Dreamstation calibration off?

I'm a longtime (11+ years), 100% compliant CPAP user, and yesterday I switched from my original Respironics REMstar M to a Respironics Dreamstation DSX500T11. Both devices are in auto mode with a range of 7-20.

For the past 5-6 years, I've been averaging 90% at 8.5cm on my REMstar, which has shown my AHI to be around 0.6 most of the time.

But, last night, I used the Dreamstation for the first time. I got into bed, pulled on my mask, flipped on the machine, and it nearly blew my head off with high pressure. I figured the ramp might be set wrong, so I turned if off. (I never use it anyway.) The pressure was still way too high, so I waited a few minutes to see if it would drop as I settled down. No luck. I was still struggling to breath against the flow. (Haven't had that happen since the first week I ever wore a CPAP!)

So, I went into the clinical settings and lowered the range to 4-15. I slept comfortably after that, and I felt pretty well-rested this morning. When I checked the readings, though, it said I was 90% at 6.0 with an AHI of 5.8.

Something tells me the 6.0 cm must be wrong and the machine is mis-calibrated. At my last sleep study two years ago, my prescription was for 10cm on fixed CPAP, and I haven't had any major changes that would cause that to drop -- no weight lost, no surgeries, etc. My original Rx 11 years ago was for 8.5cm on CPAP, so I've never been as low as 6.0.

What do you all make of it?

Two other notes: First, I noticed that the date is off by one day, and I don't see a way to fix it. I've adjusted the time zone, but that didn't correct the date. Second, I've been able to connect to the app via Bluetooth, and while it says it is transferring data, the app won't show any data before yesterday. I have a feeling the incorrect date could be causing that.

The device has a wireless modem installed, but that seems to be useless. I'd like to connect it to the Internet to recalibrate and get the right time, but I see no way to force that. I'm not interesting in sharing data with my doctor (who doesn't want it), insurance company (doesn't request it), or Phillips or the DME (who don't need it).

There is a user manual, I will try to find the link.

...

Chris8243 wrote: ↑

Sat Dec 15, 2018 10:44 pm

https://www.apneaboard.com/dreamstation ... structions

I'm sorry that's not quite what I was looking for. I have a full manual as a PDF, got the link from someone here.

Kalnel2 wrote: ↑

Sat Dec 15, 2018 7:19 pm

So, I went into the clinical settings and lowered the range to 4-15. I slept comfortably after that, and I felt pretty well-rested this morning. When I checked the readings, though, it said I was 90% at 6.0 with an AHI of 5.8.

Something tells me the 6.0 cm must be wrong and the machine is mis-calibrated. At my last sleep study two years ago, my prescription was for 10cm on fixed CPAP, and I haven't had any major changes that would cause that to drop -- no weight lost, no surgeries, etc. My original Rx 11 years ago was for 8.5cm on CPAP, so I've never been as low as 6.0.

What do you all make of it?

Well, your pressure is probably way too low, I wouldn't trust the data off of an 11 year old machine without some other verification....

First thing to check on the dreamstaiton is whether or not the hose type is set right, if you don't have a heated hose.

Also you might want to try turning on flex to provide some exhale relief

Set the dreamstation to a fixed value, let's say 6.

Then find a ruler with centimeter markings. If you're stuck with inches, 6 cm is about 2.4 inches.

Take a glass of water.

Turn the machine on.

Shove the hose into the water. As you start, air should bubble around out the hose. However, once the hose reach a depth of 2.4 inches, the bubbling should stop.

That's what 6 means. The equivalent of pushing against 6 cm of water.

Anyway, that's the theory. I haven't tried it. Maybe I'm all confused about this.

But if your bubbling stops when submerging the hose to a depth of 2.4 inches, then you can safely conclude that your DreamStation is calibrated properly.

I had an excessive pressure issue on a PR System 50 some long time ago. After the second instance, I took it back to the DME (after getting a backup machine on my own) and they finally agreed to send it to Respironics who replaced it with a new machine. Because of that experience, I've never been without a backup machine even after being moved to an ASV machine (the cost is an ouchy!!!)

The suggestion to measure the pressure yourself is a good one. Get a meter scale (Staples, WalMart, etc.) and connect one end of a small diameter hose (Home Depot, Lowes, etc.) to your CPAP hose so that the CPAP hose is completely plugged except of the little hose and, with your small diameter hose taped to the meter scale, insert it into the water as suggested until it stops bubbling. The measurement on the scale is the actual pressure in CmH2O the machine is producing as compared to what the clinician menu setting is calling for. If it is different by more than maybe 0.2 cm H2O, then its off to the DME for a replacement.

Or, you can build or buy a manometer and measure it directly. CPAP.COM sells them https://www.cpap.com/productpage/fisher ... 25-chamber but there are other sources.

The usual drill for the home handyman is to get a meter scale that is at least 50 cm long, some 1.4 inch diameter tubing (say 5 feet), and a cork that fits into the end of the CPAP air hose connection. Drill a hole in the cork, insert the hose and make sure it is sealed and tape the other end of the hose to the upright meter scale draping it down to the bottom and then back to the top again. It helps to tape the two pieces of tubing to the meter scale so they don't move. Add a little water to the tubing so that it fills the bottom and goes up both sides maybe 20 or so cm. The set the machine to a fixed pressure, insert the cork into the air outlet, and see what the difference in levels is between the CPAP side and the other (open to the air ) side. That difference is the actual pressure the machine is actually producing. CAVEAT: Make sure the meter scale is always upright and below the CPAP machine so that there is NO CHANCE that water from this device can flow back into the machine.

Much cheaper digital manometers are available on eBay.