My CPAP does air "pumping" during inhalation and simulated "central apnea" event !?

[arminio]

It is now a month since I started CPAP therapy. I still use the same F&P ESON mask an the same CPAP machine - Resmed s9 Auto with the same settings (APAP 4-14, EPR 1, Humidity 1, RAMP 20 min) and last night I woke up in the midddle of the night and noticed strange noise - simmilar like boiling... like "bubbling" watter in kettle! My humidifery works well and there is no difference in settings, water is warmed up as usuall (not boiling at all, of course), no condensation in hose nor mask... but that noise worried me. But I continue to sleep and in the morning I noticed something else - whenewer I inhale, machine start to "pump" air - like it try to simulate fast breathing!

It is not noticeable during low pressure (almost none) - but it is very noticeable when pressure was high (and it was around 13 in the morning when I woke up - as I've seen based on graph I checked at sleepyhead). I am sure I did not notice that on previous nights/mornings so I am a bit worried that my machine maybe is faulty or become faulty...

There were some leaks during night but boilling noises comes from machine and not mask, and pumping air also definitelly comes from machine because I just performed test with "mask fit" option and mask on my face that I fit perectly and without any leaks for test - and yes - when I inhale rapidly, machine start to pump air for a few secons and then stabilise as my brething stabilizes! Also, if I hold my breath in a way that I close my "nose and mouth cannals" with toungue and back of my throath so air can't flow from mouth and I simulate obstructive apnea, everything is fine - air flows from machine is normal. But when I simulate central apnea and just stop breathing with "cannals open" (just inhale and keep air that way for few seconds and does not exhale but not close anything with back of my throath nor tongue), machine starts to pump air!

Is this OK way Resmed S9 autosense works or something is gong bad with my device? And if it is fine, it is strange I didn't notice that before... or it just become faulty in just a month of useage...

I would be very thankfull if somebody who has the same machine can test this with "mask fit" option and post here does his/her S9 autoset works the same way or I really need to send my machine for inspection to my supplier...

I must mention that my AHI for last night was 1.3 and graph and everything was fine and without any anomalies and I feel fine - so looks like machine did the job well, except I am worried because of this air pumping and boiling noises...

[justMongo]

It's a bit difficult to understand what you are describing; and that may be my fault.
Are you absolutely sure you have an S9 Autoset machine? What you describe sounds like how an ASV machine would operate.

[arminio]

It is S9 autoset - not ASV.

Sorry for my English - I'll try to be more specific and try to explain better. So:

When I inhale air and keep my breath at the peek of inhalation and simulate "obstructive apnea" (when I am awake I can block air flow with my palate by simulating "snoring" and completelly block air flow simmilar to obstructive apnea - then I don't breath and air from machine can't go to my lungs), machine works normally - air goes constantly without short burts and without pulses of air.

When I inhale air and keep my breath at the peek of inhalation and simulate "central apnea" (I don't block air flow with my palate - I just inhale and does not exhale and I just stop breathing but air from machine can flow to my lungs), machine starts to send pulses of air (quick burstst of air) and do that for few seconds and then "calms" down to normal air flow. The same thing happens when I inhale quickly/rapidly (like "panic atack" or when you are frightened and take quick deep breath in).

All that bursts are not very noticeable - by this I mean you can feel it but not much, but you can clearly hear it from the machine (you hear ventilator/motor or whatever engine is in the box that do this bursts while in the mask you just feel it slightly and gently). Also, all this happeny on higher pressure - I felt it on 13, while on 4 it is not noticeable (so I don't know does it happen or bursts on 4 are just too small to be noticed).

Pretty strange is that I left machine for few hours and before half hour I tried again with "mask fit" test and repeat my breathing and apnea "simulation" - and now there is no more air bursts!?

Hm. Coud be some temporary problem maybe...

I've seen on the net that some problems with strange noises can come from dirty filters - so I just removed filter and shake it a bit to remove any dirt (although it looks clean) and put it back (I'll change it as soon I receive replacement filters - currently ordered and waiting for them) so we'll se will there be more "boiling" sounds. And about "air pumpings/burtsts of air" - can't get that any more for now... I'll see tomorrow morning how following night will pass...

[Jimsp1]

I believe these machines send out test pluses to determine if the apnea is obstructive or clear. Perhaps this is what you are sensing.

[Crimson Nape]

The "boiling" sound can be caused by either; 1. Overfilling the humidifier(even slightly) or, 2. Trapped condensation in the hose. I'm sure there is possibly a #3 but by the time I have gone through 1 and 2, I've found the problem.

I hope this may help.

[justMongo]

I believe these machines send out test pluses to determine if the apnea is obstructive or clear. Perhaps this is what you are sensing.

Yes. It's called the FOT algorithm. The machine sends out a 4 Hertz, 1 cm-H₂O string of pressure pulses and "listens" to the reflected wave via the flow sensor.

An obstructed airway reflects the pulse train at higher amplitude that an open airway. (Open airway has the aveoli in he lungs to dampen the reflected pulses.)

[arminio]

I believe these machines send out test pluses to determine if the apnea is obstructive or clear. Perhaps this is what you are sensing.

I though that too because I read that this is the way S9 detect type of apneas! Yes, could be that...

The "boiling" sound can be caused by either; 1. Overfilling the humidifier(even slightly) or, 2. Trapped condensation in the hose. I'm sure there is possibly a #3 but by the time I have gone through 1 and 2, I've found the problem.

I hope this may help.

No. 1 is not the case - water is on the second mark below max - I always fill it up to that point, never below and never over that "middle" mark.

No. 2 - that might be a case - because, as I stated in first post in this thread, that is what I checked first when I woke up - there were no condesation in hose nor in mask - but I did not checked it in the middle of the night, and maybe condensation were there and gone until morning (and in the morning that "sound effect" dissapeared)...

[PsychoMike]

Arminio, yes, the Resmed machines use air pulses to check if the airway is open or closed. If you inhale or exhale too long for the pattern it has been reading from you, it assumes you are having an event and tries to catalog it. So, if you are breathing normally and then decide to take a nice, long, relaxing breath, it'll pulse and probably count it as an event.

If you are getting "boiling" noises, you could also be getting some "rain out" in the tubing....there is condensation in the tube and your air flowing through it makes it sound like it is boiling or bubbling.

[arminio]

This morning everything was fine - no boiling noises (it was rather cold the night before so condensation is very likely reason for "boiling" noise because hose was under my blanket while in room was a bit colder than usual), and "pumping" is still there - but only when I focus to it, I notice it. It is OK if it is machine feature - I was just worried that there is some fault...

Many thanks to all of you for help!

[SpeedyD]

This is very interesting. I have noticed this also. Good to have an explanation of those pulses.