Questions about BiPAP/Vent

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Very helpful member
Dec 11, 2014
Here is some background.

My breathing was affected fairly early in my progression. My first PFT showed an FVC of about 60%. That degraded steadily to an FVC of about 30% over a period of several years. The progression slowed down and over the last 2 years has slowly decreased to my current FVC of 16%. These numbers are all from tests with me sitting up. I have never had a test while supine.

A series of ABGs have shown that have the ability to clear CO2. My CO2 has never been high and is often low.

Surprisingly, to me, at least, I have not been on a BiPAP. My pulmonologist, who I very much like and respect, has said that with my pattern of breathing, a BiPAP has not been necessary. He said I would probably be ready for one this year.

Due to living at high altitude (our house is at over 8,500 feet above sea level), I have been on supplemental oxygen. I use a continuous flow of 2 liters at night (always) and then 1 to 2 liters during the day as needed. This has worked very well and I am able to be pretty active given my FVC and overall weakness.

So far, I have seen separate doctors that I have picked based on their experience and knowledge. I am very happy with them all.

Recently, my neurologist switched to a different practice that does not accept my insurance (he went to an HMO). He referred me to another neurologist that I am very comfortable with. That neurologist works at a major medical center. I have decided to concentrate my care there and move away from visiting doctors at separate location.

The result is that I now have a new pulmonologist who I saw for the first time on Friday. He knows my previous pulmonologist very well and confirmed that he is an outstanding doctor.

The new pulmonologist said that it is time to start using non invasive ventilation. He said there were two machines to consider and neither he nor his staff pushed me toward one or the other. One is the Philips Respironics Trilogy, which many folks on this forum are familiar with. The other is the ResMed Astral ( presume the 150, but don't know for sure).

They said that either device would fully support my needs and that I could start with one and switch to the other at any time. Based on this, and knowledge that the ResMed Astral has a much longer battery life (very important for our trips to Yellowstone), I selected the ResMed Astral.

They tried me out on the Trilogy to get an initial set of parameters for the prescription. It will probably be weeks before I actually get the device.

Now, with all that background, I have two specific questions.

First, is there any compelling reason that I should go with the Trilogy over the ResMed Astral? If so, I could change the order. But, the Trilogy does have a very large negative compared to the ResMed Astral, which is the battery life.

Second, Doing the trial on the Trilogy was amazing! Wow! After a minute or two of cognitive dissonance as I got used to air being pumped into me, I found that I could simply relax and stop breathing. The machine did everything for me. It was wonderful, though certainly an odd feeling that will take some time to get used to. We experimented with a variety of settings and got things to where I was pretty comfortable, though there are still tweaks that need to be made.

After about 10 to 15 minutes (it seems), we were finished and they took me off the trilogy. I found that I could not all. It was quite disconcerting. I was not able to alert anyone to this, as I could not talk because I could not breathe. After a minute or two, my diaphram slowly started responding to my efforts to breathe. I was able to communicate that I was in distress and they monitored me as I recovered my ability to breathe.

After about 10 minutes I was able to breathe well enough that they let me go, but it really took several hours for my breathing to return to what is normal for me.

Has anyone else experienced this? Can I expect that this will occur again? Every time I disconnect from the ventilator? Am I likely to become fully dependant on the ventilator 24/7 when I start using it?

In some sense, the answers to this second question don't really matter much. I am at a point where the ventilator is needed. I am just curious about how much of a life change I may encounter when I start using it.

I would appreciate any insight others can share with me.

There is no reason not to start with the Astral. I personally prefer the ResMed volume control algorithm (have worked with both Respironics and ResMed machines) and others here have found it smoother. The only reason most here start with Trilogy is the number of contracts Respironics has.

As to the problem when you disconnected, if they had it on settings that "did everything," I am wondering what the settings were. My guess is that either the trigger threshold was set very low, so you had to start breathing very little to trigger a breath, or it was in a mode where you had to do no triggering at all.

Usually these kinds of "no hands" settings are not where PALS start out, though it can be where they end up (though not usually, since triggering ability usually is less critical to longevity in ALS than ability to expel air).

So if you basically handed over your triggering ability to the machine, it is small wonder that it took you time to regain it but if it took several hours before you settled back in, I am thinking that they probably overdid the volume and your lungs got overstuffed, which you would be least likely to perceive your first time on BiPAP.

What new findings or test results prompted BiPAP initiation?

When you put your car on cruise control and then take it off, if it is going 60, it will still be at 60 for a while, even you normally never hit the highway. That probably made very little sense.

Your case is obviously unusual, but in most any scenario I can think of, we don't usually help PALS trigger more than they need help, or offer more volume than they need. The short answer is no, you should not respond as you describe after your first BiPAP excursion and so that would suggest further optimization of your mode and settings.

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My PALS, Frank, has described a feeling of difficulty breathing immediately after coming off BIPAP every morning, although it is not close to being as severe as what you describe, Steve. He is on BIPAP via trach only at night time and this has remained stable for the past 4 years.

He told his pulmonologist about this and was told to put the head of the hospital bed more upright after coming off BIPAP. I don't think this has really solved the problem. Fortunately, this only lasts a short time and then he is back to breathing normally without the Trilogy. This has not led to the need for BIPAP during the day, as I thought it would.

I think your settings need to be adjusted, as Laurie said. When Frank started on BIPAP they started him on "very gentle settings" (as the respiratory therapist said) and he did not have any problem.


I've been very reluctant to post about my experience with BiPap on the forum but it appears that I should.

My first FVC was about 68 (2014). When I had a full pulmonary function test at Mayo, it was in the normal range in all areas. However, by then my local pulmonologist had put in the order for the Trilogy.

I like to experiment with things. Before I received the Trilogy, I tried out a friend's CPap on a pretty low setting. The minute I stopped using it, I felt like I couldn't breathe. I was moving lots of air in and out but it felt like the air wasn't oxygenating my body. Within a couple of minutes, I recovered. My housemate has a CPap. He never experiences this problem. I tried his and got the same result. When my Trilogy arrived, same thing. That's when my Trilogy finally arrived, along with a cough assist. Every time I use the Trilogy, when it comes off, same thing. That experience is what made me buy my own professional breathing measurement equipment. I can move air very well, my MVV is well over 100% and that is a measure of how much air you can move in and out in 12 seconds. My MIP and MEP are both over 100%. My FVC has always been 80 or below but my SVC is always above 80. Interestingly, my FVC is higher surpine than sitting up or even standing. I think my anatomy might play a role in it.

Your situation is entirely different than mine. My ABG are also normal and Co2 on the low end of normal, which is good. That has been consistent for four years.

My feeling regarding your situation is that you've probably needed a BiPap for awhile, especially with the high altitude and what you're feeling is the difference between breathing well and the difference between not breathing well, if that makes sense.

My biggest challenge is total lung volume. It has always been 60%. I use my cough assist in reverse to expand my lungs and it actually improved my FVC. I should do it more often.

I'll know the day I start needing my Trilogy and will use it without hesitation. For some of us, it's complicated. My whole ALS history is complicated and frustrating.

Let us know how it goes.
Laurie, Sharon, and Kim,

Thank you so much for sharing your experiences and helping to educate me on this next new step.

I can accept feeling uncomfortable coming off the bipap each day, so long as I have confidence that it is something that will only last a few minutes.

Laurie, I am sure the parameters were set in a way to cause this. I don't know the parameters, but I do know they were set so that the machine breathed for me. Normally, I only breathe with my diaphragm. My chest muscles don't work and my chest does not move as I breathe. When I was connected to the trilogy, my wife immediately mentioned that my chest was moving with each breath and she had not seen that in years!

A real eye opening moment was when I decided to just stop trying to breathe and let the machine breathe for me. I only did that for a few moments, but they were moments of effortless bliss. I did not have to expend any of my energy breathing, which was amazingly wonderful.

I will plan to start off with the machine just augmenting my current ability to breathe rather than having it do the breathing for me, but I am glad I got to experience letting the machine completely breathe for me so that I know what it feels like.

The breaths were much, much higher volume than I can take by myself. It felt wonderful when I was on the machine, but it did cause my chest to be sore for a couple of days.

Sharon, I started using a hospital bed two weeks ago. It is really nice to be able to sleep with my upper body elevated. With the trilogy trial, I was seated in my wheelchair, which is normally where I breathe the best. I will evaluate body position when I get the bipap and monitor how it affects the way I feel when disconnecting from the machine.

Kim, thanks for sharing your details. I suspect we have a lot in common when it comes to breathing. My lungs are great and I have no problem taking shallow breaths. I just can't take a deep breath. My breathing is shallower when I am supine. Many people, including me, have wondered why I have not been on a bipap already.

I am looking forward to getting the bipap and getting it set up to work for me.

Hmmm, I’m no expert but I have been using a Trilogy since right after my first ALS clinic visit. So I’m experienced! My breathing wasn’t bad but just enough to qualify and my neurologist believes it is good to start early. It’s been over a year now and I use it every night. I’ve never had the feeling of being unable to breathe on my own after taking the mask off so I can’t advise you on that. The first night I used it I woke up clear headed and no headache.

I think there are two different modes - one is a simple timed pattern and the other does something more forceful or automatically. I accidentally got on the second one a few months ago and the respiratory technician who came out switched that off very quickly saying it was wrong for my needs. Perhaps someone else knows what I mean and can correct anything I’ve said that is wrong.

I too think you were overdue to start using a bipap - glad you are getting started.
Yes, there are multiple modes like PC (all breaths timed) and T (all breaths machine-controlled) that provide more machine intervention than the S/T that most PALS without trachs do best with.
Both the Astal and the Trilogy are hybrid (combination or multimode) ventilators that can provide several types of breathing assistance (non-invasive CPAP, BiPAP, AVAP) and full ventilation (invasive through a trach for those who have very little or no ability to breathe). Either will work for you but if all you need at this point is BiPAP, be aware that the cost of a BiPAP machine rental is less than the rental of a hybrid machine with its multiple modes, of which you will be using only BiPAP. (On Medicare, you own the BiPAP after 13 months but a Trilogy or Astral is always a rental) If you need other modes later, there will be no problem in upgrading to a different machine. There is a significant difference in battery power. Battery life on the Trilogy is 3 hours per lithium battery (2 are usually used) and 3 hours of an internal battery. Battery time for the Astral is 8 hours internal with 2 external at 8 hours each. Lithium batteries are smaller, weigh less but last only a year or so before needing replacement at a cost of about $400 per battery if you have no insurance coverage for replacement batteries.
For traveling, either vent can be plugged into the vehicle with a DC adapter cable available from your vent supplier.
Another option to consider is running your vent off your wheelchair battery. This requires an adapter but even with the wheelchair and vent drawing on the wheelchair batteries (12 Volt deep cycle marine type batteries) you get 16 - 18 hours. This reduces the need to replace the lithium batteries at intervals, the wheelchair batteries have a longer charge and life and lower cost of $150 to $200 each (you need 2). Only one battery to charge, none to carry along.
Doglady, thanks for your input. It is reassuring to hear that you have not experienced what I did.

Diane, I was hoping you would comment. Thank you for sharing your knowledge. The doctor has said that BiPAP is not appropriate for me and that I need the ventilator.

I currently need the ventilator when I am sleeping, so don't need to power it from the wheelchair yet. I am comfortable putting in the electrical bits (a buck converter and appropriate fuses and connectors) when the time comes to power the ventilator from the wheelchair.

In the meantime, we plan to rely on the ventilator batteries, the motorhome batteries, or the motorhome generator when we are camping in a place that does not have electricity.

The campgrounds where we camp have electrical power available, just not at the campsite. In an emergency, we will have power, whether it is from the campground outlet or from the motorhome's generator. The campground rules prevent us from running the generator overnight, but in an emergency, we certainly would.


When I read your description of your Bipap trial and the fact you could not initiate a breath for a period of time it made me wonder if the settings they had you on blew off so much CO2 that it stopped your brain's respiritory drive which is primarily CO2 driven.

I spoke with our respiritory therapist regarding your expierence and he said that could definitely have been the cause ( and thinks it was). He wondered if they were monitoring your CO2 before, during, and after? From his experience he said it is very important to make adjustments to one's breathing in small increments, in this case relative to your own breathing . Also, make sure they are monitoring your CO2 throughout. Most hospitals have capnography machines that have sensors that they attach to you to give real time CO2 levels. Some machines are more accurate than others , he said the Sen Tec is extremely accurate.

The "ventilators" (Astral, Trilogy, among others) are certainly more portable since they have internal batteries. But for clarification for newbies, it's worth noting that the vast majority of PALS will be using them as portable BiPAPs -- making use of mostly the same features as a "no battery" BiPAP would have. We can get people confused talking about BiPAP and Trilogy as if they have to be really different.

As Diane point out, the Astral and Trilogy-type machines ("ventilators") can also be used for more "auto-pilot" breathing, as would be used with tracheostomies, but most PALS have enough respiratory drive left that auto-pilot (e.g. not being able to choose how long a breath is, or when it starts) would be uncomfortable, or, as Kate points out, potentially dangerous if some of the other settings are ramped up too high.

Among the PALS I have helped with BiPAP, where an adjustment to initial settings for pressure range and/or target volume is involved, in 90% or so, it's a downward adjustment. But just as it's how you play your cards in poker, the other settings, like trigger/cycle/AVAPS rate, help you make the most of the air flow to be able to trade off what's needed/safe vs. what's comfortable.
My husband had 2 different machines through his course. First a dedicated BiPap machine, and then when he was trached, a trilogy and yes it has different settings. At first they tried him on the S/T for during the and AC at night, which did all the work for him. However, he didn’t have the ability to trigger properly and he felt like he wasn’t getting air (yes the settings were worked with in the hospital by pulmonary), so he ended up coming home with the machine doing everything for him.

His biggest issue when he first got his biPap was getting used to the mask and how drying the air can be. He complained of nightmares being stuck in the desert. It took him about a month to fully make it through the night, so do be surprised if it takes time to adjust, esp if they have you on true biPap vs. the machine working for you.

When he first got the trilogy and it was doing all the work, he said at first it was scary for him, but that lasted a very short time.

Just our experience.

Good luck to you
I thought Trilogy was just a brand name for a common type of bipap.
Doglady, my understanding is Trilogy is a specific product manufactured by Philips Respironics. It has the capability to operate as a BiPAP, but can also operate as a full up ventilator. I am new to this, so others should be along to correct me if I am wrong.

To everyone else, I have followed your comments very closely.

I am back to breathing normally on my own, but am scheduled to receive the vent "soon".

As with all things provided through a Durable Medical Equipment (DME) provider, it is taking longer than I had anticipated. When I was at the doctor's office, it sounded like I would have the ventilator very soon, certainly by now. It turns out that the prescription/order/whatever has not even been generated yet. The DME I work with is waiting for the order and I have been trading voicemails with the clinic. As of now, it will certainly have to wait until the long holiday weekend (Labor Day here in the US) is over.

We received the hospital bed a couple of weeks ago (donated from a CALS who's PALS passed some time ago). The hospital bed has made a significant improvement, because I can sleep with my entire torso elevated, rather than just having my head and shoulders supported by pillows.

The hospital bed, along with four pillows, seems to be making a significant difference.

My oxygen saturation is manageable to be above 90% with supplemental oxygen, but I currently have no idea where my carbon dioxide levels are. Historically, my CO2 has been in the low to mid part of the acceptable range.

Steve, you are correct in you description of the Trilogy, it is a one stop shop, does biPap and vent. It was DH’s vent. I’m a little surprised the clinic didn’t get right on the script for the vent, since they tested you and determine it was needed.

Happy to hear the hospital bed is working well for you. I know when DH got his, it was a huge blessing for him.

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