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* From Rush-Presbyterian-St. Luke’s Medical Center, Chicago, IL.
Correspondence to: Ellen H. Elpern, RN, MSN, 1725 W. Harrison, Suite 054, Chicago, IL 60612; e-mail: eelpern{at}rush.edu
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Abstract |
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 TOP Abstract IntroductionMaterials and MethodsResultsDiscussionAppendix 1References |
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Design: Analysis of information obtained by means of a structured written questionnaire.
Setting: Outpatient pulmonary rehabilitation programs in the United States and Canada.
Participants: Clinical coordinators of 75 pulmonary rehabilitation programs.
Interventions: None
Results: Timed walk tests were obtained in 71 of 99 programs surveyed. Considerable variability in all aspects of testing practices was evident. Fifty-seven respondents (80%) based results on a single walk. Walk tests were completed in a hallway (73%), on a walking track (9%), and on a treadmill (7%). In 29 programs (44%), a walk supervisor carried or pulled the oxygen source, while in 25 programs (38%), the oxygen was carried or pulled by the patient. Informal nonstandardized instructions were provided to patients prior to walking in 41 programs (58%). In 53 programs (76%), the walk supervisor could direct a patient to speed up, to slow down, or to rest. Evaluations of breathlessness and perceived exertion were measured during the walk by 73% and 16% of programs, respectively.
Conclusions: Practices regarding performance of timed walk tests are poorly standardized among pulmonary rehabilitation programs. Further research is needed to evaluate the impact of certain variations in testing practices on test results.
Key Words: exercise testing • outcome assessment • rehabilitation
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Introduction |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionAppendix 1References |
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Six- and 12-min walk tests are usually self-paced and require an individual to walk as far as possible on a designated surface for a specified time interval. The distance walked during the test, measured in feet or meters, is used as the outcome measure. The widespread acceptance of walk tests relates to their convenience, simplicity, low cost, and presumed ease of completion. Although attractive as field tests of function and disability, conduct of walk tests may be poorly standardized. Lack of standardization in areas known to potentially influence results could impose considerable difficulty in interpreting and comparing walk test results obtained at different times or from different testing sites.
Factors known to potentially influence results of walk tests have been reviewed recently by Steele.2 These include learning, motivation, and methodologic variables, such as instruction, encouragement, encumbrances while walking, and use of assistive devices to ambulating. With a goal of standardizing walk-testing procedures, a protocol for conduct of a 6-min walk was proposed. Similarly, the American Association of Cardiovascular and Pulmonary Rehabilitation (AACVPR) sanctioned the value of timed-distance walk tests as outcome measures for pulmonary rehabilitation, and cautioned of the need to standardize test procedures. The AACVPR recently published guidelines for pulmonary rehabilitation programs, and included a procedure for conduct of timed-distance walk tests.3 Both Steele and the AACVPR indicated the necessity for standardization of the number of baseline tests, patient instructions, reinforcement during testing, and use of supplemental oxygen. Both sources specified the use of a premeasured hallway or track of at least 100 feet for conduct of walk tests. The AACVPR specifically advised against use of a treadmill. Both sources provided scripts of prewalk instructions to be given to patients. Steele specified the number of walks to be recorded for baseline determination of walk distance; the content and timing of words of encouragement to be provided during testing; how to inform patients about elapsed time; parameters to be monitored before, during, and after testing; and posttest documentation. The AACVPR provided suggestions rather than directions regarding the number of walks to be completed; how oxygen equipment is to be transported; whether or not intermittent-flow oxygen devices should be allowed; whether or when to use wheeled assistive devices; whether or when words of encouragement should be used; what parameters other than oxygen saturation should be monitored; and posttest documentation.
Although the sources discussed above emphasized the need for standardization and consistency in the conduct of walk tests, we were unable to find data regarding how walk tests are applied in pulmonary rehabilitation programs, particularly as regards testing practices and procedures. Our aims in the present study were as follows: (1) to determine the frequency of inclusion of walk tests as an outcome measure in pulmonary rehabilitation, and (2) to identify the presence and nature of variations in the conduct of walk tests performed in pulmonary rehabilitation programs.
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Materials and Methods |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionAppendix 1References |
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Questionnaire
A questionnaire was devised to provide information about the
following categories: rehabilitation program characteristics;
walk-testing practices; testing conditions; instructions; role of walk
supervisor; and parameters monitored before, during, and on completion
of walk tests. Portions of the questionnaire are included in the
Appendix.
Data Analysis
All completed surveys returned were included in the analysis. To
calculate response frequencies, the number of total responses provided
for each item on the questionnaire was used as the denominator. Data
were described as proportions. Central tendencies were calculated for
numeric variables.
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Results |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionAppendix 1References |
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Number and Duration of Walk Tests
Of the 71 programs providing data, 57 respondents (80%) indicated
that walk tests were performed on all program participants, and 11
respondents (16%) indicated that walk tests were completed on some,
but not all participants. Six-minute walk tests were performed in 62 of
71 programs (87%), while 4 programs (6%) completed 12-min walks and 5
programs (7%) used both 6- and 12-min walks. Fifty-seven of 71
respondents (80%) based test results on a single walk. Nine programs
(13%) based results on the best of two walks, and three programs (4%)
based results on the best of three walks.
Testing Conditions
Our findings regarding specific aspects of walk test performance
are summarized in Table 2
. In 52 of 71 programs (73%), walk tests were completed in a hallway.
Six programs (9%) reported using a walking track, and five programs
(7%) used a treadmill to perform walks. Fifty-four programs reported
the length of the walking track or hallway; lengths ranged from 25 to
660 feet. Forty-six of the 54 programs that provided this information
used tracks or hallways at least 100 feet in length.
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Of the 66 programs that did not use a treadmill for walk tests, 45 programs (68%) allowed use of wheeled devices for arm support during walks. Thirteen programs (20%) did not. Eight respondents indicated they had not encountered this situation.
Instructions/Supervisor Role
Thirty of the 71 programs (42%) indicated that prewalk
instructions to patients were standardized and either read by the walk
supervisor (27%) or given verbally from memory (15%). In 41 programs
(58%), informal and nonstandardized instructions were provided to
patients prior to walking.
During the walk, 67 of 71 respondents (93%) indicated that the walk supervisor provided patients with information about elapsed time, either routinely (62%) or if the patient asked (31%). Forty-one of 71 respondents (58%) indicated the walk supervisor provided patients with information about distance covered during the test, either routinely (28%) or if asked by the patient (30%). Forty-three of 71 respondents (61%) routinely provided verbal encouragement to patients during walks. In 11 programs (16%), verbal encouragement was provided sometimes, but not consistently. Fifty-three of 70 respondents (76%) affirmed that during a walk test, the walk supervisor could direct a patient to speed up, to slow down, or to rest. Such direction could be provided if the supervisor believed the patient appeared to be working too hard or too little (27%), if the supervisor believed the patient potentially might be harmed by self-pacing (39%), or in either circumstance (3%). Four respondents indicated that patients were given prescripted reminders that they could speed up or slow down at any time during the walk test.
Of the 70 respondents to the question, 48 respondents (69%) indicated that oxygen flow rates could be adjusted during walks at the discretion of the walk supervisor (58%), at the patient’s request (6%), or in either circumstance (6%).
Parameters Monitored
Specific parameters monitored before, during, and after completion
of walk tests, and the frequencies with which these parameters were
monitored by respondents are summarized in Table 3
. Heart rate and arterial oxygen saturation were monitored almost
universally before, during, and after walk studies. Evaluations of
breathlessness and perceived exertion were measured by the majority of
programs, but less often than heart rate and oxygen saturation.
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Discussion |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionAppendix 1References |
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We found that walk tests were used in a great majority of pulmonary rehabilitation programs. Ninety-six percent of respondents routinely used walk tests. If one assumes that all nonresponding programs did not employ such testing, the minimum use of walk testing was then 71% of programs surveyed. Interest in and acceptance of timed walk tests in pulmonary rehabilitation may account in part for the very high questionnaire return rate after a single mailing. Significant variability was noted in testing practices and directions provided to patients that might influence results of timed walk tests and preclude transfer of results among programs.
Number and Duration of Walk Tests
Although it has been shown repeatedly that a training effect is
observed in the performance of walk tests, 80% of respondents based
results on a single walk. Studies indicate that practice sessions are
necessary to establish optimal performance. Larson and
colleagues4
had 48 subjects with COPD perform four 12-min
walks at 1-week intervals. Average walk distances improved
significantly through the third test. Differences of 46 m (151
feet) occurred between the first and second walks, and 78 m (256
feet) between the first and third walks. Similar results have been
reported by other investigators. Mungall and Hainsworth5
found significant variability between the first and third 12-min walks
in 13 individuals with COPD. Similarly, McGavin et al6
demonstrated 11% improvement from the first to the third walk. These
investigators recommend that when conducting repeated measures at
relatively short intervals two practice tests are necessary to allow
patients to learn and to establish optimal performance. The
present survey indicated that such practices are rare.
Testing Conditions
Most respondents performed walk tests in a hallway. Less often, a
walking track or treadmill was used. Three investigators have compared
distances achieved by individuals with COPD walking in a hallway to
distances achieved on a self-paced treadmill. Data from these
investigations suggest that individuals with chronic lung disease walk
farther in a hallway than on a treadmill. Depending on the study,
average hallway distances exceeded treadmill distances by 49 m
(161 feet) in 12 min,7
by 82 m (269 feet) in 12
min,8
and by 168 feet in 6 min.9
At least one
of the respondents to the survey indicated that treadmill speed was
increased at predetermined intervals during the tests, rather than
self-paced by the patient. No data were available comparing walks
performed on a walking track to hallway or treadmill walks.
Oxygen needed during walks can be provided by gas sources that are carried, pushed, or pulled. Fifty-six percent of the programs that conducted tests in hallways or on walking tracts indicated that patients transported their oxygen during walks, either routinely (38%) or occasionally (18%). The deleterious effect of carrying a portable system on tolerance of walking has been reported by two investigators. These studies suggest that supplemental oxygen improves walking performance but the gain in oxygen-supported exercise tolerance may be partially or completely offset by carrying the portable device. Leach et al10 had 30 individuals with obstructive or restrictive lung diseases perform a series of 6-min walk tests when carrying portable cylinders ("sham" cylinders containing compressed air), and when unburdened with such devices. The work of carrying the portable gas supply reduced 6-min walking distance by 14%, compared with an unburdened walk. However, 6-min walk distance improved by 19 to 36% when subjects were carrying and receiving supplemental oxygen, compared with distances when carrying and receiving room air. Leggett and Flenley11 walked eight individuals with COPD with and without supplemental oxygen, and with and without carrying the oxygen cylinders. In these patients with chronic hypoxemia and pulmonary hypertension, carrying a 4.5-kg oxygen cylinder hindered walking performance (decrease of 73.6 m). Carrying the oxygen cylinders completely offset the advantage obtained by breathing 2 to 4 L of supplemental oxygen while walking, instead of room air (increase of 51.6 m).
Devices that deliver intermittent rather than continuous flow of oxygen are designed as oxygen conservors. Our survey indicated an almost equal split among programs that allowed the use of intermittent-flow devices during walks and those that did not. Most investigations have focused on how use of these devices influenced oxygenation at rest and with exercise. Only one study12 was found that evaluated walk distances. Ten patients with COPD completed six 12-min walks while using continuous-flow oxygen and five different intermittent-flow devices. Practice walks were not provided. Marked variability was noted between individual responses to each system tested. However, only one intermittent system produced significantly shorter distances when compared with continuous-flow oxygen. From these limited data, the effect on walking of intermittent-flow devices cannot be predicted.
More than half the programs we surveyed either used a treadmill for walking or allowed patients to use wheeled devices for arm support while walking. Although we inquired about wheeled devices used for arm support, we do not know how often such devices were allowed purely as arm supports and not as aides for ambulation. It is well known that exercise tolerance may increase if upper-extremity support is provided. Investigation has shown that individuals with13 and without14 cardiovascular disease increased treadmill time when handrail support was provided during exercise. In a study by Wesmiller and Hoffman,15 12 subjects with COPD walked 1,274 feet in 12 min without the use of an arm supportive device, and 1,426 feet with the use of a wheeled device that provided arm support while walking. Six subjects who were unable to walk 1,000 feet in 12 min experienced the most benefit from the use of arm support, increasing their distance by 225 feet (46%). Of note, each subject performed only one walk under each condition, although the order was randomized. Honeyman and colleagues16 studied 11 subjects with COPD who performed four 6-min walk tests, twice unaided and twice aided by a wheeled walking aid. Use of the wheeled walker significantly increased walking distance (mean increase, 33.6 m [110 feet]), reduced hypoxemia, and decreased dyspnea.
Instructions/Supervisor Role
Most of the programs surveyed provided verbal encouragement to
patients while walking, although not always consistently. The effect of
encouragement on test outcomes was studied by Guyatt and
colleagues.17
Inclusion of standardized encouraging phases
to patients every 30 s was associated with an average increase in
distance of 30.5 m (100 feet) in 6 min, compared to distances
achieved when the supervisor remained silent. To our knowledge, the
effect of encouragement on walk performance has not been studied
subsequently.
Most programs indicated that patients could be given information about elapsed time during walk tests, although about one third of the respondents gave such information only if the patient requested it. There are data to suggest that patient awareness of test duration may influence walking distance. Guyatt et al17 had 43 individuals with chronic respiratory or cardiac failure complete a series of 2-min and 6-min walks. Individuals walked further during the 2-min walks than during any 2-min segment of the 6-min walks. Butland and colleagues18 found high correlations among distances covered in 2-min, 6-min, and 12-min walks in 30 individuals with chronic respiratory disabilities. It is not yet clear whether individuals with respiratory disabilities tend to pace themselves differently, depending on their awareness of walking duration or if they prefer to maintain a steady pace regardless of walking duration.
We assessed other factors that we believed intuitively would influence walking distance, such as instructions given prior to walking, monitoring during walks, awareness of distances accomplished while walking, and directions given to patients while walking. The influence of these factors has not been investigated, but likely influence performance. Our data confirmed that in a majority of instances, walk test instructions were not standardized. Over 90% of programs monitored heart rate and oxygen saturation during walking, and 23% monitored BP during walks. Logically, one would expect patient walk distances to be influenced by the presence and the pace of a walk supervisor accompanying a patient while walking, as would be necessary when oxygen and monitoring equipment must be pushed or carried. It is likely also that adjustments to oxygen doses made during a walk, as practiced by a majority of respondents, would affect walking pace and distance. Certainly, instructions given to patients to speed up, slow down, or stop would affect the distance walked. In the present study, such direction was commonly provided at the discretion of the supervisor, even when the patient did not appear to be harmed by self-pacing. Finally, information provided to patients during walking about distances accomplished may affect pacing and total distances achieved. However, there are insufficient data published on this subject.
Our study has certain limitations. First, as with any questionnaire, these are self-report data and may or may not accurately reflect actual practice. However, given an expected tendency to report positively (consistent with what was perceived to be optimal performance), our data likely represent underreporting of variability in performance of walk tests. Second, there was a < 100% response rate to our questionnaire. We believe, however, that a 76% response rate should provide representative data regarding practices in pulmonary rehabilitation programs. Third, while we have documented that walk tests are poorly standardized, we can only speculate whether variances would be associated with differences in walk distances. If so, we cannot conclude the direction of the differences or whether differences would be significant from a statistical and/or clinical viewpoint. Finally, some areas regarding performance of walk tests were not addressed in the questionnaire. For example, we did not inquire specifically if respondents followed a written protocol for walk tests. We did not ask and therefore cannot comment on how decisions were made to complete walk tests in those programs that did not perform tests on all participants. It would have been interesting to know also whether information regarding oxygen saturation during testing was provided to patients.
In the modern-day clinical community, great emphasis is placed on evidence-based practice and standardization of performance. It is through the accumulation of data that "best practices" emerge. Standardization of best practices can then reduce variations likely to produce negative or confounding results. Based on our findings, considerable efforts are needed to clarify how walk-testing practices may influence results, as well as to develop standardized protocols for testing. Given the extensive use of walk tests, it is surprising that limited progress toward standardization has occurred. Although guidelines for test performance from authoritative sources have been in the literature for several years, most of the programs we surveyed do not follow them. Testing variations and lack of internal consistency hinder comparisons of results both within and among rehabilitation programs. Furthermore, walk tests are commonly used as outcome measures in clinical studies, including evaluation of controversial innovations such as lung volume reduction surgery. Lack of standardization imposes difficulty in interpretation and comparison of test results.
It would be prudent to require consistency in all tests performed in any given program or, at minimum, in multiple tests performed by a given patient. Provision for practice walks, testing site, instructions given before testing, inclusion and content of verbal encouragement, and feedback about elapsed time and distances achieved should be standardized. Although limited, data available in the literature suggest that the type of oxygen delivery system in use, transport by the patient of supplemental oxygen devices, and arm support during walking may affect distance achieved during walk tests. Until the influence of these factors is clarified through investigation, constancy in these areas of testing is warranted.
In summary, walk tests are used in a majority of pulmonary rehabilitation programs to measure functional status. Practices regarding performance of walk tests are often not standardized within a given program or among different programs. Variances reported include aspects of walk performance likely to influence results. It is possible that variations in performance of unstandardized walk tests may account for differences in results ascribed to treatment effects. Interpretations and comparisons of walk test results obtained within and among programs should not be undertaken without knowledge of specific methods used for walk test performance. Such protocols should be provided when walk test distances are reported. Further research is needed to evaluate the influence of variations in testing protocols.
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Appendix 1 |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionAppendix 1References |
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In our program, walk tests are
a. completed on all patients
b. completed on some patients
c. not used
If your response to the above question is "c," please return your questionnaire without responding further.
The duration of the walk tests we perform is
a. 6 min
b. 12 min
c. other (specify)
We report walk test results based on
a. a single walk
b. the best of two walks
c. the best of three walks
d. other (specify)
Our walk tests are performed
a. on a walking track (approximate distance of track )
b. on a treadmill
c. in a hallway (approximate distance of hallway )
d. other (specify)
If walk tests performed on a treadmill, how is treadmill speed set?
a. by the patient (starting speed )
b. by the walk supervisor (starting speed )
c. do not use treadmill
d. other (specify)
Before walking, the following measurements are taken (circle all that apply)
a. spirometry
b. peak expiratory flow rate
c. heart rate
d. cardiac rhythm
e. BP
f. respiratory rate
g. oxygen saturation
h. dyspnea/breathlessness
i. other (specify)
During the walk, we monitor (circle all that apply)
a. heart rate
b. cardiac rhythm
c. BP
d. respiratory rate
e. oxygen saturation
f. dyspnea/breathlessness
g. other (specify)
On completion of the walk test, we measure (circle all that apply)
a. heart rate
b. cardiac rhythm
c. BP
d. respiratory rate
e. oxygen saturation
f. spirometry
g. peak expiratory flow rate
h. perceived exertion
i. dyspnea/breathlessness
j. distance walked
k. number of rests
l. duration of rests
m. symptoms experienced during walk
n. other (specify)
How are patients given instructions before the test begins?
a. instructions are read from a standardized script
b. standardized instructions are recited from memory
c. informal, nonstandardized instructions are provided
d. other (specify)
During the walk, are patients given information about elapsed time?
a. yes, routinely
b. yes, if they ask
c. no
During the walk, are patients given information about distances they have covered?
a. yes, routinely
b. yes, if they ask
c. no
Do you give verbal encouragement to patients during their walk tests?
a. yes, routinely
b. yes, sometimes
c. no
If patients require supplemental oxygen during the walk test, what type of oxygen source is used?
a. whatever system the patient provides
b. we use our own source
c. no particular preference
d. other (specify)
May patients use pulsed-dose or intermittent-dose oxygen systems during walks?
a. yes
b. no
Who carries or pulls the patient’s oxygen source during walks?
a. the patient
b. the walk supervisor
c. someone else (specify)
d. no particular arrangement
Are oxygen flow rates adjusted during walks? (circle all that apply)
a. no
b. yes, if the patient requests adjustment
c. yes, if the walk supervisor judges an adjustment to be needed
If they wish, may patients use wheeled devices (such as a wheelchair or wheeled walker) to provide arm support during walking?
a. yes
b. no
c. have not encountered this situation
During the walk tests, can the walk supervisor direct a patient to speed up, slow down, or rest? (circle all that apply)
a. yes, if the patient appears to be working too hard or too little
b. yes, if the walk supervisor feels the patient potentially may be harmed by self-pacing
c. no
d. other (describe)
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Footnotes |
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Received for publication August 19, 1999. Accepted for publication February 10, 2000.
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References |
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TOPAbstractIntroductionMaterials and MethodsResultsDiscussionAppendix 1References |
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This article has been cited by other articles:
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  V. Bansal, K. Hill, T. E. Dolmage, D. Brooks, L. J. Woon, and R. S. Goldstein Modifying Track Layout From Straight to Circular Has a Modest Effect on the 6-min Walk Distance Chest, May 1, 2008; 133(5): 1155 - 1160. [Abstract] [Full Text] [PDF]
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D. Verrill, C. Barton, W. Beasley, and W. M. Lippard The Effects of Short-term and Long-term Pulmonary Rehabilitation on Functional Capacity, Perceived Dyspnea, and Quality of Life Chest, August 1, 2005; 128(2): 673 - 683. [Abstract] [Full Text] [PDF]
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 T. Troosters, J. Vilaro, R. Rabinovich, A. Casas, J.A. Barbera, R. Rodriguez-Roisin, and J. Roca Physiological responses to the 6-min walk test in patients with chronic obstructive pulmonary disease Eur. Respir. J., September 1, 2002; 20(3): 564 - 569. [Abstract] [Full Text] [PDF]
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J. E. Johnson, D. J. Gavin, and S. Adams-Dramiga Effects of Training With Heliox and Noninvasive Positive Pressure Ventilation on Exercise Ability in Patients With Severe COPD* Chest, August 1, 2002; 122(2): 464 - 472. [Abstract] [Full Text] [PDF]
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 T. Troosters, R. Gosselink, M. Decramer, T. M Steffen, T. A Hacker, and L. Mollinger Six-Minute Walk Test: A Valuable Test, When Properly Standardized Physical Therapy, August 1, 2002; 82(8): 826 - 828. [Full Text]
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 British Thoracic Society Standards of Care Subcomm Pulmonary rehabilitation Thorax, November 1, 2001; 56(11): 827 - 834. [Full Text] [PDF]
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