EBME Forums Forums Maintenance Technical Assistance IBP Testing for Propaq monitors

Hello friends,

We have a couple of Propaq monitors with IBP and Etco2 Function, can anyone please help me on how to check on them within our biomedical department, prior being used on patient into the OT !

Best Regards
Nimish
nimishpancholi@yahoo.com

IBP can be checked out with an appropriate tester.

EtCO2 is checked with Cal Gas.

Ideally you check the functions using the manufacturers recommended procedures.
In the absence of this and with limited equipment the following can be used for verification purposes.

IBP leads usually consist of 4 connections, a positive and a negative pressure signal input, and to the monitor (+/-)
a positive and a negative excitation voltage output from the Propaq monitor.
The IBP module supplies a differential excitation voltage to the pressure transducer that connects to the IBP lead.
The monitor provides this excitation voltage to the pressure transducer

The pressure transducer usually gives a differential output voltage from the bridge of 5uV/V/mmHg or 40uV/V/mmhg
i.e. 5/40uV per volt excitation per mmHg pressure applied to the transducer.

Once you know the IBP pin outs, it is relatively easy to simulate static pressures in older monitor types. (Newer monitors
will not give you a reading unless it senses an attached transducer. Build a bridge with 1k resistors in the legs
and an extra 100R in the fourth leg with a short out switch across it).

So check of IBP consists of a Cal mode static pressure zero mmHg and a span (say 300 mmHg)

So with 5uV sensitivity, and an excitation voltage of 10.000 volt, (you use a dc calibrator, or dc power supplies and a multimeter
with suitable resolution) you can provide and provide a simulated pressure signal of
1.5 mv across the positive and negative pressure signal inputs this should simulate a static pressure of 300 mmHg.

0.000005 X 10 X 300 = 0.0015 Volts (1.5 mV)

Like wise with a 40uV sensitivity

0.000040 X 10 X 300 = 0.0120 Volts (12.0 mV)

Alternatively if you have an IBP transducer, check zero and span with a manometer.


EtCo2, ideally you need a sample line, calibration gas (nominal 5% CO2) and a regulator and follow the cal procedure.
A quick verification can be performed by sampling exhaled breath after a few exhalations into the sample line.
Check the monitor EtCo2 waveform is detecting Co2 and check numeric readings.

Many years ago, when we didn’t have all the flash test equipment we had to make do with what was available.

Happy Days....

Good stuff, Sean.

However, "many years ago" we didn't have EtCO2 either, as far as I recall!

Base principles, what a wonderful thing.

IBP, can be tested with nothing more than a cable and transducer from the system, a three-way tap, some tube, a manual bulb and a calibrated pressure meter.

Connect all three together, pump up the bulb until the pressure meter show (say) 100mmHg and check that the monitor says the same. A static measurement I will grant you but a "down and dirty" way of doing checks. In modern systems, if this is accurate, so will the dynamic readings be.

As for ETCo2, cal gas is only good if we are talking side-stream however, mainstream systems often have a "cal check" window system attached. If nout else is available, I would go with the "breathe down the sensor and see what results you get" method. Not auditor friendly but very accurate (check with the nursing staff for correct results 'cos I can't remember).

Ok Geoff, ........... over to you for why this is all wrong

No problems* here, Mate. That's the default situation for many of us, after all.


Yes. Very true. Another way of testing IBP is if you happen to have a spare artery hanging around somewhere!

* Apart from spelling, of course (nowt)!

Dear Friends

I was busy in some other work so could not check on it, guys thanks to all of you for describing this procedure we will start tom. morning on this and will let you know all what happened next...

sean, geoff, davec .. many thanks again..

Best Regards
Nimish

Hi Nimish

You can download the service manual from the Welch Allyn web site;

Propaq Encore

Propaq CS

Most of our manuals are available this way, just find the product. And go to the "Technical" tab on the box at the bottom of the page.

I wish more manufacturers did this - and the same for user manuals.
Thank you WA
RoJo