assistance with analyzing cpap data

[jentlesoal]

Hello members,

I'm hoping someone on the forum can help me interpreting the data from my Philips Dreamstation 1. I'm using the Dreamstation 1 with nasal CPAP nasal pillows. Although I have been using the unit faithfully for over 5 years, sleep quality is poor and sleep has NEVER been restorative. This lead me to see if the CPAP data can provide answers as to why the sleep quality has not improved with CPAP.

Below are screen shots from one night. The same abnormalities in this sleep session, are common to some degree every night. To summarize the abnormalities; there are reduced flow rate, abnormal waveform (expiratory pressure seems to be reduced when compared to inspiratory pressure), and reduced tidal volumes, often in the 200s. My tidal volume reference value should be 580. This is occurring with normal respiratory rate, so the abnormalities do not appear to be deep sleep or rem sleep related.

Questions:

1. What causes a reduced flow rate?
   
2. What causes a wave form that is not symmetric? In my data, it appears that the pressure is longer on the inspiratory effort, and shorter on the expiratory effort. Am I correct that both lengths should be equal?
   
3. What causes low tidal volume with normal respritory rate? The basal tidal volume for my height and weight should be approx 580. The data shows my tidal volume average is 380 over the past year and often dipping the single digits and often 100-200 through the night. Is that normal, and if not what does that suggest?
   
4. Am I correct, that these metrics appear to indicate nocturnal hypoventilation?
   

Thanks everyone/anyone for reviewing my post and providing any feedback!

[Jay51]

I have been diagnosed with hypoventilation, and you possibly could have it.  But it is too early to tell.  

Your flow rate graph from a pretty far distance in the upload you provided looks like the tops are a little bit pointed.  Probably some flatness to them also.  

Could you please upload images of the regular OSCAR that shows your pressures, and all of the important information so you can get much better suggestions as to how to proceed?  

I went back and looked at your old posts, but they did not have the tidal volume included on them or other important information.  

Thank you very much.          Organize your OSCAR Charts

[jentlesoal]

Hi Jay,

Thanks so much for the reply. I was able to download my lateset stats, which are attached.  Please let me know if you need the screen shots as well. Im just trying to find some answers and improve my sleep qlaity, and sincerialy apprecaite your opinon.

Thanks again!

JS

[Phaleronic]

Hello jentlesoal

I use a similar machine (dreamstations), it is a good machine and actually in my years of trying different makes and models (and vendors) it's one the better ones, if you take apart the motor air chamber it has a much more robust motor than the other vendors (and you can use flex/epr without having to increase pressure or lose apnea/hypopnea control) so you're on the right track. Please change the flex mode to cflex or cflex plus, and set min pressure to 11cm (your 95 percent pressure is right around that). A-flex does not work quite as well.

Also please disable ramp and if you are able use F12 in the daily tab to save a full screenshot and attach it here.

I will check out your first group of charts now.

[Jay51]

You are welcome JentleSoal.  It looks like you are in APAP mode with 8 min 15 max.  With a flex set to 3.  I must admit I am not an expert on this machine.  There are some experts on this particular machine that may be able to give you much better suggestions.  

Your flow limitations data is still missing.   That is important.  Also, your median, min, 95%tile and 99th%tile numbers are missing also.  They are usually seen just above the statistics that you posted on the left hand side of your OSCAR chart. 

No worries.  We are getting there.

[jentlesoal]

Good morning.

I  just wanted to take this opportunity to thank all of you for taking the time out of your daily schedule to address the needs of countless people, including me, that you have not met and may never meet.  Your charity of time and knowledge is deeply appreciated, and indictes that you all are the epitome of good Samaritans.  

Phaleronic, thanks for the feedbck. I haven't yet had the opportunity to apply the changes to the Dreamstation changes that were suggested, which I plan to do.  Once Ive made the changes I will provide updated data, and a sleep quality summary of the impact of the changes, as well as F12 data screen capture.

Jay51, I will try to determine why the values that you are requesting are not being displayed, but I'm pretty confident I will figure it out, as its most likely a setting.  Also, in reading over your profile, I see that your assured flow rate is 500! OMG, I can only dream about such an outstanding value! Hopefully one day soon I will be there as well, and given the feedback I've received so far, I'm confident that I'm now on the right path.

Thanks again to the both of you, and have a great day!

Jentlesoal

[jentlesoal]

Hello friends.


So I have made one of the changes suggested.


Phaleronic- I changed the setting from A-Flex, to C-flex. I wanted to try this change first before making any pressure changes to see if it improved my sleep quality and resolved my sleep symptoms. Unfortunately, the change did not. I plan to give it a few more days before increasing the pressure incrementally, starting at .5 per night.


Jay 1- unfortunately I cannot get neither the flow limitations, or 95% and 99% numbers to display. I've read somewhere that by default, the flow limitation data does not display with the Dreamstation. I went on to read that you can “trick” the machine into displaying the data by changing certain pressure settings. I will need to do more research and see what I can do to get the data to display. Do you have any suggestions?


Below are three screen captures from last night. When reviewing the images there are several facts to consider.

• Screen capture (1), shows the top half of the sleep data, as well as the session metrics. It also shows multiple abnormalities including flow restriction.
  
• Screen capture (2) shows a zoom in on the flow restriction, which appears to show an abnormal pattern including flattening of the waveform.
  
• Screen capture (3) shows the machine settings as well as the bottom half of the CPAP data which shows the tidal volume is in the 200s. Also worth noting, the minimum tidal volume is 50, which seems alarming low, and even more alarming, some other nights have the minimal tidal volume in the teens!
  

Thanks for any feedback, regarding whats been provided thus far, as well as any additional suggestions.

[Jay51]

Thank you for posting all of that.  0.74 flow limitations (from your larger chart).  I am not sure how that translates to a 95%tile.  

Inspiration time 2.5 and expiration time 1.2  This is abnormal if it is correct.  I:E ratio should be at least equal (or exhalation slightly larger time than inhalation).  This points to flow limitations.  

Your close ups of your flow chart doesn't look that great.  It should be smooth and round tops, but it seems like you start to breathe, then encounter resistance, and finally push through with a full inhale.  Looks like a lot of effort.  It could get better than this.

[jentlesoal]

Hi Jay51, please excuse the delay in replying.

Its fair to say that it appears that I have multiple issues going on, and I suspect they all may have a more complex etiology. To get a better perspective, along with un-refreshing/un restorative sleep, breathing is a main concern I'm having with with CPAP. After approx 4 hours of sleep max, I wake up every night with a sense of shortness of breath/suffocation, every night when using cpap!

Please correct me if I'm wrong, a normal I:E ratio when sleeping is 1:2 minimum; 2X more Expiratory volume then Inspiratory volume. My results indicate my expiratory volume is approx .5X, where it should be 2X, indicating a -1.5X deficit in my expiratory volume. And according to the flattened waveform, it also appears that I'm having difficulty inhaling when sleeping as well. This may explain the shortness of breath/suffocation symptom, and most likely fragmented sleep. I went back and reviewed my data throughout the year and the 1:.5 ratio is a constant value.

I have a few “peer” questions that I'm hoping you can share your opinon on. I'm also ok, if you cant offer any feebacks on the questions.

• Am I correct of my I:E assessment that Expiratory should be 2X greater than Inspiratory?

• Have you seen the type of chronic abnormalities that are present in my data (abnormal I:E ratio and abnormal waveform pattern), and if so, what does it normally indicate, nocturnal hypoventilation, which I suspect? 

• Would nocturnal hypoventilation by default also produce to a certain degree hypoxia and hypercapnia?

• Is it possible that hypoxia and hypercapnia is waking me up? My doctor has discussed switching me to a bi pap, which I suspect would help with the expiratory pressures, but not the inspiratory pressure. Do you know anything about those devices?

I'm just trying to determine, what is going on with my sleep and if there is anything I can do personally to help resolve these issues.

Thanks again for all your feedback, which is sincerely appreciated!

[Jay51]

Not a problem.  Your I:E ratio is not concerning.  If there is a lot of movement around the zero line, I:E ratio can be distorted.  Yours look ok to me (not abnormal).  Your main problem from the close up zoom you provided of your breathing waves is flow limitations.  A normal inhalation (the top part of the wave) should basically be round (like the top half of a circle).  Flow limitations show up on your charts as "pointed tops" and more than one "peak" - you have some waves with at least 2 peaks to them.  When the line goes upward, you are inhaling.  When it goes sideways or back down, you are encountering resistance somewhere along your upper airway.  This of course excluded exhalation which is a downward slope once you hit the very top of your inhalation.  

The most popular thing to combat flow limitations is your cflex or aflex.  It gives a little boost to inhalation to help overcome the resistance in your airway.  Another thing that might help is raising your min pressure.  

If you can tweak settings so that your waves when sleeping look more normal (rounded tops with only one peak), then that should take care of the bulk of your problem IMO.