ResMed S8 vs S9 auto CPAP

[john5757]

There seems to be a big difference in therapy between the S8 and the S9. It seems that the S9 is less aggressive and changes the pressure much less than the S8. Is this typical? Also the air flow on the S9 seems to be softer than the S8. I had to change the tubing size from standard to slimline while still using the standard hose and it is more like the S8. Can an auto CPAP be checked for calibration? I am trying to answer a questions from a friend. Thanks

[RandyJ]

If you set wrong tubing size, you might not get correct pressure at the mask.

I would be more confident I were getting the correct pressure from S9 than the older S8. The S8s scored hypopneas more aggressively, but that is simply a reporting issue. I am not familiar with algorithm of S8 Autoset, but I seem to remember hearing that at settings greater than 10cm it would not increase pressure to respond to certain types of events.

[john5757]

The S8s scored hypopneas more aggressively, but that is simply a reporting issue. In other words no difference in the amount of pressure increase when the S9 finds a event over the S8? Does the 90 or 95% pressure requirements changed when going from the S8 to the S9?

[RandyJ]

The S8s scored hypopneas more aggressively, but that is simply a reporting issue. In other words no difference in the amount of pressure increase when the S9 finds a event over the S8? Does the 90 or 95% pressure requirements changed when going from the S8 to the S9?

There may be a difference (someone else may remember what it is and respond). However, the Autoset algorithm for the S9 should be improved over that of the S8, so I would be of the opinion that the S9 should offer better therapy.

I would not look for ways to duplicate what the S8 felt like, but rather adapt to the S9 or, according to therapy data from Sleepyhead or ResScan, make appropriate changes to settings.

[RandyJ]

Here is the post about the A10 algorithm said to be used in the S7 and S8 Autosets:

jdm2857 wrote:

At pressures above 10, it responds differently than above.

The following was part of a moderated chat (http://www.talkaboutsleep.com/sleep-dis ... chat.htm#2)
with a ResMed representative back in the S7 days, but the A10 algorithm discussed was used in the S8s too.
The S9s, which can detect open-airway (central) apneas, have a new and improved algorithm.

ResMed Rep. wrote:6. Why does AutoSet Spirit (and AutoSet T™) have the A10 algorithm?

ResMedSimon answers: The A10 algorithm increases pressure in response to Flow Limitation, Snore, and Apnea up to 10cm H2O.
Above 10cm H2O, pressure response to Flow Limitation and Snore continues, but there is no response to Apnea.
AutoSet Spirit and AutoSet T do not differentiate between obstructive and central apneas.
Increasing pressures above 10cm H2O in response to apnea can lead to "runaway" central apneas.

Notice that hypopneas never cause a pressure increase.

Here is a link to the entire thread: viewtopic.php?f=1&t=87913&p=804340&hili ... hm#p804340

I don't believe the S9 machines are limited in this respect; above 10cm they will still respond to apneas and increase pressure. Someone will correct me if I'm wrong...

[john5757]

My main question is:
Does moving from the S8 to the S9 changed the overall 95% reporting level for pressure?

[LSAT]

My main question is:
Does moving from the S8 to the S9 changed the overall 95% reporting level for pressure?

NO

[jdm2857]

Both the S8 and S9 report the 95% pressure as the pressure the machine was at or below for 95% of the sleep period.
The calculation has not changed.

But, if the S9 is supplying different pressure(s) in response to your events the 95% pressure will be different, too.

The new S9 algorithm does not have the same rules at pressures above 10. Because the S9 can detect open-airway
(central) apneas, it can be more aggressively treat apneas at pressures over 10 without concern of increasing pressure
in response to central apneas.

The change to less-aggressive scoring of hypopneas (more in line with the other brands) should not affect the pressure
response of the machine. I'm pretty sure that the new algorithm still only uses snores, flow limitations, and apneas
to determine the pressure supplied. Hypopneas do not affect the pressure determined by the algorithm.

[john5757]

Thanks that is what I am tying to under is there overall pressure change from the S8 to the S9. The reporting of events can be different but wanted to know from users that moved from the S8 to the S9 did the algorithm net pressure changed at all or was the same. The 95th percentile being reported by ResScan is lower on the S9 as compared to the same setting on the S8.

[jdm2857]

There's no blanket answer; It all depends on your particular data.

The pressure calculated by an S9 may differ from that of an S8, and the
difference is due to the number and types of events that the user experiences.

As one example, an S8 user with pressures below 10 and some central apneas
will probably have lower pressures on an S9 than an S8. At pressures below
10, the S8 will increase pressure in response to central apneas. An S9 won't,
because it can detect them. So the S9 pressure will be lower.

But without more detail on both algorithms and your data, there's no way
to even guess at an answer to your question.

[LSAT]

When I moved from S8 Autoset to S9 Autoset I kept the same pressure range and my 95% stayed in the same range...(It obviously changes slightly night to night). My AHI ranges from 1,5-2.5.

[shao from Philippines]

I have brand new tubing and mask but the CPAP Machine ResMed S8 still knocks my sleep with the "irritating" CHECK TUBE!! problem... Can anybody help solve this problem?

[LSAT]

I have brand new tubing and mask but the CPAP Machine ResMed S8 still knocks my sleep with the "irritating" CHECK TUBE!! problem... Can anybody help solve this problem?

This is what it says in the S8 manual about tube issues......Helpful???

Check that the air tubing is connected securely to your mask and the air outlet on the front of the S8 Elite II.When you have checked the air tubing, press the Start/Stop key to restart the device.If this does not clear the message, disconnect the power cord and then reconnect it to restart the device.