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Can anyone please explain to me why CPAP is normally limited to a high of 20cmwp and BiPAP and ASV are allowed >20cmwp. It would seem to me that no matter what type of machine the limitations would be the same. This is a concept I have yet to be able to wrap my brain around.

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I sure have no explanation!!!

Maybe it has to do w/the difficulty of acclimating to such high pressures when the CPAPs are limited in the amount of expiration pressure relief they can provide?

Respironics never tells us how much pressure relief their C-Flex and A-Flex is able to provide but the Resmeds provide their EPR in 1 cm increments and 3 cms of pressure relief is the most they can provide.
I think it's because exhaling at a pressure over 20cmH2O is really difficult. Protocols vary from sleep lab to sleep lab, and Dr. to Dr. At one lab I work with, once someone titrates to 16cm, they are switched over to BiLevel. Occasionally, I've seen prescriptions for CPAP at 20, but it's very rare.
At my lab we are allowd to titrate to 20cmwp. It is very rare though. The earliest we are allowed to switch to bipap is 13cmwp. i do belisve it has something to do with exhaleation. I also believe that it has something to do with maintaining a respiratory rate. thanks for tyour input.
Rock Hinkle, keep in mind that I have COPD so my numbers are NOT going to fit the "normal" stats. I've often wondered since being able to access my CPAP and then VPAP data how far off my COPD Respiratory Rate and Exhalation rates are from "normal" people.

My Median RR has been averaging 18, my 95th Percentile 20 and Maximum 24 BPM. I tried asking that Mayo sleep pulmo this question but he was off on his tirade about the unreliability of data from these xPAPs and I'd never thought to ask my local sleep doctor.

My only data on Exhalation rate is from a Peak Flow Meter, not from my CPAP, APAP or VPAP Auto so I don't know how that would stack up with the data you would get w/a PSG. I run about 130 to 150 LPM. Three years ago my "danger" level via Peak Flow Meter was 230 and my "medication" level was 410.

I would suppose this last question would be better asked of Rock Connor since he is an RRT. But since I have your attention ....
Judy honestly I do not know. I am very good at normal CPAP titrations. I am getting better at BiPAP, but I haven't really done enough at my current lab, and I have done 1 asv titration. So I will wait for Rocks answer with you. Sorry I would rather say Idon't know than give you a wrong answer. I could use some info on COPD though.
Well, there is an excellent support group mailing list w/at least one great RT who takes part quite often there. The posts can also be read in an archive format. Its called EFFORTS. I haven't been taking part in probably a year or better - but it IS really a very valuable site. EFFORTS = Emphysema Foundation For Our Right To Survive. COPD just isn't as "interesting" as OSA and xPAPs *weak wicked smile* I would encourage ANYONE who has COPD to take an active part in Pulmonary Rehabilitation if it is available to them tho. PR can make a HUGE difference in how well one does and how much one can do!!
I'll bring this to Rock Conner's attention by leaving a link to this page on his profile page, just in case he doesn't check this thread on his own. by the way, this is an excellent way to get someone's attention about anything as a general rule -- just leave a comment on their profile page.
Back in the olden days there was nasal CPAP for obstructive sleep apnea, & there was mechanical ventilation for a variety of respiratory disorders. As technology & practice have advanced, the line between those two modes have blurred.

I struggled with it until my medical director got it through my little head that I understood that ASV is really very smart face positive pressure ventilation. Twenty cm H2O is a very high pressure for CPAP, but for a ventilator it's pretty moderate. Similarly, bilevel w/o a rate is just like the old pressure support mode on mechanical ventilators. Whereas the vent in pressure support mode might be set at PEEP 4 cm H2O & PS 20 cm H2O, to achieve the same ventilation one could set a bilevel unit at 24/4 cm H2O.

ASV is an advanced pressure support ventilator that keeps track of a rolling time window & maintains that ventilatory pattern should the patient drop off for obstructive or central reasons. An ASV device is like an auto-adjust ventilator, though that similie is limited. As an RRT, the idea of mechanical ventilation without alarms & response teams is scary, so it has taken me a while to warm to ASV. Now, though, after having seen patients respond to ASV & get their sleep on, I'm an advocate, though I remain vigilant for the distinction between ASV & life-support mechanical ventilation.
Typically folks w/ COPD take more frequent, smaller breaths than the norm, & their peak expiratory flow rates decrease as the disease progresses.

I haven't done any testing or research about the reliability of accuracy & specificity of the data reported by xPAP devices, but I pretty much take them as trends & estimates except for the respiratory rate. We can get good & useful info from download info without trusting it as we would have trust the accuracy of a blood gas report or O2 analyzer.

Judy said:
Rock Hinkle, keep in mind that I have COPD so my numbers are NOT going to fit the "normal" stats. I've often wondered since being able to access my CPAP and then VPAP data how far off my COPD Respiratory Rate and Exhalation rates are from "normal" people.

My Median RR has been averaging 18, my 95th Percentile 20 and Maximum 24 BPM. I tried asking that Mayo sleep pulmo this question but he was off on his tirade about the unreliability of data from these xPAPs and I'd never thought to ask my local sleep doctor.

My only data on Exhalation rate is from a Peak Flow Meter, not from my CPAP, APAP or VPAP Auto so I don't know how that would stack up with the data you would get w/a PSG. I run about 130 to 150 LPM. Three years ago my "danger" level via Peak Flow Meter was 230 and my "medication" level was 410.

I would suppose this last question would be better asked of Rock Connor since he is an RRT. But since I have your attention ....
Here's a decent explanation of flow rates in the COPD process.
http://www.sierrabiotech.com/bt_copd_pat_copd.html


Rock Conner RRT said:
Typically folks w/ COPD take more frequent, smaller breaths than the norm, & their peak expiratory flow rates decrease as the disease progresses.

I haven't done any testing or research about the reliability of accuracy & specificity of the data reported by xPAP devices, but I pretty much take them as trends & estimates except for the respiratory rate. We can get good & useful info from download info without trusting it as we would have trust the accuracy of a blood gas report or O2 analyzer.

Judy said:
Rock Hinkle, keep in mind that I have COPD so my numbers are NOT going to fit the "normal" stats. I've often wondered since being able to access my CPAP and then VPAP data how far off my COPD Respiratory Rate and Exhalation rates are from "normal" people.

My Median RR has been averaging 18, my 95th Percentile 20 and Maximum 24 BPM. I tried asking that Mayo sleep pulmo this question but he was off on his tirade about the unreliability of data from these xPAPs and I'd never thought to ask my local sleep doctor.

My only data on Exhalation rate is from a Peak Flow Meter, not from my CPAP, APAP or VPAP Auto so I don't know how that would stack up with the data you would get w/a PSG. I run about 130 to 150 LPM. Three years ago my "danger" level via Peak Flow Meter was 230 and my "medication" level was 410.

I would suppose this last question would be better asked of Rock Connor since he is an RRT. But since I have your attention ....
THANK YOU, Rock Connor!!! I've only read that first page so far and since I have dial up, didn't "do" the video yet, but WOW! Just the type of info that DOES grab my interest and DOES answer a couple of questions I've had. AND, this lady's progress and duration of "success" was awesome and inspiring!!!! I will be pouring over the full article and video later this evening - or tomorrow. Horse show today and lots of fresh air and walking and I'm a bit tuckered.

Gotta brag!! The last class of the day was a Relay Race. My granddaughter and her cousin. She rode down to the box. He raced to the box to hand the baton. The two horses decided to jump apart so they couldn't reach far enough for the hand off. I don't know what he was thinking but he TOSSED the baton to her! AND she caught it!!! She was so shocked it took her a second to remember to race outta the box and down the arena. THEY WON THE CLASS! This is the high school Equestrian Team competitions. We were all so stupified NONE of us video taped it! To add frosting to the cake our Equestrian Team won their Division.

But back to .... Mike, thanks for drawing Rock Connor's attention to this thread. jnk, thank you for sharing your heart. That's sweet of you. Its the FRUSTRATION of not having someone who understands the VPAPs, VPAP therapy, pulmonary function, to just sit down with and ask questions and have some things explained and .... grrrrr. Heck, I would happily BUY an hour of such an RRT's time - if it weren't for the freaking doctors putting the ki-bosh on that idea!! There are times I'd like to pack the whole lot of doctors in a barrel and set them adrift over Niagra Falls!! Maybe we need some PAs and NPs w/an RRT "sub-specialty" on staff at each and every sleep lab to schedule consults with as needed or requested by the patient. Yeah!! Maybe THEN the dang sleep doctors would loosen up - probably not tho.

And now, to check thru the other threads and then dig into that article Rock Connor has shared. THANKS again, Rock!!

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