Is here a difference in what Resmed and Respironics define as Hypopena?
I have for some years been using a Resmed S9 Auto CPAP but have recently bought a Respironics DreamStation Go Auto machine for travelling. Both seem to be working as well as each other, but I have been surprised by the differences that have seen in the AHI results I have been getting. Both give similar Apnea events - generally 0, 1 or 2 such events over a normal 8 hour sleep. But the number of Hypopnea events recorded using the Respironics machine are far greater than those from the S9. Over a considerable length of time I have been getting an average AHI reading from the S9 of about 0.2. The Dreamstation over the last 3 weeks averages 1.6 however. The difference is all in the Hypopneas - much greater numbers of these with the Dreamstation.
I am not sure if this is a real difference in the way that these two machine record events or if it is a real difference in my sleep. When I first got my S9 I was surprised to get such a low AHI as I had a previous used an earlier Resmed machine which gave results similar to what I now get from the Dreamstation. I actually brought the S9 back to the provider and asked if it was faulty but he informed me that Resmed had changed their definition of what they scored as a Hypopnea and that all was well with my new machine. So I do think it possible that I am seeing a similar artificial difference of this type.
I would thus be grateful to learn if others have seen differences between the AHI results from the S9 and the Dreamstation line of machines.
Elliot
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
Differences could be in the different algorithms used resulting in a slower response with the PR. Also ResMeds EPR will treat hypopneas better than PR's Flex.
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
Slightly OT, but relevant, I used a Resmed S9 for five years before switching to a Devilbiss Sleepcube a few weeks ago. When I dial in the same pressure on both machines, the Devilbiss definitely blows harder. Obviously, I would expect machines to vary a little, but in my case the difference appears to be quite large. I think it is fair to assume that CPAP machines, being medical devices, are calibrated pretty accurately, but ...
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
(03-18-2019, 07:34 PM)StevesSp Wrote: Slightly OT, but relevant, I used a Resmed S9 for five years before switching to a Devilbiss Sleepcube a few weeks ago. When I dial in the same pressure on both machines, the Devilbiss definitely blows harder. Obviously, I would expect machines to vary a little, but in my case the difference appears to be quite large. I think it is fair to assume that CPAP machines, being medical devices, are calibrated pretty accurately, but ...
PAP machines are designed to maintain a pressure. If you are comparing the flow from an open circuit, that is just the capacity of the fan to move air. I suspect the pressure is similar between the two machines, although there may be differences in its qualitative delivery.
03-18-2019, 08:52 PM
(This post was last modified: 03-18-2019, 08:53 PM by StevesSp.)
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
(03-18-2019, 07:47 PM)Sleeprider Wrote: (03-18-2019, 07:34 PM)StevesSp Wrote: Slightly OT, but relevant, I used a Resmed S9 for five years before switching to a Devilbiss Sleepcube a few weeks ago. When I dial in the same pressure on both machines, the Devilbiss definitely blows harder. Obviously, I would expect machines to vary a little, but in my case the difference appears to be quite large. I think it is fair to assume that CPAP machines, being medical devices, are calibrated pretty accurately, but ...
PAP machines are designed to maintain a pressure. If you are comparing the flow from an open circuit, that is just the capacity of the fan to move air. I suspect the pressure is similar between the two machines, although there may be differences in its qualitative delivery.
Not open circuit, no. Both machines are set to 13.5/13.6 at the moment, with a short ramp. I am operating the newly-repaired Sleepcube in CPAP mode, just like the S9. That pressure works fine on the Resmed but, when I wear the mask and turn the Sleepcube on, I have to tighten the straps quite a bit once full pressure is reached, otherwise the mask leaks like crazy and I feel like it's trying to jump off my face.
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
If the supplied pressure is out of specification, that can be demonstrated on a simple manometer. Any DME has them, the are available for purchase, and you can even make a pressure manometer. If teh Sleep cube is out of calibration, it was improperly repaired.
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
(03-18-2019, 07:22 PM)bonjour Wrote: Differences could be in the different algorithms used resulting in a slower response with the PR. Also ResMeds EPR will treat hypopneas better than PR's Flex.
I don't think the difference is the better response to hypopneas by the Resmed S9. It actually does not seem to get that far - it normally reports detecting very few. But is could well be that the S9 recognises the development of hypopneas before they occur and actually deals with them preemptively.
Either way the figures are not particularly disturbing.
03-18-2019, 11:06 PM
(This post was last modified: 03-18-2019, 11:06 PM by Hydrangea.)
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
I started with a DreamStation, and have dabbled with a ResMed. While I feel I sleep the same, my AHI scores are very different (much lower on the ResMed). But by studying my Sleepyhead charts (which admittedly I don't know a ton about), I instinctively concluded that the 2 machines *score* things differently, and I think it's in the hypopneas.
I do not believe I'm better treated with one over the other. I simply think they differ in how they score events.
And to also agree with other comments on this thread, I have noticed that my perception of the pressure from each machine is different. Even though I use the same mask and the same settings, upon turning on my machine I feel the ResMed shoots the air out stronger. I've been told this is impossible, because of calibration. Who knows?
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
There is an article in an open access Dove Press Journal, "Treatment of sleep-disordered breathing with positive airway pressure devices: technology update", Medical Devices: Evidence and Research, 23 October 2015, p425 that outlines differences in the algorithms used by various cpap machines to score hypopnea. The details are probably proprietary so the discussion is somewhat sketchy. In addition the pressure setting, to be accurate must take into account the tubing used and the mask volume, which may depend on the machine software.
My second sleep test in a sleep lab was on a respironics BiPAP machine with a 9 foot slim line tube. I brought my own mask (P10) and asked the tech running the machine if he had to make adjustments because of my mask type. He had no clue and when he started the treatment at my normal (8 cm H2O pressure) it was clearly too low and had to be raised to 9.5 for me to feel comfortable.
RE: Is here a difference in what Resmed and Respironics define as Hypopena?
(03-22-2019, 02:22 PM)Grandpapa-G Wrote: There is an article in an open access Dove Press Journal, "Treatment of sleep-disordered breathing with positive airway pressure devices: technology update", Medical Devices: Evidence and Research, 23 October 2015, p425 that outlines differences in the algorithms used by various cpap machines to score hypopnea. The details are probably proprietary so the discussion is somewhat sketchy. In addition the pressure setting, to be accurate must take into account the tubing used and the mask volume, which may depend on the machine software.
My second sleep test in a sleep lab was on a respironics BiPAP machine with a 9 foot slim line tube. I brought my own mask (P10) and asked the tech running the machine if he had to make adjustments because of my mask type. He had no clue and when he started the treatment at my normal (8 cm H2O pressure) it was clearly too low and had to be raised to 9.5 for me to feel comfortable.
This article does not make easy reading for those of us not expert in the field! But it does make it clear that the algorithms used by different companies are very different and it is hardly surprising that the yield different statistics. What is still unclear is how much they affect the real outcomes in terms of the patient experience.
On a personal note, there is one thing that worries me. The article does talk about the need to take into account the mask volume. I am currently using a Dreamstation Go auto with Resmed masks. I have tried both an N20 and an Activa. These have very different volumes but the general advice appears to be setting the Mask Type parameter to "off". The other alternatives a series of numbers that only relate to Respironics masks. The Resmed machines use mask types such as Nasal, pillows etc rather than just a number. So at least here it is possible to make a decent guess even if you are not using a Resmed mask.
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