6 Minute Walk Test.

 

Six minute walking Test

PKGhatak,MD

The six minute walk test (6MWT) is a useful tool for the evaluation of cardiac, pulmonary, and musculoskeletal systems. The test is low tech and requires practically no tools - an even surface long corridor, a pulse oximeter, a few chairs to sit along the path, a stopwatch and a distance measuring wheel, all that are needed. A 30 meter (100 feet) long corridor is ideal, but a shorter corridor also serves well.

Why do the 6MWT test.

In previous generations, the cardiopulmonary reserve was evaluated by a maximum voluntary ventilation test. This test was more suited for Olympic prospects or astronauts. The expired air had to be collected while exercising and analyzed for oxygen consumption. 6MWT test does not require any gas collection. It allows the patient to walk at his own pace, may stop, sit down and then can resume the test again. Only the distance walked in 6 minutes is recorded. Pulse oximetry is now quite familiar and popular for those who want to measure oxygen saturation in order to know when to go to a hospital if contacted covid. The patient may wear the smartwatch to detect the abnormal heart rhythm.

Cardiac stress test vs 6MWT.

6MWT is a safe initial method to evaluate cardiac and pulmonary status following an adverse coronary event or a respiratory disease. 6MWT does not replace cardiac tests, it is a useful supplement.

How 6MWT is performed.

No preparation is necessary. The patient should wear a pair of comfortable shoes, should continue to use oxygen, if on oxygen and use at the same flow rate. Use a cane or walker if used to. A 10 minute rest is required. Attach a pulse oximeter to a fingertip. Then start walking when a signal is given by the test supervisor. Continue to walk at the same pace, sit and rest on a chair on the way, if required, then resume walking again. When 6 minutes are up - stop walking. The supervisor marks the end distance and the test is complete.

Interpretation of 6MWT.

The formula for men.

A normal 6 minute walk distance (6MWD) = 1140 m(meter) – 5.61 x  BMI(body mass index) – 6.94 x age of the patient.

To obtain the lowest normal distance - subtract 153 m.

The formula for females.

6MWD = 1017 m – 6.24 x BMI – 5.83 x age.

To obtain the lowest normal distance - subtract 139 m.

The patients' results are given as the distance in meters and also as a percentage of the normal.

The initial results are then used to monitor the progression of the disease, improvement of therapy, alert possible arrhythmia potential, drop in oxygen saturation, hypotension, potential drop attacks, the onset of chest pain, etc.

Indication of 6MWT.

The ideal candidates for this test are -

1. Recent cardiac events, 2.Pulmonary atrial hypertension,3. Peripheral arterial disease, COPD in need of oxygen therapy.4. Frail patients suffering from chronic diseases requiring rehabilitation, 5. the elderly who want to live independently and 6. anyone else is starting cardiopulmonary rehab from the existing morbid condition.

What the test predicts.

The test indicates cardiac and pulmonary reserve capacities, response to therapy and long term prognosis of chronic illnesses.

What is the advantage of 6MWT.

6MWT is a simple but highly duplicate test. Situated for the elderly population suffering from Pulmonary arterial hypertension, peripheral arterial disease, or had an adverse cardiac event,

What are the contraindications.

The patient having unstable cardiac arrhythmia should not do this test. Those who have experienced cardiovascular collapse and the reason remained unexplained, and those in respiratory distress are not suitable for 6MWT.

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