Low O2 Levels During Sleep with Low AHI

[cmpman1974]

Is it possible to have acceptable AHI numbers using a CPAP/BiPAP, but still drop O2 levels on an oximeter to bad levels during sleep?  I know they use a pulse meter during polysomnograms at the sleep doc's office.  However, what about the other 364 days per year?  I'm asking because I also have pulmonary hypertension.  My daytime levels have been in an OK range. Not perfect, but nothing terrible.  I do wonder if nightly events could be much different.  I know they make a device that plugs into the ResMed machines, but it's very costly from what I can tell.

[srlevine1]

 I know they make a device that plugs into the ResMed machines, but it's very costly from what I can tell.

The ResMed pulse-oximeter using the ResMed kit, including ResMed's proprietary Pulse-Ox adapter, a Nonin 3012 LP pulse-oximeter, sensor, and cables, runs about $850 or more. Since the setup does not work with the newer S11 machine, it is a sunk cost unless you plan to stay with the S10 devices.

However, there are a number of substantially cheaper alternative recording pulse oximeters on the market. Some integrate better than others with OSCAR.

From Oscar's Oximeter page...

Pulse Oximeters are medical devices used to measure blood oxygen saturation. During extended Apnea events and abnormal breathing patterns, blood oxygen saturation levels can drop significantly, and can indicate issues that need medical attention.

OSCAR gives you the ability to track Oximetry data alongside CPAP session data, which can give valuable insight into the effectiveness of CPAP treatment. It will also work standalone with your Pulse Oximeter, allowing you to store, track and review your recorded data.

OSCAR is currently compatible with Contec CMS50D+, CMS50E, CMS50F and CMS50I serial oximeters.
(Note: Direct importing from bluetooth models is probably not possible yet)

You may wish to note, other companies, such as Pulox, simply rebadge Contec CMS50's under new names, such as the Pulox PO-200, PO-300, PO-400. These should also work.

It also can read from ChoiceMMed MD300W1 oximeter .dat files.

Contec CMS50D+ devices do not have an internal clock, and do not record a starting time. If you do not have a CPAP session to link a recording to, you will have to enter the start time manually after the import process is completed.

Even for devices with an internal clock, it is still recommended to get into the habit of starting oximeter records at the same time as CPAP sessions, because CPAP internal clocks tend to drift over time, and not all can be reset easily.

And there are others. I am sure fellow forum readers will have their recommendations to assist you in your search.
Best, 
Steve

[cmpman1974]

Thanks for the info.  I've tried to do a lot of research on this today.  It seems accuracy is all over the board with these meters.  I also see one called O2 ring from Wellvue.  I'm mostly curious how many here have had good AHI numbers reported on their machines, but had confirmed O2 levels that were lower than desired range.  I saw a couple Youtube videos on the topic by one person.  In actuality, how common is this?  I believe this would mean even though an airway is open since the machine is doing its job, the patient doesn't get adequate O2 levels.  Is this even possible really?  Wouldn't they at least get to ther awake baseline under those circumstances?   That awake baseline may still be poor though due to many reasons (COPD, lung issues, etc.).  I assume a morbidly obese individual will never get desired O2 levels awake or asleep regardless of therapy.  Any thoughts?

[staceyburke]

What are the reading that you have had?  Below 88 for a sustained period of time is something that O2 can be added to the cpap very easily.  If they are only spikes that go under 88 that is usually not a problem but a movement of the sensor on the finger.

[cmpman1974]

No one has ever monitored the O2 levels with BiPAP therapy except for the re-titration tests once every year or two.  I have no idea what my resting O2 levels are during sleep the other 364 days a year.  That's my concern.

[srlevine1]

A note on accuracy.

A patient does not require the precision or accuracy of a medical lab. Most pulse-ox devices have an accuracy between 2-3%, depending on the range involved. Since most of the anomalous readings are artifacts introduced by sensor motion, you are looking for trends and repetitive patterns over time, not specific readings. Since you will be using the same device, it's the relative readings that count. Sort of like getting weighed with your bathroom scale only to find out it is not the same reading at your doctor's office (especially when you are likely to be dressed.)

[Sleeprider]

We see members all the time that monitor SpO2 with various oximeters, and some experience low oxygen levels at night, even with good AHI. Many of our members require supplemental oxygen to improve the fraction of inspired oxygen (FiO2) to maintain a good oxygen saturation level. There are many reasons this can occur including high AHI event rates, but once the AHI is resolved and oxygen remains low, further investigation may be required. You are using a ST-A bilevel, so we can infer there is something going on you have not disclosed, and we can't even be certain the ST-A is the best device for your condition which is also undisclosed. Are we talking about COPD or a neurological or obesity hypoventilation, or are you being treated for complex or central apnea with the wrong machine? An Oscar chart might help.

[cmpman1974]

We see members all the time that monitor SpO2 with various oximeters, and some experience low oxygen levels at night, even with good AHI. Many of our members require supplemental oxygen to improve the fraction of inspired oxygen (FiO2) to maintain a good oxygen saturation level.  There are many reasons this can occur including high AHI event rates, but once the AHI is resolved and oxygen remains low, further investigation may be required. You are using a ST-A bilevel, so we can infer there is something going on you have not disclosed, and we can't even be certain the ST-A is the best device for your condition which is also undisclosed.  Are we talking about COPD or a neurological or obesity hypoventilation, or are you being treated for complex or central apnea with the wrong machine?  An Oscar chart might help.

I am new to this group so still leaning the ropes.  You have brought up some very good points.  I'll do my best to explain.  I honestly am doing everything in my power to try to understand why I'm on this particular machine too.  I am getting more confident it is because my sleep doc believes I have obesity hypoventilation syndrome.  I have been researching this a lot of the evening and many things fit the box.  However, my PACo2 on an ABG test was 43, which doesn't meet the min of 45 stated.  My PAO2 is higher than the typical limits. It was a random reading at a random time though so perhaps it would be different an hr or two later?  I checkbox a LOT of other qualifications with that illness though so it's a reasonable assumption.


I have tons of health issues including pulmonary hypertension, Hashimotos, had a Bone Marrow Transplant 7 yrs ago for Acute Lymphoblastic Leukemia, bad spine issues, etc.  My sleep studies have not shown much if any Central Apneas ever to my knowledge. Maybe a very few a couple times, but irrelevant in the big picture I believe.  Please tell me which OSCAR chart(s) you would find beneficial.  I am trying to figure out which OSCAR charts are most beneficial to focus on, especially when the AHI numbers are in a great range. For example, is the Tidal Volume chart when using a ST-A machine indicative of my own volume w/o assistance or a combined personal effort along with the machine-assisted breath when required? There's so much to learn.

I am going to invest in some form of a continuous oximeter as I feel this is a critical piece that can't be overlooked.  It only makes sense.  I just need to find the best option for the $$$.

[cmpman1974]

I am very curious exactly what was happening during this block of time.  Many Unclassified Apneas that night, but leak rates weren't bad. I'm kind of focused on this night because the next day I felt severely bad with a lot of odd symptoms throughout the day.

[staceyburke]

I'm sure other people will say the same thing...  You have positional apnea.  That is where you get into a position where you cut your own airway off.  It can not be helped with any Cpap machine, you must find out how not to get into that position.

We also call it chin tucking where your chin drops down to your sternum cutting off your airway.  It happens more often when sleeping on your back.  Or maybe to high of pillows forcing your chin down.  If you can't control it you may need to get a collar.  I have a link to collars in my signature.  It shows people without a collar and the SAME people with a collar on.  HUGE difference.