Central vs Obstructive Apnea

[ChadBSr]

I know the stock answer that resmed sends a pulse and tries to detect and obstruction to determine how an event is flagged, but I just don't see it.  Can someone tell me why one of these are obstructive and the other central?  I've zoomed in on every event and compared every chart and I just can't figure out what is being used to decide this.

[srlevine1]

The key to understanding the data is to realize that the ResMed algorithm makes the classification decision and that OSCAR only reports the data recorded by your ResMed device. Without access to the algorithm and the raw sensor data, it is impossible to answer your question definitively.  

Considering reported values may be close to a decision boundary, it's an algorithmic coin flip to which bucket the event is placed. All devices have noise and transients that can change the results.

Is there any reason you are using CPAP mode rather than the more response auto-titrating mode which is more responsive to encountered conditions?
Best,  Steve

[ChadBSr]

Yes, but I see people on here often saying centrals look real or not. I don't know how anyone can say that if they all look the same. And the machine is a coin toss, but we're in here adjusting pressure up or down ?

[srlevine1]

It is my understanding that those comments may result from sleep/wake junk or the simple act of holding one's breath when one turns over in bed. My mentor always told me to ignore the minutiae of data unless you were a specialist and that you treat the whole patient rather than chase data transients.

[ChadBSr]

ResMed technology
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Device innovation: Our features & algorithms
Each ResMed device is designed to promote a peaceful sleep environment while remaining easy to use and understand. Engineered to fit discreetly into a patient’s lifestyle with a sleek and streamlined design and simplified navigation, our devices also offer an intuitive interface and easy-to-read LCD screens, as well as a variety of advanced, proprietary features to promote patient comfort and clinical outcomes.

AutoSet™ algorithm
VAuto, Vsync and S algorithms
CSA/CSR detection and RERA reporting
Central sleep apnea (CSA) detection is an advanced technology that uses the forced oscillation technique (FOT) to determine whether a patient’s airway is open during an apnea. When an apnea is detected, small oscillations (1 cm H20 peak-to-peak at 4Hz) are added to the pressure.

If flow is detected, the airway is open and the apnea is from CSA. The algorithm uses the resulting flow and pressure (determined at the mask) to measure whether the airway is open or closed. If no flow is detected, the airway is closed from an obstruction. The device responds by either increasing pressure or maintaining current pressure and recording the event for the patient’s apnea–hypopnea index (AHI) report.

I see no difference in flow or mask pressure

[SarcasticDave94]

One thing I saw between these 2 events, FWIW, the CA flagged event has a higher dip just before the flat event area. However the breath after both events look similar to me.

[ChadBSr]

Yeah, I've seen minor differences like that but then I go through and find the opposite. I've even seen centrals with flow limitation or snoring right before or after. I'm just not sure I believe the resmed flagging anymore. I'll get some more examples posted.

[ChadBSr]

Here is an example of a series of events that some are flagged central that looks suspect to me.  With the pattern and all the flow limitation I think these were actually obstructive.

[paulag1955]

If some of your central events are actually obstructive, then raising your pressure should reduce the number of events you're seeing. It can't hurt to give it a try.

[Sleeprider]

I think you should move to an Autoset mode and implement the use of EPR to relieve the flow limits, low tidal volume and RERA. It's up to you if you want to improve comfort and results, but you would do better at minimum pressure 7.0 maximum pressure 11.0 and EPR 3. With regard to your original questions, the events cannot be accurately classified because you appear to be in a state of arousal. The OS event was preceeded by a double inhale, followed by an exhale with a swallow in the middle of it and a breath-hold leading into the apnea. The CA event does not show the respiration ahead of it, but it looks mixed.