need advice on a new machine

[grammie11]

I'm about to get a bipap. My current machine is the Resmed Auto set for her with the heated hose. Before I got this machines I checked here to ask what machine is the best and I got good advice. Now that I need a bipap I want to ask what bipap is the best to get?
Do I need a different type of mask with a bipap?

[Julie]

This has already been answered in thread "Bi-pap", not far away.

[grammie11]

sorry, I can't seem to find it.

[Julie]

"bi pap" about 5 (at the moment) below this one.

[Bill44133]

"bi pap" about 5 (at the moment) below this one.

Here is the link to the other posting: viewtopic/t95137/bi-pap.html

[robysue]

EDITED to reflect new information on PR System One ramp settings (4/13/2014)
EDITED to add information about using both machines with a battery (4/21/2014)

What's the best bilevel PAP (BiPAP/VPAP) out there---the Resmed S9 VPAP Auto or the PR System One BiPAP Auto?
Both the Resmed S9 VPAP Auto and the PR System One BiPAP Auto are nice machines. But asking, "Which is the better bi-level machine?" is a bit like asking, "Which is better---Coke or Pepsi?" There are dedicated Coke and Pepsi fans who have a very strong preference and really dislike the other drink, but for the average consumer? The difference in taste is marginal and either one will do when the person is wanting a cold cola-based soft drink.

It's a similar situation with the bi-level PAPs. Both the Resmed S9 VPAP Auto and the PR Series 60 System One BiPAP Auto are top notch machines and both are capable of delivering high quality therapy. But there are some real differences between the S9 VPAP Auto and the System One BiPAP Auto and for a small minority of PAPers, these differences are quite important. But it's not like everyone prefers the S9 over the System One---just like there are people who prefer Pepsi to Coke, there are people who prefer the System One to the S9. But for the average new bi-level PAPer? The average new bi-level PAPer probably can't tell any real difference between the two machines and will adjust just fine regardless of which one they choose.

But there are differences between them.

The three big categories of differences, in my humble opinion are:

• Price
• The comfort features
• The recorded data, the on-board data, and the software choices
• The auto algorithm itself

Which machine to chose may depend on your own needs and preferences in each of these categories.


Price
On-line prices for the PR System One BiPAP Auto are quite a bit cheaper than on-line prices for the S9 VPAP Auto. That may be a consideration if this is an OOP purchase.


The Comfort Features
Humidifier and heated hose
Both machines come with integrated heated humidifiers and optional heated hoses. The System One's humidifier has two kinds of settings (a "smart" kind of setting and a "classic" kind of setting) when you are using the humidifier without a heated hose. The "smart" setting, the humidifier takes into account the ambient room temperature and humidity and adjusts the heat provided under the tank to minimize rainout. (This system works well in my very cold bedroom). The "classic" setting allows for much more humidity to be added, but at the risk of creating rainout problems.

The S9's humidifier kind of splits the difference between the two types of settings on the System One if you don't use a heated hose.

On the S9, the heated hose's default setting allows you to pick a temperature and the humidity is supposed to be set to 80% relative humidity. Some people find that's not enough humidity and others find it's too much. On the System One, in the default mode for the heated hose you've got a choice of "temp" and "humidity" settings where the humidity settings (1, 2, 3) seem to correspond to 70%, 80%, and 90% relative humidity respectively.

On both machines you can change the heated hose setting from the default mode to a completely manual mode, and this allows you to control the hose temperature and the humidity separately. (On the System One, the is accomplished by using the "Classic" settings for the heated humidifier.)

The S9's heated humidifier can be preheated and that's a plus. The older System One humidifiers cannot; but I believe the newer versions of the Series 60 machines that are using the most up-to-date firmware do allow you to pre-heat the humidifier. When I start out the night my nose always feels cold and damp until my (old Series 50) System One humidifier heats up---it only takes about 10 minutes, but it's still a long ten minutes on a cold night. Check that with the DME if the ability to pre-heat the humidifier is important to you.


Exhalation Relief
The PR System One has Bi-Flex as an exhalation relief system. Bi-Flex will provide a small bit of additional pressure drop beyond that provided by simply going from the IPAP to EPAP settings. In other words, if IPAP = 15 and EPAP = 10, at the start of the exhalation, the pressure will actually drop a bit below 10 cm and then the machine will increase the pressure back up to 10cm before the exhalation is complete. (But if Bi-Flex drives you nuts, it can be turned completely off.)

The S9 VPAP does not have any additional pressure relief beyond that provided by the drop from IPAP to EPAP: The transition between IPAP and EPAP and back to IPAP is already a modified version of the EPR system in the S9 Elite/AutoSet. What I mean by "modified" is that in the S9 VPAP, the pressure drop at the beginning of the exhale obviously not limited to a max of 3 cm. And there is a very slight difference between how and when the VPAP and the Elite/AutoSet increase pressure back up at the end of the exhale or start of the inhale. There's an very old thread that gives a lot of details about this. You can read it by clicking here. (The thread is still there, but the wonderful images by -SWS on pages 2, 3, and 4 seem to have disappeared. )


Ramp
Many experienced users discount the importance of the ramp. Indeed, many old hands at PAPing will routinely tell newbies that their problems are all due to overuse of the ramp. While there may be some truth in that, it's also true that many people, newbies in particular, do find the full force of 10+ cm of air blowing down their throat just as they are trying to get to sleep enough to make them more awake and less sleepy. While a improperly set ramp can indeed add to a newbie's adjustment woes, a properly set ramp can be a godsend---particularly in the first several weeks or months of PAPing when everything about the whole "sleep with a mask on my nose while having air pumped down my gut" is new and somewhat disturbing.

On both machines, the RAMP feature is disabled if the minimum EPAP pressure setting is set to 4 cm since the minimum starting EPAP ramp pressure is 4cm. On both systems the RAMP feature allows the user to start the session at an EPAP pressure below the minimum pressure setting. The starting IPAP pressure depends on the machine: On the S9 VPAP, the starting IPAP = starting EPAP + PS; on the PR System One BiPAP, the starting IPAP = starting EPAP + min PS on the Series 60 machines. (On the older Series 50 System One BiPAPs starting IPAP = starting EPAP + 2.) Both the EPAP and IPAP pressures will slowly ramp up (in a linear fashion) until the EPAP reaches the min EPAP setting over a fixed amount of time that can be controlled through the settings.

Many DMEs will typically use 4 or 5 cm as the default starting ramp EPAP pressure and 30 or 40 minutes as the default ramp time. For many newbies, this does provide some real measure of comfort if they feel overwhelmed by the airflow at their prescribed pressure settings. But many other people have real trouble breathing with EPAP = 4 or 5 cm of pressure because at this low of pressure there is a sensation that there's not that much air coming through the mask. (In reality, there's still plenty of air being blown through the system even at EPAP = 4 or 5 cm.) As a consequence many people find the ramp a double-edged sword. It may help during the first few weeks or months, but it may make things more difficult because the feeling of "not enough air coming in through the mask" can lead to a sense of panic.

Ramp on the Resmed S9 VPAP Auto
The starting ramp EPAP pressure on the Resmed S9 must be set from inside the clinical menu. It can be set from 4cm to anything less than the patient's minimum EPAP pressure setting. The ramp time can be set from the patient's set up menu and it can be set in 5-minute increments from anywhere between 5 minutes and 45 minutes. The longer the ramp time, the gentler the increase in pressure will be. The smaller the gap between the starting ramp pressure and the minimum pressure setting, the gentler the increase in pressure will be.

Any time the S9 is turned off and then back ON during the night, the machine will start at the beginning of a full ramp period and there is no way to easily disable this in use. In other words, it is impossible to use a 45 minute ramp at the beginning of the night and then allow yourself to turn the machine off and back on for a bathroom break in the middle of the night. without restarting the ramp.

During the ramp up period, the S9 VPAP will NOT record flag any events and it will NOT respond to any events. If you fall asleep well before the end of your ramp period and start having apneas or hypopneas because the pressure is still far below your therapeutic pressure, these "ramp period" apneas will NOT show up in the data---regardless of whether you look at the data on the LCD, in ResScan, or in SleepyHead.

Because the ramp cannot be temporarily disabled on the S9 and because the S9 does not flag or respond to events that occur during the ramp period, it is critical that S9 users who chose (or need) to use the RAMP feature be conscious of the following things when setting up their ramp settings:

• The ramp time should be set to approximate the user's most typical latency to sleep. If the ramp period is set much longer than the typical latency to sleep, the user may have long periods of sleep where the machine provides inadequate protection AND the events during these ramp up periods will NOT be flagged.
• The starting ramp EPAP pressure should be set as close to the user's minimum EPAP pressure setting as possible for comfort. (And the minimum EPAP pressure setting should not be too far below the user's titrated EPAP pressure needs.) This will insure that during the time the patient is sleeping during the ramp period, the EPAP pressure will at least be something closer to therapeutic, and hence of some therapeutic use in preventing at least some of the user's typical OSA events

Ramp on the PR System One BiPAP Auto
Both the starting ramp time and the starting ramp EPAP pressure can be set from the patient's set up menu if the clinician gives access to the ramp settings in the clinical menu. The ramp time can be set 5 minute intervals up to 45 minuts and the starting ramp pressure can be set anywhere between 4cm and the patient's minimum EPAP pressure setting. The longer the ramp time, the gentler the increase in pressure will be. The smaller the gap between the starting ramp EPAP pressure and the minimum EPAP pressure setting, the gentler the increase in pressure will be.

In order to use the ramp, the patient must both turn the machine ON and press the RAMP button, which is a small button with a triangular icon on it. The RAMP button may be pressed at any point when the machine is ON during the night. When the RAMP button is pressed, the machine will lower the EPAP and IPAP pressures to the starting RAMP EPAP/IPAP pressures and the machine will then increase the EPAP pressure back up to the minimum EPAP pressure setting over the RAMP time period. If the patient turns the machine off during the night and then back on without pressing the RAMP button, the machine will start with the EPAP pressure set to the minimum EPAP pressure rather than the starting ramp EPAP pressure; I believe that the starting IPAP = starting EPAP + 2. (I know this is true for the Series 50 System One BiPAPs, but I'm not quite sure about the Series 60 System One BiPAPs; on the Series 60 machines, it may be that starting IPAP = starting EPAP + min PS.)

The System One will record and respond to obstructive apneas, hypopneas, snores, RERAs, and flow increases during the RAMP period with an appropriate increase in EPAP or IPAP pressure as dictated by the System One's BiPAP Auto Algorithm. For example, if the machine detects two or more apneas in close proximity, the machine will increase the EPAP (and IPAP) pressures by 1cm and continue the ramping up of the EPAP pressure to the minumum EPAP pressure setting from there. The events detected during the RAMP period will show up in the data when you look at it in Encore and SleepyHead. (They'll also be part of the averages on the machine's LCD averages.)

Overall, the Ramp is a bit more flexible on the System One. But even so, it is important for a new user to still be aware that continually hitting the Ramp button to lower the pressure below the minimum EPAP pressure setting may not be a good idea----particularly if the ramp time is extremely long and if the starting ramp EPAP pressure is much lower than the minimum pressure setting.


Auto On/Off
Both machines offer these things. On the PR System One, they are controlled separately through the Auto On and Auto Off settings. On the Resmed S9, you have to turn them on (or off) together with the SmartStart setting. From what I've seen, they can be a bit touchy----particularly for people using low pressures and nasal pillows. Me? I turn my machine on and off manually---it's just not that hard to hit a very large button.


Mask fit, mask alarm, and leak data
PR has a "Mask off alarm" that's not loud enough to actually wake most of us up. It's pretty much useless; Resmed doesn't have a "Mask off alarm"

Resmed has Mr. Green Smiley and Mr. Red Frowny to let you know if the mask fit was "good enough." But Mr. Red Frowny only shows up if you are in Large Leaks for at least 30% of the night.

The leak data on the LCD of the System One is pathetic. You have to have SleepyHead or Encore to track your leaks with a System One.


Using the machine with a battery
Both machine's specs say they can be used directly with a battery, but ...

Using the S9 with a battery
The S9 seems to be very, very picky about its power supply. Directly plugging an S9 into a 12 volt battery (such as the typical car battery or marine battery) seems to be problematic; in order to use a 12 volt battery, it appears that you must purchase the DC Converter 24V 90W For S9™ Machines for $84.95. Of course, since this cable is a converter, it does eat into battery life.

The proprietary battery from Resmed that is guaranteed to work with the S9 lists for $699 at cpap.com (See https://www.cpap.com/productpage/resmed ... hines.html). The $699 package includes a (relatively lightweight) lithium ion battery and the DC cable needed to hook the machine to the battery. As a cheaper (but heavier) alternative to the Resmed battery pack, you can also purchase the Respironics Battery Kit for S9 Machines from our hosts at cpap.com for $379.95, which includes a lead acid battery and the DC Converter 24V 90W For S9™ Machines.

Using the System One Series 60 with a battery
The PR System One Series seems to be much less picky about the power supply. The PR DC power cord for System One Series 60 machines can be bought from our host for $29.95 and it can be used to to directly connect the PR S1 Series 60 machine into a 12 volt battery (such as as the typical car battery in something like a DieHard Platinum Portable Power source and jump starter) without the use of an inverter.

You can also buy a Respironics Battery Kit for PR System One 60 Series Machines from cpap.com for $328.95, which includes a lead acid battery and the DC power cord. Or you can buy the CPAP.com Battery Kit for PR 60 Series System One Machines, which includes a lightweight lithium ion battery and the DC power cord for $269.95.

REQUESTING HELP: If you use a Resmed S9 with a battery setup OTHER than the Resmed Battery Pack, please PM me with any corrections to the errors that I have undoubtedly made in describing what it takes to run an S9 off a battery. Likewise if you use a PR System One Series 60 machine with a set up other than the PR Battery Pack, please PM me with any corrections to the errors I may have made in describing what it takes to run a System One Series 60 off a battery.


The on-board data, the software choices, and the detailed data
On-board data
The S9 shows an incredible amount of detailed summary data right on the LCD; the System One does not.

S9 VPAP
The on-board data on the S9 VPAP is excellent: You get nightly, weekly, and 30 AHI numbers broken down by type of event. You get 95% unintentional leak rate figures. And there's a mask-fit feature that may be useful. The overnight data is available within a minute of turning the machine off. But you do have to view the overnight data before noon local time. And you can set the clock through the clinician's menu.

Finally, you can change the clock in the clinical menu of the S9 and nobody can change the clock on the System One. Both machine's have some problems with clock drift over time. There are some bugs in ResScan where clock drift was apparent back when I was still using an S9.

System One BiPAP
The on-board data on the PR System One BiPAP is very, very limited. The new Series 60 machines give you AHI numbers for the last 24 hours, 7 days and 30 days and the AHI is not broken down at all by event type. And the System One's on-screen "Percent time spent in Large Leak" data are virtually meaningless: PR doesn't seem to define or describe what constitutes a Large Leak anywhere. And there's the annoying fact that the System One updates its data at noon Greenwich Meridian Time. And that you can't change this. And that you can't change the clock setting---even in the clinical menu.


Software
Both machines work well with SleepyHead. It is possible to get your hands on the "official" software from Resmed and PR if you want it. The newest version of ResScan will work with the S9 VPAP. Encore Basic and Encore Pro will both work with the Series 60 System One BiPAP Auto.


Detailed Data--General Comments
Both machines record full efficacy data, including the wave form, events, and leak data onto a standard SD card. There are some differences in how the two machines record the efficacy data however.

The Resmed S9 overwrites the wave flow data on the SD card every seven days and the other "detailed" daily data every 30 days. If you want all the data, you must download it at least weekly. The PR does not ever seem to overwrite the detailed data, so when you download to SleepyHead you'll see everything that's been written to the card. (But Encore will only download the last night's wave form for some silly reason.)

If you forget to put the SD card back into the S9, the machine will write the summary data to the card when you insert it, but all the detailed data will be lost. If you forget to put the SD card back into the System One, the machine will write all the data except the wave flow to the SD card when you put it back in to the machine. (Both machines write the wave flow data directly to the SD card.)

The Resmed S9 is very picky if anything is written to the SD card by the computer system---this is a problem if you use a Mac or a Windows 8.1 machine and you forget to "lock" the card before inserting it into the computer. The PR System One doesn't seem to care much about things the computer might write to the card. I routinely forget to lock my System One's SD card when inserting it to my Mac and I know the mac writes some hidden .files when I do that. The System One doesn't care.

Finally, you can change the clock in the clinical menu of the S9 and nobody can change the clock on the System One. Both machine's have some problems with clock drift over time. There are some bugs in ResScan where clock drift was apparent back when I was still using an S9.


Leak data
The ResMed S9 VPAP records only the excess leak rate, and, like all ResMed machines, a Large Leak is defined as anything over 24 L/min. The PR System One BiPAP records the total leak and PR has no official published definition of how bad the leaks have to be to get flagged as a Large Leak.


Efficacy data
Apneas and hypopneas: Both machines flag apneas (and classify them as OAs or CAs) and hypopneas. The proprietary algorithms for deciding whether a given apnea is a CA or an OA are different. The Resmed S9 uses a Forced Oscillation Technique (FOT) and the PR System One uses a Pressure Pulse (PP) system. The FOT consists of many very small oscillations in pressure; the PP consists of one or more very short 1 or 2cm "bursts" of increased pressure that last for a very short time.

Flow limitations: Both machines record flow limitations, but the way they record it is very different. The S9 VPAP Auto presents the flow limitation data as a continuous graph with respect to time. The PR System One BiPAP Auto records "flow limitation events" as tick marks on the flow wave graph. Each method has advantages and disadvantages But the System One BiPAP Auto records flow limitations only when it is running in Auto Mode. If you use the System One in fixed BiPAP mode, the machine simply doesn't record the flow limitation tick marks. (Editorial Comment: It seems like a really stupid decision on PR's part to suppress the Flow Limitation data when the machine is running in fixed mode. It's an even dumber decision to report FLI = 0.0 day after day in Encore.)

RERAs: The System One flags RERAs (respiratory effort related arousals) using a proprietary algorithm. The S9 VPAP does not try to score RERAs. The problem with accurate detection of RERAs, of course, is that neither machine has an EEG for measuring the sleep state and a RERA requires an EEG arousal. The PR RERA algorithm has to be based on statistical analysis. My guess is they've identified changes in the flow wave shape that statistically correspond to the shapes of RERAs scored on PSGs. How good the PR System One algorithm is at scoring RERAs is a good question. Clearly Philips believes the algorithm is good enough to include in their commercially released products.

Periodic Breathing: The System One BiPAP also flags what it believes to be periodic breathing, including Cheyne-Stoakes breathing patterns. The S9 VPAP Auto does not flag these areas of the flow wave, but if you know CS breathing is an issue, you can often spot it by zooming in on the wave flow .

Snoring: Both machines record snore data, but the way they record it is very different. The snore data and the flow limitation data are recorded as continuous functions on the S9; they are discrete tick marks on the System One. (SleepyHead's version of the snore data is very different than Encore's version of the snore data from a System One machine.)The snoring data is presented quite differently on the two platforms.

Snoring on the S9 VPAP Auto
The S9 VPAP Auto presents the snoring data as a continuous graph with respect to time. The scale seems to be a 0 (no scoring) to 3 (Loud snoring), but exactly what the scale is measuring, nobody knows.

Snoring on the System One BiPAP Auto
The System One BiPAP Auto records snoring data in two different ways, although this was not known to users until JediMark released an early version of SleepyHead. In Encore Viewer, the snoring data is all lumped together as tick marks on the Events table and there is a "VSI" number. Although exactly what that number is, I have not been able to determine. (Editorial comment: Given the snore "counts" available in SH, it's clear that VSI is NOT equal to (# of snores)/(time machine was on) *sigh*) In Encore Pro, the snore data is split between the snores that pop up on the Events table and those that pop up as tick marks superimposed on the wave form. In SH, the snores that show up on the wave form are called VSs. The snores that show up only in the Events table are called VS2's.

And like flow limitations, the VS snores are recorded only when the machine is in Auto mode. (Editorial note: This too is a dumb decision on PR's part.) In SH, JediMark has restricted the VSnore index to VSs; unfortunately that means that users of PR machines run in fixed pressure mode see a VSnore index of 0.0 night after nigh regardless of the loudness or persistence of their snoring. JediMark is aware of this problem and I think he means to change it to NA or not report it at all in some future release of the software.

JediMark has also discovered that the System One does record enough snore data for SleepyHead to provide a snore graph as well as the tick marks. The SH snore graph is based on the VS2 data, if I recall correctly. What the vertical scale measures is not known, but in general, the higher the number, the more intense the snoring seems to be. But I have no idea what "level" corresponds to "freight train" snoring and what "level" corresponds to "cat purr snoring".

JediMark does present the VS2 snore data as ticks in the Event table as well as the snore graph that he draws based on that data.


The Auto Algorithms
The Auto Algorithms used by the Resmed S9 VPAP and the PR System One BiPAP auto are NOT the same. And the differences may be important to you in the sense of how it feels to use the machine all night long. And which algorithm would feel best to you may be hard to predict.

That said, here is my understanding of the differences between the two Auto algorithms:

Both the Resmed S9 VPAP Auto and the PR S1 BiPAP Auto have algorithms that automatically adjust the IPAP and EPAP pressures in response to the various events detected by the machine. But the two companies have taken quite different approaches in their algorithms. Informally this difference can be described as follows:

• The Resmed S9 VPAP adjusts BOTH the EPAP and IPAP by the same amount in response to OAs, hypopneas, snoring, and flow limitations. Like the S9 AutoSet, the VPAP tends to respond quickly to clusters of events and then slowly reduces both pressures back down at the same rate until more events occur.
• The PR S1 BiPAP Auto adjusts EPAP and IPAP independently of each other: EPAP is increased in response to OAs and snoring, and IPAP Is increased in response to hypopneas, flow limitations, and RERAs. In addition to these things, the PR S1 also uses the same "hunt and peck" algorithm that the PR S1 Auto uses to test whether the shape of the wave flow data improves with a slight increase in pressure. The hunt and peck algorithm is only applied to the IPAP pressure for increasing pressure. After events that trigger an increase in IPAP or EPAP are resolved, the S1 does a reverse hunt and peck to find out how far it can lower the pressure: As long as the flow wave remains stable, the PR keeps lowering the appropriate pressure, but if the flow wave becomes more ragged, the S1 will raise that pressure back up to the last level where the flow wave was stable

To make the some of the differences between the two machines' auto algorithms clearer, we need to introduce a setting that only Auto Bi-level PAP machines have---the PS (pressure support setting). Loosely PS is the difference between IPAP and EPAP and the value of the PS setting affects the way the EPAP and IPAP pressures are adjusted. The way PS is implemented on the S1 and the VPAP is quite different however:

• On the Series 60 System One BiPAP Auto, the PS settings determine the minimum and maximum allowable value for IPAP - EPAP. (On a Series 50 System One BiPAP, the minimum value for IPAP - EPAP is 2.) The upshot of this is that whenever min PS < IPAP - EPAP < max PS, the IPAP and the EPAP are allowed to vary independently of each other. But when IPAP - EPAP = min PS or IPAP - EPAP = max PS, there are some constraints on how the pressures are increased or decreased. In other words:
  
  • When min PS < IPAP - EPAP < max PS:
    • If the IPAP needs to be increased, only the IPAP will be increased, the EPAP stays the same.
    • If the IPAP needs to be decreased, only the IPAP will be decreased, the EPAP stays the same.
    • If the EPAP needs to be increased, only the EPAP will be increased, the IPAP stays the same.
    • If the EPAP needs to be decreased, only the EPAP will be decreased, the EPAP stays the same.
  • When IPAP - EPAP = max PS:
    • if the IPAP needs to be increased, then both IPAP and EPAP will increase at the same rate.
    • If the IPAP needs to be decreased, only the IPAP will be decreased, the EPAP stays the same.
    • If the EPAP needs to be increased, only the EPAP will be increased, the IPAP stays the same.
    • if the EPAP needs to be decreased, then both IPAP and EPAP will decrease at the same rate
  • When IPAP - EPAP = min PS:
    • If the IPAP needs to be increased, only the IPAP will be increased, the EPAP stays the same.
    • if the IPAP needs to be decreased, then both IPAP and EPAP will decrease at the same rate.
    • if the EPAP needs to be increased, then both IPAP and EPAP will increase at the same rate.
    • If the EPAP needs to be decreased, only the EPAP will be decreased, the EPAP stays the same.
  • And at the start of the night, EPAP = min EPAP and IPAP =min EPAP + 2.
• On the VPAP, the PS setting is the fixed value for IPAP - EPAP. Hence IPAP and EPAP are always increased together on the VPAP. (And that's why the ResScan reports for VPAP machines can show the pressure info with only one curve.) At the start of the night EPAP = min EPAP and IPAP = min EPAP + PS.
• So the net result of all this is that on each machine, we get the following ranges for pressure settings:
  • PR System One BiPAP Auto:
    • min(EPAP) <= EPAP <= max(IPAP) - min PS
      min(EPAP) + min PS <= IPAP <= max(IPAP)
      min PS <= (IPAP - EPAP) <= PS
    Resmed VPAP Auto:
    • min(EPAP) <= EPAP <= max(IPAP) - PS
      min(EPAP) + PS <= IPAP <= max(IPAP)
      IPAP - EPAP = PS

Of course the big questions are: Which system is more effective? and Which system is more comfortable? As a mere patient, I haven't the foggiest if one of these systems is inherently better at treating apnea. And obviously both machines have been run through the full range of efficacy testing required by the government. But it's easy to believe that some folks might respond better to one of the two algorithms than the other.

In my case, I am rather glad (in retrospect) that I was forced to get the (Series 50) System One BiPAP because the S9 VPAP Auto was not yet on the market at the time I was switched to bi-level back in Dec 2010. The reason I say this? It's because of my own patterns of pressure increases. On my System One, the most common reason either the IPAP or EPAP is increased is the machine detecting flow limitations and the hunt-and-peck algorithm that picks up very subtle flow limitations. Both of these only increase my IPAP. And so I start the night off at 6/4, but tend to spend significant chunks of time at 7/4 and 8/4 most nights. My EPAP rarely goes above 5cm these days. Since my old S9 AutoSet also increased pressure in response to flow limitations, I would strongly suspect that if I were using a S9 AutoSet, my EPAP would not remain at 4cm for most of the night and my guess is that it would regularly be above 5cm. And for me, aerophagia problems were a major reason for trying BiPAP, and it's keeping that EPAP as low as possible that helps with my aerophagia problems. (Those rare nights I snore enough to have the machine increase my EPAP to 6cm are strongly correlated to my worst aerophagia issues.)

But it's not that one machine's algorithm is inherently better. It's how it fits an individual's needs: I don't mind only a 2cm difference in IPAP and EPAP at the beginning of the night, but every increase in EPAP comes with a risk of triggering aerophagia. Hence, I'm better off with the PR System One's Auto mode. But others find the Resmed S9 algorithm works better for them because the pressures do increase in tandem.

[sawinglogz]

Holy smokes, that's quite the exhaustive dissertation! I can answer one of your questions:

on the PR System One BiPAP, the starting IPAP = starting EPAP + 2. (I know this is true for the Series 50 System One BiPAPs, but I'm not quite sure about the Series 60 System One BiPAPs; on the Series 60 machines, it may be that starting IPAP = starting EPAP + min PS.)

At least for the 960 (ASV), the ramp starting IPAP = starting EPAP + min PS.

[John Chowder]

robysue that is fantastic info, thank you! I've also just been prescribed bipap and this is tremendously helpful.

[robysue]

Holy smokes, that's quite the exhaustive dissertation! I can answer one of your questions:

on the PR System One BiPAP, the starting IPAP = starting EPAP + 2. (I know this is true for the Series 50 System One BiPAPs, but I'm not quite sure about the Series 60 System One BiPAPs; on the Series 60 machines, it may be that starting IPAP = starting EPAP + min PS.)

At least for the 960 (ASV), the ramp starting IPAP = starting EPAP + min PS.

sawinglogz,

Thanks for the info. I'll take the time to up date the dissertation later.

For folks who are wondering: This post was really just putting together a whole bunch of things that I've written in the past here and there into one coherent whole. Thanks to those who take the time to tell me they appreciate it.

[poppi2]

robysue that is fantastic info, thank you! I've also just been prescribed bipap and this is tremendously helpful.

+1

I hope I can find this excellent info if/when I need this next level of treatment. Thanks, Earl

[RandyJ]

robysue,

I read your 'dissertation' the first time you published it, but at the time I had not been able to try both machines. Now that I have had the S9 VPAP Auto for several months and have retired my PRS1, I can say that I definitely prefer the S9. Both are comfortable, I sleep well with both, but for some unknown reason my AHI is better with the S9 (using the same settings), usually between 0.1 and 0.4, and the S9 seems to keep my snoring to a minimum.

My PRS1 was a 750, so no heated hose or useful nightly data onscreen, and I really like those features with the S9. (I understand the 760 includes those features now according to your updated post.)

Thanks for taking the time to work it all out for us.

[grammie11]

Roby Sue, Thank you for all that information. I think I'll go with the S9. It must have taken you quite a while to write all that info and I really appreciate it.

[robysue]

Holy smokes, that's quite the exhaustive dissertation! I can answer one of your questions:

on the PR System One BiPAP, the starting IPAP = starting EPAP + 2. (I know this is true for the Series 50 System One BiPAPs, but I'm not quite sure about the Series 60 System One BiPAPs; on the Series 60 machines, it may be that starting IPAP = starting EPAP + min PS.)

At least for the 960 (ASV), the ramp starting IPAP = starting EPAP + min PS.

Sawinglogz,

I've updated the appropriate passage in the dissertation to reflect your information about the starting ramp pressure. Thanks for letting me know how it works.