Goodknight 420G vs Resmed S8

I bought the Goodknight 420G with heated humidifier several years ago to travel with and use it anywhere from a night at a time to several weeks when away from home. Since diagnosed with sleep apnea in October 2005 I use Resmed S8 Elite and Vantage with H3I at home. All three machines are set for the same pressure, no ramp, no epr and the Vantage is set to operate as a CPAP. The Vantage when set to APAP would use high pressure and I had more events according to the software, woke up more, and was tired during the day, tried lowering the pressure limit and it turned out that 8.4 was the best. I have total events below 3 most of the time. Rarely up to 4 or 5, sometimes below 1. The original sleep study at Mayo Clinic showed that I had some central apnea events that the doctor felt should reduce with the machine therapy. The study called for 8.0 pressure.

Over the years, I noticed that I felt more rested while using the Goodknight, and thought it was because of the vacation environment. Overall cpap is a non-event, set it up, put on the mask, go to sleep, wake up, take it off, etc. Only a few problems with nasal congestion, as the allergy season comes, I will use some medicine until the fall. The Resmeds provide much the same therapy, but, feel sleepy during the day more often (seat of the pants since Goodnight 420G has no software). I like the automatic start and stop of the resmed and the integrated humidifier. It is nice to wake up well rested and refreshed.

Last night I decided to exchange the Goodknight for the Resmed, using the same activa mask which the Resmeds are calibrated for. Today I feel more rested than normal. I guess you could say, well use the Goodknight and be happy, my question is, how to set the Resmed to act like the Goodknight? I will use the Goodknight for several weeks to see if the therapy is better for me than the Resmed.

I have received many good ideas from this forum and thank you all for it, hanging hose, cloth sock for the hose, salt water nasal rinse and the cpap.com folks are easy to buy from. Maybe my next purchase will be the 420E which should work with the humidifier I have. Do you think it will work like the 420G?

An interesting situation. The only significant thing I can think of between the 2 machines is that the PB420G has an internal pressure sensing airline in the main hose & that it is going to be better at sensing the actual pressure at the mask vs the S8.

Interestingly the older Resmed Autoset T had a sensing line but by the S7 model they dropped it & that left PB as the remaining large manufacturer who still uses the auxilliary pressure sensing lines in the main hose on a cpap or auto (The current Resmed Vpap Adapt SV has one but it is external to the main airline).

Beyond the above difference, and assuming cpap mode, I can't see how the air from a cpap can vary in a way that changes the therapy outcome.

I know that different people prefer different auto algorithms - a number of people have commented over time, that they prefer the Respironics auto algorithm to the Resmed auto algorithm, often saying they felt the Resmed algorithm 'feels more aggressive'. I have never been able to translate that into identifiable machine activity but, having said much the same myself when comparing the Bipap Auto SV to the Vpap Adapt SV, I know what the intention of the statement is. I definitely prefer the SV modality as applied by the Bipap Auto SV but find I get the best daytime results when using the Vpap Adapt SV.

But getting back to a cpap, that in theory just delivers one pressure all the time. Am danged if I can figure what may make a difference other than the use of the auxiliary air pressure sensing line & how that regulates the airflow to the mask.

DSM

I would think it's either a calibration problem, or the machine's ability to compensate for leaks.

If one machine is not calibrated - or even both - you will simply have to start jogging the S8's pressure up (or down) to achieve results similar to those you get with the PB 420G

O.

dsm wrote:An interesting situation. The only significant thing I can think of between the 2 machines is that the PB420G has an internal pressure sensing airline in the main hose & that it is going to be better at sensing the actual pressure at the mask vs the S8.

There must be some other explanation. The 420G doesn't have a pressure sensor in the main hose. I believe this feature was in the 420E and, perhaps, some other PB models.

greyhound wrote:

dsm wrote:An interesting situation. The only significant thing I can think of between the 2 machines is that the PB420G has an internal pressure sensing airline in the main hose & that it is going to be better at sensing the actual pressure at the mask vs the S8.

There must be some other explanation. The 420G doesn't have a pressure sensor in the main hose. I believe this feature was in the 420E and, perhaps, some other PB models.

Thanks for that correction, on reflection the machine I had was a 420S and it did have the internal sensing line. The only diff with the 420G that I was aware of was that the S collects nightly data whereas the G doesn't - other than that I was quite sure they both had that internal pressure sensing line.
http://www.puritanbennett.com/prod/Prod ... S2=&id=274 (differences between models).

http://www.internetage.ws/cpapinfo/pb42 ... c07747.jpg This is the hose from the 420S I had.

Thanks

DSM


#2
Greyhound - you are right
Here is the patent app for the PB420G and indeed they do NOT mention sampling pressure at the mask which the patent for the PB420S & PB420E does.
http://www.fda.gov/cdrh/pdf2/k020886.pdf
So in fact there really is nothing discernibly different to the therapy delivered by an S8 cpap vs a PB420G cpap.

DSM

The 420G was my first machine. That's the only reason I knew it didn't have the pressure monitor in the hose.