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EMS Medical Equipment Services Tips

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EMS Medical Equipment Services Tips

Everyday EMS
by Greg Friese

Stethoscope Calibration

By Greg Friese

Category: Oddities

Photos by Greg Friese
It is critical that all EMS equipment be properly calibrated. You probably need to work with your local hospital or an industry service technician to calibrate and service some of the more complex equipment like IV pumps, cardiac monitors, patient cots and sphygmomanometers. Fortunately, there is one piece of equipment that you can self-calibrate: your stethoscope.

Carefully follow this sequence of calibration steps:

  • 1) Place ear pieces in your ear canals.
  • 2) Place bell of stethoscope on your left superior chest at the mid-clavicular line, at about the third intercostal space.
  • 3) Listen carefully for a rhythmic thub-dub.
  • 4) Count thub-dubs for 30 seconds.
  • 5) Place bell of stethoscope on your left mid-axillary line at about the fourth intercostal space.
  • 6) Listen carefully for a rhythmic thub-dub.
  • 7) Count thub-dubs for 30 seconds.
  • 8) Multiply both count tallies by two. Add the two counts together. Then divide by two.

This number is your stethoscope calibration benchmark. Write it down and store it in a safe place. Each month, repeat and document the calibration test. If there is a variation more or less than 15 percent, seek out assistance from your training officer, service director or medical director. If your benchmark calculation result is less than or equal to zero, request immediate medical assistance.

Please post your calibration benchmark in the comments area, which will be used for an important research project.

About the author

Greg Friese is Editor-in-Chief of He is an educator, author, paramedic, and marathon runner. Ask questions or submit tip ideas to Greg by e-mailing him at
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Alan W. Rose Alan W. Rose Monday, April 01, 2013 3:02:21 PM Do you count the 'thub' AND the 'dub?"
Markus Mbitions Markus Mbitions Monday, April 01, 2013 3:03:48 PM uh oh...what does a thub dub click mean?
Alan W. Rose Alan W. Rose Monday, April 01, 2013 3:05:11 PM Tiime to get a new 'scope. Those clicks are indicative of a fatal flaw in the conduction obturator.
Markus Mbitions Markus Mbitions Friday, April 05, 2013 8:53:41 AM Hi Alan.... I was actually more responding towards it re: April fools ....haven't heard any clicks fortunately
Cj Ewell Cj Ewell Wednesday, April 02, 2014 9:40:55 AM The bell is the hollowed out end. What you are showing is a stethoscope that only has a diaphragm.
Catherine Kayiganwa Catherine Kayiganwa Tuesday, June 17, 2014 12:35:38 AM Is there any other way to calibrate stethoscope?
Harika Mallemala Harika Mallemala Monday, August 18, 2014 8:18:12 PM 100