New to S9 – my first FOT experience.

[BasementDwellingGeek]

I've been using a Respironics PR System One REMstar Pro CPAP Machine with C-Flex Plus for about 9 months. Last week I saw an ad on Craigslist for an unused S9 Autoset. After a few emails we met, I inspected the machine and confirmed zero blower hours and handed over the cash. Yesterday I set it up in CPAP mode @ 13cmH2O, as was my Respironics. The DME had originally set my my Respironics with C-Flex 3x which I never even experimented with, so I set up the S9 with EPR 3.

Last night on at least two occasions I was woken by a weird, to me, kind of fluttering, popping, sensation in my nose that I have never felt in the Respironics. A sharp inhalation seemed to clear the problem. I was now awake enough, for long enough, to make me want to roll over and look at the clock. This morning I popped my SDcard and fired up SH and went scrolling to the times in question.



Having spent many, many hours looking at waveforms and Pressure Pulses in Respironics data I deduced this must be an FOT. I then zoomed to the single CA and single OA to find the same ripply pattern on the Mask Pressure graph.


This kind of cemented the idea that these are FOTs. Now I need to learn to ignore and sleep though them, it was easy enough to do with Respironics PPs.

[avi123]

In a ResScan the FOT looks more subdued:








Also, in ReScan there is no "Mask Pressure". Only Pressure, and it does not show the FOT.

I never feel the FOT. Is it possible that the noise that you heard was from water either in the hose or on the floor of the humidifier?

BTW, have you seen this sensor of body position:


http://www.buzzpod.com.au/product.html

[Slartybartfast]

I hear/feel it all the time. Usually just as I'm dropping off to sleep when strange things tend to happen to one's breathing. You can hold your breath and after 10 seconds you'll feel the pressure flutter and if you hearing is good, you might be able to hear it. And you're right, all it takes is a single breath to stop it. Machine's just checking up on you and trying to discern whether you've got an open or closed airway apnea so it can decide whether to bump up the pressure or leave well enough alone. I suppose if one was a light sleeper it might be a little annoying. But I strap on and am usually out in a few minutes, much to the disgust of my insomniac wife.

[zoocrewphoto]

What is an FOT?

[archangle]

What is an FOT?

Forced Oscillation Technique. It's how the data capable S9s attempt to detect central apnea. It's a rapid series of small puffs of air. The machine measures the airflow changes to see if the air is reaching your lungs or not. (Simplified version)

[BasementDwellingGeek]

During my second night on the S9 I detected them again. It was mostly a hearing kind of thing. Maybe my ear was on the hose? As I laid awake prior to getting out of bed I held my breath for a while to see if I could detect the FOT. I felt it it but it was incredible faint. I couldn't hear it. I feel fairly confident that I will learn to tune it out with time.

AVI: that gizmo looks kind of cool. I did just a little looking for info on it after your introduction. I didn't see any place where a price was mentioned. The fact that

BPOD also stores up to three weeks of positional data which is then uploaded to a computer at your local sleep clinic so that your doctor can accurately diagnose and treat your condition.

seemed like the medical profession brotherhood insuring billables for it's members. The belt looks nice. I'd like to get something like that to slip my accelerometer into rather than taping up with an ace bandage.

[zoocrewphoto]

What is an FOT?

Forced Oscillation Technique. It's how the data capable S9s attempt to detect central apnea. It's a rapid series of small puffs of air. The machine measures the airflow changes to see if the air is reaching your lungs or not. (Simplified version)

Thanks.

I think I felt that once. I turned on the machine, and within a minute, it did that, and I couldn't figure out what it was, so I turned it off and back on again. It felt like when the pressure first turns on, then off again, then on again, several times really quickly.

[avi123]

During my second night on the S9 I detected them again. It was mostly a hearing kind of thing. Maybe my ear was on the hose? As I laid awake prior to getting out of bed I held my breath for a while to see if I could detect the FOT. I felt it it but it was incredible faint. I couldn't hear it. I feel fairly confident that I will learn to tune it out with time.

AVI: that gizmo looks kind of cool. I did just a little looking for info on it after your introduction. I didn't see any place where a price was mentioned. The fact that

BPOD also stores up to three weeks of positional data which is then uploaded to a computer at your local sleep clinic so that your doctor can accurately diagnose and treat your condition.

seemed like the medical profession brotherhood insuring billables for it's members. The belt looks nice. I'd like to get something like that to slip my accelerometer into rather than taping up with an ace bandage.

I am waiting for an email from this Assie about the buzzpod.

http://www.buzzpod.com.au/product.html

I'll ask for price.

It seems to me that it is built with mercury tilt switches.

[BigLou]

Not sure if I understand. It appears that the apnea occured after the FOT......did the FOT induce the apnea? I looked back on my data from last night and found the same pattern that you both have. I am on straight CPAP of 10.

[yarrow]

AVI: that gizmo looks kind of cool. I did just a little looking for info on it after your introduction. I didn't see any place where a price was mentioned.

There's a place in Melbourne selling it: "Buzzpod for positional sleep apnoea $419.00 trial for just $50.00". Australian dollars are almost one-for-one with USD right now, but I imagine shipping would be a killer.

[Jason7]

I use both a PRS1 and a S9. I never noticed a FOT using the S9.
However with the PRS1 occasionally when I am about to fall asleep I feel a relatively strong blast of air -- is this how the FOT feels on the S9?
Thanks,
Jason

[avi123]

Not sure if I understand. It appears that the apnea occured after the FOT......did the FOT induce the apnea? I looked back on my data from last night and found the same pattern that you both have. I am on straight CPAP of 10.

Check this:

http://www.resmed.com/us/assets/documen ... -paper.pdf

In Resmed's ResScan software the flag is placed after the apnea.

[BigLou]

Thanks for the link avi123.......very enlightening.

[BasementDwellingGeek]

However with the PRS1 occasionally when I am about to fall asleep I feel a relatively strong blast of air -- is this how the FOT feels on the S9?

Rather than one big pulse the FOT is bunch of little pulses, but pretty much the same ting.

[avi123]

On a second thought, since FOT occur only during apnea, either open or closed airway, you should NOT feel it. Because if you are aware of it then it means that you are awake. And if you're awake then you overcome the apnea by respiring regularly and the FOT stops. If you feel the FOT it might be an indication that your machine malfunctions.

From Resmed:

The enhanced AutoSet algorithm applies FOT only when
an apnea is detected and turns it off once normal breathing
has resumed. A 1 cm H2O amplitude sine wave at a
frequency of 4Hz is superimposed on the current pressure
and the resulting pressure and flow are measured within
the device using a pneumotachograph.

The 1 cm H2O amplitude pulses are able to be perceived
by a patient if they are awake but are not large enough to
arouse them from sleep