Parameters to Monitor During a 6-Minute Walk Test
During a 6-minute walk test, you must monitor distance walked, oxygen saturation, heart rate, dyspnea and fatigue levels (using the Borg scale), and observe for signs of distress that require immediate test termination. 1
Pre-Test Baseline Measurements
Before starting the test, obtain and document the following after the patient has rested for at least 10 minutes: 1
- Pulse rate and blood pressure 1
- Baseline oxygen saturation (SpO2) and heart rate if using pulse oximetry (optional but recommended) 1
- Baseline dyspnea and fatigue levels using the Borg scale (0-10 scale) 1
- Verify contraindications are absent and confirm appropriate clothing/shoes 1
Pulse Oximetry Considerations
While the ATS guidelines state pulse oximetry is optional 1, continuous SpO2 monitoring is strongly recommended for patients with chronic lung disease given that profound oxygen desaturation (SpO2 <80%) is the most common adverse event, occurring in approximately 6% of tests. 2 If using pulse oximetry, the device must be lightweight (<2 pounds), battery-powered, and secured (e.g., in a fanny pack) so the patient doesn't need to hold it. 1 Note that many pulse oximeters have motion artifact that prevents accurate readings during walking. 1
During the Test: Primary Outcome
The primary outcome is the total distance walked in meters, measured by counting laps with a mechanical lap counter and adding the partial final lap distance using wall markers. 1 The technician must not walk with the patient and should remain at the starting line, clicking the lap counter each time the patient completes a lap. 1
During the Test: Continuous Observation
Watch the patient continuously for signs requiring immediate test termination: 1
- Chest pain
- Intolerable dyspnea
- Leg cramps
- Staggering
- Diaphoresis (excessive sweating)
- Pale or ashen appearance
If any of these occur, stop the test immediately and have the patient sit or lie supine. Obtain blood pressure, pulse rate, oxygen saturation, and physician evaluation as appropriate. 1
During the Test: Oxygen Saturation Monitoring
For patients with chronic lung disease, continuous SpO2 monitoring identifies exercise-induced desaturation, defined as a drop of ≥4% to <90%, which is the key criterion for ambulatory oxygen therapy eligibility. 3 Research shows that 47% of patients with chronic obstructive pulmonary disease exhibit significant desaturation during the 6MWT, and pre-exercise SpO2 is the strongest predictor of desaturation. 2
Common pitfall: Do not use the SpO2 for constant real-time monitoring by walking alongside the patient—this violates standardized protocol. 1 If worn during the walk, record the nadir (lowest) SpO2 value at test completion. 4
Post-Test Measurements
Immediately after the 6-minute timer ends: 1
- Record post-walk Borg dyspnea and fatigue levels 1
- Measure SpO2 and pulse rate from the oximeter (if used) 1
- Ask "What, if anything, kept you from walking farther?" 1
- Calculate total distance walked by adding complete laps plus partial lap distance 1
Additional Parameters for Oxygen Therapy Assessment
When evaluating for ambulatory oxygen therapy, the walk test should demonstrate clinical benefit by meeting at least 2 of 3 criteria: 3
- SpO2 ≥90% throughout the test with supplemental oxygen
- ≥10% increase in walking distance from baseline (room air)
- Improvement in Borg dyspnea scale of at least 1 point
The test should be performed with the patient carrying or wheeling the oxygen device as they would in everyday life, as carrying the device can negate the therapeutic effect. 3
Critical Safety Monitoring
Adverse events occur in approximately 6% of tests, with profound oxygen desaturation being most common. 2 Emergency equipment must be immediately available, including oxygen, sublingual nitroglycerin, aspirin, albuterol, telephone access, and an automated electronic defibrillator. 1 The technician must be certified in Basic Life Support cardiopulmonary resuscitation. 1
Standardization Requirements
Use only standardized phrases of encouragement at specific time intervals (every minute), as enthusiasm and encouragement can alter the 6-minute walk distance by up to 30%. 1, 5 Do not use additional words of encouragement or body language to speed up the patient. 1