HDM Z1 Auto

[FrankF]

I've been using a ResMed Air Sense 10 for over a year with the default auto setting 4 -20. The average pressure has been about 12. My previous machine was set by the sleep lab at 6.
Last week I bought a Z1 Auto for travelling and used it 4 nights. Overall, I am happy with the machine, not as quiet as the home unit, but quieter than the hotel HVAC and I slept as good as when home. However, the morning report said the pressure was only 4 with the auto set at the default 4 -20. Last night I raised the min to 6 and it started about 6.2, then dropped to 6.0 for most of the night.
I just downloaded the ResMes software (thanks, I wish I had it a long time ago) and got the detailed reports saying my median has been 10.6; 95% percentile was 13.2.
Also the Z1 only detected a total of 4 AHs over the 4 nights, 2, 1, 0 & 1, while the ResMed Says AHI is 1.3 or about 10 in an average 6 hours night.
Could the Z1 be defective?

[trish6hundred]

Hi FrankF,
WELCOME! to the forum.!
Much success to you with your CPAP therapy.

[under pressure]

Each manufacture uses their own proprietary software and algorithms, there will always be a difference in each machine whether it be Resmed, Philips, F&P, or whatever. I have owned and used Auto machines from five different manufacturers. The Resmed always wants to go to a higher pressure than any of them because it's so sensitive to Flow Limitations, I actually have to limit the upper end pressure in the settings to keep it from going too high (higher pressure than I really need). My F&P Auto Icon never gets anywhere near my Resmed and I could leave the upper Limit wide open (20cm) and it never goes above 12cm whereas the Resmed would climb up around 15 or 16. My Z1 Auto stays even lower than my F&P Auto, as does my Transcend Auto.

You'll have to learn what your machines want to do and use your Sleep Test numbers as a reference point to set your lower and upper pressures where you want them. I think you are on the right track by increasing the lower pressure setting on your Z1, your Z1 is just never going to get up where it needs to be unless you force the pressure up where you need it by increasing the low end setting, as you are doing.

I think the Resmed is probably the most accurate and sophisticated in terms of its algorithm (although it can get too high in certain cases) so use your Resmed as the model to set up your Z1. Increase the low end of the pressure range on your Z1 so that it runs closer to the your average pressure that you get with the Resmed. I don't think your Z1 is defective, it just is an inferior auto algorithm - they haven't been in this business very long like a company such as Resmed or Philips, so although it's a nice size travel machine it just doesn't rival the big boys in sophistication. But you can force it to do what you want/need in terms of therapy pressure.

[under pressure]

I'll add one anecdote to what I wrote up above, I could never get my Z1 to go up above 10cm even when leaving the upper range wide open, and I know from experience that I need a minimum most nights of about 13 cm to keep my airway open and limit my obstructive apneas to get my AHI down around 1.5 or lower.

So on one of my motorcycle trips using the Z1 Auto I had the miss-fortune of catching a cold and getting stuffed up. When I woke up the morning after catching the cold I discovered that the Z1 had finally responded and the pressure had gotten up around 15 cm, and of course my resulting ahi had risen too due to the cold and all the congestion that resulted.

I use this example to illustrate that the Z1 will respond with higher pressures, but it just isn't as responsive and sensitive to apneas, and flow limitations as a home machine like your Resmed.

[HermannTheGerman]

The Z1 is a machine that is primary build for mobile use together with a batterie.
I believe that they gave it an algorithm to keep the pressure low as long as possible just to safe batteriepower.

[FrankF]

Thanks a bunch for the helpful advice.
I like the portability of the Z1, I'll just raise the minimum pressure a little more.

[GingerMan512]

I may have to return my recently purchased Z1. It's loud, I can still sleep but it's annoying when I'm awake. The exhale feature on it is horrible at least compared to my AirSense 10. I just can't get used to it. The pressure is set to 11 but feels so much stronger than the 11 on my ResMed at the same pressure, with the same exact mask.

[bill-e]

I may have to return my recently purchased Z1. It's loud, I can still sleep but it's annoying when I'm awake. The exhale feature on it is horrible at least compared to my AirSense 10. I just can't get used to it. The pressure is set to 11 but feels so much stronger than the 11 on my ResMed at the same pressure, with the same exact mask.

Do you have a Z1 Auto ann the latest firmware from their website? I'd agree that the exhale relief wasn't as good as my System One but now with the new firmware, it definitely is....check.

[bill-e]

FrankF

I run my Z1 Auto at 14-20 and usually stay around 14 with the ocasional blip up to 15. I attribute that to my normally low AHI while on CPAP. When I first got my Z1 I spent some time comparing my Z1 to PRS1 data and I concluded that they are close enough to convince me that the Z1 software was accurate.

I typically use my Z1 Auto 4 nights a week 35-45 weeks a year so I can switch back and forth between machines without issue.

[bill-e]

FrankF, as for noise, do you use the included small tubing? I found that the small tubing is very noisy and just going to a full sized, flat inside tubing worked wonders. Also, I find that the Q-Tube muffler works great and makes the machine much more quiet.....quiet enough that when I'm testing and using it at home my wife no longer complains. If you don't want to spend the money, Google some DIY muffler solutions.

Lastly, I think mask design contributes to increased, or less noise depending on the exhale ports on the mask. I've said before that the way the small machines create enough airflow is by spinning a small blower at very fast speeds and push high velocity air out the vents....I've recently been doing some informal testing between masks and I noticed that my Eson is noisier than my PR gel mask...and the noise is from the vent.