Are Finger Pulse Oximetry Devices reliable?

[Noel]

I recently bought my finger ox from amazon by a brand called accU-rate which was a CMS 500 DL and was having second thoughts if these devices were reliable in charting PT VS. Obviously for spo2 and HR. I don't want to seem reliant on technology to do my job due to already having skills to acquire VS, but it'd be nice having a little help w/charting VS on such short PT transports.

 

[ThadeusJ]

I have been to many international trade shows where these things can be stacked like packs of gum and sold for a few dollars. Technically they should be calibrated for accuracy, however as licensed medical devices they should be considered accurate enough to rely on. That being said, technology is only as good as the person using it (and who recognizes those limitations). Whether its accurate enough to obtain a signal when you need it the most or whether the output will change the way you treat a patient is another matter altogether.

 

[Aprz]

I would consider it reliable if it fits the patient's presentation. Use multiple methods to confirm it is correct.

 

[Flying]

Pulse oximeters are quite reliable no matter what you buy. By design they are increasingly less precise at readings below mid-80%, but at that point we can usually accept that there is a problem from just the gross examination and/or history of the patient and act on it (or not at all).

As Aprz said, confirm your readings with the patient first. Correlate the plethysmograph with the patient's pulse. If your device does not have a pleth, you're better off just timing the palpated pulse in the first place.

 

[Qulevrius]

I recently bought my finger ox from amazon by a brand called accU-rate which was a CMS 500 DL and was having second thoughts if these devices were reliable in charting PT VS. Obviously for spo2 and HR. I don't want to seem reliant on technology to do my job due to already having skills to acquire VS, but it'd be nice having a little help w/charting VS on such short PT transports.

Always ask the sending facility for baseline v/s, then take your own initial v/s on scene (your partner is an ideal candidate to do that while you get the verbal and handle the rest of the paperwork), followed by another immediately prior to transport. If pt is stable and transport time is shorter than 15 min, take your last v/s @ the receiving facility. That's plenty of data to populate the PCR and you don't kill yourself over it. As far as pulse ox devices go, they're helpful with baseline O2 sat readings and HR but since they don't show the hemoglobin count, it can be quite dangerous in certain situations. I would suggest not blindly relying on SpO2 reading but supplement the readouts with pt's presentation and general impression.

 

[ThadeusJ]

If you've never used one, heed those words stated by our esteemed colleagues above. I don't know how many times I've seen HR recorded as 300 bpm when the patient has the shakes or as 25 when there's lousy circulation. I actually had to come right out and tell someone that if they recorded 300 I'd report them (just because they insisted that they record what the machine tells them).

 

[joshrunkle35]

I put it on my own finger and take my pulse at the beginning of my shift. I am good with about a 5% difference in pulse rate. (Also, finger vs radial technically could be slightly different). Pulse ox can be unreliable for things like CO poisoning.

Never forget what I'm sure everyone learned on day one of EMT school: treat the patient, not the monitor. Go with your general impression of the patient rather than what your gear tells you. Until we're all doing echocardiograms, ultrasounds, MRIs, lab values, etc...gear is a tool to help you. Not a definitive piece of diagnostic equipment.

 

[NomadicMedic]

Really? A monitor isn't a price of diagnostic equipment?

Tell me again where you're a medic, so I never go there.

 

[Underoath87]

I don't know whether you're questioning the reliability of a cheap pulse-ox, or the efficacy of pulse oximetry in general. However, I can say that I've used dozens of different $30 CVS pulse oximeters, and they read the same as one connected to any expensive monitor.

You just need to be aware of the factors that can cause a false-low reading. I've never seen one read falsely high (though I know it would for CO poisoning). So long as the pleth is reading well, the pulse rate should be accurate.

 

[Qulevrius]

I've never seen one read falsely high (though I know it would for CO poisoning).

It's more about the SpO2 reading which is never reliable. Can easily be 80% O2 with 15% CO2 but the meter will show a solid 95%. No bueno.

 

[joshrunkle35]

Really? A monitor isn't a price of diagnostic equipment?

Tell me again where you're a medic, so I never go there.

I'll note that you changed my wording, and therefore my context. I said "Definitive". I never stated that it wasn't a piece of diagnostic equipment. Taking something out of context and then jumping down someone's throat for it is silly.

 

[NomadicMedic]

I'll note that you changed my wording, and therefore my context. I said "Definitive". I never stated that it wasn't a piece of diagnostic equipment. Taking something out of context and then jumping down someone's throat for it is silly.

So with rapid pulse rate you don't use that monitor to definitively diagnose VT, Afib or SVT? You don't use that glucometer to determine hypoglycemia in an altered patient?

I'd say that using technology to definitively diagnose and start a treatment pathway is pretty important.

Making statements like "treat the patient, not the monitor" is pretty shortsighted. How about you treat the patient and the monitor and leave the EMS "pearls of wisdom" where they belong... In the past.

 

[Underoath87]

It's more about the SpO2 reading which is never reliable. Can easily be 80% O2 with 15% CO2 but the meter will show a solid 95%. No bueno.

I don't think you understand how a pulse oximeter works (or even RBC's)...

 

[gotbeerz001]

.....

 

[joshrunkle35]

So with rapid pulse rate you don't use that monitor to definitively diagnose VT, Afib or SVT? You don't use that glucometer to determine hypoglycemia in an altered patient?

I'd say that using technology to definitively diagnose and start a treatment pathway is pretty important.

Making statements like "treat the patient, not the monitor" is pretty shortsighted. How about you treat the patient and the monitor and leave the EMS "pearls of wisdom" where they belong... In the past.

Something being "indicative of" vs "definative" are separate things. A monitor can indicate V-Fib, and yet you can have artifact, loose wires, etc...hence why we treat the patient not the monitor first. I'm not going to shock someone who's alert and oriented and talking to me if the monitor indicates V-Fib. Additionally, electrophysiology is way more complicated than the few weeks of schooling we paramedics have on it. That's why doctors who are specialists in those areas exist. Just because the monitor "absolutely" says they have one thing, even after I check the leads and confirm in more than one lead...I have an indication, which informs me of how to most appropriately begin treatment as best as I understand it at the time. However, it is way more complicated than that, and my best indication is not the same thing as a definitive diagnosis. In the same way, a pulse oximeter is a tool, also used to indicate findings, but it is not definitive. If it were, there wouldn't be doctors who specialize in placing arterial IVs to read capnography, arterial pressures, etc. We wouldn't bother with blood gases or CBCs if pulse oximetry was definitive.

Indicative is not definitive!

 

[joshrunkle35]

It's more about the SpO2 reading which is never reliable. Can easily be 80% O2 with 15% CO2 but the meter will show a solid 95%. No bueno.

CO2 and CO are not the same thing.

 

[Qulevrius]

I don't think you understand how a pulse oximeter works (or even RBC's)...

Ok mate, so which part do you think I do not understand ? The one where RBCs carry hemoglobin that O2, CO and CO2 bind to or the one where a pulse oximeter doesn’t tell you if pt is retaining CO2 or has CO in his/her blood ?

 

[Run with scissors]

it's as reliable as a parachute. it's supposed to work, if you use it right. but some times. you have to pull out your back up method.

 

[Flying]

Ok mate, so which part do you think I do not understand ? The one where RBCs carry hemoglobin that O2, CO and CO2 bind to or the one where a pulse oximeter doesn’t tell you if pt is retaining CO2 or has CO in his/her blood ?

Pulse oximetry works by measuring the amount of red/near-red light reflected by activated heme (hemoglobin carrying something).

First, the major problem is that the ability of CO2 to form a stable complex with hemoglobin is far inferior to CO. So we are not worried so much about CO2 messing with the reading.
Second, it doesn't matter whether or not a pulse oximeter can differentiate between CO2 and O2 because the majority of CO2 in the body is in the form of bicarbonate ion.
Third, the HbCO2 complex does not reflect red light and is in fact blue, contributing to the trademark colour of deoxygenated blood.

Pulse oximetry has been around for a few decades now. Its simplicity and the ubiquity of the electronics has made the tool very reliable.

it's as reliable as a parachute. it's supposed to work, if you use it right. but some times. you have to pull out your back up method.

This statement is too general to take anything useful from.

 

[Flying]

Addendum:
By "trademark colour", I mean darkish brown/red blood, not blue venous blood.

One could argue that the 10-20% of CO2 bound to hemoglobin in the blood might-maybe-sort-of mess with the SpO2 reading, but we're waaay past that in the 21st century. The wavelengths of light that are being used in current devices take this into account and they have been pretty much set in stone since the 90s.