Apnea events vs SP02(%); does this sound reasonable?

[jonnybee]

Last night, for whatever reasons, according to my S9 readout as displayed in ResScan, during a one hour period, I experienced a cluster of 48 obstructive apnea events. Included in the total for this specific hour period, during one 7 minute period 5 events of 40, 35, 40, 42, 42, & 54 secs were recorded. That's a total of 253 secs or 4.2 mins.

I was wearing my oximeter during the session and the meter indicated the min SP02(%) during the period the cluster occurred was approximately 94% with the average low SP02(%) for the entire session was 94.7.

If I'm not breathing for 4.2 mins out of 7.0, how could I have maintained an SP02(%) min of 94 as recorded by my oximeter? Am I totally screwed up in my thinking?

I have experienced clusters before but never anything of this magnitude. I was titrated at 5 cm and was using pressure set at 5 cm in cpap mode last night. My average AHI over the last month is 3.3.

Leakage was zero.

Any ideas, comments, or suggestions?

[M.D.Hosehead]

Your thinking is fine. One of the two is wrong.
Can you review the waveform at the time the "clusters" occurred to see if they were genuine apneas?
What kind of oximeter? Did the O2 graph bounce around--possibly indicating movement artifact and thus inaccuracy?

[jonnybee]

Your thinking is fine. One of the two is wrong.
Can you review the waveform at the time the "clusters" occurred to see if they were genuine apneas?
What kind of oximeter? Did the O2 graph bounce around--possibly indicating movement artifact and thus inaccuracy?

Thanks for the reply, MDH.

ResScan appears to confirm apneas. Oximeter is a CMS50E. Oximeter readout started fluctuating between 94 and 98 at onset and leveled off at apparent conclusion of apneas. My problem is that I don't know enough to interpret the graphs adequately.

Attempted to PM you a couple of screenshots of the ResScan and Oximeter graphs but apparently you can't attach documents to PM's.

[jonnybee]

Maybe someone can make something out of these. Both graphs are for basically the same time period although the times don't agree.

[Slartybartfast]

Now I can't argue with what your sleep lab prescribed, but [Slapping my hands to either side of my face:] Oh My Goodness! Bump up that pressure! You're not getting any good out of your machine at that level, judging from all those obstructive events. I did a double take when I read that your pressure was 5. Then I saw that you're running in CPAP mode. Hells bells, I can't even breathe through my pillows mask at 5 cm. I'd turn blue and likely die in my sleep!

Your oximetry shows that you're not doing badly, though, which is fortunate. But the level is bouncing around, which is consistent with all those obstructive apneas. Your flow trace shows why. If you look at each time your flow decreases, you'll see that corresponds with an obstructive apnea. Then suddenly your flow goes wild. That indicates you're suddenly gasping for air, flopping around like a fish out of water. Ok, I mixed the metaphor there, but you get the idea. The time lag between when blood in your lungs gets to your finger and all the mixing that takes place en route to your fingertip doesn't allow your SPO2 to faithfully correspond with breathing events, so don't strain yourself looking for that. The important thing is your SPO2 never drops even as low as 90%. 95% is fine. But you're not getting good sleep if you're gasping like that. I'd bet money you're waking up, with each gasp. Maybe not enough to be aware of, but I bet you are. If you zoom in on your flow trace to the 1 minute scale I bet the breath peaks become rounded following each obstructive apnea, before slowly morphing into a more triangular, or sawtooth pattern which indicates sleep. That indicates you're waking up in order to breathe, gasping a few times, then falling back to sleep (sort of). You can't get any rest like that. The reason your SPO2 isn't consistently low is that, when your O2 is down, it doesn't take more than a breath or two to bring it right back up if your lungs are working efficiently, which yours apparently are. Everyone is different in that regard. When I was gasping like that, my SPO2 dropped into the low 80s, and as low as 66 during my initial study. You're better off than I was.

I'd sure be interested in what would happen if you'd set your machine in AUTO mode and set the minimum pressure about 8 cm and let it run for one night.

FWIW, what you have shown us here is a case in point for the advantage of APAP over CPAP. Were you running your S9 in Auto mode it would have headed off those events. Every night is different. We don't always need the same pressure night after night. CPAP can't be expected to provide effective therapy under all conditions. Running in AUTO mode allows the machine to analyze what's going on and treat you on, as the S9 marketing literature says, "a breath by breath basis."

You've got a great machine there. In my opinion it's the best APAP on the market. Were I you, I'd run it in AUTO mode. But only you should make the decision to do so. There may be reasons that I'm unaware of that you need to run your machine in CPAP mode. I notice your pulse is low. That, and the periodic breathing, if that's what it is, makes me wonder whether you might have congestive heart failure to some degree. Best talk to your doctor, rather than some guy on an unmoderated internet forum, though.

Ok, and another thing. I keep noticing stuff on those traces. I don't see any periods of well-defined REM sleep. Normally there should be 4 or 5 periods of erratic breathing during the night. Each period lasts between a half hour and 90 minutes. If you're constantly falling asleep, then choking and waking up to gasp for air, you'll never fall into deep enough sleep to do the REM-thing. And they tell us that REM sleep is essential to have in order to feel rested during the day.

[M.D.Hosehead]

Am I reading your post correctly? That the night shown on the graph above is an anomaly? It's hard to see how you could have an average AHI of 3.3 over a month, with several nights like the one you posted. Someone here once said, "every night is different," and sometimes you get a tracing that's a head scratcher. What pattern of obstructions appears on a typical night? What happens to the O2 typically? And how do you feel?

On this particular night, on the green O2 line, the descents and ascents resembling stairsteps are genuine physiologic desaturations (i.e., not artifacts), probably the result of apneas. The good news is is your O2 didn't go down very far, which means vital organs are probably spared damage. I think it's unusual to have so much apnea and so little desaturation; I can't think of an explanation.

The other good news is you don't have a leak problem.

OTOH, like Slarty says, on that particular night, it doesn't appear that your apneas were being treated. Typically, with so many obstructive events, sleep is significantly disturbed, and a person doesn't feel good the next day.

But if that tracing is an anomaly, it isn't a basis for changing settings, IMO. Can you let us see the sleep data and O2 for a typical night?

[Slartybartfast]

[snip]

I think it's unusual to have so much apnea and so little desaturation; I can't think of an explanation.

Right. That's got me wondering what's going on, too. I agree that the dips on the green line are real, they're just not in synch with anything you can see on the CPAP data because of the delay I mentioned. But the SPO2 bouncing like that is consistent with periodic breathing, which the flow trace appears to show. That and the low pulse makes me suspicious that maybe something else is going on. On the other hand, if this is really just an anomalous night, chalk it up to maybe Chinese food .

Is a puzzlement.

Still thinking here. I wonder if any meds are involved. OP didn't indicate if he's on medication. Or (don't take this wrong) maybe alcohol. Some folks like to quaff a glass of wine before bedtime. The tannins and sulfites in wine can do funny things to some people.

[greg-g]

I have to agree with the above posts. You need more pressure.
I would certainly put the machine in auto mode, even if you only use a restricted pressure range like to 5 - 7, although I would prefer to see at least 6 - 8 to start with.
The automatic pressure setting will then guide you on what pressure you should have.
While an SpO2 of 94 is not perfect, it's not that bad either.
I was never titrated for pressure as I was always going to get an automatic machine. I leave mine at 7 - 20. The 7 is to allow me to breath easily. My pressure has never gone above 15 and is normally about 8
Best of luck.

[jonnybee]

My sleep lab was conducted last September. Diagnosis was mild sleep apnea. Titration indicated a pressure of 5cm . Was issued a ResMed S8 Escape (I was clueless) which I used with pressure set as directed at 5cm. Noticed an immediate improvement in the way I felt. No falling asleep during the day.

After joining the forum, I realized I had been issued a machine with no data capability so I talked with my PCP who in turn contacted the DME who then replaced the S8 with an S9 Elite. Used S9 Elite (5cm) for a while but did not feel I was getting the results that I had experienced with the S8. Average AHI while using the Elite was 2.4 but didn’t “feel” as well.

After joining the forum, realized that most felt that the S9 Autoset was a “must have” so I paid $300 out-of-pocket and traded up to the S9 Autoset.

Wanted to get the AHI down from the 2.2 average I had experienced with the Elite so I started to experiment with the auto function. Started out at 4.0/9.0. Av AHI remained around 3.0 but noticed pressure bumping 9.0 max line so I increased the limits up to 5.0/11.0. Finally ended up with a range of 7.6/11.0 with the pressure bumping the 11.0 line. Changes in pressure were interrupting my sleep constantly. Decided to go back where it all started to cpap 5.0cm. AHI still in 3.0 range but started to experience the clusters as shown. Don’t know what is going on. Had another cluster last night similar to the one shown. This was after bumping the cpap pressure up to 7.0.

I don’t have a sleep specialist anywhere near me (nearest about 60 miles away) and my DME is clueless. I think it’s time to try and find a sleep specialist who maybe can help me sort this thing out since I obviously don’t know what I’m doing and could make things worse.

I plan to switch back to auto mode tonight with pressures of 8.0/12.0 and see what happens.

I have no history of heart disease except for an arrhythmia caused by benign PVC’s. My pulse rate has always been low.

I’ll wear the oximeter tonight and report back concerning results of switching back to auto. The pressure changes really bother me in auto.

Thanks to all who commented.

[Pugsy]

Is it possible that these clusters are related sleep position? Typically people can be worse (have more events) while sleeping on their back? Odd that you do so very well for the bulk of the night. REM related clusters would normally present more than once as we cycle in and out of REM.

If the pressure variations using APAP mode bug you but you still want to see where the pressure wants to go during those clusters, try a little tighter range than 4 cm between min and max. Example... 6 min 8 max or 7 min and 9 max.

[Slartybartfast]

Thanks for the clarification. So if you're otherwise healthy, and you've only been diagnosed with mild OSA, and your desaturations aren't bad, it's just a matter of getting your pressure set correctly so you can get better sleep.

If the machine is bumping against the top limit you've set, it's telling you that you need more pressure. While I don't notice pressure changes at all, I understand that some folks do. So for you, as Pugsy suggested, try a narrow range of pressures, but at a higher level than 5 cm. I can't understand how the sleep lab came up with 5 cm for you. That's like idling a high performance car down the street. Your clusters of events indicate that you need to burn rubber! You must have have, just by chance, had a good night in the sleep lab, and they prescribed your pressure accordingly.

It might be worthwhile talking to your PCP and maybe even show him the charts which indicate that the prescribed 5 cm pressure isn't doing what it's supposed to. Perhaps you can get a new sleep study done elsewhere. I think our sponsors, CPAP.com, have on their website a link to referrals at sleep-apnea-services-locator.php. That might help. If you do have another sleep study, it's a good idea to make sure they're fully accredited. I count 7 of them within 75 miles of Charlotte.

Best of luck getting this under control.

[jonnybee]

Is it possible that these clusters are related sleep position?

I think you're on to something Pugsy. I went back through all my ResScan detailed data (beauty of having a data capable machine) for the last eight months and almost without exception the clusters occurred first around 1:00 am, which is about two hours after I go to bed around 11:00 pm. If I experience more than one cluster during the night they are almost always spaced about an hour apart. I normally go to sleep on my right side so most likely I'm turning over on my back a couple of hours later which probably precipitates the first cluster, and then maybe an hour later I turn over again etc. Very interesting.

I plan to switch back to auto tonight and use a narrow range and see what happens.

BTW, I'm pretty sure I slept the majority if not all of my sleep study on my right side.

Again, thanks alot for the comments/advice. I'll report back on what happens tonight. I'll wear the oximeter as well and post results.

[Lizistired]

John, I have the same problem with auto. My titrated pressure was 7. When I experimented with auto ranges, I was up well over 9. Whatever range I set, the machine spent most of the night at the top and never made it to the bottom without an event sending it back up. My AHI did not consistantly improve.

A couple of weeks ago, I was standing outside during strong sustained winds. It occured to me that sometimes unconsciously I closed my airway, and sometimes I just didn't breathe but my airway was open. So I think my brain responds the same way to pressure while I'm sleeping and may explain why increased pressure can cause centrals. For me anyway.

So I went back to CPAP 7.4 and adjust it 0.2 at a time depending on how I am doing.

I would like to see what your O2 looks like on a good night. Mine sits at about 93-94 with drops to 88-90 during the night. So yours is still dropping that much, you just have a healthier starting point.
Do you just not fool with setting the clock on your oximeter? It is kind of a pain. I set my alarmclock time the same as my s9 so it's easy to set the oximeter to the same time. It makes viewing data so much easier.

[jonnybee]

John, I have the same problem with auto. My titrated pressure was 7. When I experimented with auto ranges, I was up well over 9. Whatever range I set, the machine spent most of the night at the top and never made it to the bottom without an event sending it back up. My AHI did not consistantly improve.

A couple of weeks ago, I was standing outside during strong sustained winds. It occured to me that sometimes unconsciously I closed my airway, and sometimes I just didn't breathe but my airway was open. So I think my brain responds the same way to pressure while I'm sleeping and may explain why increased pressure can cause centrals. For me anyway.

So I went back to CPAP 7.4 and adjust it 0.2 at a time depending on how I am doing.

I would like to see what your O2 looks like on a good night. Mine sits at about 93-94 with drops to 88-90 during the night. So yours is still dropping that much, you just have a healthier starting point.
Do you just not fool with setting the clock on your oximeter? It is kind of a pain. I set my alarmclock time the same as my s9 so it's easy to set the oximeter to the same time. It makes viewing data so much easier.

Hi Liz,

A few nights ago I decided "what the heck" and did not use the machine at all and wore the oximeter just to see what would happen. My SP02 min was 94.0 and my av low was 94.7. A night or two later, I set the machine on cpap with a pressure of 4.0 to try and get some idea about what would happen if I didn't use the machine at all. I ended up with an AHI of 2.5 with the pressure set at 4.0. So I set it to cpap 5.0 and that's when the clusters started. Go figure. The thought has certainly crossed my mind that maybe I don't actually have a real problem with apnea and that the machine/pressure is what's causing me grief. Like you, it seems that the higher the pressure I set in auto, the more the machine wants to supply the max.

Yeah; just too lazy to set the oximeter clock. Maybe I will from now on; would definitely make graphs easier to compare.

[yrnkrn]

Is it possible that these clusters are related sleep position?

I think you're on to something Pugsy. I went back through all my ResScan detailed data (beauty of having a data capable machine) for the last eight months and almost without exception the clusters occurred first around 1:00 am, which is about two hours after I go to bed around 11:00 pm. If I

If it's happening at same time after going to bed every night, it's likely to be during REM sleep.
Low average AHI is not so good as it seems since it is the average of no events before REM and many events during REM.