AUTO v FIXED PRESSURE?

[hsrunning]

Just a quick one fellow forum members,

Is there a tremendous difference between using an AUTO machine over a fixed pressure one? I am sure I read somewhere that AUTO machines do have a disadvantage in that they do not respond as well to a certain type of event !!! what or when I do not know.

If an AUTO machine is far better then I will consider buying my own, does anyone know how often they need to be serviced and the cost involved?

Presently using REMSTAR PRO, looking at REMSTAR AUTO.

Can someone guide me how I display footer information on posts (ie) equipment used etc. I have filled this info in on the user profile page but it is still not displaying !!!

Thanks in advance

HSRUNNING

[gvader]

Hi,

A CPAP or fixed pressure machine does not respond to ANY event - all it does is pump out a constant pressure.

An APAP is set with a high and a low pressure limit and will start at it's low pressure and increase the pressure incrementally when it detects an event, at the end of the event it will start to reduce the presure incrementally until it either gets back to the low pressure or it detects another event and starts again to increase the pressure. The increase in pressure is faster than the decrease.

There are pros and cons for both types. A CPAP set to the correct pressure will be very effective but if the machine doesn't have any form of exhalation pressure relief (EPR) then you may get tired lungs, an APAP may detect and react to events and you can wind up with a higher pressure than you had with the CPAP resulting in a gale blowing from all points of your mask as the straps try to keep 19cm of pressure at bay.

It's horses for courses.

I had a ResMed S8 Escape provided by the NHS but didn't like the lack of EPR (although later models of this machine do have this) and sometimes woke up tired. So that I could try and work out whether this was due to incorrect pressure on the CPAP or other underlying conditions I decided to buy my own APAP. As the average pressure from the sessions on this is lower than the pressure set on the CPAP it would indicate that the occasional tiredness was due to other factors.

The option of buying your own machine is not a cheap way to go, if an NHS machine goes wrong then they'll replace it but if your own machine goes wrong then it's all down to you. Shortly after getting my APAP from Intus I went on holiday and managed to knock my mahcine off of the bedside table it was on cusing water from the humidifier to flow into the machine - took me 4 days to get it working again and if I hadn't been able dry out the insides with a strategically placed hairdyer then I would have been looking at a bill for a new machine.

As for the footer information, it's under signature on the users control panel.

[hsrunning]

Am I Stupid?

Thanks GVADER

I am unable to find the "signature" under USER CP here is my USER CP. HELP!!!Settings & OptionsEdit Email & PasswordEdit ProfileEdit OptionsEdit AvatarEdit Profile PicturePrivate Messages vbmenu_register("nav_pmfolders"); FoldersInboxSent Items
List MessagesSend New MessageTrack MessagesEdit FoldersSubscribed Threads vbmenu_register("nav_subsfolders"); FoldersSubscriptions
List SubscriptionsEdit FoldersMiscellaneousEvent RemindersBuddy / Ignore ListsAttachments

[Tigers Fan]

A word from the self-appointed expert

Hi hsrunning

I bought and used to use a REMstar APAP but now use an NHS REMstat Plus CPAP.

My PAP career began with the auto and I set it at 4 and 20 cm in the belief that it would self-calibrate - only to find I was woken frequently by the gales of which gvader speaks. The low pressure wasn't enough to prevent an event so the machine followed its program and blew harder at me. It wasn't long before I was increasing the base pressure to try to prevent events and reducing the max pressure to try to contain the gales. I finished up at a CPAP pressure for the minimum with the max only a couple of cm higher.

Then I bought a travel CPAP from James and noticed that I slept remarkably well with CPAP, set at the min pressure I used at home on my APAP (it diesn't have exhalation relief and I struggle for the first half hour of the first couple of nights away).

When I got home, I went back to APAP and didn't sleep as well as I had while away. So I set the APAP (with exhalation relief) up as an CPAP and have never looked back.

I now have a NHS CPAP with exhalation relief and sleep very well indeed in the main.

Other folk will tell you the same story the other way round, I'm sure.

For me, the crucial thing is exhalation relief. Second is either a constant or low modulation air pressure - so I can set my mask and forget it. Third is a relatively high ramp start pressure - lifts the mask off my face. I'm taking humidification as a given. Hose lifts and heated hoses for winter, sheathed hoses for summer are also essential bits of kit, in my view - not forgetting RemZzzs all year round, of course.

TF

Addition: About those gales - the algorithm takes the pressure up very quickly when an event is detected - but then keeps it there until the machine is well and truly convinced that you are breathing normally again. The machine thinks this takes 20 to 30 minutes - by which time you are awake, been to the loo, set up, donned mask and hit the ramp button. I'm not aware that the elapsed time at max pressure can be modified other than by persuading Respironics to re-write their software.

[James @ Intus]

I am unable to find the "signature" under USER CP

Have a look under "Quick Links" about half-way down. Direct link:

http://forums.cpap.co.uk/profile.php?do=editsignature

[hsrunning]

Not Permitted

Thanks to GVADER and James.
Still not able to find the "quick links menu", if I try the direct link you sent me James I get an error message saying " YOU ARE NOT PERMITTED TO HAVE A SIGNATURE" - Maybe there is a software problem, I don't know, as it would appear that not all my list of menu items on the left is there either.

Please Help!

HSRUNNING

[James @ Intus]

I see what it is... You've only just crossed the 10 posts (outside general chat) and just now you've become a "trusted registered user". Added priviliges of proving in 10 posts you're not a spammer are signatures and a few other bits and bobs. So congrats on this milestone, enjoy!

[Alleycat]

The only reasons a APAP will ramp up to the gale of 19cmH2O is either because a) you need that pressure to open up your airways
b) you have such a poor fit on your mask and there is such a big leak that the machine can not properly detect your airflow and hence thinks you are still obstructed.

It does not take anything like 20-30 minutes for the pressure to decrease if you no longer need it as you would see from the daily data on any APAP software, where in someone who is only sleeping lightly or struggling to sleep may have brief (couple of minutes max) minimal increases then return to baseline. If you do wake with increased pressure then you can easily reset by stopping and restarting or hitting the ramp button. However, someone who would otherwise have an AHI of 30+, ie an event every 2 minutes or less may never see the pressure return to baseline whilst they are asleep as they start having another event as soon as the pressure starts to decrease.

IMHO for the majority APAP is far superior to CPAP and studies have shown that in general the overall pressure given with APAP tends to be lower than with CPAP as CPAP will both over and under treat events. Some people have such wide variation in their night to night and even during a single night pressures that CPAP would always be less comfortable than APAP.

The real key to comfortable CPAP use however, is the mask fit. There are so many different masks available and what one person will love others will hate and vice versa, so getting the one that best fits you and getting things right like need for or not as the case may be, humidification also helps.

EPR is available on all the Respironics models- the CFlex and Aflex, and on the newest Resmed. Fisher and Paykel don't have EPR but do have something called Wakesmart (? or something like that) which actually detects when you have woken and immediately drops the pressure back to the minimum set.

Hope this helps
AC
x

[Tigers Fan]

A different world

Hi Alleycat

Your theory seems sound but I challenge your practice. I don't find that the gales are caused in the either...or way you suggest, but by a both ....and experience. Yes, I need an increased pressure because of an event and my mask begins to leak at those increased pressures because the straps are not tight enough to withstand it - they are set for a lower pressure for reasons of facial comfort.

With experimentation, I find CPAP pressures - periodically, I vary the setting a half cm up and down according to my stats - that prevent all but a few events and almost never experience mask leakage. On CPAP I maintain an AHI below 2 and wake once if I'm unlucky. On APAP I stuggled to get an AHI below 5 and used the loo twice a night - always because a gale woke me.

As for the 20 to 30 minutes - well, I'll conceed that I've never "been to the loo, set up, donned mask and hit the ramp button" while still wearing my mask and carrying the APAP on a long lead so I could time it, but with my REMstar APAP, the pressure most certainly stays up there for a very, very long time - long after I'm awake and know that I'm breathing normally.

TF

[gvader]

Hi Alleycat,

Not sure what type of machine your figures refer to but to take a quote from the Intus web page on the Sandman Auto (which happens to be the one I use):

Where some Auto-CPAPs (APAPs) leave no room for personalisation of their algorithms which determine the pressure, the Sandman Auto offers a choice of standard and accelerated pressure drops after it rose to compensate for an event.

Traditionally, when an event was detected and the Auto-CPAP upped the pressure to remedy the event, as a precaution it would not lower the pressure for sometimes as long as 20 minutes and then only reduce the pressure in 0.1 hPa increments per a set number of minutes. Some patients experience this as too much pressure for too long.

The Sandman Auto-CPAP however, can be told to operate in "Default Mode" responding a lot faster when it detects the airway is stable again or in "Slow Mode". The default is the fast mode which uses 0.5 hPa increments every minute after an initial 5 minute precautionary period. The slow option adjusts by 0.2 hPa steps every minute after this 5 minute period. As oppose to APAPs with much slower 'back to normal' curves, the Sandman Auto-CPAP makes sure the patient gets the lowest, most comfortable pressure possible without compromise.

Now if the machine increases the pressure from 10hPa to 16hPa then the reduction back to the lower limit is 5 minutes + 12 minutes at it's fast setting or 5 minutes + 30 minutes at it's fast setting. That to me reads like 20 - 30 minutes!