6 – Minute walk test in patients
with COPD: clinical applications
in pulmonary rehabilitation
Vasanthi .J
Author : Sue C.Jenkins
Physiotherapy
Volume 93
2007, 175 – 182
Introduction
COPD is the leading cause of morbidity
and mortality worldwide.
Develop progressive disability and
impairment in quality of life.
The prevalence of COPD is increased in
many parts of world as the result of ageing
and increase in cigarette smoking.
Assessment of functional exercise
capacity in pulmonary rehabilitation
Pulmonary rehabilitation is strongly endorsed as
an evidence based intervention for the
management of patients with COPD.
In clinical practice 6-minute walk test and
incremental shuttle walking test are commonly
used to assess.
Both tests have validity, reliability after one
familiarization test, capacity to detect changes
following Pulmonary rehabilitation.
Compared with other lab based tests
these have increased availability, low cost,
and because ground- based walking is
more representative of ADL.
Is the 6 MWD a valid measure ?
Demonstrated by moderate to good
relationship between 6 MWD and VO2peak
Examination of relationship between
6MWW ( product of Body weight and
6MWD) and VO2peak reveals a stronger
relationship than 6MWD because 6MWW
represents work done.
Does 6MWD provide information
about physical activity during daily
life?
Dyspnoea during ADL in COPD patients due to
inactivity and associated problems of
deconditioning and muscle weakness.
Compared to healthy controls COPD patients
spent less time standing and walking during
ADL.
In one study (Pitta et al ) concluded that a
reduced 6MWD (<400m)is the best marker of
inactivity during daily life in patients with COPD.
Is 6MWD associated with survival?
Stronger predictor of survival than FEV1.
Because 6MWD is influenced by skeletal
muscle dysfunction as well as pulmonary
impairment and so reflects both the
primary pulmonary and secondary
systemic manifestations of COPD.
selection of patients for lung
volume reduction surgery or
transplantation
In patients undergoing LVRS reported that
a 6MWD < 200m was associated with high
level of mortality 6 months post op.
6MWT was a useful tool in the
assessment of when to list patients for
lung transplantation and that a 6MWD of
<400m appeared to be a reasonable
marker corresponding to when a patient
should be listed.
Is a reliable measure?
Requires a strict standardization protocol.
Factors that affect are
- track length
- course layout
-instructions
- encouragement
- no of tests
Familiarization test is needed for new.
Dypnoea is main limiting factor so repeat
the test after 20 – 30 min rest period by
which time the patient will recover.
Familiarization test always ?
No need in co morbid limiting status
- Musculoskeletal or claudication pain
- Cardiac disease – 85% of age
predicted Max HR
- Profound oxygen desaturation (SpO2
< 80 %).
When 6MWT is repeated at long – term
follow up Familiarization test may be
needed
Standardized protocol
ATS guidelines:
-safer, easier, better tolerated
-better reflects ADL
- do not walk along with patient
-pulse oxymetry is optional
-do not use treadmill
-do not use circular track
- count the laps with lap counter
- Familiarization test is not needed for most
clinical settings.
Australian physio association &
aust lung foundation
Perform in two occasion
Best result recorded
At least 30 min rest in between
Walking track must be same for all tests
Comfortable ambient temp and humidity
should be maintained for all tests
Before test:
- medical H/o,precautions, CI
- comfortable dress, footwear
- aviod eating before 2 hrs
- inhaled BD
- rest for 15 min before test
-record – BP,HR,SaO2, Dyspnoea
score
At the end:
- put a marker on the distance walked
- seat the pt
- record – BP,HR,SaO2, Dyspnoea
score
If patient stops during:
- allow to sit
- measure HR,SaO2
- ask reason why stopped
- record the time stopped
- tell that begin as soon as you feel
better
-monitor untoward symptom
Stop the test:
- chest pain
- mantal confusion
- light headedness
-intolerable dyspnoea
- leg cramp
-SaO2 <85%
Normal 6MWD
Age , height, weight, gender are significant
contributors
Can predict by equation
6 MWD pred = 218 + (5.14 * Ht cm – 5.32
* age ) – 1.80 * wt kg + 51.31 * gender.
Male = 1
Female = 0
Different for geographical regions so
calculate own range.
Minimum clinically important
difference (MCID)
54 m
What percentage achieve MCID?
If standard protocol followed 1/3 can
reach 54 m
Walking prescription
Prescribing ex on the base of 6MWD for
walking laps
80% ( 6MWD ÷6 ) ×prescribed duration
6MWD ÷6 = distance in 1 min
For distance in 30 min = 1 min distance ×30
For distance in 20 min = 1 min distance ×20
For distance in 10 min = 1 min distance ×10
Rollator
COPD pt less dyspnic in rollator
6MWD can be used to quantify the
benefits of rollator and identify which
patient benefit from.
To detect ex induced hypoxemia
Desaturation common in 6MWD
Because of varying body position and un
supported arm while walking.
Marked desaturation during 6MWT is an
indication to prescribe an intermittent
walking training protocol and identifies the
requirement of more frequent saturation
monitoring during ex.
Is useful in acute exacerbation of
COPD?
A low 6MWD < 367m associated with
readmission
Helps to quantify the impact of acute
exacerbation on a patient’s functional ex
capacity.
Has been used as a outcome measure of
pul rehab following acute exacerbation .
Conclusion
This review highlighted the clinical
applications of 6MWD in patients with
COPD undergoing pul rehab.
Future research – further refine the
applications, new applications in COPD.