Two CPAP questions.

[Bowiefan]

I recently bought a used Remstar Auto-M with C-Flex and just started using it. It seems to work fine. I woke up a couple of times on my back which makes me think I stopped breathing. I set all of the pressures myself making sure the low was 4 and the high was 20 to cover a wide range of conditions. Ramp setting on. Also set C-flex on. Is it still possible to still have apnea's while using CPAP? Also I noticed toward morning that I was hearing sort of a growling sound which did not appear to be coming from the machine, not an air leak sound, but a growling sound. I could still hear it through earplugs which I thought was strange. Any help on these two issues would be appreciated. Thanks.

[cflame1]

If the low pressure is too low for you, then you could still be having apneas as it will take too long to get to where it needs to be.

Did you have a titration study? If so what did they find for a pressure for you?

[dtsm]

Not familiar with your machine and setting such a wide band might create potential problems. As a 'general rule' for apap use:

1. What is your titrated pressure? Or based on apap usage, what is your 95th percentile?
2. Use #1 as a start point and set your lower range to that pressure [or 1 less]. For instance if #1 is 11, set your lower range at either 10 or 11.
3. Set your upper range anywhere from 13-20, the upper range is of less importance.

Can't help with growl noise

[Janknitz]

When you have a wide open setting like that (4 to 20), it often takes the machine too long to "chase" your apneas, so you may have a higher AHI than with a more narrow range. You may also have more centrals than necessary if the pressure is too high.

Such a setting is sometimes useful for self-titration (if you know what you are doing), but rarely useful in the long term. Your theory that a wide setting will "cover a wide range of conditions" is flawed because of the limitations of the machine algorithm and the response times inherent in the machine.

You should not be doing this on your own without software and a better understanding of what it is you are doing.

As for the "growling" sound, my guess is it was coming from your mask. Particularly with flex enabled, there can be conducted noise in the mask and hose and it can sound like growling. It's usually a very low sound and you will get used to it over time.

[cflame1]

If you use the aflex setting, which is similar to EPR, you need to adjust #1 by the same corresponding aflex setting. So, if you use aflex 1, increase lower range by 1, in my example above, then set to either 11 or 12.

Can't help with growl noise

dtsm... aflex doesn't work like EPR... neither does CFLEX or BiFLEX... there isn't a 1 to 1 correlation on the numbers used for FLEX.

[Bowiefan]

Thank you for the replies. The suggested setting from my sleep study was 11. Should that be the low auto pressure number set on my machine?

[Hawthorne]

Your minimum pressure should only be 1 or 2 cm below your titrated pressure or right on your titrated pressure so that the machine does not have to take so long to deal with events. Being on your back does not necessarily mean that you stopped breathing. If you have positional sleep apnea (many more apneas in one sleeping position - usually that is the back if you have positional) then you may have stopped breathing (had an apnea) briefly while on your back.

You will still have apneas , hypopneas, etc even though you are using a cpap machine. You do have sleep apnea of course and the machine is not a cure but rather a treatment. The sleep medicine profession uses an AHI of 5 as the gold standard. The AHI is the apnea-hypopnea index and the aim is to have your pressure set so that you have an AHI of under 5 for your therapy to be effective. The lower the AHI the better the therapy.

It is best to have software for your machine so that you can see exactly what is happening in your sleep and make pressure adjustments accordingly.

I'm not a medical person, just a person with 8+ years on cpap and a lot of reading on the subject.

[Julie]

A good setting range for you could be 10 thru 14-15, as a narrower range is more effective than wide open. Try to rig something, pillows or something attached to the back of your PJ's, to keep off your back as it will provoke a lot more events.

[GumbyCT]

Also I noticed toward morning that I was hearing sort of a growling sound which did not appear to be coming from the machine, not an air leak sound, but a growling sound. I could still hear it through earplugs which I thought was strange.

Could this be gurgling from water in your hose? Just a WAG. If so, turn down the humidifier.

[RDawkinsPhDMPH]

In my lab we use auto's exclusively. We never ever set it for the full range. Normally we set a range of 4 to 6 from the minimum to the maximum pressure. Everyone gets a machine with a modem so we can review their data when they come to the lab or our support group. We do our titrations specifically with the intent to use an auto so we don't titrate to a single pressure.

You can check my website for a link.

[Bowiefan]

Thanks everyone! Your answers were helpful.

[Chaos-Jones]

You should probably set you minimum pressure higher than 4cm. I would start with 6cm to 10 or 12 and watch what
the average pressure is on the machines display over a week or so. Once you have that average pressure you can set
your machine 1cm below and 3 or 4cm above to cover all bases.

As others said the noise could be your mask or water from the humidifier. That or some thing is not right with
your machine as I have no problems like that with my Auto M.