Patient assessment assessing exercise capacity

Transcription

1 Patient assessment assessing exercise capacity STEP 1 Learning objectives This module will provide you with an understanding of what is required when assessing a patient s exercise capacity. By the end of this module you will be able to: STEP 2 outline the reasons for assessing exercise capacity identify the tests used to measure exercise capacity identify the measures required to ensure patient safety explain the practical issues when assessing exercise capacity identify the steps involved in conducting a Six-Minute Walk Test outline additional walk tests such as the Incremental Shuttle Walk Test. Reasons for assessing exercise capacity Exercise capacity should be measured as part of the initial assessment for entry into a pulmonary rehabilitation program. Assessing exercise capacity in patients undergoing pulmonary rehabilitation is important because it allows the health professional to: determine the level of functional impairment and activity limitation determine the factors that limit exercise capacity provide information that will guide exercise prescription identify oxygen desaturation during exercise and aid prescription of supplemental oxygen during training evaluate the effectiveness of rehabilitation in altering exercise capacity and exertional dyspnoea. 1 In a later module you will learn how to evaluate the effectiveness of the program in relation to exercise capacity by repeating the same exercise capacity assessment at program completion. STEP 3 Tests to measure exercise capacity Exercise capacity can be measured via a field walking test. Three commonly used and validated field tests of exercise capacity for patients with chronic obstructive pulmonary disease (COPD) are: Six-Minute Walk Test (6MWT) Incremental Shuttle Walk Test (ISWT) Endurance Shuttle Walk Test (ESWT). The 6MWT is the test most widely used in Australia. 2

2 STEP 4 The Six-Minute Walk Test (6MWT) The 6MWT measures the maximum distance walked in 6 minutes on a flat walking track. The test is a self-paced test and allows the individual to rest if they need to (although the stop watch must be kept going). The Advantages The 6MWT is: STEP 5 Safety valid and reliable in adults with chronic respiratory disease responsive to changes following pulmonary rehabilitation inexpensive to perform requires minimal equipment. 3 Before performing an exercise test, the health professional should have already obtained a medical history for the patient to evaluate whether the patient is safe to exercise and should participate, taking into account any contraindications and precautions. All health care professionals responsible for supervising exercise testing and training should be aware of the following. Safety issues associated with exercise testing: STEP 6 The health professionals supervising the exercise testing and exercise training program will need to be trained in cardiopulmonary resuscitation. Local area safety procedures should be reviewed during program set-up. If performed outside of a hospital environment (e.g. community facility) adequate emergency procedures should be in place including a telephone to call an ambulance. If the patient is on long-term oxygen therapy, the exercise test should be carried out using the prescribed level of inspired oxygen for physical activities. 4 Contraindications and precautions There are many contraindications and precautions to look out for when performing an exercise test on a patient. These include: Unstable angina* or myocardial infarction during the previous month. Resting heart rate > 125 beats/min after 10 minutes rest (relative contraindication). Systolic blood pressure > 200 mmhg ± diastolic blood pressure > 110 mmhg (relative contraindication). Resting oxygen saturation (SpO 2 ) < 85% on room air or while breathing the prescribed level of supplemental oxygen. To be sure this is a real reading check signal adequately by strength/perfusion index/waveform on oximeter and that the heart rate from the oximeter matches the manual pulse rate. If SpO 2 remains < 88% exercise assessment should not proceed and the referring doctor should be notified.

3 Physical disability preventing safe performance. Decompensated heart failure. Active cancer or metabolic disease. unstable diabetes. * Stable exertional angina is not an absolute contraindication to exercise but the test should be performed after administration of anti-angina medication and with GTN spray/anginine available. 4 STEP 7 Monitoring during walking tests During walking tests, the health professional should ensure that: Pulse oximetry is used to measure pulse rate and SpO 2 (i.e. the patient sphysiological response to exercise). It is recommended to use a heart rate monitor when possible. This will provide a more accurate measure of the patient s heart rate response to exercise than pulse oximetry the patient s perception of breathlessness during exercise is measured using a validated scale such as the Borg scale for perceived dyspnoea. 4 The Borg Scale The Borg scale is a scale that asks patients to rate their breathlessness. It starts at number 0 where breathing is not breathless at all and progresses through to number 10 where the patient is maximally breathless. 0 Nothing at all 0.5 Very, very slight (just noticeable) 1 Very slight 2 Slight 3 Moderate 4 Somewhat Severe 5 Severe 6 7 Very Severe 8 9 Very, very severe (almost maximal) 10 Maximal STEP 8 Exercise test termination criteria Exercise test should be terminated if the patient displays any of the following symptoms: unusual headache signs of poor perfusion including light-headedness, confusion, ataxia, pallor, central cyanosis, nausea, cold clammy skin or sweating physical or verbal manifestations of severe fatigue failure of heart rate to increase with exercise (unless the patient has a fixed rate pacemaker). 4 tachycardia (i.e. heart rate > 210 age) patient requests termination of test (e.g. intolerable dyspnoea, which is not relieved by rest and

4 causes patient distress) onset of angina or angina-like symptoms development of an abnormal gait pattern (e.g. leg cramps, staggering) Clinical judgement and local protocols are required to decide the next step if any of these events occur. Criteria to impose a rest SpO 2 < 80% STEP 9 Practical issues Equipment Performing a 6MWT does not require a large amount of resources or equipment. The following are the requirements for performing a safe and effective test: flat track at least 30 metres long marked out in metre intervals so that the distance can be easily calculated (you may need to use a wheeled measure to measure this distance if it is not possible to mark out metres on some tracks) stopwatch dyspnoea/borg breathlessness score pulse oximeter heart rate monitor if available chairs/witches hats/markers appropriately placed oxygen, nasal prongs, bronchodilators if available recording sheet and clipboard stethoscope and sphygmomanometer or blood pressure machine. 6 Environment and track The environment and track can have a significant effect on the outcome. The track should be a minimum of 30 metres. The track may be continuous (oval or rectangular) or point-to-point. The site should adhere to the following: a flat, hard surface should be chosen for the track the site should be well lit and have good ventilation the site should not be too hot or cold the site should be free from obstacles e.g. dogs or cars if outside the walking track should be the same layout for all tests for a patient. 6 STEP 10 Advice to patients It is important that you ensure you advise patients to: wear comfortable clothing and appropriate walking shoes avoid eating for at least two hours before a test bring their reliever medication with them bring their usual walking aids bring their portable oxygen if prescribed. If the test is performed outdoors and it is a hot day, a health professional should use common sense and ensure the patient does not become dehydrated. 3

5 STEP 11 What to measure and how to measure it Specific measurements should be taken before, during and after each test. Also note: number and duration (seconds) of rests during the test use of walking aids oxygen use leg fatigue - ask the patient to rate his/her perception of leg discomfort using the modified Borg scale 3 use of bronchodilators (e.g. if used and time of last dose). At the beginning of the test measure: heart rate use a heart rate monitor otherwise record pulse SpO 2 attach the pulse oximeter via a finger, ear or forehead probe (note: forehead probe reads slightly above finger probe by about 2%) breathlessness - show the patient the Borg scale and give standardised instructions on how to obtain a score blood pressure. At the end of the test measure: heart rate SpO 2 - pulse oximeter breathlessness - Borg score. During the test measure: heart rate and SpO 2 - record the peak heart rate and lowest SpO 2 distance walked in metres. STEP 12 Standard instructions and encouragement It is important that the 6MWT is performed in a standardised manner. For this reason the same instructions and encouragement should be given to the patient each time the test is performed. Tip: It is useful to have the standard instructions and encouragement printed out so that each patient receives the same information. Standard instructions Describe the walking track to the patient and then give the patient the following instructions: You are now going to do a Six-Minute Walk Test. The aim of this test is to walk as far as possible for 6 minutes. You will walk along this hallway between the markers, as many times as you can in 6 minutes. I will let you know as each minute goes past, and then at 6 minutes I will ask you to stop where you are. 6 minutes is a long time to walk, so you will be exerting yourself. You are permitted to slow down, to stop, and to rest as necessary, but please resume walking as soon as you are able. Remember that the objective is to walk AS FAR AS POSSIBLE for 6 minutes, but don t run or jog.

6 Begin the test by instructing the patient to: Start walking now. 3 STEP 13 Performing the 6MWT The patient should commence the test once they have been: assessed for safety informed about the way the test will be conducted given the standard instructions. STEP 14 Where possible the patient s oximetry should be measured continuously on their first 6MWT. If an oximeter is small and lightweight, it may be attached to the patient and checked throughout the test without interfering with walking pace. The clinician should observe the patient closely throughout the 6MWT and if appropriate (e.g. fear of the patient falling over) walk behind the individual for safety during the test but avoid influencing the walking pace. 3 STEP 15 Common questions that may arise If the patient stops/rests during the six minutes: Note the time the patient stopped (but keep the stopwatch running). Allow the patient to sit in a chair if they wish. Measure the SpO 2 and heart rate. Measure breathlessness with the Borg scale. Ask the patient why they stopped. Monitor the patient for untoward signs and symptoms of distress or discomfort. Give the following encouragement (repeat this encouragement every 15 seconds if necessary): Begin walking as soon as you feel able. Record the time when the patient recommences walking. 3 If SpO 2 is less than 85% during the test: Instruct patient to rest and record the time.* Keep clock running. When SpO 2 is above 85% give the following encouragement (repeat this encouragement every 15 seconds if necessary): Begin walking as soon as you feel able.. Record the time when the patient recommences walking. * Note: Depending on the experience of the supervising staff, the patient s clinical presentation, the facility where the testing is performed and the local protocols agreed with referring physicians, the test may continue even if SpO 2 < 85%. (Please note that the finger probe of the pulse oximeter relies on good peripheral perfusion which may be affected by factors such as cold hands, connective tissue diseases such as scleroderma and if the patient is wearing nail polish etc. Check signal strength/perfusion index/waveform on oximeter and that pulse rate matches manually palpated pulse)

7 STEP 16 At the end of the 6MWT put a marker on the distance and measure the distance walked immediately record SpO 2, heart rate, dyspnoea rating and blood pressure on the 6MWTrecording sheet (refer to the Resource Kit) have a chair available if the patient requests to sit down ensure the patient remains in a clinical area for at least 15 minutes following an uncomplicated test. 3 STEP 17 Number of walks Repeating the 6MWT can increase the distance walked through learning effects related to reduced anxiety, familiarity with the track, increased confidence and increased understanding of the test protocol. 6 Therefore the test should be performed twice and the better of the two tests recorded, as people often walk further in the second test. One Australian study of 245 patients with COPD showed that 85% of the patients walked further on their second 6MWT at their pre-rehabilitation assessment. 7 The best result of two tests is important because: 1. Any improvement in the 6-Minute Walk Distance (6MWD) after the exercise program can be attributed to real improvement in exercise capacity. 2. It optimises the prescription for walking training at the commencement of rehabilitation. 3. It enables the patient s test performance to be compared with predicted normal values. STEP 18 Performing a second walk test There should be at least 20 minutes rest between tests. The second test can be performed on another day but less than a week apart. The best result is recorded. 6 A second 6MWT may not be indicated in certain circumstances. For example when the 6MWD is limited due to: other problems e.g. leg pain oxygen desaturation to less than 85% (may need to repeat the test with supplemental oxygen) abnormal response during test such as excessive fatigue. STEP 19 Documentation and reporting outcomes The following should be recorded from a Six-Minute Walk Test: distance walked number and duration of rests resting and peak heart rate SpO 2 range, blood pressure at each minute dyspnoea (using the Borg score)

8 presence of leg fatigue or a score for leg fatigue. The 6MWT reporting document is below (see toolkit for downloadable pdf). STEP 20 Using the outcomes of the 6MWT 6MWT predicted values The results of the 6MWT can be compared to predicted normal values. Normal values for Australian (Caucasian) individuals aged years can be calculated using the following equations: Predictive equation for males o 6MWD (metres) = 867 (5.71 x age in years) + (1.03 x height in cm) Predictive equation for females o 6MWD (metres) = 525 (2.86 x age in years) + (2.71 x height in cm) (6.22 x BMI) 8 STEP 21 6MWT as an outcome The change in the distance walked in the 6MWT can be used to evaluate the efficacy of an exercise training program or to trace the natural history of change in exercise capacity over time.

9 The minimum important difference (MID) (i.e. improvement) in the distance walked in a 6MWT has traditionally been estimated as 54 metres (with 95% confidence limits of 37 to 71 metres) 9. More recently a distance of 35 metres (95% confidence limits 30 to 42 metres) was identified as representing an important effect in COPD, although this distance did not appear to be important to patients. 10 In an Australian study of 75 patients with COPD the MID for 6MWT was identified as 25 metres (95% confidence limits 20 to 61 metres). 11 In interstitial lung disease, a MID of 31 metres (95% confidence limits 19 to 45 metres) has been identified. 12 A patient s 6MWT results can be used to prescribe a training intensity for a walking program. This will be covered in more detail in a later module. STEP 22 Other field walking tests While the Six-Minute Walk Test is the test most widely used in Australia it is helpful to know about two other tests that are used for assessing exercise capacity in people with chronic respiratory disease. They are: The Incremental Shuttle Walk Test (ISWT) The ISWT was developed to simulate a laboratory-based cardiopulmonary exercise test. In brief the ISWT involves the following: The patient is required to walk between two cones in time to a set of auditory beeps played on a CD. Initially, the walking speed is very slow, but each minute the required walking speed progressively increases. The patient walks for as long as they can until they are either too breathless or can no longer keep up with the beeps at which time the test ends. The number of shuttles (laps between the cones) is recorded. Each shuttle represents a distance of ten metres. The results of the ISWT can be used to prescribe the intensity of walking exercise. 13 The Endurance Shuttle Walk Test (ESWT) The ESWT measures how long a patient can maintain a constant pace walking around a 10-metre shuttle walking course. The speed of walking is calculated at 85% of the individuals predicated maximal oxygen consumption estimated from performance during an incremental shuttle walk test (ISWT). 14 STEP 23 Other tests of exercise capacity Laboratory tests Exercise capacity can be measured via laboratory based tests that use the following equipment: Treadmill. Cycle ergometer. Laboratory tests of exercise capacity, such as incremental maximum tests or constant workrate endurance tests, may also be used. These tests provide detailed physiologic measurements that are useful for assessing the cause of exercise limitation and prescribing exercise. Constant workrate tests are responsive to changes in exercise capacity following pulmonary rehabilitation. However, these tests require complex equipment, are costly and not available outside specialist centres. These test require the

10 patient to wear a facemask or mouthpiece so that expired gas can be analysed for information on metabolic parameters. Further information can be obtained from ATS/ACCP Statement: Cardiopulmonary Exercise Testing (2003) and Lavoilette (2008). 15 Upper limb tests A number of upper limb assessment tools are available, such as the incremental unsupported upper limb exercise test (Takahashi 2003) and the grocery shelving task (Hill 2008). These tests are reliable and sensitive to change, however the minimal important difference has not been established. Upper limb 16, 17 tests are not routinely performed in pulmonary rehabilitation. Strength tests A number of strength tests such as the one-repetition maximum, sit to stand, hand-held dynamometry, isokinetic and isometric tests have been used in clinical research with patients with COPD. These tests are not routinely performed in pulmonary rehabilitation. For further details, see ACSM's Guidelines for Exercise Testing and Prescription, Eighth Edition. STEP 24 Module summary This module provided you with an understanding of what is required when assessing a patient s exercise capacity. You should now be able to: outline the reasons for assessing exercise capacity identify the tests used to measure exercise capacity identify the measures required to ensure patient safety explain the practical issues when assessing exercise capacity identify the steps involved in conducting a Six-Minute Walk Test outline additional walk tests such as the Incremental Shuttle Walk Test. REFERENCES 1 Pulmonary Rehabilitation Toolkit Reasons for Assessing Exercise capacity Revised 2017 < > Accessed 06 June Pulmonary Rehabilitation Toolkit Assessing Exercise Capacity Revised 2017 < 6> Accessed 06 June Maguire GP, Boyle E, Allan H, Alison J. Breathe Easy, Walk Easy Better lung health for rural and remote Australia: Pulmonary Rehabilitation Training Manual. 1 st edition. Brisbane, Queensland: Australian Lung Foundation 2010, Pulmonary Rehabilitation Toolkit Safety Issues Relating to Exercise Assessment? Revised > Accessed 06 June Borg G. Psychophysical bases of perceived exertion. Med Sci Sports Exer. 1982;14, Pulmonary Rehabilitation Toolkit Six-Minute Walk Test Revised > Accessed 06 June 2012

11 7 Six-minute walk test in pulmonary rehabilitation: Do all patients need a practice test? Jenkins S, Cecins NM. Respirology. 2010; 15: doi: /j x. 8 Jenkins S, Cecins N, Camarri B et al. Regression equations to predict 6-minute walk distance in middle-aged and elderly adults. Physiotherapy Theory & Practice 2009; 25: Redelmeier DA, Bayoumi AM, Goldstein RS, Guyatt GH. Interpreting small differences in functional status: the six minute walk test in chronic lung disease patients. Am J Respir Crit Care Med. 1997; 155; Puhan M, Scharplatz M, Troosters T, Walters EH, Steurer J. Pulmonary rehabilitation following exacerbations of chronic obstructive pulmonary disease. Cochrane Database of Systematic Reviews 2009, 1; Art. No.: CD DOI: / CD pub2 11 Holland AE, Hill CJ, Rasekaba T, Lee A, Naughton MT, McDonald CF. Updating the minimal important difference for six-minute walk distance in patients with chronic obstructive pulmonary disease. Arch Phys Med Rehabil 2010; 91: Holland AE, Hill CJ, Conron M, Munro P, McDonald CF. Small changes in six minute walk distance are important in diffuse parenchymal lung disease. Respiratory Medicine 2009; doi: /j.rmed Pulmonary Rehabilitation Toolkit Incremental Shuttle Walk Test Revised 2009 < 0> Accessed 06 June Revill SM, Noor MZ, Butcher G, Ward MJ. The endurance shuttle walk test: An alternative to the six-minute walk test for the assessment of ambulatory oxygen. Chronic Respiratory Disease; 2010; 7; Weisman IM. ATS/ACCP Statement on cardiopulmonary exercise testing. Am J Respir Crit Care Med 2003; 167: Takahashi T, Jenkins SC, Strauss GR et al. A new unsupported upper limb exercise test for patients with chronic obstructive pulmonary disease. J Cardiopulmonary Rehabilitation 2003; 23: Hill CJ, Denehy L, Holland AE, McDonald CF. Measurement of functional activity in chronic obstructive pulmonary disease: the grocery shelving task. J Cardiopulm Rehabilitation & Prevention 2008; 28: 402-9