen content.The Fick Equation states that VO2max equals the amount of blood pumped per heart beat at maximum heart rate times the amount of oxygen the working muscles are able to extract from the blood passing through them. The maximal heart rate times the volume of blood pumped per beat is referred to as maximal cardiac output, while the amount of oxygen being extracted by the working skeletal muscles is called the Arterio-Venous Oxygen difference (A-V O2 Difference) and is classified as the difference between the oxygen delivered to a working muscle (the arterial concentration) and the oxygen levels of the blood leaving the working muscles (the venous concentration).

Arterial Blood Gas Assessment During Exercise

• In patients who present with unexplained exertional dyspnea, pulmonary disease should be considered as a potential underlying cause.

• It is important to quantify gas partial pressures in these patients because oxygen desaturation may occur during exertion.

Indications for Terminating Exercise Testing

• Drop in systolic BP of ≥10 mm Hg with an increase in work rate, or if systolic BP decreases below the value obtained in the same position prior to testing when accompanied by other evidence of ischemia

• Moderately severe angina (defined as 3 on standard scale)

• Increasing nervous system symptoms (e.g., ataxia, dizziness, or near syncope)

• Signs of poor perfusion (cyanosis or pallor)

• Technical difficulties monitoring the ECG or SBP

• Subject’s desire to stop

• Sustained ventricular tachycardia

• ST elevation (+1.0 mm) in leads without diagnostic Q waves (other than V1 or aVR)

ABSOLUTE INDICATIONS

Indications for Terminating Exercise Testing

• Drop in systolic BP of ≥10 mm Hg with an increase in work rate, or if systolic BP below the value obtained in the same position prior to testing

• ST or QRS changes such as excessive ST depression (>2 mm horizontal or downsloping ST-segment depression) or marked axis shift

• Arrhythmias other than sustained ventricular tachycardia, including multifocal PVCs, triplets of PVCs, supraventricular tachycardia, heart block, or bradyarrhythmias

• Fatigue, shortness of breath, wheezing, leg cramps, or claudication

• Development of bundle-branch block or intraventricular conduction delay that cannot be distinguished from ventricular tachycardia

• Increasing chest pain

• Hypertensive response (SBP of >250 mm Hg and/or a DBP of >115 mm Hg).

aVR, augmented voltage right; BP, blood pressure; DBP, diastolic blood pressure; ECG, electrocardiogram; PVC, premature ventricular contraction; SBP, systolic blood pressure; V1, chest lead I.

RELATIVE INDICATIONS (cont.)

Postexercise Period• Regardless of the postexercise procedures (active vs. passive

recovery), monitoring should continue for at least 6 min after exercise or until ECG changes return to baseline and significant signs and symptoms resolve.

• ST-segment changes that occur only during the postexercise period are currently recognized to be an important diagnostic part of the test.

Postexercise Period (cont.)

• HR and BP should also return to near baseline levels before discontinuation of monitoring.

• The HR recovery from exercise is an important prognostic marker that should be recorded.

Imaging Modalities

• Exercise echocardiography

• Cardiac radionuclide imaging

• Pharmacologic stress testing

• Computed tomography

The ACSM Clinical Exercise Testing Key Points are as follows:

• Although a clinical exercise test may not be indicated for most individuals about to begin an exercise program, the high value of information obtained from this procedure is not debatable.

• Aerobic capacity may be one of the single best prognostic markers in all individuals regardless of health status.

• Standard clinical exercise testing is well accepted for the assessment of individuals with signs and/or symptoms suggestive of CVD.

• The use of cardiopulmonary exercise testing, which combines standard clinical exercise testing with simultaneous ventilatory expired gas analysis, is common practice in patients with CHF as well as those with unexplained exertional dyspnea.

• The recent recognition that appropriately trained nonphysician personnel can safely perform a clinical exercise test may result in the expanded use of this valuable procedure in various clinical settings.

Exercise Testing for Disease Severity and Prognosis

• The magnitude of ischemia caused by a coronary lesion generally is

– directly proportional to the degree of ST-segment depression, the number of ECG leads involved, and the duration of ST-segment depression in recovery; and

– inversely proportional to the ST slope, the rate pressure product (RPP) at which the ST-segment depression occurs, and the heart rate maximum, SBP, and metabolic equivalents achieved.

Exercise Testing AfterMyocardial Infarction

• Exercise testing after myocardial infarction can be performed

– before or soon after hospital discharge for prognostic assessment,

– for exercise prescription,

– for evaluation of further medical therapy, and

– for interventions including coronary revascularization.

Exercise Testing AfterMyocardial Infarction (cont.)

• Submaximal exercise testing provides sufficient data to assess the effectiveness of current pharmacologic management as well as activities of daily living and early ambulatory exercise therapy recommendations.

• Symptom-limited graded exercise tests are considered safe and appropriate early after discharge (~14–21 d) for exercise prescription and physical activity counseling and further assessment of pharmacologic management efficacy.

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