Ventilator-Patient Synchronization

[Ra7y]

I was a CALS for a time and my PALS was my beloved wife of 57 years, Marilyn. I read the alsforums almost daily and the advice and knowledge you good folks provided nearly kept my head above water. Your guidance was almost always better than what I got locally. Thank you thank you thank you.

Marilyn passed away on June 30 and now I am just a mourner. I don’t know why, but I still read the alsforums.

My grieving has been dominated by my guilt over my management of Mar’s respiratory therapy. A particular question is literally costing me a lot of sleep and so I am asking you good folks to straighten me out so I can progress. I’m trying to be as terse as possible so I am leaving out many things so I can get to the point.

A post by timorous beast on April 25 (mis/adventures in BiPAP, #5)prompts this. TB lists the settings on their new Breas Vivo 45LS. They are nearly identical to the settings we were given on the same machine. My big question mark is the breathing mode, PCV (A+Tgv). The Breas User Manual says this about the PCV (Pressure Controlled Ventilation) breathing mode: “In the PCV mode the ventilation is controlled by the Vivo 45 LS. This is done at the preset pressure, breath rate, inspiratory time, and rise time settings set by the operator.” I have read that this mode is used when the patient is comatose or sedated and does not have a respiratory drive, that is the patient is not spontaneously breathing. Why is this useful for an ALS patient?

The Vivo can also supply a breathing mode called PSV (TgV) (Pressure Support Ventilation). The User Manual says, “In the PSV mode, the patient’s spontaneous breathing is assisted by the ventilator. The patient controls the start of inspiration through the inspiratory trigger and the start of exhalation by the expiratory trigger.” This sounds more useful to me.

I observed my PALS closely while she was on the Vivo in the PCV mode. I saw and heard that she and the ventilator were NOT synchronized. Because the Vivo was supplying a steady 14 breaths per minute and Marilyn was spontaneously breathing at 20 BPM there were very few times when she was actually inhaling when the Vivo was supplying inspiratory pressure. It looked and sounded very wrong to me. Everything I read about respiratory therapy stressed strongly the need for complete synchronization between the ventilator and the patient.

I complained about this many times but the RT said it was the proper way to treat a PALS.

Marilyn was hospitalized briefly twice and in each case I observed that the hospital ventilator was in very good synchronization with her normal breathing. It was strikingly different from what I saw and heard at home with the Vivo.

What am I missing? Why was Marilyn’s ventilator almost completely out of synchronization with her breathing?

 

[lgelb]

I am very sorry about Marilyn.

As it happens, the CALS that you mentioned and I worked out more appropriate settings than those initially set, including the use of the PSV (TgV) mode, which, you are right, is better for most PALS than the PCV mode. As you point out, the "C" is for control; the "S" is for support, so it does allow for better synchronization, and you are also right that synchronization is the goal as you saw in the hospital.

The TgV (target volume) applies in both cases because in ALS, unless someone is coughing/choking or actively dying, you are generally aiming for a consistent target volume of air to be moved -- not too much, not too little.

I am also sorry you were misinformed by the RT. I see this a lot. They might benefit from a followup letter or email if you find yourself able to do that at some point.

But do not feel guilty. You did the best you could and pushed back on what seemed wrong. And I am sure you were an excellent husband and caregiver to her. That matters way more than anything.

 

[Finndoodle]

I found this post very informative! My husband just started NIV and having a difficult time adjusting so I’m going to check these modes!!! Thank you for the post!

 

[lgelb]

I am always happy to help with settings -- I'll PM you.

 

[TFB]

I received a Louisa bi-pap a week ago. I, too, am having trouble adjusting to sleeping with it. I have the full mask that covers my nose and mouth. I told the RT that, at times, the machine blows longer than usual, and it freaks me out because I am ready to exhale. She came and made adjustments to it, but it still does it at times. Maybe it is responding to something I'm doing when it blows longer than usual. Sometimes I'll lay there for an hour trying to initially go to sleep or trying to go back to sleep when I wake up at 2 or 3am. Eventually at 2 or 3 am, I give up and take it off. Usually, I get about 3 hours on it, but last night I got 4.5 hours. My insurance requires 4 hours, but I believe she said I have 90 days to adjust. I feel like I need to synchronize my breathing cycle with the machine, so that occupies my mind, and I can't go to sleep. Also, breathing naturally becomes shallower when asleep, but when I wake up, it's still blowing hard. I've read other posts in this thread, but I'm kinda afraid to mess with the settings. Have other PALS experienced what I've described here and how did you overcome?

 

[lgelb]

Synching with your natural respiratory drive is critical, for sure, and the 16 settings in Luisa's VAPS mode (the mode that most PALS need) are not something you can expect an RT to get right in a few minutes on spec. Plus, your own breathing changes over time as ALS progresses.

From your description, the machine may be overcompensating for leaks, which is often the case when your pressure range and possibly target volume are too high (pretty common given the myth that you can overload weak muscles with air in ALS and it'll all work out).

As you say, timing settings should mesh with how you want to inhale/exhale. The RT may have also set an unrealistic backup rate, triggering breaths you don't need, especially in deep sleep. And backup breaths, which we can usually avoid triggering anyway, often have the most disruptive settings precisely because they are not breaths your body asked for.

I'll PM you to see if you're interested in help.