Are Machines Different on the Inside (CPAP, APAP, Bi-L, ASV)?

[Spy Car]

I'm curious about, say, the array of ResMed (or Philips) machines. Are the guts different between all the different flavors of Bi-level, CPAP/APAP, and ASV?

Are the gut the same and the difference is just software? Or do these have different parts (and different parts? Or some of both?

Anyone know?

Bill

[Walla Walla]

I'm pretty sure they're all the same within each company and just the firmware is different. It's more cost effective that way.

[Spy Car]

I'm pretty sure they're all the same within each company and just the firmware is different. It's more cost effective that way.

That's what I've wondered about.

Which (if so) would mean the difference in cost between a (roughly) $750 AutoSet 10 and a $5000 ASV would reflect most differences in software/firmware (plus R&D and regulatory costs)?

Bill

[Ron AKA]

I don't know, and could only guess. The AirSense machines are rated to produce 4 to 20 cm of pressure. The AirCurve ones go up to 25 cm of pressure. It is possible this takes a bit larger fan/motor combination. It is possible the fan response time has to be faster in the ASV and BiPAP models and may need an upgraded control system. The ASV in particular is doing a bit more "thinking" and controlling of the pressure based on what it detects for required flow vs actual flow. That thinking may require a bit more powerful microprocessor and more memory. But as was pointed out already, the major difference is likely just the firmware.

[Reznik]

I'm curious about, say, the array of ResMed (or Philips) machines. Are the guts different between all the different flavors of Bi-level, CPAP/APAP, and ASV?

Are the gut the same and the difference is just software? Or do these have different parts (and different parts? Or some of both?

Anyone know?

Bill

I believe that almost all of the Resmed machines are the same on the inside, except for the software, with one exception.

I base that conclusion on the form factor, weight, and power consumption of the machines, which are all identical, and on common sense.  In order to function, all CPAP machines need a device to generate flow/pressure, a mechanism to measure the pressure and the flow, and a computer to read the measurements and adjust the flow generator.  Beyond that, what the machine does is software.  

A machine in CPAP mode has a computer that is programmed to maintain a fixed pressure as you inhale and exhale.  As you start to inhale, the pressure starts to go down, and so the computer tells the flow generator to do more work to keep the pressure constant.  As you exhale, it senses that the pressure is going up and so the computer tells the flow generator to do less work.  You can hear that happening everytime you inhale or exhale, because machine makes different noises as you inhale and exhale.  

A Bi-Level varies the pressure to two fixed points as you inhale and exhale.  An ASV varies the pressure on a breath by breath basis.  It is conceivable that the BiLevel and ASV machines have a faster processor, since they conceivably do more computing as you're breathing.  

Most Resmed machines will use a flow meter to record your breathing throughout the night and to detect apneas and hypopneas.  Flow measurements are also used in Central Apnea Detection (which I hate because it wakes me up).  The machine sends a series of pulses, measures the flow generated by the pulses, and then guesses about whether your airway is open or not based upon the amount of flow generated.  This method is actually reliable in detecting obstructive apneas, but no so reliable at detecting centrals.  In other words, if it says you're obstructed, you almost certainly are.   If it says you're not, then there's still a chance that you are obstructed.

The one exception may be the AirStart line, which was a discounted model that ResMed discontinued after about 2 years.  It appears that the AirStart line has fewer heating elements on the humidifier mechanism.  As a result, it takes longer to heat up and the settings 1-8 don't generate the same temperature as the AirSense and AirCurve models.  On an Aircurve/AirSense, humidifer level 1 is equivalent to level 4 on the AirStart.  This is also confirmed in the ResMed battery guide, which indicates that the AirStart at humidifer level 4 uses less energy than an AirSense/AirCurve on level 4.  AirStart also gives no reporting and no central detection, and so it wouldn't need any kind of flow meter, just a pressure meter.  I haven't taken one apart to see if it's there, but since the machine doesn't do anything that would require flow information, I doubt it has one.

[Sleepster]

I'm curious about, say, the array of ResMed (or Philips) machines. Are the guts different between all the different flavors of Bi-level, CPAP/APAP, and ASV?

Are the gut the same and the difference is just software? Or do these have different parts (and different parts? Or some of both?

Both, I think. There are hardware differences, but there also cases where the only only difference is firmware. Note that these companies are not keen for us to have access to firmware updates. Philips Respironics is downright paranoid about this.

[2PAPs]

I think there's a difference, but not as much what's being charged. It's mostly what the market will bear. regulatory expenses, and stocking. It costs money to run a specialized line. Chinese will sell some decently equipped auto cpaps for $500-600. BiPAPs for about $800 and S/T BiPAPs for about $1000. Those things are medical devices and are being certified around the world. They seem to sell primarily to Eastern Europe and developing nations where people are on their own money. Places with insurance seem to gravitate towards ResMed and Respironics.

[Spy Car]

It doesn't seem like we have any definitive answers.

Costs of R&D, regulatory costs, and maintaining separate lines left aside:

Are there any differences between these machines aside from the firmware?

Bill

[LarryRapp]

I am a complete novice and do not know the answer, however I think there would be a difference in the fan (compressor) as it has to respond far more quickly if it is a bilevel or ASV.  There is a huge difference with a plain CPAP.  The microprocessor is relatively minor compared with that.