Blocked Filter

Hi, I went to use my ResMed Autosense 10 last night however instead of it starting gently at a 4 on autoramp the air pressure was up, down all over the place "hunting" we called it in the automotive industry.

Switched it off and slept without it and do decided to do some basic checks for obstructions etc.. as these machines aren't cheap and I don't have a spare.

Took a look at the inlet air filter and although it was a little discoloured I would be hard pressed to say I thought it was blocked however I changed it and the machine seems ok again although tonight will be the test.

My question is has any one else found their ResMed to be sensitive to air inlet obstruction?

I have not had the problem, and I am not diligent about changing the filter. I will change mine today, as it has been a long time. In the past when I have looked at them, I have not seen anything significant in the filter. It certainly may cause the hunting effect on pressure.

I haven’t had the problem, because I DO change the filter reasonably regularly. However, I think it is very likely that a blocked filter could cause that or other problems. Anytime a pump is trying to pump against resistance of any kind, it will stress out, and perhaps, burn out the motor. That’s why they have “safeties” on wells pumps.

Hi Sierra and PSATB, A follow up to my original post, I used the pump for 7 hours last night and it was good as gold, so the original issue was certainly caused by a restricted inlet filter, it's not the original, I do remember changing it 6 months or so ago. If I'm able to find it I will take a photo of it next to a new one and post it here. Less technical people may not think to work through a fault finding process and might well incur significant inconvenience and cost trying to get their machine "fixed"

Spot: You might want to check on the recommended replacement schedule for the filters as well as all the other peripherals. Wrt the filters, I believe it is monthly re the RESMED machines. While it may differ somewhat wrt the Philips machine, I doubt that it is as long as six months.

I know it’s a nuisance (not to mention a cost) to keep up with the recommended replacement schedule. But given the concerns about foam degradation and off- gassing of plastics, it might be advisable to adhere to the recommended schedule. Also, I wouldn’t get creative about washing the filters, that could superimpose another cause of contamination. But I would be very concerned about a filter that was so dirty that it was blocking the air flow. You don’t want to be breathing air that’s gone through something that dirty. (Your lungs are a filter, too, and that’s the important one.)

Hi PSATB, Yes, will do with the schedules and have attached a side by side of the dirty filter and a new one, as you can see it's discoloured but there's no loose dirt or dust, is it possible the filter was manufactured with a little more density than normal - will never know.

I'm a little surprised they didn't build some form of cyclonic block into the inlet side, some of these machines operate in wide range of environments.

The manual states the air inlet filter should be replaced every 6 months, I'm surprised I didn't get some form of error message as well as the user guide states an error 004 may be a blocked air filter among others.

Spot- It really doesn’t look that bad. I’m inclined to concur with your differential density thesis.
Anyway, you have it working well again, and that’s what counts….

Well I checked my filter and that of my wife's S9. Ouch! Both were very bad! This photo is of mine, and a new filter beside it. I have no idea how long since it was changed, but probably at least a year or more. Will have to set a reminder for 6 months! Thanks for the reminder. However, seeing how bad our filters were, it may not support your theory that a plugged filter was the source of your problem. Your filter looks quite clean in comparison...

I looked up the recommended replacement cycle on-line and I found a range: three to six months. A lot probably depends on whether the environment is humid, dusty or otherwise tough on filters. (I became a little overly conscious of filters, generally, after buying a house from my Mom and finding an air filter in a vent behind a bookcase that looked like concrete and had probably not been changed in many years. One visual experience can make an impression.)

Wow, ouch is a good description Sierra, your filter is so much worse than mine, just out of curiosity I weighed my old filter and a new one, came up with a consistent difference of 1 grain, not sure that means much apart from it's doing it's job.

Have to agree with you that my issue might not be that simple but my machine worked fine for 7 hours, let's see what future nights bring!!

It's one of those issues were you don't know if you're all starting from the same baseline, you know 4. 8volts here 5.0 volts there, can't imagine all the semi conductors and transducers came from the same batch so we will always get variations. Anyway good thing you've changed those out!!!!

PSATB - couldn't agree more, horses for courses, should have seen some of the filters we pulled out of tanks and 113's, they had it all, hot, wet, dry, humid, dusty, muddy - and worse!!!!

Since the air pressures are controlled by an algorithm on a chip, and strives to be sensitive to even anticipating changes in your breathing patterns and hence pressure needs throughout the night, it might not take much to throw a monkey wrench into the process. It appears a little delicate…. Early in my use of PAP filters, I had one that seemed to develop a white growth on it. That alarmed me.

Ordered some filters from Amazon. There seems to be about three or four different choices of filter material. I noted that one of them was a thin paper like material (perhaps like a coffee filter?). One user commented that they plug up and then get sucked into the machine. That would not be good! I ordered some that look somewhat finer than the original, but hopefully not so fine that they plug up fast.

I got the filters from Amazon and now have one in my machine with another original filter in my wife's machine. My plan is to try them both for 3 months and see how they compare. The Amazon filters seem to be finer than the original ones. I'm a little concerned they may plug up faster than the more open weave ones. Here is what they look like. Original on left, and Amazon one on the right.

Hi, Sierra! What was the point if getting them from Amazon? Better pricing? Faster availability? If they are too different, is it a good idea? They DO look less porous than the original….

Hi Sierra, Will be very interested to hear your report on the filter "trial" in 3 months time, my pump and consumables are supplied at no cost to me by Veteran's Affairs here in Australia, I get a package every 6 months, heated hose, water tank, filters , headgear and nasal pillows and going by ResMed prices to you that adds up to a significant amount of money in running costs. I note the "service life" of the ResMed 10 is 5 years so will be interesting to see if they send me a new one at that time. I have had 2 of the Power Station II battery pack's supplied however both of them will only run the pump for about 4 hours if the heater is left running which is a little disappointing given in this country that's nearly $1k's worth!

No repeat of the hunting problem since the change of filter so I'm pretty certain that was the culprit, very odd to say the least, my filter was clean compared to yours.

We have the RESMED Airsense 10 machines. With a pressure requirement of about 12, and using the FREEDOM batteries (without humidity or heat in the hoses) we get about 13 hours per FREEDOM battery. Also, we use the pigtail connectors. So, with four batteries altogether, we get about three to four nights coverage, each. And the batteries are quite small and easy to store or transport.

I hear you re the S9, but I would recommend that you start the process moving to get a replacement, because there is shortage of machines generally out there, and it could take you months to get a new one. And, if the old S9 curls up it’s toes and dies in the meantime, you may be without a usable machine….

All good ideas, I will look into the ResMed 12 to 24 converter and I have the batteries and charger covered however I'd be interested to know the amp hour capacity of the 12volt battery you talk about Sierra?

Update on initial thread.

Hi Guys, Went to use my ResMed 10 again last night and would you believe it starts "hunting" again and I know it's not the filter so was thinking this machine will have to go for service. As I was making sure all the hoses were connected properly I pushed on the water tank and it moved just the smallest amount, maybe a millimeter or two and bingo pressure drops to normal and all is well!!!

So the original problem wasn't the filter at all, it was the tank not being fully seated which I presume creates a leak significant enough to cause the hunting but not enough to shut the pump down - makes me feel like a bit of a dill but there it is. Reminds me of the KISS principle.

In addition Sierra, I have obtained one of the ResMed 12 to 24 transformers as suggested but am still to set it up and test it, thanks for the link to the battery guide, very helpful.

Just tried the DC to DC convertor after determining on the chart that I would need a 50AH deep cycle battery, put my Fluke in series with it and maximum current draw was just under 4.5amps and that occurred when I took the mask off and the pump went open circuit for a few seconds, most of the time it was drawing between 2 and 3 amps so 50AH will be more than adequate.