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+--- Thread: Best to Lower FlowLimitation or AHI (/Thread-Best-to-Lower-FlowLimitation-or-AHI)
Best to Lower FlowLimitation or AHI - zzzZorro - 07-29-2018
[Quote] ..an experiment in which two groups of patients diagnosed with OSA were treated with different CPAP pressures. The first group was treated with CPAP pressures targeted to eliminate flow limitation and the second group treated with CPAP pressures targeted to treat apneas, hypopneas and snores. The pressure requirements for the first group were higher than for the second group; however the first group had an increase in sleep time and more consistent improvement in maintenance of wakefulness testing.
The role of flow limitation as an important diagnostic tool and clinical finding in mild sleep-disordered breathing
RE: Best to Lower FlowLimitation or AHI - Walla Walla - 07-29-2018
It's kinda like asking if it's better to put out the brush fire or put out the match. Flow limitations being the match. As Sleeprider has said many times the key is pressure support more than just higher pressures.
RE: Best to Lower FlowLimitation or AHI - sheepless - 07-29-2018
WW, this is something I've asked about a several times but got no replies. can you explain in a little more detail?
if FL's are one end of the continnum of disordered breathing and apnea is the other, it isn't clear to me why lower pressure wouldn't nip the formative stages of apnea (FL) and higher pressure would be required to resolve full obstructive apnea. instead, it seems to be the opposite.
also, I don't really understand how pressure support is different from pressure/ipap. doesn't pressure support simply increase pressure (ipap) on top of epap? epap + ps = ipap? guess I'm confused about how pressure and pressure support differ. or ipap vs ps.
maybe what you are saying is min ps is key to dealing with FL's?
RE: Best to Lower FlowLimitation or AHI - Walla Walla - 07-29-2018
(07-29-2018, 12:50 PM)sheepless Wrote: WW, this is something I've asked about a several times but got no replies. can you explain in a little more detail?
if FL's are one end of the continnum of disordered breathing and apnea is the other, it isn't clear to me why lower pressure wouldn't nip the formative stages of apnea and higher pressure would be required to resolve full apnea. instead, it seems to be the opposite.
also, I don't really understand how pressure support is different from pressure/ipap. doesn't pressure support simply increase pressure (ipap) on top of epap? epap + ps = ipap? guess I'm confused about how pressure and pressure support differ. or ipap vs ps.
maybe what you are saying is min ps is key to dealing with FL's?
I'm no expert on this subject. I have a problem with flow limitations even when the apnea is controlled. With a CPAP the maximum pressure support I could use was 3cm. This led to me having to increase the Minimum pressure higher to try and control the flow limitations. When I use a BPAP I can increase my pressure support to 4cm which controls the flow limitations without having to increase the Minimum pressure (EPAP). Though due to the higher pressure support the IPAP is higher it still is easier to exhale. The added benefit is it also helps increase Tidal Volume which can help with O2 levels. Why does pressure support work? I dunno know ask sleeprider.
RE: Best to Lower FlowLimitation or AHI - sheepless - 07-29-2018
WW, thanks for the informative response. I think what I got from it is that we're talking about min epap (for asv, which I use, 'cause I think bipap has one epap setting?) and min ps rather than pressure generally, meaning (to me) probably max epap and max ipap. still a little confused though. Sleeprider?
meanwhile I think I've gleaned from here and another thread that we use epap to control oa; min ps for h and fl's. for the asv, I believe that's min epap? I've been leaving max setting at max to let the machine determine how high to go. frequently ipap max reaches 25cm so I use max settings despite increased aerophagia. not sure if/when to reduce max epap.
devil's in the details.
not meaning to hijack zzzZorro's thread. hopefully still relevant despite my asv auto vs Z's vauto.
RE: Best to Lower FlowLimitation or AHI - Walla Walla - 07-29-2018
Yeah ASV is a whole different animal.
RE: Best to Lower FlowLimitation or AHI - sheepless - 07-29-2018
I may be wrong of course but assume the 'mechanics' of titration are similar w respect to what each adjustment option is used for. need to hear from other bilevel users and Sleeprider and/or a link to a reference for clarification.
RE: Best to Lower FlowLimitation or AHI - zzzZorro - 07-30-2018
No Takers? Ideas?
RE: Best to Lower FlowLimitation or AHI - Crimson Nape - 07-30-2018
I look at the two as being different, thus different methods for treating them. The flow limitation can be controlled by increasing the pressure delta between inhale and exhale. The OSA can be treated by increasing the exhale pressure high enough to provide a back pressure necessary to keep the airway open. I don't see why you would only address one of them. Unless I'm missing something, I look at this like Apples and Oranges. Both are spherical, but I sure wouldn't want a slice of Orange pie.
RE: Best to Lower FlowLimitation or AHI - Sleeprider - 07-30-2018
I think treatment of flow limitation with CPAP is a very unreliable approach and the use of bilevel can be much more effective. This is one of the reasons I really like the Resmed Autosets with EPR vs Philips Dreamstations with Flex. Although the Resmed machines are limited in pressure support/EPR to 3-cm, that can help. Bilevel may be the ideal therapy approach for flow limitation and UARS as suggested in this article by Dr Krakow in our Wiki. http://www.apneaboard.com/wiki/index.php?title=Flow_Limitation/UARS_and_BiPAP