You have probably heard of 6-minute walk test (6MWT) in your travels as a respiratory therapy student, and thought: “I wish a benevolent, handsome instructor would write a paper about that.” Well today is your lucky day! Well, at least as far as the benevolent part.
The most basic explanation of what a 6MWT is: it is a test to see how far a person can walk in, you guessed it, 6 minutes. At its core, it really is that simple, and is not a procedure that requires a lot of fancy equipment, high tech gadgets, or money.
A properly trained healthcare professional, with a minimal amount of basic gear, can put a patient through a 6MWT and gain a lot of clinically useful information about their exercise capacity that can play an important role in the care of that patient.
A Little More Background….
For decades, patients with cardiopulmonary disorders like COPD and CHF were sort of told that the best medicine for their condition was simply to rest. If you feel short of breath just sitting there, why would you want to exert yourself and make it worse? It was felt that those patients were just “too sick” to exercise, or in some cases, even to do activities of daily living. Maybe they were given supplemental oxygen for their shortness of breath, maybe some drugs for their heart and blood pressure, but for the most part, they were told “Good luck with that” as they suffered ever decreasing quality of life.
It was a miserable existence. There was a radical change in thought in the late 1950’s and early 60’s; physicians started to buy into the idea of exercise and cardiac and pulmonary rehabilitation, and that while patients may be suffering from progressive diseases, tailored exercise programs could actually improve quality of life and more optimally use the lung and heart function that was still there.
As is the case when things like this evolve, there was little consensus on techniques and protocols, and there were growing pains as practitioners struggled to make sense of the data that was being collected in the research in this growing field.
Many different testing techniques and procedures were used by providers from many fields in healthcare, and there became a need for a standardized approach. To that end, the American Thoracic Society developed a first set of standard guidelines for the 6MWT and released them in 2002.
A 6MWT is considered a submaximal test, that is, it does not push a patient to their physical limits, although they will definitely be a little worn out by the end. There are other professional groups that have released similar guidelines for a variety of exercise testing, but this paper will focus on the ATS guidelines specifically.
Why is the 6MWT important to us as respiratory therapists?
The 6MWT does give us a pretty simple and practical way to gather information on a patient’s functional status and capacity for exercise, and it is pretty well tolerated buy patient’s with moderate to severe cardiopulmonary disease and other disorders.
It puts the patient in charge- they dictate the pace and what they can do. It not only gives us information about the heart and lung function, but the circulatory, muscular, and neurological systems as well.
It also gives us an objective, reproducible way to assess and investigate progression of disease, success of therapeutic treatments and drugs, and in some case, can act as a marker or predictor of successful surgical outcomes or even mortality.
It is a very common test done in both cardiac and pulmonary rehabilitation units, physical therapy and exercise science departments, outpatient pulmonary clinics, and is becoming increasingly used in discharge planning to get the patient hooked up with the right resources.
Do I need to know this for the NBRC RRT board exams?
Let’s be honest here for a minute. As a respiratory care student or a recent graduate preparing for the big bad NBRC credentialing exams, what you really care about, is the answer to that age old question: “Do we need to know this for the test”? And that answer is a resounding “Yes. Yes, you do.”
You will find questions concerning the 6MWT on both the TMC and CSE exams. Just use some common sense here, and know the situation presented in a question. If your patient is in the ER suffering from an asthma attack, or in the throes of a COPD exacerbation, that would not be the time to consider doing a 6MWT. Likewise, your intubated, septic, critically ill patient in the ICU would not be a candidate for a 6MWT.
But how about that stable patient with known COPD who is getting ready to be discharged home? Could a 6MWT help get a baseline idea of what their functional status is, and maybe even get them to buy into the idea of pulmonary rehab or an outpatient exercise program? Absolutely! Or how about if they actually get themselves into an outpatient pulmonary rehabilitation program or clinic; couldn’t serial 6MWT’s serve as a motivation to them to continue working hard?
They will see objective proof that the exercises are working when they see actual improvement in the distance they walked; the numbers do not lie.
Like with most patient scenarios presented on both the TMC and CSE you need to ask yourself a couple of basic questions when it comes to the 6MWT:
- Is the test safe to perform at this time?
- What information do I hope to gain from this test- is it valuable to this case?
If you can answer “yes” to those, then you should strongly consider the 6MWT as one of your choices.
What are the limitations of the 6MWT?
Just like anything in life, there are limitations to a 6MWT. Obviously, you are not going to do this on a critically ill, unstable patient in the ICU. It is a pretty simple test, so sometimes it is difficult to know what to do with the results; there is still a lot of grey area, and it is not a substitute for more detailed exercise testing procedures.
If a patient has vital signs or values outside of the standard limits suggested, the physician may need to decide if the test is really worth attempting, or maybe it can be modified.
The testing area itself must have the appropriate equipment and trained personnel (ACLS preferred) present in case things do go south with a patient; the test may need to be postponed if these simple safety concerns are not met. If a patient is having chest pain, crazy dyspnea, or just plain looks bad, the test should be stopped immediately before things spiral out of control.
- Should be hemodynamically stable with no unstable angina or MI within the last month, and ideally at the time of testing a resting HR< 120, a systolic BP <180 and diastolic BP <100.
- Must wear comfortable clothing and shoes to walk in.
- Walking aids may be used, and normal medication regimen should be continued (including supplemental oxygen as prescribed).
- Light meals are okay before testing.
- They should not have exercised vigorously within 2 hours of the test, nor should they “warm up” pre-test. Have them sit in a chair for about 10 minutes prior to testing (great time to assess vitals and explain the procedure).
- A timer or stopwatch to track 6 minutes of time
- A lap counter
- 2 cones to mark a 30-meter distance on the floor (which should be level and hard)
- A device to mark/measure distance on the floor (many use tape markers to indicate 3 meter lengths on the floor as well)
- Resuscitation equipment (crash cart, AED, etc.) readily available
- Moveable chairs in case the patient becomes too exhausted/symptomatic to keep going
- Oxygen source
- Pulse oximeter (to at least check pre and post-testing, not recommended to monitor continuously)
- Sphygmomanometer and stethoscope
- Charting sheets, A Borg Scale to assess perceived level of dyspnea (or similar tool), and a clipboard
The actual technique
- Recommended that repeat testing try to be done at about the same time of day for consistency sake
- No “warm up” period- have the patient sit in a chair close to the starting line for at least 10 minutes prior to starting
- Get pre-procedure vitals (RR, HR, BP, resting pulse ox) assure patient is stable to proceed
- Stand patient up and assess patient perceived dyspnea using the Borg scale or similar tool
- Prepare lap counter and stopwatch for use, and proceed with patient to starting point
- Review standardized instructions for the testing procedure) do not ad lib or alter the instructions- keep things consistent with every patient and read the script the same way)
- Stand near the starting line, then start the clock when the patient starts to walk
- Do not walk with the patient or do anything to alter their performance, other than stating the scripted messages, in an even tone, along the line of “You are doing well. You have 5 minutes to go” and so forth
- Try to make sure the patient can actually see you click the lap counter
- Make sure there is adequate room for the test; courses that are too short require the patient to make too many turns and can alter results, and likewise, courses that are too long (like an indoor oval track) can make have an impact
- If the patient becomes tired, you may allow them to rest and lean against the wall, but the timer should be kept going. If it becomes obvious that they cannot continue for the full 6 minutes, wheel a chair to them and allow them to sit and rest
- Instruct the patient to stop and stay where they are at the end of 6 minutes. Make a mark on the floor to indicate their position, then allow them to sit if they need to rest
- Calculate and record the distance the patient covered in the 6 minutes (laps, plus any additional meters, and round to the nearest meter)
- Measure and record all the same data you collected pre-procedure (vitals, Borg scale, etc.) and ask them “What, if anything, kept you walking farther?”
- Assure patient comfort, tell ‘em good job
- Usually, 6MWT’s are performed before and after an intervention (drugs, therapy, exercise/rehab program) to see if there is a significant change; hopefully an improvement, but they can also be done just once as a measurement of a patient’s functional status
- Emphasis is on the hard data and actual values- you are looking for a real meter improvement in meters walked
- There are published sets of data in the literature that state what are predicted normals, what a significant change in meters walked actually is, if numbers can be predictors of mortality for certain conditions, and other things
- Minimum clinically important difference (MCID) is an important concept: it is the observed difference in walked distance that is felt to be important, and there are several different equations and calculations in the literature regarding how to arrive at this; you will need to be familiar with what a particular institution or rehabilitation unit uses
- The 6MWT test can be used to assess exercise capacity in a variety of cardiopulmonary (CHF, pulmonary hypertension, CAD, PAD, COPD, etc.) disorders, as well as many conditions involving the nervous system and skeletal muscles (Parkinson’s, traumatic brain injury, Alzheimer’s/dementia, arthritis, stroke)
- 6MWT have been proven useful in all ages of patients, from preschool to geriatrics
- Other testing may be indicated to further investigate the patient’s issues (PFT’s, cardiac function testing, cognitive level of functioning, etc.)
I hope this summary of what the 6MWT is all about was helpful.
Until next time, this has been your Respiratory Buddy,
- American Thoracic Society. ATS statement: Guidelines for the six-minute walk test. Am J Respir Crit Care Med 2002; 166: 111-117.
- Ghofraniha, L. et al. The six-minute walk test (6MWT) for the evaluation of pulmonary diseases. J Cardiothorac Med. 2015; 3(2) 284-287.
- Casaburi, R. A brief history of pulmonary rehabilitation. Respiratory Care September 2008 (53) No. 9 1185-1189.
- Bittner, V., Singh, S. Cardiology The 6 minute walk test. Retrieved from: https://www.thecardiologyadvisor.com/home/decision-support-in-medicine/cardiology/the-6-minute-walk-test/
- Jefferson, R.6MWT re-visited, now with the MCID! Posted on January 20, 2016. The PFT Blog Retrieved from: https://www.pftforum.com/blog/6mwt-re-visited-now-with-the-mcid/