Understanding pulse oximeters & their usefulness

[WAFlowers]

Tom, you and others like yourself, blow me away. How you could even begin to think of how to make a working pulsox, let alone one that works with Windows, makes me feel like the stupidest person on earth, which I know I'm not. Where do people like you come from? Did you always have a scientific analytical mind or did you learn through books?

Tom is a unique individual with a double degree: EE and CompSci. He has an inquiring mind that loves to solve problems. I sure miss working with him!

Whether it is designing and building a foot bridge to span 20' with no center supports that can be broken down and transported in the bed of a pickup (and that has weathered 8 years of hard Canadian winters and summers so far) or thinking completely outside the box on leading-edge, ground-breaking software, Tom's your man! (And he and I have worked together on both of those things and more.)

Actually, Tom doesn't think outside the box. First he uses some judiciously placed C4 to eliminate the box, then he just thinks! .

[dsm]

<snip>

As far as an oximeter, I have looked around quite a bit, and this one seems to be the cheapest that will do the job, although it is not cheap.

http://www.nonin.com/products/3100.asp

Nonin, is one of the leaders in this technology, if not the leader. To get access to all the features you need the software as well, another $700 I think.

Cheers,
BP

BP,

That looks like a realistic type of device for us novice respiratory scientists

light weight - can be used for overnight info gathering. We probably don't need the $700 software.

Saves buying a big chunky Nellcor clinic discard

I like it

Thanks

DSM

[LoneRider]

Okay Bill and Lori, y'all are just too kind. I'm just lucky enough to have worked on no less than 3 medical devices over the last 3 years.

My experience has given me a little bit of insight into what goes on behind the walls of a big corporate medical equipement makers. This list has given me more inisght on what goes on behind the doors of a DME.

BTW Bill, don't know if I told you about the project on the other side of that cubicals. They are working on doing a cop Tivo, thanks to a couple of guys I work with, the program "cops" will never be the same. Imgine DVD quality real live take downs Anyway, so here they are trying to write streaming mp2 data to a hard disk. Yup, as you would guess they would come accross interesting bugs, then I would explain to them what the OS and the file system are doing under the covers, and they of course say ahhhhh. And of course the bridge project was fun. Got any digital pictures of it?

cheers,
Tom

[Sleepless on LI]

Bill,

You left out, Tom's modest, too.

[Guest]

WAFlowers: Besides ResMed S7 or S8, the DeVilbiss 9054 auto also offers add on recording pulse oximeter with software readout.

[dsm]

DeVillbiss seem to me to make a very good product & I am surprised they don't have a larger market share. I am guessing that because their business is so diverse and they don't have a big xPAP division, they don't have big visibility.

I have long been keeping my eye out for a DeVillbiss machine I could 'dissasemble' to see what it is like inside.

DSM

PS if anyone has an old machine deceased or otherwise & will mail it (I will pay postage charges) I am happy to publish the post mortem

DSM

http://www.internetage.com/cpapinfo/

[rested gal]

Earlier this year, a friend bought a used recording pulse oximeter through eBay for less than $400. Friend let me borrow it for a couple of weeks.

It was used, but was the same model as this one for $1,600!
Invacare Sleep Printing Pulse Oximeter - model IRC735B

No software was needed for 12 hour recording sessions that showed as much data as I wanted to see. It contained a little roll of paper - easy to print out in the morning. I used it every night for more than a week, several times while not using any cpap at all (gosh, it felt strange to lie down without putting a mask on!) several times with cpap. Hung the little oximeter machine in a fanny pack fastened to the side of the bed so I wouldn't accidentally pull it off a nightstand or something while turning over. Also hung the fanny pack on me in the daytime a couple of days for some ambulatory wide awake 12 hour daytime recordings.

It used 4 little batteries. Had a reusable finger probe and a few disposable ones.

Each printout took up a strip of about 14 inches in length of a little roll of paper like a handheld adding machine would use.

Here's an example of one of the printouts it gave me in the morning, after a night of using cpap:
_________________

Oximetry Summary
Patient Name (blank)
Date (blank)
Diagnosis (blank)
Comments (blank)
Start Time (blank)

Total Duration 09:31:44 (9 hours, 31 min, 44 sec.)

Excluded time 00:04:16

Total valid sample 09:27:28

Low SpO2 89% (saturated pulse O2)
At 08:51:12 (that's not the time of day...that's how many hours, minutes, seconds...at what point into the recording session the "low" took place.)

High PR 113 bpm (pulse rate in beats per minute)
Low PR 48 bpm
Ave SpO2 96%
SpO2 STD 1%

Statistics
% time per SpO2 range

%SpO2 --- %Time
95-99 ------ 83.6
90-94 ------ 16.4
85-89 ------- 0.0
80-84 ------- 0.0
70-79 ------- 0.0
0- 69 -------- 0.0

Time per Sp02 range
%Sp02 --- Duration
95-99 ------ 07:54:04
90-94 ------ 01:33:20
85-89 ------ 00:00:04
80-84 ------ 00:00:00
70-79 ------ 00:00:00
0- 69 ------- 00:00:00
____________________

With that much info on the little paper printout, I found out what I wanted to know without needing any software for it.

Pretty cool, and fun to use...once I finally got used to wearing that #$%! reusable finger probe.

So....if a person is patient and regularly checks the auction sites, you might also come across a good deal on a recording pulse oximeter.

[Sleepless on LI]

RG,

Thanks so much for posting the readouts from your oximeter. The one the DME gave me today doesn't look like it has anywhere to print anything out, nor does it look like something that has a connection to a computer. I wonder if they put in some type of code and are able to read it off a display? I can't figure this out.

So your lowest O2 was 89% without CPAP or with it? Were those actual readings? I guess if you're still on the machine, you need to use it. You may be interested in the post regarding oxygen therapy as opposed to CPAP therapy for hypoxemia that I submitted this afternoon viewtopic.php?p=49235#49235. But, then again, I forgot who I was talking to and you've probaby read and know by now just about everything on this topic that isn't new, and most of the stuff that is.

[Sleepless on LI]

Last night I slept with the Respironics 920M pulse oximeter. I was directed by my DME to put it on 5 mins. before bedtime to do a "warm-up" and to leave it on for a few mins. after waking. When I was at the DME's office, he ran a baseline test for O2 readings and heart rate. The pulsox said I had a 99% reading yesterday morning; however, he said there will be a definite difference in the supine and prone positions, and that it changes with our breathing pattern changes that occur while sleeping. And since the only time my O2 dropped below 90 was in REM, that is where they are most interested.

Well, when I put it on last night to warm it up, it read 97-98%, fluctuating. I kept it on in the upright position for about 5 mins. When I laid down, immediately the rate dropped and stayed between 94-95%, occasionally going to 96%. I was very surprised that a simple position adjustment like that caused it to drop so significantly. I know when we're dealing with O2 percentages, one percent can make a difference, although actually under 92% is what you start to pay attention to. The DME informed me that he believed, under Medicare guidelines, that they may ask your doctor for a reason to put you on CPAP/oxygen therapy at 89%, but anything below that they don't question. Mine was 84 during REM in my first study.

When I awoke this morning, first thing I did was look at the display (mind you, this is NOT on CPAP), and it read 98%. However, who knows what it dipped down to last night during REM. And unfortunately I won't know until they send the report to my doctor. The DME is actually picking the machine up from my home today, sometime this afternoon, and he said I should have the report faxed over probably by tomorrow. So it's a matter of waiting right now to see what happens. And, by the way, they are not charging me anything for this service. It comes with being one of their patients.

I will let you all know what the outcome is when I find out. Either it's off therapy all together or perhaps on to oxygen. I cannot believe they are going to want to put me back on CPAP, though, since my events are so few and far between and after reading up on hypoxemia, it seems patients do better on O2 therapy than room air therapy (CPAP). Oh, the waiting is the hardest part...

[WAFlowers]

And of course the bridge project was fun. Got any digital pictures of it?=

Yeah, I've got some at home in my archives. I'll have to dig them up if I remember.

[WAFlowers]

You left out, Tom's modest, too.

Yes, he is. Unlike me who brags about everyone, myself included! .

[WAFlowers]

WAFlowers: Besides ResMed S7 or S8, the DeVilbiss 9054 auto also offers add on recording pulse oximeter with software readout.

I stand corrected. Thank you, mysterious stranger.

[rested gal]

So your lowest O2 was 89% without CPAP or with it? Were those actual readings?

Lori, that was using cpap and yes, those were actual readings.

Here's an example of one of the printouts it gave me in the morning, after a night of using cpap:

Lori, the drop to 89% that was noted on that night while I was using cpap is insignificant if a person really looks at all the statistics listed there and notices how long that one drop lasted: 4 seconds.

Other than for 4 seconds at 89%, my O2 stayed up beautifully all night on CPAP. My autopap, actually.

The oximeter reported an average of 96% during that nine hour sleep session. The vast majority of the time (83% of the time) was spent up at 95-99 and 16% of the time was spent at 90-94. Right up where it should be while sleeping...90 and above.

That 4 second blip of 89 wasn't even enough to be included in the list for "% time per SpO2 range" which just mentions minutes. Discard that and look at the real picture. Gotta not get distracted by a fraction of a decimal point here and there....remember? Unless it's on a check!

Yup, I do need the machine and do use it every night. Luckily for you, you might not need to. The oximeter recording you just finished doing while not using cpap will give some valuable info to consider, along with the other pieces of the puzzle your doctors need to consider.

[Sleepless on LI]

Laura,

So far, I've been doing all this without my doctor's input except to write the script for the pulse oximeter. But if it turns out that I'm still desaturating, I think it's crucial for me to get to the bottom, especially if my son is correct with his suggestion that it could be cardiac-related. Who would have thought that after believing I was finally cured of my heart problems, which is four years ago, that I would now be having oxygen desats due to my heart not pumping as efficiently as it should. That is not good for a 48-year-old, or anybody for that matter. I will have to go for a cardiac workup and see what the heck is going on with me. Does it ever end? I guess when it does, we won't know about it.

So I am taking it one step at a time. I am very interested to see what the results of last night's test are. But I have to say, I am feeling pretty good for someone who has not been on the machine for three nights. It used to be, prior to CPAP, I wouldn't sleep all night anyway. The past three nights I really have slept great for me, even with the restricted wire from the pulsox last night that pulled me back and woke me up a few times. But 5 and 5 3/4 hours without waking up is just about a record for me since starting therapy. I just couldn't sleep for a stretch except for the first night on melatonin, or second night...whatever. To go to bed the night before and wake up to daylight got my adrenaline rushing through the old veins. Felt so good to finally sleep again.

Your O2 readings were really good. Aren't you curious to know, though, what they would have been off the machine, if the therapy made a difference? I don't believe, if I remember correctly, which I do a lot more of lately, that you actually went for a PSG, did you? You are a self-taught and self-diagnosed CPAP-er, no? So to find out what your readings were without therapy would be interesting to know. Maybe DSM will actually BUY an oximeter, instead of just browsing the eBay ads, and lend it to you for some heavy-duty lab ratting sessions.

[rested gal]

Aren't you curious to know, though, what they would have been off the machine, if the therapy made a difference?

I sure was curious to know that, Lori. That's why I did this with the borrowed recording pulse oximeter:

I used it every night for more than a week, several times while not using any cpap at all (gosh, it felt strange to lie down without putting a mask on!) several times with cpap.

I think you're absolutely correct, Lori, to be concerned:

But if it turns out that I'm still desaturating, I think it's crucial for me to get to the bottom, especially if my son is correct with his suggestion that it could be cardiac-related.

I was very glad to hear you did some overnight oximetry recordings. I know you're anxious to hear the results. Hope it turns out to be good news for you!!