Bipap and starved flow with masks

dataq1 · Post by **dataq1** » Wed Jan 03, 2007 4:32 am

I began with CPAP a bit over two years ago, then to APAP, and for the past several months on AutoBiPAP. My DME dropped the machine off with (I think)... I was using a Ultra Mirage FF at the time. Then DME suggested the FP 431. I started that and liked it better than the Ultra Mirage. Lately I been trying to use the Hybrid. I like that even better but it taking some getting used to.
My main stumbling block is that during therapy, whenever I take a deep breath about half way through it I suddenly feel like I'm being starved for air. I thought that I'd get used to it, my breathing would self-modify, but it continues to be a event that wakes me up with the feeling that I'm being strangled.
I tried going back to the FP 431 full face mask and find that the same thing takes place but it much more subtle. On the FP mask, it's as if there is just a little "hitch", a little "bump" if I'm lying awake and quietly breathing then take deeper breath. I wonder if the volume of the masks or the amount of air that is normally vented has anything to do with this.

If I watch the pressure display on the LCD there seems to be a pressure "divot" occuring inhalation. During inhalation, the pressure display says 8.0 cm, at some point (while still inhaling) the pressure drops to 4 or 3cm. What causes this?

I'm also wondering about my settings. Those autobipaps please help me!
My current settings are:
ABFLE, 4.5 EPAP MIN, 15 IPAP MAX, 7 PS, 2 Flex, 0:20 ramp, 4.0 Ramp Start, 0:00 Start.

Julie · Post by **Julie** » Wed Jan 03, 2007 5:39 am

Hi, you might ask your MD to refer you to a pulmonologist, or at least for a basic respiratory test (not the same as a PSG) to see more specifically where the problem is. PS - Hope to be able to PM you later today or tomorrow with other news.

dataq1 · Post by **dataq1** » Wed Jan 03, 2007 8:30 am

Hi Julie;
I'll look forward to your news later today. Actually my MD is a pulmonologist. After I took a pulmonary function test that was found to be normal, then was sent for sleep study. But any additional thoughts on the subject would be appreciated.
I'm thinking that perhaps the functionality of the biflex setting maybe somewhat between different masks. I'm not suggesting that the machine functions differently (although I suppose that possible), but rather that the smoothing at the end of a cycle may feel different to the user.
I also thought that the "smoothing" with the biflex and cflex functions was at the end of exhalation and the beginning of inhalation. In my case however something seems to be happening just before the end of the inhalation phase.
thanks to all,

dsm · Post by **dsm** » Wed Jan 03, 2007 4:21 pm

[quote="dataq1"]I began with CPAP a bit over two years ago, then to APAP, and for the past several months on AutoBiPAP. My DME dropped the machine off with (I think)... I was using a Ultra Mirage FF at the time. Then DME suggested the FP 431. I started that and liked it better than the Ultra Mirage. Lately I been trying to use the Hybrid. I like that even better but it taking some getting used to.
My main stumbling block is that during therapy, whenever I take a deep breath about half way through it I suddenly feel like I'm being starved for air. I thought that I'd get used to it, my breathing would self-modify, but it continues to be a event that wakes me up with the feeling that I'm being strangled.
I tried going back to the FP 431 full face mask and find that the same thing takes place but it much more subtle. On the FP mask, it's as if there is just a little "hitch", a little "bump" if I'm lying awake and quietly breathing then take deeper breath. I wonder if the volume of the masks or the amount of air that is normally vented has anything to do with this.

If I watch the pressure display on the LCD there seems to be a pressure "divot" occuring inhalation. During inhalation, the pressure display says 8.0 cm, at some point (while still inhaling) the pressure drops to 4 or 3cm. What causes this?

I'm also wondering about my settings. Those autobipaps please help me!
My current settings are:
ABFLE, 4.5 EPAP MIN, 15 IPAP MAX, 7 PS, 2 Flex, 0:20 ramp, 4.0 Ramp Start, 0:00 Start.

dataq1 · Post by **dataq1** » Wed Jan 03, 2007 4:37 pm

DSM, Thanks for your observations.

I've toyed with the idea of blocking some of the vents on the Hybrid but wanted to get a firmer understanding on what was happening before experimenting and ending up with too many variables "in the air".

Also sounds like all masks don't play nicely with all XPap machines. That will be a shock to my DME.... they have told me over and over that the FDA (or someone in Washington) makes sure that masks are interchangeable (between XPap machines). The only reason for different kinds of masks is for different facial structures, different comfort levels and different breathing issues).

Anyhow, thanks for your info.

dsm · Post by **dsm** » Wed Jan 03, 2007 4:46 pm

To get an idea of just how different masks are take a look at the fixed leak rates here

http://www.internetage.com/cpapinfo/leak-rates-1.html

Also it is well known now that different masks have quite different 'deadspace' volumes. This affects the amount of re-breathed CO2. Some CO2 is a neccesity for most of us but each type of mask will vary this greatly.

Good luck.

DSM

rested gal · Post by **rested gal** » Wed Jan 03, 2007 8:23 pm

dataq1 wrote:I also thought that the "smoothing" with the biflex and cflex functions was at the end of exhalation and the beginning of inhalation.

It's just the opposite. Bi-flex and C-flex drop the pressure some at the beginning of an exhalation.

The amount of drop they give is almost completely dependent on the force of a person's exhalation, regardless of their setting ("1" being least drop, "2" being more drop, "3" being most drop.)

When using Bi-Flex with a bipap, I think of Bi-Flex as being icing on the cake...a bit of additional drop to the beginning of an already lower pressure setting for EPAP -- the exhalation pressure.

It's normal to feel the "regular" pressure come back in before an exhalation is entirely finished, whether the "regular" pressure is the lower EPAP pressure in a BiPAP machine with BiFlex enabled, or the "regular" pressure in a CPAP or AutoPAP machine with C-Flex enabled.

That, of course, is not the same thing as the bump, hitch, or cutoff you feel when taking in a very deep breath during the IPAP (inhalation) pressure phase. At the first hint of dwindling during a very long inhalation, the machine will sense the lessening of inhalation as the inhalation ending and yes, will switch to the lower exhalation pressure. That can certainly feel like a premature cutoff while still inhaling.

Nasal congestion causing "sniffing" or any kind of stutter while breathing in through the nose can cause the bipap to change from IPAP pressure to the lesser EPAP pressure. Usually the only time I feel that happen while inhaling, using any kind of mask, is if I deliberately take an unusually long inhalation. Very deep breath.

If it were me, I think I'd raise the EPAP pressure to 7 or 8 on your BiPAP Auto's settings. I'd turn off the ramp (0:00) but that's an individual preference.

christinequilts · Post by **christinequilts** » Wed Jan 03, 2007 9:18 pm

From the Respironics website:

Bi-Flex "softens" airflow at inhalation and exhalation, making breathing more natural and comfortable for patients. In Bi-Flex mode, patient-adjustable pressure relief is provided at the critical stages:
1. EPAP to IPAP
2. IPAP to EPAP
3. During exhalation

Since BiFlex has the potential to affect more aspects of the IPAP-EPAP cycling, why not turn it off? I know it was possible on the older style autoBiPAP, leaving you with Rise Time only to help smooth the transition from IPAP to EPAP. Rise Time only affects how quickly it transitions from IPAP to EPAP; 1 is very fast (100msec) to 6 (600mscec). Having used a Synchrony BiPAP ST, 3-4 was very comfortable; 1 was way too rapid of a change (think hairpin curves). Like CFlex, BiFlex is not a quantifiable relief, its based on how you inhale & exhale, so it will vary from one time to another; Rise Time will be the same each time and it only affects one part of the IPAP-EPAP cycle.

Rested Gal's suggested of raising your lowest setting is a good idea too, as most people would feel starved for air at 4. The dip to 3 or 4 is caused by the BiFlex's momentary pressure relief, which allows it to go lower then your EPAP min for a breath second, as shown in the diagram above.

curtcurt46 · Post by **curtcurt46** » Wed Jan 03, 2007 9:34 pm

I used to feel the cutoff quite a bit when my EPAP was at 5cm. I have since gone to 9cm and I don't get that cutoff feeling.
I believe Rested gal is right on the point. Try the pressure increase as she recommended and I bet the cutoff is reduced or not very noticable.

oldgearhead · Post by **oldgearhead** » Thu Jan 04, 2007 7:53 am

At an EPAP pressure of only 4 + CFlex, you may be experiencing the
seal of the check valve un-seating, then re-seating. Raise the EPAP
pressure. Also shut off the ramp.

_________________

CPAPopedia Keywords Contained In This Post (Click For Definition): cflex, seal

dataq1 · Post by **dataq1** » Thu Jan 04, 2007 2:44 pm

Great insights and information.... I knew that I could count on the community to help !
Thanks much, I'll be putting suggestions into action tonight.

Bipap and starved flow with masks

Bipap and starved flow with masks

Re: Bipap and starved flow with masks