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my experience with LT vs 418P (long)

Posted by BeardedMan on January 20, 2002 at 20:58:21:

I thought I'd write my observations on using both the Autoadjust/LT and the GoodKnight 418P. I think my experience underscores what anyone who is thinking of buying/using a auto-CPAP should consider.

I've been using an Autoadjust LT for almost 18 months now. It's been a great machine for me. I never had any problems with it (other than a chip going out and a couple weeks waiting for it to be fixed and being consigned to a regular CPAP machine for the duration). I had only used a CPAP (Resperonics Solo Plus) for several months before deciding (based on the discussions here) to buy an Autoadjust/LT. I got it, got the settings worked out and haven't looked back since. Then the 418P came out and the thought that maybe this would be a better machine for me started working on my head. After the power in my area went out several times and getting really poor sleep because of this, the thought that I should try it became stronger.

Due to the likelihood of power going out, I wanted to get another machine that would run on DC power so that regardless, I would have a machine to use. Also, it would just be nice to have a machine around that could serve as a backup if something happened to my main one. So, since I'd been hearing good things about the Goodknight 418P, since it will work on DC power, and I like to be able to track how I'm doing, I decided to go ahead and order it as a backup machine.

I got it in and I'll have to say that it's a nice machine. Quiter than the LT and has a slightly smaller (if higher) footprint. I thought the cost of the machine was quite reasonable (approx. $900). The cost of the software, however, is on the silly side. Four disks at only $150 per! More detail than I really need, but it does have some features that I like better than the LT's software.

Well, I had to try it out. I started thinking that maybe I'd just go ahead and use it as my main machine and have the LT as my backup. I could get a battery and have it hooked up so that I wouldn't have to do anything if the power went off in the middle of the night. It would just keep going. Anyway, I fired up the software and set the settings to what I have them set to on the LT (min. 5, max. 9 - prescription is 8) and went to sleep.

Due to the way that the software works, I needed to download my data every morning or I'd lose the data for the previous night. The first couple of nights, I noticed that I had a LOT more apneas than I ever usually got with the LT (my average is usually 1-3 total apreans - apneas (0-1) and centrals (1-2)). Somewhere in the neighborhood of 10 - 15. Well, I bumped up the minimum pressure by 1 and did a couple more nights. Less apneas but still more than I wanted. Bumped it up again and tried for a couple more nights. Now, I was just 1 under my prescribed pressure and I was still getting around 5 apneas per night.

During all of this, I was starting to feel more tired and sleepy in the evenings. Then I started feeling really tired in the middle of the afternoon. I was having headaches more and more frequently. I was NOT feeling good at all. I suspected it was the way the 418P was responding to my OSA.

I switched back to my LT and almost immediately (after 2 nights) was feeling more my regular self. I did some searching and found some advice that Perry had concerning some of the differences between the machines. Mainly that one, the 418P, is a flow limitation based machine, whereas the LT is not. Digging a little deeper, I have come to the realization that I don't have a "good flow limitation precursor", to quote Perry. If I understand this correctly, I don't always snore before I have an apnea. Armed with this knowledge, I realize that the 418P is probably NOT the best machine for me. It will work fine for the original reasons that I want to use it for - backup if main machine breaks or power goes out.

I guess that the point that I wanted to convey was that if I had started out on a flow limitation machine first, I would have a much different view on auto-CPAP machines than I do now. I would not have had the quick, wonderful response that I had with the LT. Instead of feeling great and rested, I would have been more tired (because of the more frequent apneas) and such and taken much longer to get to my normal rested self. It's really a shame that something like this is not regularly told to us as patients when we have our sleep studies performed, if the data is readily available or could be easily gleaned.

Anyway, this was my experience. Your mileage may (and probably will) vary. I'm glad that I know now what type of machine I should be looking for in the future when I buy another in a couple of years. I was alway curious about the difference between a flow and non-flow limitation machine. Now I know first hand. Very useful knowledge, I would say.

Hopefully, this will be of some help or interest to others.


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