LifePak FiCO2 Alarm

18G · Sep 1, 2014

I got an FiCO2 alarm on my LifePak 12 today for the first time. I've never seen this alarm before. The patient's EtCO2 was within normal values for condition (29-33mmHg). Specifically, the alarm indicated "FiCO2=9" and another time "FiCO2=12".

What exactly is this alarm saying?

Thanks.

Av8or007 · Sep 1, 2014

FiCO2 is fraction of inspired co2 - same idea as FiO2.

I didn't even know the lp could display fico2.

TransportJockey · Sep 1, 2014

I didn't know it could either. I'm gonna play with my lp tomorrow mornin before I leave and see if I can figure it how you did that

Akulahawk · Sep 1, 2014

I'm quite surprised that the LP can do that. I'm not surprised that the capability exists... because all it needs to do is measure the gas and it probably doesn't necessarily "care" if the gas is going in or out. That the LP alarmed for an FiCO2 level is quite amazing, really, because if it's set up to do that, you know the machine is helping you ensure that the gas delivered is good. If it alarms again, perhaps you have a contaminated (with CO2) oxygen delivery system... possibly in the tank or it's drawing air from a dirty source.

MrJones · Sep 1, 2014

Aside from the remote possibility of a contaminated O2 source, possible causes for high FiCO2 levels include the patient inspiring exhaled CO2, an incorrectly attached monitoring device, or the oxygen flow to the mask has been interrupted/stopped.

Carlos Danger · Sep 1, 2014

I think it's probably a programming error. I seriously doubt the LP has the capability of analyzing inspired gases.

Especially with an ico2 of 9-12 with an etco2 in the low 30's....that would clearly be inaccurate.

medicdan · Sep 1, 2014

18G said:
I got an FiCO2 alarm on my LifePak 12 today for the first time. I've never seen this alarm before. The patient's EtCO2 was within normal values for condition (29-33mmHg). Specifically, the alarm indicated "FiCO2=9" and another time "FiCO2=12".

What exactly is this alarm saying?

Thanks.

This is indeed interesting.... Did it bring the "baseline" of waveform co2 on the patient up? What type of device were you using to measure co2 on this patient?

TransportJockey · Sep 1, 2014

I can't find a way ti get my 12 ti do it. Maybe in the cct versions

Carlos Danger · Sep 1, 2014

MrJones said:
Aside from the remote possibility of a contaminated O2 source, possible causes for high FiCO2 levels include the patient inspiring exhaled CO2, an incorrectly attached monitoring device, or the oxygen flow to the mask has been interrupted/stopped.

Good point, perhaps it simply interprets a failure of the waveform to return to baseline as an fic02.

As I wrote before, I don't see how it could actually measure inspired vs. expired gas, without separate inspiratory and expiratory circuit limbs and gas analyzers.

With a single sample line how could the monitor possibly know how much of the measured c02 was inspired before being exhaled?

MrJones · Sep 1, 2014

Remi said:
Good point, perhaps it simply interprets a failure of the waveform to return to baseline as an fic02.

As I wrote before, I don't see how it could actually measure inspired vs. expired gas, without separate inspiratory and expiratory circuit limbs and gas analyzers.

With a single sample line how could the monitor possibly know how much of the measured c02 was inspired before being exhaled?

I've never been able to find a satisfactory answer to that question. Until I do, I'm working under the assumption that the system senses the direction of flow to differentiate between inhalation and exhalation.

Handsome Robb · Sep 1, 2014

Now that's a weird one...All my ideas have already been stated.

Carlos Danger · Sep 1, 2014

MrJones said:
I've never been able to find a satisfactory answer to that question. Until I do, I'm working under the assumption that the system senses the direction of flow to differentiate between inhalation and exhalation.

Possible I suppose, but it seems highly unlikely. That would require flow sensors as sophisticated and more compact that those found on the high-end ICU vents and anesthesia machines.

NomadicMedic · Sep 1, 2014

I would bet you looked quickly and it was a CO alarm. Occasionally, our lifepack 15's would change from SPO2 to CO. The CO and SPO2 window are in the same place on the monitor screen, and it was usually due to not using an ambient light shield. :/

18G · Sep 1, 2014

Thanks for everyone's input...

The FiCO2 alarm occurred while caring for a patient having an asthma exacerbation who was receiving continuous nebs via face mask over a 90min transport. I was of course using the cannula type filter line for monitoring EtCO2. I have never seen this alarm in the past. A quick Google search does show FiCO2 as an alarm in the LifePak user manual.

Like I said, the displayed EtCO2 was clinically appropriate for patient condition as was the waveform so I ignored it. But it definitely got my attention.

Akulahawk · Sep 1, 2014

@18G , I'm going to have to say that's very interesting... Good to know!

MrJones · Sep 2, 2014

Remi said:
Possible I suppose, but it seems highly unlikely. That would require flow sensors as sophisticated and more compact that those found on the high-end ICU vents and anesthesia machines.

Really? The capnogram waveform indicates when inspiration begins and ends (commonly labeled as the D-E slope), so why couldn't the volume of CO2 be measured during that phase?

Carlos Danger · Sep 2, 2014

MrJones said:
Really? The capnogram waveform indicates when inspiration begins and ends (commonly labeled as the D-E slope), so why couldn't the volume of CO2 be measured during that phase?

What I'm saying is I don't see any way for the LP to actually analyze the inspired gas separately from the exhaled gas, the way that an anesthesia machine does.

Estimating it from the waveform would not be a true measurement of the % inspired gas, simply an estimate based on the waveform, which could also be caused by air trapping or bronchospasm and would not necessarily indicate that C02 was actually being inspired.

MrJones · Sep 2, 2014

I reckon the only way to settle this is to ask physio how they do it. So I have - I'll post their answer if/when I receive it.

Christopher · Sep 2, 2014

Reading over Oridion's patents on CO2 technology (12/607,936, 11/597,643) and Nellcor's big patent (07/458,974), seems to show that without a second connection there is an algorithm which compares the flow and partial pressures versus detected events in the sampling line. The sampling appears not to be continuous, and there is some cycling between drawing in through the line and allowing backflow via computer controlled valves. Most units detect inhalation and exhalation via flow against/with these valves. It appears the actual definition of the FiCO2 term is the instantaneous final inspiration concentration of CO2.

Obviously sidestream detectors use a delayed sample, but they have extremely low volumes in their sampling lines. Even mainstream detectors utilize an inferred approach rather than a direct measurement. Only coupled-ventilator/anesthesia systems seem to do direct measurement of FiCO2. It also appears from a smattering of related patent applications that many now use adaptive algorithms that measure the breath-to-breath rate to determine the optimal sampling time.

Christopher · Sep 2, 2014

Further reading of the patents on Oridion/Covidien's technology finds that they measure it like so (which appears to be ubiquitous across cardiac monitors):

c) S- FiCO2 - Spontaneous fractional concentration of final inspired CO2: If a breath cycle is recognized, then, according to some embodiments, the lowest CO2 (concentration) value in the breath cycle (Spontaneous fractional concentration of final inspired CO2; S-FiCO2) may be used and the value obtained and optionally displayed being the lowest collected over the last "u" seconds (possibly 1 to 60 seconds). Again, it may be updated every period of time (once a second for example). If for "t" seconds (for example, 20 seconds) there is no new breath, the S-EtCO2 value may be determined and optionally displayed as invalid (for example a dash is provided in place of the value).

LifePak FiCO2 Alarm

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