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How to explain SpO2 dip, flow limit and snore graphs
How to explain SpO2 dip, flow limit and snore graphs
I'd appreciate help with interpreting the dip in SpO2 as shown in the attached graphic, particularly between the two vertical rulings, approximately from 4:45 to 5:25 am. I see unusual relationships among my sleep measurements.

It is only in the last 10 minutes of that 40 minute period that Tidal Volume (TV) and Respiration Rate (RR) departed much from central values (as the larger amplitudes of the low SpO2 also show).

Most puzzling to me is the fact that right after 5:25 Snore kicks in hard and joins large medium to large Flow Restrictions (FR) but SpO2 rises to its more normal level as it was at 4:15. (A10 outlet Pressure rose from 10.9 cm at 5:18 to 12.5 by 5:25, and to the 13.1 peak by 5:38.)

For the record:  

1. Leaks are trivial and not shown for the night. During the 40 minutes, Leak dropped from 12.5 L/min at the 4:45 start to 2.6  by 4:50, then to 1.2 or less until 5:25.

2. I find that (now my second CMS50I) is sensitive to shifts of the "rubber" finger sensor in the stick-slip's split instant, but it readings are not highly sensitive to usual small displacements of the sensor after a few seconds have passed. There was a drop out of SpO2 recordings from about 5:50 to 6:20 when I got up for a toilet break.

3. The red horizontal trace in the top graph shows that at 4:45 I rolled farther over from about 70  degrees (off of supine) on my right side to about 110 degrees (not unusual) and stayed their quieter than I had been until then (as indicated by fewer little red "twigs").

4. The Perfusion Index also reflects the big SpO2 hit for 40 minutes.

5. It has been interesting to shift the alignment rulers left and right on such graphs and see that almost very Snore is accompanied by a significant large spike in FR and a shift in body or neck position (as shown by short red vertical "twigs" off the horizontal red trace). It's clear that sound quiet sleep is not assured by low AHI. The accelerometer data graphed in the red trace is from a device by Gulf Coast Data Concepts. I wear it on the front flat surface of a cervical collar. (Ignore a bit of its underlying data located in the upper left corner of the graphic.)


Any help would be appreciated.

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RE: How to explain SpO2 dip, flow limit and snore graphs
Not sure, but maybe someone will answer.
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RE: How to explain SpO2 dip, flow limit and snore graphs
I'm confused by the position data. The low SpO2 seems to relate mostly to the position, but I'm unsure what we're looking at.
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RE: How to explain SpO2 dip, flow limit and snore graphs
(11-01-2018, 03:13 PM)Sleep2Snore Wrote: Not sure, but maybe someone will answer.

(11-01-2018, 05:46 PM)Sleeprider Wrote: I'm confused by the position data.  The low SpO2 seems to relate mostly to the position, but I'm unsure what we're looking at.

Thanks for looking at this S2S and Sleeprider,

I'll check back in soon to continue here. I am reviewing similar SpO2 and PI drops in the recent past (since late July 2018) during which I have had position information. In the more distant past, before getting the accelerometer and when using my previous CMS50I (lasted 2+ years 'til irreplaceable battery died [April 2018?]), I had similar drops that occurred occasionally, but mainly for a period upon returning to bed after getting up in the night. I can't recall seeing that contradictory info in the graphs in my OP. Also, as again last night, I am seeing these drops in oxygenation earlier in my sleep and in time intervals that match--begin and end between--motion events like turns, shifts and snore-spike motions.

My newer (May 2018?) CMS50I's data may  reflect either a pulmonary or a device problem.  I have seen two instances of what I call drop outs lasting, say, 20-30 minutes, where no data recorded and I had not turned off the device in that sleep session. Further, downloading sometimes reports the device is not found when in fact a couple of repeated click sequences will bring up the graphs. I think I will be sending both devices back to China, one for a new battery, the other for repair or replacement.

Sleeprider, is it the graph of position that gives rise to uncertainty or the breathing question I raised? The red graph line in graphics like the top one in the OP have been most helpful to me in convincing and forcing me to prevent supine sleep, almost eliminating OSA's and making me more aware that getting good scores does not assure the most restful sleep; it just yields better sleep. Those spikes in the Flow Rate and, say, Tidal Volume curves are almost all accompanied by varying amounts of motion as shown by varying sizes of the offshoots from the red graph line. 

Thanks again.

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RE: How to explain SpO2 dip, flow limit and snore graphs
Oximeters are known to report false drops due to the wire connections getting jostled during position movement during the night. I would guess this is probably what your seeing.
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