The Information below is provided by Brian McGreevy, a person with LGMD2I who has experience with breathing assistance. Brian is not a professional with certification in breathing devices. He is a patient that cares to share what he learned in order to help others. This is for informational purpose only.
We are grateful to Brian in sharing his knowledge about such an important aspect of LGMD2I care.

From Brian McGreevy:

It’s a lot of info, but if I had it spelled out for me in the beginning, I might have actually been able to sleep the first couple weeks :-).

I have a Trilogy 100 by Philips Respironics.
“Volume ventilation” is great because the machine ensures that I receive enough air over time. For example, it is much easier for me to breath on my side; however, when I roll onto my back, my breath is very shallow. The machine senses this and therefore increases the pressure needed in order to continue to supply me with the configured volume of air. This feature is called average volume assured pressure support or AVAPS. I believe BiPAP machines offer this feature too, but there are other factors that make “ventilators” better than BiPAP machines.

Comfort is a major factor. The Trilogy has many configuration settings that can be tweaked to provide a comfortable breathing experience. Here is how I explained the flexibility to someone in the FB’s Breathe with MD group…
Pay particular attention to the difference between the Therapy Modes PC, S/T, and AE (see below) and the add-on feature AVAPS, which can be turned on or off for the various modes to modify the way the mode works. AVAPS itself is not a mode but seems to get a lot of focus. Pro-tip: Watch the RT closely when the technical expert adjusts your settings.
When I started using a Trilogy 100, I had lots of problems due to my initial configuration (AE AVAPS) — fluttering on exhale, high expiratory pressure, unwanted/uncontrolled breaths that were too long or too short, etc. After a few days with the manual and trying different things (with the RT), we’ve resolved all of these issues, and it has been quite comfortable for me since. This thing is a pretty amazing device. Before I share what I’ve learned, I feel it’s important to say that I use the Trilogy 100 for night time breathing assistance only, not for life support.

The uncomfortable fluttering on exhale I mentioned above is a “feature” of the AE therapy mode. The AE mode (Auto EPAP, or Auto-titration) measures and attempts to continually adjust the EPAP (Expiratory Positive Airway Pressure) in order to provide upper airway pressure support (to keep the airway open). As someone without Obstructive Sleep Apnea, and with a weakened diaphragm, the AE therapy mode is not appropriate for me. Beyond the sleep disruption from the fluttering, anything but the lowest safe EPAP is uncomfortable for me. Some EPAP is necessary to vent the CO2 out of the line/mask, and I find a constant (low) EPAP value is much less disruptive than the changing value provided in AE mode.
The feeling that I was not in control of my own breathing was caused by a combination of the breath backup rate (BPM) being too high and the Inspiratory Time being too short. Mine was originally set for 12 BPM and Inspiratory Time of 0.8 seconds. This caused mandatory breaths much too frequently for me, and when they occurred, it took me a fraction of a second to react and begin to inhale, but by then, the Inspiratory Time was reached and IPAP ended, choking off my natural breath. VERY uncomfortable. Additionally, since the Inspiratory Time was so low, even when I initiated my own breath, I was never able to take a deep sighing breath without getting choked off.

With the AE therapy mode out of the picture, given that I want to control of my own breaths, and still want some level of backup breath rate, I was left with a choice between PC (Pressure Control) and S/T (Spontaneous / Timed) therapy modes. According to the manual, and from my own experience, these two modes are identical, except for one feature. Here are the descriptions of each, directly from the manual:

  1. “In Spontaneous/Timed (S/T) mode, the device delivers bi-level pressure support. This mode provides Spontaneous and Mandatory breaths. A Mandatory breath is delivered if the patient does not spontaneously breathe within the prescribed Breath Rate (BPM) setting. This ensures that the patient receives a minimum number of breaths per minute. In this mode, an IPAP is delivered during inhalation and a lower EPAP is delivered during exhalation. The duration of a Spontaneous breath is determined by the patient effort. The duration of a Mandatory breath is determined by the inspiratory time setting.”
  2. “In Pressure Control (PC) mode, the device delivers bi-level pressure support. This mode delivers Assist and Mandatory breaths. This mode is identical to S/T mode, except that all breaths have a fixed inspiratory time”

The S/T mode gives me control over my own breaths, with a backup when needed. By setting the backup Breath Rate (BPM = 9) slightly lower than my own natural breath rate (which I determined with a timer over several minutes to be 10 BPM), it allows me to initiate the vast majority of my own (spontaneous) assisted breaths. By setting the Inspiratory Time longer (2.5 sec) than even my most drawn out deep sighing breath (~2.4 sec), I always have plenty of time to inhale without getting choked off. Since S/T monitors for my exhale on a spontaneously initiated breath, it does not force me to inhale for the entire extended length of the Inspiratory Time setting — it immediately drops to the EPAP setting whenever I choose to exhale. The only time I am given IPAP for entire duration of the Inspiratory Time is when a rare mandatory backup breath occurs. This is what makes S/T mode more comfortable than PC mode, where IPAP is given for the entire duration of the fixed Inspiratory Time setting regardless of whether it was a spontaneous or mandatory breath.

That brings me back to AVAPS (Average Volume Assured Pressure Support), which is not a therapy mode itself, but rather an add-on feature which is really quite amazing. With the AVAPS feature turned ON, the Inspiratory Positive Airway Pressure (IPAP) value varies between IPAP Min and Max settings to provide a consistent target Tidal Volume of air whether on my side, on my back (higher pressure), or sitting upright (very low pressure needed). This combined with a nice low EPAP value of 4 or 5 cmH2O makes inhaling and exhaling quite comfortable regardless of my position.

Finally, there are the alarms. The very first thing my RT did was disable each and every one of them. He said if this was for life support AND I had someone here to respond to them, then he would carefully choose which alarms to implement.

BiPAP machines are more basic in function.
The biggest feature that people easily overlook at first is battery backup. Ventilators have it, BiPAPs don’t. If the power goes out while I’m in bed, I know the batteries will allow me to breath for another 6-8 hours. I won’t even know the power went out. It’s happened to me several times.