ATS Guidelines for the Six-Minute Walk Test

DR.KARTIK SOODJR1

DEPTT OF PULMONARY MEDICINEERA’S LUCKNOW MEDICAL COLLEGE

CLINICAL EXERCISE TESTS AVAILABLE FOR THE OBJECTIVE EVALUATION OF FUNCTIONAL EXERCISE CAPACITY INCLUDES-

6MWT shuttle-walk test detection of exercise-induced

asthma cardiac stress test

Six minute walk test

Introduction Assessment of functional capacity has

traditionally been done by merely asking patients the following:

How many flights of stairs can you climb ?

How many blocks can you walk ? However, patients vary in their

recollection and may report overestimations or underestimations of their true functional capacity.

In the early 1960s, Balke developed a simple test to evaluate the functional capacity by measuring the distance walked during a defined period of time.

A 12-minute field performance test was then developed to evaluate the level of physical fitness of healthy individuals.

The self-paced 6MWT assesses the submaximal level of functional capacity.

In an attempt to accommodate patients with respiratory disease for whom walking 12 minutes was too exhausting, a 6-minute walk test came into being.

The 6MWT is a practical simple test that requires a 100-ft hallway but no exercise equipment or advanced training for technicians.

It evaluates the global and integrated responses of all the systems involved during exercise but It does not provide specific information on the function of each of the different organs and systems involved in exercise or the mechanism of exercise limitation.

However, because most activities of daily living are performed at submaximal levels of exertion, the 6MWD may better reflect the functional exercise level for daily physical activities.

It is a powerful tool in evaluation of functional status and prognosis of patients with a variety of functional impairments.

INDICATIONS FOR THE SIX-MINUTE WALK TEST PRETREATMENT

AND POSTTREATMENT COMPARISONS

1. Lung transplantation 2. Lung resection 3. Lung volume reduction

surgery 4. Pulmonary rehabilitation 5. COPD 6. Pulmonary hypertension7. Heart failure

FUNCTIONAL STATUS

1. COPD 2. Cystic fibrosis 3. Heart failure 4. Peripheral

vascular disease 5. Fibromyalgia 6. Older patients

Contraindications

ABSOLUTE

1) Unstable angina2) Myocardial infarction during previous month RELATIVE 1) Resting heart rate >120/ min2) Systolic blood pressure > 180mm Hg3) Diastolic blood pressure > 100mm Hg Stable exertional angina is not a

contraindication but patients having it should perform the test after taking anti angina medications and rescue nitrate medication should be readily available.

Technical aspects Test Is performed indoors Along a long, flat, straight, enclosed

corridor with a hard surface that is seldom traveled.

The walking course must be 30 m in length thus a 100-ft hallway is required.

The length of the corridor should be marked every 3 m.

The turnaround points should be marked with a cone.

A starting line, which marks the beginning and end of each 30-m lap, should be marked on the floor using brightly colored tape.

Patient preparation

Comfortable clothing should be worn.

Appropriate shoes for walking

should be worn.

Patients should use their usual walking aids during the test (cane, walker, etc.).

The patient's usual medical regimen should be continued.

A light meal is acceptable before

early morning or early afternoon tests.

Patients should not have exercised

vigorously within 2 hours of beginning the test.

Measurements

Repeat testing should be performed about the same time of day to minimize intraday variability.

A "warm-up" period before the test should not be performed.

Pulse oximetry is optional. If it is

performed, measure and record baseline heart rate and oxygen saturation (SpO2)

The patient should sit at rest in a chair, located near the starting position, for at least 10 minutes before the test starts. During this time, check for contraindications, measure pulse and blood pressure, and make sure that clothing and shoes are appropriate.

Have the patient stand and rate their baseline dyspnea and overall fatigue using the Borg scale.

Set the lap counter to zero and the timer to 6 minutes.

Then the patient walking at a comfortable pace walks and every lap that is covered by him is marked on the sheet.

The patient if gets tired while walking then he is allowed to rest but the timer is not stopped.

The patient is informed about every passing minute but no words of encouragement or instructions to hurry up is given to the patient.

Once the timer rings the patient is asked to stop where he is and following things are carried out :

1. Post-test: Record the post walk Borg dyspnea and fatigue levels.

2. Record the number of laps from the counter

3. If using a pulse oximeter, measure SpO2 and pulse rate from the oximeter .

4. Calculate the total distance walked, rounding to the nearest meter.

5. Congratulate the patient on good effort and offer a drink of water.

Borg scale

0 Nothing at all0.5 Very, very slight (just noticeable) 1 Very slight2 Slight (light)3 Moderate4 Somewhat severe5 Severe (heavy)67 Very severe8910 Very, very severe (maximal)

This Borg scale should be printed on heavy paper and preferably laminated.

At the beginning of the 6-minute exercise, show the scale to the patient and ask the patient to grade his shortness of breath and fatigue according to the scale.

Post test he is reminded of his previous scores and is asked to grade his shortness of breath and fatigue after completion of test again.

Then the result of pre and post treatment value is compared and the result is given as an absolute value like patient improved by 50 meters.

Reliable reference equations establishing standard performance during six minute walk test in healthy individuals is not available.

Test should be terminated in case patient develops :

1. Chest pain2. Severe dyspnea3. Leg cramps4. Diaphoresis5. Profound oxyhemoglobin

desaturation.

SAFETY ISSUES

Testing should be performed in a location where a rapid,appropriate response to an emergency is possible

Supplies that must be available include oxygen, sublingual nitroglycerine, aspirin, and albuterol (mdi)

technician should be certified in cardiopulmonary resuscitation

If a patient is on chronic oxygen therapy, oxygen should be given at their standard rate

Factors reducing six minute walk test

Short height Older age Female sex Higher body weight Impaired cognition Short corridor i.e. walking distance Pulmonary disease (COPD, asthma, cystic

fibrosis, interstitial lung disease) Musculoskeletal disorders (arthritis, ankle,

knee, or hip injuries, muscle wasting, etc.) Cardiovascular disease (angina, MI, CHF,

stroke, TIA, PVD)

Factors increasing six minute walk test

Male sex Higher motivation Taller height or long legs A person who has performed the

test previously Medication for a disabling disease

taken just before the test

CONCLUSION

The 6MWT is a useful measure of functional capacity targeted at people with at least moderately severe impairment. The testhas been widely used for preoperative and postoperative evaluation and for measuring the response to therapeutic interventions for pulmonary and cardiac disease

SHUTTLE WALK TEST

Purpose of this measurement tool is to assess the functional capacity

Indications are chronic airflow obst. Chronic heart failure, cardiac disease,rheumatoid arthiritis,people awaiting heart transplantation,patients with pacemakers,undergoing cardiac rehab,intermittent claudication,chronic respiratory failure.

SWT is a performance based test that measures exercise performance levels.

Distance walked is measured in meters.

Longer the distance walked signifies better performance

For this test you need a quiet treatement area that is atleast 12 meters in length and a tape player .The standard instructions are given on the audio cassette tape . Subjects are required to walk back and forth ,turning around two cones placed 9 meters apart making the shuttle distance 10 meters long.The subject must keep pace with the prerecorded auditory signal such that they complete a turn as each sound beeps every minute an audio signal sounds at increasingly shorter intervals.

One beep indicates the length of one shuttle and three beeps indicates an increase in speed .

There are 12 levels of speed beginning at 0.5 m/s and ending at 2.37 m/s.

If the patient chooses to stop or fails to keep up with the audio signals after one warning the test will end.

The test will also terminate if the patient reaches 85% of their maximal heart rate or their oxygen levels go below a preset limit .

Time required is 15 to 45 minutes depending on the patients condition .

ADVANTAGES

• Reliable,valid and fast assessment

• Since this test is externally paced meaning the pace and form of the patients walk is determined by factors outside their control .this eliminates the encouragement that is typical of self paced tests ,which makes this test more like gold std for measurement of exercise capacity

Detection of exercise induced asthma

Exercise induced asthma is bronchoconstriction and symptoms of shortness of breath , chest tightness and cough that develop when you exercise

Symptoms may occur shortly after a brief period of exercise or 10 to 15 minutes into a longer period of exercise and resolve with rest in not more than 30 to 60 minutes.

Most commonly a form of exercise testing with pre and post exercise spirometry is used to confirm the diagnosis

Exercise is done on a treadmill or stationary bycycle until you reach 85% of your expected maximum heart rate.

Diagnosis is confirmed if FEV1 falls more than 10 % with exercise .

Use of bronchoprovocation challenge test and peak flows (pre and post exercise) are not recommended to diagnose exercise induced asthma becoz results are often inaccurate.

The 6MWT is safer, easier to administer, better tolerated, and better reflects activities of daily living than other walk

tests (such as the shuttle walk test).

HOW DOES THE 6MWT COMPARE TO THE SHUTTLE WALK TEST

With the 6MWT the instructions to the patient are to “walk as far as you can during 6-minutes,” whereas the shuttle walk test pressures the patient to meet multiple deadlines, according to beeps from an audio cassette tape. The 6MWT is self-paced, and a patient is probably less likely to push himself beyond his endurance or through angina or other pain than during the shuttle walk test. The shuttle walk test is better correlated with peak oxygen uptake, as measured by a full cardiopulmonary exercise test, but not as many people are using the shuttle walk test.