Clinical Perspectives

PULMONARYFUNCTION TESTING: The Six-Minute

Walkby Janet Test C. Sclafani, RRT, RPFT

ince the introduction of the most comprehensive evalua- tainly, clinicians can use this data the 12-minute walk test by C.R. tion tool. At the conclusion of as proof of a successful rehabili- SMcGavin and colleagues in 1976, the rehabilitative process, the tation program when competing time-distance walk testing has six-minute walk may be used to for health care reimbursement become widely used as an indica- determine the outcome of the for their patients. tor of functional capacity. In physical conditioning compo- 1982, J.A. Butland further nent of the program. The test has Testing environment and defined the test into two- and been used as part of the selection performance issues six-minute increments. While criteria of when to place patients A measured walking distance the two-minute version of the on the lung transplantation list. of at least 100 feet is required for test is less discriminatory and the The six-minute walk test is a performing this test. The walk- 12-minute test too long for most valued assessment tool by ing path should be as unob- chronic obstructive pulmonary National Emphysema Treat- structed as possible, with mini- disease patients, the six-minute ment Trial (NETT) centers dur- mal traffic and no stairwell or test has proven to offer the best ing the pre-surgical and post-sur- elevator exits into the walkway. results in terms of objectivity gical rehabilitation progress. The path should have rest areas and clinical indications.1 Even patients themselves have where the patient can either sit This test has become a stan- realized their own success with or stand with support. dard evaluation tool at the start the results of the six-minute test. Blood pressure, heart rate, res- of a rehabilitation program to Patients who have achieved piratory rate, and resting blood assess the patient’s exercise approximately 170 feet increase saturation by pulse oximetry capacity and set the exercise pre- in distance have rated them- should be obtained prior to test- scription. Exercise testing with selves as doing “a little better” on ing. The patient, after being gas analysis generally precedes evaluation tools assessing their familiarized with the 10-point the use of the six-minute walk as perception of disability.2 Cer- Borg Dyspnea Index Scale,

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should rate their perception of the mendations for evaluation of The patient should be familiar- level of shortness of breath at rest. desaturation, SpO2 (oxygen satu- ized with both the walking path If patients are using supple- ration as measured by pulse and the Borg scale prior to test- mental oxygen, it is best to test oximetry), heart rate, and dis- ing. The less apprehensive the them on the system that they tance should be recorded every patient is during the test, the bet- currently use. Supportive de- minute. A recovery saturation ter the results. Assurances should vices such as canes and walkers reading after the walk should be be given that they can stop the may also be used if needed. Rest noted. The test should be per- test at any time, medications may stops are permitted as often as formed two times, with a mini- be used, and they will be per- necessary, and the timer contin- mum of 15 minutes of rest forming two tests with a rest ues to run during rest stops. between trials. Though not period in between each one. According to the American essential, testing on separate Thoracic Society (ATS) recom- days is the most ideal. Guidelines for desaturation The ATS “Pulmonary Function The six-minute walk test is a valued Laboratory Management and Procedure Manual” provides guid- assessment tool by NETT centers during ance for oxygen titration at rest and with exercise.4 Each depart- the pre-surgical and post-surgical ment should have a well-defined policy for oxygen titration. At our facility, we have successfully used rehabilitation progress. the following procedure. For Clinician’s role patients who desaturate to less than 88 percent on room air dur- Staff supervising the walk test ing a six-minute walk test, it is rec- should instruct the patient about ommended to titrate the adminis- the walking path and test guide- tration of oxygen until the desired lines. They should also carry the SpO2 is achieved. This should be patient’s oxygen, if needed, and followed with an arterial blood gas walk slightly behind them so measurement after 20 minutes on they do not “pace” the walking the new liter flow. If the results are speed. The patient may use any acceptable, the test is then medication needed prior to the repeated on 2 L/min. Arrange- test and use their prescribed liter ments may then be made for the flow of oxygen for activity. patient to use the new liter flow Words of encouragement during during activity. the test have a positive effect on Patients who desaturate to less the results.3 The patient should than 88 percent on their pre- follow instructions to walk the scribed liter flow should have their path and cover as much distance liter flow increased by 1 L/min. for as possible in the six-minute time 20 minutes. The test is repeated at frame. The patient should not the increased liter flow, the physi- talk while walking. At the con- cian is contacted, and adjustments clusion of the test, patients are made to the prescribed liter should again be rated on their flow with exercise. These changes level of shortness of breath. can then be discussed with the Instructions to the patient are patient before they leave. Patients necessary to place them at ease presenting with a saturation level with the test. less than 88 percent on room air

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are not tested. The physician references should be contacted for further instructions and testing criteria. 1. Butland, R.J., Pang, J., Gross, E.R., et al. (1982). Two-, six-, and additional Pulse oximetry devices 12-minute walking tests in respi- reading When using a pulse oximetry ratory disease. British Medical American Association device, the limitations and valid- Journal, 284(6329), 1607-1608. for Respiratory ity of the results must be consid- 2. Redelmeier, D.A., Bayoumi, Care. (1991). ered. The patient should be A.M., Goldstein, R.S., & Guyatt, AARC clinical assessed for low perfusion and G.H. (1997). Interpreting small practice guideline: Pulse history of abnormal hemoglobin differences in functional status: oximetry. Respiratory Care, that may alter the results. Nail The six minute walk test in 36(12), 1406-1409. polish should not be worn. The chronic lung disease patients. stability of the readings and American Journal of Respiratory Connors, G. (1999, March). NETT motion artifact should be con- Critical Care Medicine, 155(4), seminar. Presented by the American sidered when reporting results. 1278-1282. College of Chest Physicians in The clinician needs to assess 3. Guyatt, G.H., Pugsley, S.O., Orlando, FL. the agreement between the pal- Sullivan, M.J., et al. (1984). Effect of encouragement on walking pitated heart rate and the read- Kadikar, A., Maurer, J., & Kesten, S. test performance. Thorax, ing on the device, along with the (1997). The six-minute walk test: A 39(11), 818-822. guide to assessment for lung trans- clinical appearance of the 4. American Thoracic Society. plantation. The Journal of Heart and patient. The two determine the (1998). Pulmonary function labo- Lung Transplantation, 16(3), 313-319. accuracy of the displayed results. ratory management and proce- The condition and placement of dure manual. New York: Ameri- McGavin, C.R., Gupta, S.P., & the probe is of particular consid- can Thoracic Society. McHardy, G.J. (1976). Twelve-minute eration. The fit of the probe 5. Harrington, S., Henderson, D., walking test for assessing disability in should not allow for exposure to & Burton, G.G. (1999). Reliable chronic bronchitis. British Medical ambient light conditions. Newer pulse oximetry during exercise Journal, 1(6013), 822-823. technology in pulse oximetry testing [Abstract]. Respiratory now affords the identification of Care, 44(10), 1226. venous blood signals. The venous signal can be canceled, Oxygen devices Reporting results allowing the arterial signal to be Continuous flow or pulse Reporting formats vary from measured. Signal Extraction delivery systems may be used institution to institution; however, Technology (SET®) looks during testing. It is recom- vital information must be included promising in relation to using mended that patients use their uniformly. Heart rate, blood pres- pulse oximetry during move- personal system to assess their sure, respiratory rate, and a resting ment and by decreasing the oxygen needs during activity. dyspnea index are basic evalua- number of false alarms gener- Patients who desaturate with a tions that clinicians will look for ated. Certainly this technology pulse delivery system may initially on the report. A list of will afford the respiratory thera- require continuous flow during medications, current symptoms pist a more accurate reflection of activity. the patient may be experiencing, the saturation by eliminating There is no preference for and limitations of the patient motion artifact.5 If the issues oxygen delivery devices. As should also be included. The use of regarding motion artifact can be with the oxygen system, the supportive devices, such as canes, resolved in the equipment, the patient’s usual delivery device is walkers, or wheelchairs, should be clinician can make decisions used. The method of delivery documented. regarding the patient’s medical should be noted on the report as Reporting formats include care with greater confidence in well as whether the device was distance walked in feet, the aver- the device used to measure the carried by the therapist or age saturation, dyspnea index at saturation. patient. (continued on page 108)

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the very conclusion of the walk, and a recovery saturation read- ing. A notation should indicate whether the test was on room air or with supplemental oxygen and the amount of oxygen used. Rea- sons for the termination of the test should be clearly docu- mented and may include ele- vated heart rate, pain, desatura- tion, or patient request to stop. Documented oxygen desatura- tion treated with the application of oxygen and any subsequent arterial blood gases should be doc- umented. Information gathered from the second walk test should be the same as in the first and also be included in the report. Tests that are not performed secondary to low saturations should document physician noti- fication of such and any action taken.

Utility of results Used appropriately, the six- minute walk test can supply crit- ical information for the patient and the clinician. It can serve as an assessment for oxygen requirements, efficacy of the rehabilitative process, and as a part of the selection criteria for surgery. The test is simple to per- form and the results easily appre- ciated by patients, providing them with positive feedback after an exercise program. •

Janet C. Sclafani is coordinator of pul- monary rehabilitation at Sarasota Memorial Hospital in Sarasota, FL, and serves on the Executive Board of Direc- tors of the American Lung Association of Gulfcoast Florida.

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