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+--- Thread: [split] What does machine class as apnoea event? [multicast thread] (/Thread-split-What-does-machine-class-as-apnoea-event-multicast-thread)
[split] What does machine class as apnoea event? [multicast thread] - multicast - 05-12-2020
(05-10-2020, 02:11 AM)SarcasticDave94 Wrote: It sounds like SWJ so I'd disregard.
So might we say that an event scored as apnoea without a flow limitation is SWJ? Take this, e.g.:
[attachment=22864]
Unfortunately the machine responded with an increase of pressure ...
Mike
RE: What does machine class as apnoea event? - Gideon - 05-12-2020
SWJ occurs near a therapy break. No breaks are apparent in the chart and therefore no SWJ unless you know this is an awake period. We ignore all awake periods because we are lookig at treating during sleep.
RE: What does machine class as apnoea event? - Sleeprider - 05-12-2020
(05-12-2020, 09:09 AM)multicast Wrote: So might we say that an event scored as apnoea without a flow limitation is SWJ? Take this, e.g.:
Unfortunately the machine responded with an increase of pressure ...
Mike
Mke that example looks like real obstructive flow apnea that was the result of positional apnea (chin-tuck). The increase in pressure is expected behavior, and there are two additional clusters of OA that kind of confirm you might benefit from a soft cervical collar.
RE: What does machine class as apnoea event? - multicast - 05-12-2020
Thanks a lot!
Mike
RE: What does machine class as apnoea event? - multicast - 05-13-2020
Again thanks for your reply. But there's one thing I don't understand thoroughly. As stated in the clinical manual, p6.:
"An OA apnea is when the upper airway becomes severely limited or completely obstructed."
The appropriate response is a defined increasement of pressure.
"During a CA, the airway will remain open, but there is no flow" and no action is taken. This is absolutely clear to me.
Now, CA and OA have in common that there is no flow, right? The difference is that on an OA the airway is obstructed and on an CA clear. Is that right as well?
Independently the machine measured the flow rate and reacts by an increase of pressure if certain conditions are fullfilled and thus preventing OA. So far, so good.
Now my question. In the screenshot I sent the machine detects an OA and hence the pressure was raised. BUT that OA occurred without any detected flow limitation, actually the limitation was zero, whereas in my imagination it should be near 100% as the airway was very limited.
What am I missing?
Mike
RE: What does machine class as apnoea event? - SarcasticDave94 - 05-13-2020
I don't know if my thinking is accurate, but it could be that if the event escalates above just a flow limit, then via the aspect of the duration of the event, it would either be hypopnea or apnea and flagged as such. To me, flow limits are the beginning of an apnea/hypopnea event where some restriction to the airflow pathway is taking place.
RE: What does machine class as apnoea event? - Gideon - 05-13-2020
Duration does not determine the class of event. To be classified as an event, hypopnea or apnea, obstructive or Central it must be 10 or more seconds in length. This is an arbitrary duration picked to put a line in the sand. Obviously the longer an event the more severe. Also shorter events, especially when clustered can have a considerable impact.
Centrals occur when no drive, no electrical or nervous signal is sent to breathe. This occurs from a variety of causes, some known, some not (ideopathic).
Both obstructive and Central have a continuum of events from apnea, to hypopnea, to flow limits or limited breathing, and finally normal breathing. On centrals you can see this in CSR where breaths start small, get big, then back to small, then a Central apnea and repeat.
RE: What does machine class as apnoea event? - multicast - 05-13-2020
Thanks for your answer despite it didn't address my problem directly maybe because I didn't described it correctly enough -- sorry, I'm not a native speaker of your language. Here's what I was confused about: I think I had a wrong notion of what "flow limitation" is, namely that if an OA occurs there must be "no flow" because of the obstruction. That was wrong.
Here's what I've found out. An apnea is defined as a reduction in ventilation below a certain percentage of recent breathing for at least 10 seconds. Now this apnea may be obstructive or central. To classify the event, ResMed machines use a force oscillation technique to examine if the airway is closed or not. In that sense the detection of apnea is something "short-timed", momentarily.
Now "flow limitation" is "long-timed based" in contrast, calculated by some indices as flatness, breath shape, ventilation change and breath duty cycle calculated in the time of three to five minutes.
From here there is no contradiction that the flow limitation is zero when OA occurs.
Mike
RE: [split] What does machine class as apnoea event? [multicast thread] - OpalRose - 05-20-2020
Moderator Note: This thread has been split out from another members thread.