ECG Calipers is an iPhone/iPod Touch application that allows you to measure and compare the waves, segments, and intervals of an ECG. ECG Calipers displays two values. The first value, heart rate, is accurate when using regular P-P or R-R distances. The second value displays the current interval/segment length in seconds.
To use ECG Calipers, simply hold your iPhone up to the ECG and use the "rough" slider to adjust the "pin" distances until the pin lines match up with the lines of the ECG being measured. To refine the measurement, ECG Calipers has a "micro" slider control that allows you to fine tune your measurement. You can also lock in the distance between pins, so you can move the calipers to another spot on the ECG without losing your set distance.
When tested blindly, ECG Calipers excelled at picking up irregular rates and increasing p-r intervals. The program was within +/- 0.03 s of the pre-measured p-r interval (when measured by traditional calipers). Heart rates were within 2 beats/per minute of the pre-calculated rate.
ECG Calipers measurements are based on the screen size of the current iPhone /iPod touch. The screen size is 2" x 3" (50.8 mm x 76.2 mm) and the resolution is 320 x 480 pixel at 163 ppi. This means each pixel equals 0.1558282 mm. ECG Calipers uses this number to convert from pixels to mm. Finally, assuming a standard ECG strip where 1 mm = 0.04 seconds, ECG calipers converts mm to seconds.
The heart rate displayed assumes the user is measuring a regular P-P or R-R interval. It then calculates the heart rate from the measured distance.
If you have questions or ideas for improvement, please contact us at btmedtools at gmail dot com. The developers of ECG Calipers are full time physicians, so we spend lot’s of time at the hospital, but we’ll try and get back to you as soon as possible.
Thank you,
The ECG Calipers development team
