EBME Forums Forums Free discussion Free discussion Convert bpm to Hz

If you think about it the higher the frequency the larger the hertz. Therefore the higher the BPM the larger the hertz.

You can use a sine wave generator connected to an oscilloscope to show this.

And an oscilloscope on your ECG simulator to confirm BPM (R-wave to R-wave) accuracy.

Not sure that a frequency counter would handle an ECG signal that well ... but maybe they (some) would.

In principal, any repetitive waveform's frequency can be calculated, in practice using an oscilloscope on an ECG simulator would be a non starter unless you interface using a differential amp (not cheap) to convert a three terminal input (R L F etc. ECG waveform) to a two terminal device (BNC input oscilloscope)..

The frequency counter option would similarly have difficulty.
It would be nice if there was a affordable reliable alternative.
Has anyone any thoughts on a similar viewpoint ?

Sean Fearon

Sorry guys but maybe filipspace is asking for the conversion of bpm (breaths per minute)used on mechanical ventilation to hertz. Where in high frequency ventilation 1 hertz= 60 bpm (breaths per minute)and is applied to frequencies above 120 bpm.

Repetition frequency is just that - regardless of the er, frequency.

Beats per Minute, Breaths per Minute ... or Full Moons per Lunar Month ... it's still a regular pattern that can be measured. Remember, though, that Hertz is taken to mean "cycles per second" (so recording phases of the moon in Hertz would not really be appropriate)! So you're right, it's best kept for frequencies above 1 per second.

Notice here though that, in the Grand Scheme of things, we're talking about very low frequencies.

Even ELF (Extremely Low Frequency) is in the range 30 to 300 Hz.

@Sean: if repetitive pulses can be displayed, then the period can be measured.

BPM to Hertz? The reciprocal of the period (eg, R-wave peak to R-wave peak in a normal ECG waveform).

30 BPM : period is 2 seconds : 1/2 = 0.5 Hz
60 BPM : period is 1 second : 1/1 = 1.0 Hz
120 BPM : period is 0.5 second : 1/0.5 = 2.0 Hz
180 BPM : period is 0.33. second : 1/0.33. = 3.0 Hz (approx)
240 BPM : period is 0.25 second : 1/0.25 = 4.0 Hz

Whilst we're at it, here are a few more (some of which can be argued about, I'm sure):-

50 Hz mains (20 ms)
60 Hz mains (16.66 ms)

"Shortwave Diathermy" (Electrosurgery):-

- 1.8 MHz (0.555 µs or 555 ns)

Shortwave Therapy:-

- 27.12 MHz (0.0369 µs or 36.9 ns)

TENS units:-

- 15-175 Hz typical

- typical pulse width 50-200 µs

And here's a final question for you all:- if a 60 BPM ECG is considered to be a 1 Hertz signal (and I'm not agreeing to that, by the way) - then what is its wavelength?

You forgot the good old microwave oven at 3GHz as it is the frequency that makes water molocules vibrate.

Not forgotten, Billy ... there's just too many, eh?

Microwave Therapy (MWT): 2.45 GHz typical (very close, you will notice, to Wi-Fi at 2.4 GHz)!

I have certain theories about the Frequency Spectrum in general, along the lines of:- if a guy has a good grasp of all that, then he's well on the road to understanding biomed as a whole.

Colours (nanometres). Ultrasound. X-Rays. Fundamentals. Physiological signals (frequency, voltage level etc.) ... and all good stuff like that.

Next thing you have to understand is doppler effect, slant range azimuth and elevation. Then we can make a techie out of you!!

Let's take it one step at a time, Billy. You know, Monkey See, Monkey Do.

I tried to measure the ecg wave forms with an oscilloscope and a frequency counter and got nothing... it's a very low frequency
Does any one have an idea?