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Hi I have been a hosehead for around 3 months now and i feeling good with AHIs now consistently below 1. However, i am still registering a lot of RERAs with 22 last night. Whilst these are not scored as AHIs (dont really understand the difference between a hypoapnea and a RERA) they are still arousal events. My settings are presently 14-20 with ramp turned on. My 90% levels are usually between 15 and 16.5. Is there are anything i can tweak to treat the RERAs?
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RERAs count, and I had them too. In addition to AHI, you will often see the term RDI, which is the sum of AHI + RERA. The condition is often associated with Upper Airway Restriction Syndrome (UARS), and is also something that occurs alongside sleep apnea. It may respond to higher pressure, however, I found a bilevel device resolved it for me. That is not so uncommon as the pressure support is normally what can be used to overcome flow limitation and RERA while EPAP supports the airway to prevent OA.
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Hi Sleeprider - thanks for this. Is the C-Flex function on APAP not supposed to assist with this? Or, as a comfort setting, is this too passive? What does bilevel do the APAP doesnt?


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CFlex provides a brief period of pressure relief at the beginning of exhalation.  It makes initiating exhale easier and more comfortable for some people.  It is not analogous to pressure support in BiPAP where the EPAP pressure is maintained at a set level until inhalation begins and pressure rises to IPAP, also known as pressure support.  CFlex may drop pressure momentarily by as much as 2 cm, but it returns to normal pressure well before inhalation begins.  The Resmed machines actually have an exhale relief of up to 3cm that acts much more like bilevel.

In Aircurve and Airsense machines the mask pressure is charted.  Unfortunately we can't compare that to the Philips machines.  The chart below from a Resmed device shows what happens to mask pressure, and compares that to the respiratory flow rate chart.  The pressure curves in the Airsense 10 and Aircurve 10 look identical, so the Airsense is a bilevel machine limited to 3 cm pressure.  In this example I included an OA so you can see the FOT apnea detection.  Note how the pressure follows respiration. If a breath is not taken, the pressure remains at EPAP (or pressure minus EPR). Pressure increases through the inhalation phase to a peak then rapidly drops as exhale begins and stays low until the next breath.  In this example you also see a flow limited breath followed by an OA and recovery breath. The PAP unit does nothing during the event, and this is true of all CPAP and bilevel units that are not ASV or ST type. This shows respiration compared to 3 cm EPR with a pressure of 13/10.

[Image: wxNRuZuh.png]

CFlex makes a much smaller pressure change, and only as exhale begins, and pressure returns to "IPAP" before the inhale begins.  Do you see the difference?

[Image: cflex.gif]
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To add to sleeprider 's observations:
The Aflex on your dream station is closer to a 2cm drop bilevel than Cflex. So you may want to try Aflex at any setting 1,2 or 3.

Cflex is just like the curve sleeprider showed. Aflex drops the pressure by 2cm from IPAP and keeps it there until it senses the beginning of the inhalation/end of exhalation. At that time it ramps it up quickly to IPAP.
PRS1 Auto & Dreamstation Auto w/ P10 and straight pressure of 7cm. 
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I'm looking at this thread with interest. My RERA levels are much higher than they should be. Raising the minimum pressure has had very little effect on RERA. I was operating the loaner S9 on much lower levels with better results for AHI and RDI. I've posted on this before and your comments suggest that a bilevel machine might be a good choice
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Sleeprider and AshAf

Thanks for the reply. I can see the points you are making but I don’t understand them. I think this might be due to my basic understanding of the conditions (or rather my lack of understanding). In order to demonstrate this I will go out on a limb and summarise my understanding which, when corrected, might help me understand what is going on better (also remember I never had a sleep or titration study - just a pulse oximeter which showed an AHI of 52).

OK I suffer from Sleep Apnoea which is basically a number of conditions that contribute to restricted breathing. These include - OSA, which is a full restriction of the airways - secondly Hypopneas - which are partial restrictions that last for more than 10 seconds - third Clear or Central, which is where there is no breath being taken but no restriction - and then there are RERAs - which are also restrictions that create arousal events but are not as severe as hypopneas. My understanding of APAP is that it is best described as a pneumatic splint that uses pressurised air to keep your airways open. Different patients will require differing degrees of pressure support to remove the obstruction and these will also differ within a single patient during the night. Therefore, APAP as opposed to CPAP, will vary the pressures between the parameters set up by the patient in order to respond to the restriction. The machines also include comfort settings which might be helpful to come to terms with the treatment. These include, ramp - starts at a lower pressure to gradually arrive at the minimum, AFlex - this provides support to both the inhale and exhale, Cflex - this provides support to the exhalation only. EPAP - the comfort setting to assist exhalation i.e. the amount of reduction in the established pressure settings.

Here is where I start to lose my understanding. I understand that I still have apnea events, even though I am being treated, due to the machine algorithms not picking up on the event, or picking up too late (it also appears to me that the machine will also score events that are not apparent on the flow graph when fully blown out). Whilst i can understand the machine missing a few events what I don’t understand is how it can miss 22 RERAs. Why does the treatment at its present settings not prevent RERAs?

If I understand Sleeprider and Ash correctly bi-level machines achieve this by having two pressure settings that can be established for the inhalation and exhalation events (although it is hard to get my head around the machine responding with differing pressures over such short events as a breath). Secondly, when I analyse the graphs it is not immediately clear to me that there is a significant change in the flow graph at the time the event is recorded and conversely events that look like they should be recorded but are not.

I changed my settings last night to a minimum of 14.5, changed Aflex to Cflex (1) and turned ramp off - still had RERAs (12) but no other events. However, terrible night’s sleep with loads of mask issues.

Hopefully this will demonstrate my lack of understanding and you experts will be able to correct me and allow me to understand better the nuances of these treatments.

Johnboy Huhsign
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JB, I would encourage you not to get too hung up on RERA, but focus on your success and how your feel.  Also, I want to point out that while bilevel seems to do a better job with what a machine records as RERA, only the Philips BiPAP reports them.  The Aircurve does not report RERA.

As a general rule on auto CPAP, I don't recommend that you attempt to manage for RERA.  Resolve the events and get as comfortable as possible, and the rest should take care of itself.  Of all the events reported by the machines, the highest degree of uncertainty surrounds RERA.  In the Apneaboard Wiki:

Quote:Respiratory Event Related Arousal... a sequence of breaths characterized by increasing respiratory effort leading to an arousal from sleep, but which does not meet criteria for an apnea or hypopnea.”

RERA Detection in the Respironics System One data..Respiratory effort-related arousal..defined as an arousal from sleep that follows a 10 second or longer sequence of breaths that are characterized by increasing respiratory effort, but which does not meet criteria for an apenea or hypopnea. Snoring, though usually associated with this condition need not be present. The RERA algorithm monitors for a sequence of breaths that exhibit both a subtle reduction in airflow and progressive flow limitation. If this breath sequence is terminated by a sudden increase in airflow along with the absence of flow limitation, and the event does not meet the conditions for an apnea or hypopnea, a RERA is indicated.

In PSG,  for the detection and scoring of RERA, it is important to record at least three respiratory parameters: nasal/oral
airflow, thoracic effort  and abdominal effort.  Any CPAP or bilevel lacks two of these criteria, and interprets the third through a sensor in the machine, that is remote from the actual breathing circuit.  Plenty of room for error.  This is the pattern from PSG that the CPAP is trying to pick out (source: http://www.apsresp.org/pdf/esap/esap-201...gp-1-3.pdf ). How far down this rabbit hole do you want to venture?

[Image: 4gm60abh.png]

[Image: X8rBH9Sh.png]
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