What makes a good tester
Nearly every false abnormality in this suite is procedural. The person performing the studies is the largest single determinant of whether the numbers mean anything.
The six habits
1. Identical positioning, every time
Cuff height relative to the heart changes a pressure reading. So does the angle of the bed and whether a leg is externally rotated. Fix the position, write it down, and do not vary it between patients or between visits.
2. The rest period is not negotiable
Vascular and autonomic measurements taken on someone who has just walked in from the parking lot are not the measurements anyone wanted. Ten minutes supine, quiet, in a temperature-stable room. Cold extremities alone can render an optical waveform uninterpretable.
3. Check the preparation out loud, and record the answers
Fasting, caffeine, nicotine, alcohol the night before, sleep, and medication timing. Ask every one, every time. Record what the patient actually says, not what the protocol required. A reading annotated “had coffee at 7” is interpretable; the same reading unannotated is noise.
4. Prepare the skin properly
For sudomotor plates, lotion, residue, moisture and heavy callus all move the reading. For optical sensors, nail polish and artificial nails degrade the signal. Neither takes long to check and both are easy to skip.
5. Coach the maneuvers rather than reciting them
This is the biggest one. Deep timed breathing at six breaths a minute, a controlled exhale against resistance, and standing briskly from supine are all performed badly by most people on the first attempt. A badly performed maneuver produces a trace that looks exactly like autonomic failure. Demonstrate it, give a practice attempt, use a manometer for the exhale rather than instruction alone, and repeat the maneuver rather than reporting a bad one.
6. Recognize an implausible reading in the room
An ankle-brachial index of 1.6 is not a healthy artery, it is an incompressible one. A resting energy expenditure that is wildly out of keeping with the patient’s lean mass is probably a mask leak. Noticing at the bedside saves an interpretation that was never going to be valid.
What matters less than people expect
Which credential the tester holds matters less than whether the six habits above are reproducible. What is legally required varies by study, by setting and by state, and should be settled separately and in writing. Supervision and staffing.
How to tell whether it is working
Have testers measure each other, repeatedly, on the same day. If repeat measurements on the same person a few minutes apart do not agree, no result from that room is comparable to anything. That check takes an afternoon and it is the single most valuable thing to do before testing patients.
Related reading
Medically reviewed by Dr. Gurpreet Singh Padda, MD, MBA, MHP, medical director of Measura. Last reviewed .