[Diagnosis] nocturnal hypoxemia with hypoventilation, Moderate OSA

[Bruce Reynolds]

Well, I'd really like to see the PFT result cause I think there's some abnormal values there but to break the monotony.let me toss out a couple of back of the book things.

There is a tremendous incidence of PFO (patent foramen ovale) in OSA patients. This can result in some really strange O2 and CO2 values.  That said, one wonders about the severity of your OSA or is it really OHS.

[Bruce Reynolds]

Second, your comment about varying blood CO2 level struck me as odd.  Do you really have an underlying  metabolic alkalosis?  The compensation for that is (you guessed it) hypoventilation.

[vgrando]

Bruce Reynolds pid='478032' dateline='1686181584']Second, your comment about varying blood CO2 level struck me as odd.  Do you really have an underlying  metabolic alkalosis?  The compensation for that is (you guessed it) hypoventilation.

My doctors do not seem concerned about it. 

I looked at my C02 numbers,  I had five above 30 tested since 2018,  the rest around 27 to 29. But the lowest at 25 was this May after being on the APAP for a month.

I do not have heart disease had a full workup about six years ago and no plaque or other issues.

I am attaching a screenshot of my PFT. I cannot make sense of it, but they did state it was normal

This is from my in-lab study:
1L oxygen was added at 12:44am for non-apneic desaturations
 
The patient was positive for hypoventilation in sleep.  The patient's baseline TcCO2 was 45 mmHg and increased to a maximum of 56 mmHg during the study. The time greater than 50 was 35 minutes, and greater than 55 was 1 minute.

[Jay51]

Victoria,  Bruce brings up some very good points.   He is very knowledgeable in this area.  

I just have a few comments.  I have a lot of experience with etco2 - your hypoventilation #'s.  Yours are worse than mine and I am on a ventilator.  Does that say anything?   It should I guess.  By increasing your ventilation (higher tidal volumes and higher RR and higher minute ventilation); your spo2 should improve some I would think.  Right Bruce?  

Moving from diagnosis to treatment, 2 things seem very important.  1.  You are already on supplemental oxygen.  Great move. Probably necessary from now on.  Can always increase it in future, too.  2.  The move to a better machine that helps you ventilate better (increased tidal volume, RR, and mintue vent.) could help also IMO.  3.  If there was some treatment for the bilateral atalectasis, that could help also.  Just my thoughts.  Have you been tested for metabolic alkalosis like Bruce mentioned?  Any other thoughts Bruce?

[vgrando]

Thank you so much. You have affirmed my concerns. And yes Bruch has been very helpful and knowledgeable!

Although I have been a nurse for 58 years, I am not a critical care nurse, who would be much more familiar with this. I am a psych nurse. 

My situation with my sleep doctor is intolerable. Instead of having me be tested at home with an oxygen meter as suggested in the titration study, he took me off oxygen for a month! For what reason?  He did not explain why he did it. I have already been on the APAP for seven weeks, what will another month tell him? I think it was a control move on his part. He did not like that I knew I was having CAs. He dismisses me and tells me he needs the official reports. However, he had not requested them for three weeks and then told me to have them sent to him. 

I have an appointment in July with another sleep specialist. The only one in my community not connected to the Med Center.

I am going to ask the new doctor for another machine if I am still having CAs. I read that 90% of CAs clear up in three months.  I will have been on the APAP for three months when I see him. 

Take care, Victoria

[Bruce Reynolds]

Looking at PFT, it's good enough to say it's good enough, but if you look at FRC, ERV and RV there is volume reduction.  These are volumes that become important for gas exchange, with ERV particularly low (ERV is the volume from the end of a normal tidal volume till you can't exhale anymore).  Right now they are sorta bad, but they were measured when you were sitting down.  However, when you liie down to sleep, abdominal contents now squash that number down significantly and impair gas exchange.  I'm not just nosy about your weight, one needs to determine (roughly, at least) just what the effect is on lung mechanics, and IMO it creates enough of an issue that a bilevel approach should produce significant benefit.

Then comes the Rule of the 130s.  If your ventilation decreases because of hypoventilation, because CO2 and O2 have to share the same space, if one goes up the other must come down, and total of pCO2 and pO2 cannot exceed 130 on room air.  Anyway, the point is that if you normalize elevated pCO2s you'll gain ground on the oxygen end.

[Bruce Reynolds]

 
The patient was positive for hypoventilation in sleep.  The patient's baseline TcCO2 was 45 mmHg and increased to a maximum of 56 mmHg during the study. The time greater than 50 was 35 minutes, and greater than 55 was 1 minute.


My baseline C02 was 39 mmHg and I went to 49 mmHg during the study.

BTW do you have the graphs for both capnography?  That'a quite a wide range, TcCO2 isn't always accurate (especially if not monitored properly). and doesn't hurt to turn over all the rocks.

[RainbowFish]

If the issue with a FFM is periorbital edema but you find it easier to control leaks, consider a hybrid mask. I like the AirFit F30i myself, but several brands have one.

[vgrando]

Hi, I was on vacation and just got back. I know body weight is an issue, and I appreciate your concern. I have been losing weight. My BMI is now 29.3, but I also have a sliding hiatal hernia that has been giving me problems lately. I see a new sleep doctor in July; I hope he takes my issues seriously!

[Jay51]

Thank you for posting all of that Victoria.  A couple of things jump out at me; but I mainly want to focus on your CO2 levels at night because I have had a lot of testing and experience with these.  

From your upload #3 chart, your co2 chart looks kind of similar to mine.  The normal range is between 35 and 45 mm/HG.  Above 45 means hypoventilation as a person is exhaling too great a percentage of co2.  Below 35 is hyperventilation, as a person is exhaling too little co2.  I stayed between 40 and 45 for the greatest percentage of the night.  It looks like you stay close to to 45 all night.  You have one bad stretch at around the 2:05 time stamp where you go above 45 for awhile up to 50.  This is at a lower pressure (and major clusters of events).  You have a bad cluster of events around 4:05am, but you stay at around 45 (I am guessing because you are at a higher pressure and that is why?)  You can look at my thread, "I cannot fall asleep with my bipap/home ventilator. Hypoglossal nerve stimulator?" and go to page 18 and look at post # 173 to see my Co2 chart.  I actually passed this one, but did not sleep long enough for it to count.  25% of the time spent above 45mm/HG during sleep constitutes hypoventilation in my state.  The 1st one I took sleeping on my back with no collar or machine, I was avobe 45 for 66% of the time!  Horrible hypoventilation.  I have failed 4 of these tests in roughly 2 years.  It seems like you qualify for a hypoventliation diagnosis based on your charts.  

Once diagnosed with hypoventilation, I became a respiratory patient (and not just a sleep apnea patient).  I became a high-priority patient to my RT at my DME.  Overlap syndrome.  

Respiratory rate (breaths per minute - average is around 12 to 20 but varies) + tidal volume (amount of air inhaled with one inhalation) - and varies a lot also = minute ventilation (varies a lot also).  Roughly 400 to 500 (but could be less or more depending on body stature, etc.).  5 to 8 is a very rough estimate of a correct range here.  

Your respiratory rate:  if it is not good enough spontaneously (you don't average at least 12 or maybe even just 10) for the night, then a machine with a back up rate could help you.  ST (Spontaneous and timed (back up rate), ST (A) - same thing but can have a crude IVAPS also, and ASV (uses a dynamic, ever changing back up rate based on your personal breathing).  The VAUTO is close to having a back up rate in that is has a very high trigger setting (to start inhalation), but it is not a true back up rate type of machine.  

As far as tidal volume goes, IVAPS (ST-A), and IVAPS from the Resmed Astral ventilator can increase your tidal volume with each breath.  Concerning Philips, the Evo ventilator and the Dreamstation Bipap AVAPS can do this, too.  I am not familiar the Dreamstation machine, but it must have setting to control tidal volume during the night.  

I am glad that you have supplemental oxygen to use at night.  That helps with spo2 levels. Better ventilation could help in your case, too. You have room to improve your ventilation. 

Lastly, it may take educating your Sleep Dr., PCP, RT, etc. to move forward with your therapy.  As a retired nurse, you have the advantage of knowing the medical system better than most people.  Use that to your advantage.  

Anything you would like more clarification on or any other question, just ask.