Hello Guest, Welcome to Apnea Board !
As a guest, you are limited to certain areas of the board and there are some features you can't use.
To post a message, you must create a free account using a valid email address.

or Create an Account


New Posts   Today's Posts

Can anybody comment on this desaturation behaviour?
#1
Can anybody comment on this desaturation behaviour?
Hi folks

Can anybody comment on this?

I was recommended CPAP because of cardiac arrhythmias at night, and a low SpO2 at night. I had a sleep study that said (cutting a long story short AHI ~ 20). I have no common symptoms of OSA, but it was clearly present to some degree.

On CPAP (auto 5-15cm) for two weeks, AHI is always < 2, and usually < 1. OSCAR shows few, if any flow restrictions of any duration, and I can see the pressure going up and down, doing its thing. My ventilation is pretty consistent through the night, and from one night to the next. It's always higher, however, than when I'm awake.

Although the CPAP seems to fix the OSA, to the extent that I have no obvious apnea or hypopnea events,  I still desaturate by about 6-8 percentage points, every night, for a period of 1-2 hours. Typically my SpO2 falls from 98% to about 92%, with brief excursions to 90% or lower. These occur at different times every night, for different durations, and are not associated (so far as I can see) with any change in ventilation, flow, or anything else that OSCAR/ResMed reports.

I've had six months of extensive hospital heart and lung tests, and I'm told that I have normal heart and lung function, apart from a PFO (which is found in ~50% of people with OSA). The cardiac arrhythmias (usually AF or short runs of VT) occur at roughly the same time as the low SpO2, but there's no other clear evidence that they're connected.

My doctors (and I've seen a half dozen or more) are completely baffled. On bad nights my SpO2 can be < 90% for several hours but, because I have tested normal heart and lungs, the doctors don't seem to be bothered. They seem to think that it is just an artefact of measurement of some kind, although they can't tell me what would cause such an artefact. I'm fit and generally in good health.

Has anybody else seen anything like this?

Thanks in advance.


Attached Files Thumbnail(s)
   
Post Reply Post Reply
#2
RE: Can anybody comment on this desaturation behaviour?
I'm not sure that's okay to leave, personally. Even if your lung function is fine, they really need to find out if the arrhythmias are triggering the lowered oxygen, or the lowered oxygen is triggering your arrhythmias.

I have central sleep apnea, and even though my heart and lungs are ENTIRELY normal, they've given me supplemental oxygen at night. I was NOT happy at first (because it's a cop-out, they're still not treating my central apnea) but it is increasing my oxygen levels as long as I still BREATHE and my brain doesn't forget.

That said, on this chart, your oxygen levels never drop below 90% but if the bad nights are common and you're under 90% for several HOURS, then yes, you need supplemental oxygen at least - how much lower than 90% do your levels drop? Have they given you any medication for treating the runs of VF and AF? If not, that's where I would go first, personally. but I'm not a doctor, obviously.
Post Reply Post Reply
#3
RE: Can anybody comment on this desaturation behaviour?
(01-01-2022, 07:08 AM)Ratchick Wrote: I'm not sure that's okay to leave, personally. Even if your lung function is fine, they really need to find out if the arrhythmias are triggering the lowered oxygen, or the lowered oxygen is triggering your arrhythmias.

Thanks, Well, that's the sixty-four thousand dollar question, I guess -- and nobody knows the answer. There's no real any evidence that these things are even related, let alone one being the cause of the other. The arrythmias are probably a relatively new thing (well, in the last six months or so), while the desaturation has been going on for years.

The desaturation was first noted several years ago, when I was in hospital for a routine appendectomy, and it caused a four-alarm fire at the time. But, since I appeared to be perfectly well, the doctors just shrugged their shoulders and ignored it. As I did, in fact -- until the palpitations started. The arrythmias are mostly at night, but I get occasional short annoying burst of palpitations in the evening as well.

I'm on beta blockers, but there's no easy way to tell if the medication, or the CPAP does anything useful for my heart, without another spell of 24-hour ECG monitoring.

Because my heart and lungs are in tip-top condition, I don't think the doctors would consider supplemental oxygen. To be honest, I'm surprised it helps you central apneas unless, perhaps, you have something else going on as well?

For the record, for the last two weeks my overnight SpO2 has always been > 89%, and usually > 92%. However, I've had nights were the average SpO2 is under 90%, with plenty of time in the low 80's. It's an odd thing to find in a person with apparently healthy heart and lungs, who is breathing normally, isn't it? It's certainly odd to my doctors, anyway.

At present, the doctors are just kicking me back and forth like a football. The sleep guy says its a lung problem, the lung guy says it's a heart problem, the heart guy... well, you know how it goes.

Thanks, DS
Post Reply Post Reply
#4
RE: Can anybody comment on this desaturation behaviour?
I mean, that's pretty much exactly where I found myself. I woke up one day gasping for breath, and wondered if I might have some OSA despite not snoring, as I do have a small palate and difficult airway, so I got a pulse ox and that is when I found that I am tachycardic all the damn time. Heart fine, lungs fine, no disease, no PEs, no anything apart from some minor allergies (I was 34 at the time). They did a sleep study and found I had central sleep apnea but then just... shrugged and discharged me without treatment. Cue 10 years of the tachycardia and dysautonomia symptoms that I am still not sure if they're caused by the sleep apnea, the cause OF the sleep apnea, or they both just HAPPENED to arrive at the same time, and my cardio finally decides to refer me for another sleep study because I nagged him so often about the fact that nobody was treating me for this supposed Central apnea. That's when I found I was stopping breathing 80-90 times an hour, and my sats were almost always significantly under 90% - but my sats are also low, even when I'm breathing regularly, too, because the same thing that caused me to stop breathing at night is also causing me to not breathe enough (I average about 8-10 times a minute, but that is mainly from 2-4 20-30 minute stretches of I'm guessing REM sleep where my resp rate is in the 20s or 30s).

The oxygen really hasn't helped my apnea a whole bunch. All it's done is reduce the numbers *slightly* but increase the number of 8 and 9 second "almost apneas" that don't quite get marked. I have no idea why, but the ventilation clinic doctors insist that "sometimes it helps stop central apneas". Honestly, I suspect that they just wanted to kick me on for another few months, tbh. Technically, they SHOULD have started me on BiPAP because I was in respiratory failure according to my blood gases (even if it was fully compensated). But nope. Oxygen, see that after one night of virtually no sleep, my sats looked great (cos no sh*t, I was AWAKE for all but an hour maybe here and there and never got further than a light doze because of the person next to me snoring at 70 freaking decibels through BiPAP) and so that's it, they're done. I literally TOLD them I hadn't slept, that was why my numbers were good on the pulse ox (my blood gases, btw, were STILL pretty much unchanged, though).

So yeah. It doesn't really. As proven by the fact that one night I still had an AHI of 33, and it's fairly common for me to reach the 30s for at least a couple of hours of the night. But regardless of if they find a reason or not, the fact that your sats are consistently that low while breathing normally suggests that you need SOME kind of help beyond CPAP while sleeping. And if nothing else, oxygen should be an option. If the desats started first, I would guess that the heart is responding to the desats, but yeah. So frustrating getting kicked between doctors, I know...

I'm sorry I don't have anything more firm to give to you as an answer.

The only thing I would ask is about your weight? If you are on the larger side, I have discovered there is a disorder called obesity-related hypoventilation syndrome, and this might be a possible option. It often coexists with OSA too and it's definitely not rare, despite that so many docs don't seem to realise it's a thing.

Have you tried increasing your minimum pressure from where it's at? I only wonder because in some places it does seem as if your oxygen level (overall) is roughly in line with your pressure chart, and if that's the case, maybe boosting your lower pressure might help boost up your overall oxygen?
Post Reply Post Reply
#5
RE: Can anybody comment on this desaturation behaviour?
(01-01-2022, 08:59 AM)Ratchick Wrote: The only thing I would ask is about your weight? If you are on the larger side, I have discovered there is a disorder called obesity-related hypoventilation syndrome, and this might be a possible option. 
Thanks. I'm somewhat overweight, and I have the thick neck that many OSA sufferers have.
But... my minute ventilation figure remains constant, whatever my SpO2 is. In fact, sometimes my ventilation increases a little, as my SpO2 falls, as if it's trying to compensate for some other problem. I'm pretty sure I'm not hypoventilating.
The pressure thing is a little odd -- I can see that sometimes the machine wants to increase the pressure beyond the maximum that has been set. But if I'm having no apnea or hypopnea episodes, should I allow this to happen? Why does the machine even want to do this? But I guess it won't hurt to try for a few nights.

TBH, the drops in my Sp02 in the last few weeks are not really much different from those experienced by airline cabin crew every time they fly. So far as I know, those folks don't develop more cardiac problems than anyone else. What I'm really wondering is whether it's worth continuing with the CPAP, since it doesn't seem to improve my main concern.

Best wishes, DS
Post Reply Post Reply
#6
RE: Can anybody comment on this desaturation behaviour?
Desaturator, your Autoset is set to a minimum pressure of 5.2, maximum pressure 15.0 and EPR full-time at 3. You should understand that this CPAP actually delivers bilevel pressure with separate inhale and exhale pressure (IPAP/EPAP). With your current settings, the pressures start at 5.2/4.0, and the full EPR is not available until you reach 7.0/4.0. We can see in this example that your median pressure is 7.7, so my first recommendation is to increase the minimum pressure to 7.0 to get better responsiveness from the machine.

Ventilation or CPAP can significantly affect oxygen saturation by providing a "Positive End Expiratory Pressure" or PEEP. A higher PEEP recruits lung volume and increases the partial pressure in the lungs to improve gas transfer to the bloodstream. You can research these terms and you will find it is well researched, although not often discussed in CPAP therapy https://litfl.com/positive-end-expiratory-pressure/ . Your current settings provide a PEEP of only 4-cm H2O. In order to increase PEEP, you can choose higher minimum pressure, and you should be able to track the difference this makes with your pulse oximeter. There is no need to go crazy with this, but the absolute minimum pressure you should use is 7.0 with your EPR, and a higher minimum pressure like 8.0 or 9.0 is certainly something to consider if you want to see improvement in your oxygen saturation. What I'm saying is that your CPAP treats your obstructive sleep apnea with quite low pressure, but you may want to move above that pressure in order to affect your oxygen levels. In the example chart, your SpO2 stays above 90% throughout the entire night, and you would not qualify for the use of supplemental oxygen unless SpO2 was below 88% for more than 5-minutes through the night. You can however improve your SpO2 by a couple points by experimenting with higher, but still comfortable minimum pressure. Look at your chart between 04:00 and 05:15 where your pressure was at the minimum, and you will see that this is precisely where your SpO2 is lowest, in-spite of zero events and steady minute vent in that time.
Sleeprider
Apnea Board Moderator
www.ApneaBoard.com

____________________________________________
Download OSCAR Software
Soft Cervical Collar
Optimizing Therapy
Organize your OSCAR Charts
Attaching Files
Mask Primer
How To Deal With Equipment Supplier


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
Post Reply Post Reply
#7
RE: Can anybody comment on this desaturation behaviour?
(01-01-2022, 09:53 AM)Sleeprider Wrote: What I'm saying is that your CPAP treats your obstructive sleep apnea with quite low pressure, but you may want to move above that pressure in order to affect your oxygen levels.  In the example chart, your SpO2 stays above 90% throughout the entire night, and you would not qualify for the use of supplemental oxygen unless SpO2 was below 88% for more than 5-minutes through the night.

Thank you for your thorough and detailed response. I confess that it did not occur to me to consider the effect of EEP. I did try setting a constant pressure for a couple of nights, but that would still have been with 3cm EPR applied, so the EEP would probably still have been low-ish.

I'm not particularly worried about SpO2 in the 91-95% range. If the CPAP machine is keeping it there (even if only by PEEP effects), rather than the 85-90% I used to see before I started CPAP, then it makes sense to keep using it. Problem is, I don't really have any way to know if it is the CPAP that is improving my SpO2, or something unrelated. Well, apart from the obvious -- to stop using the CPAP for a while, and see what happens.

Until now, I've been reluctant to increase either the maximum or minimum pressure, because most of the OSA problems are abolished that pressures as low as 4cm (I tried). From the previous discussion, though, it seems I might need to increase both the minimum and maximum.

Having said all that, I have to admit that I'm baffled why a person with better-than-predicted heart and lung function on repeated tests would need PEEP to control SpO2. Maybe I've just got lungs that are funky in a way that does show up in tests.

Best wishes, DS
Post Reply Post Reply
#8
RE: Can anybody comment on this desaturation behaviour?
There is nothing wrong with your respiratory statistics, and the minute ventilation rate is very steady. I think we all experience some variation in SpO2, but unless it also increases CO2, there is nothing to trigger higher respiration. I really think you would find a fixed pressure of 8.0 and EPR 3 to work pretty well, and may avoid desaturation. There is no reason to over-think this. Your SpO2 results are best when pressure is above 7. If that is your objective, why the second thoughts?
Sleeprider
Apnea Board Moderator
www.ApneaBoard.com

____________________________________________
Download OSCAR Software
Soft Cervical Collar
Optimizing Therapy
Organize your OSCAR Charts
Attaching Files
Mask Primer
How To Deal With Equipment Supplier


INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
Post Reply Post Reply
#9
RE: Can anybody comment on this desaturation behaviour?
Just going to second what the others have said about maybe pushing up that pressure. It's probably only going to help your oxygen levels overnight. I'd be surprised if not, but have they tested your blood gases?
Post Reply Post Reply
#10
RE: Can anybody comment on this desaturation behaviour?
(01-01-2022, 12:24 PM)Sleeprider Wrote: There is no reason to over-think this. Your SpO2 results are best when pressure is above 7.  If that is your objective, why the second thoughts?

Because,  I guess, it's not really "normal" to desaturate like this. My concern is that, even I can fix it by instrumentation, I might have some underlying lung disorder that needs dealing with. Of course, even if that turned out to be the case, it might not be something that can be dealt with, and fixing the symptoms  might be the best I can do.

But I'm getting ahead of myself,  I think -- I need to try the higher pressure first, and see what happens. I will report back.

Best wishes, and thanks; DS.
Post Reply Post Reply


Possibly Related Threads...
Thread Author Replies Views Last Post
  AHI vs Desaturation -which is more important? vwboop 1 253 03-08-2024, 09:58 PM
Last Post: Jay51
  Sleep study review / O2 ring - Oxygen Desaturation SingleH 5 779 01-07-2024, 05:18 PM
Last Post: SingleH
  Help with 02 desaturation vgrando 14 1,294 07-26-2023, 11:40 AM
Last Post: Apnea23
  [Symptoms] SpO2 desaturation after 2 minute apnea event rwhimlin 0 507 05-19-2023, 06:11 PM
Last Post: rwhimlin
  how does apnea causes desaturation play out in time? cathyf 1 687 03-24-2022, 11:33 PM
Last Post: SevereApnea
Question Sleep study results/oxygen desaturation? kbingel 4 1,116 10-01-2021, 07:36 PM
Last Post: srlevine1
  Newbie. Hypopnea in REM. No Apnea and no oxygen desaturation CoreyW 8 1,389 05-31-2021, 05:47 AM
Last Post: Ratchick


New Posts   Today's Posts


About Apnea Board

Apnea Board is an educational web site designed to empower Sleep Apnea patients.