Pressure and the heart - any truth to this?

[earlvillestu]

First, some background, and then a question.

After an in-patient sleep study with titration, in December, I was diagnosed with severe OSA, with CPAP recommended at a fixed rate of 12. It took until May to get a machine, and in the meantime I implemented a rigid sleep hygiene study, following recommendations from the sleep center--regular bedtime, side sleeping only, bed wedge, nothing to eat or drink 3 hours before bed, screens off an hour before bed, light blocking mask, plus I lost 20 pounds. That all helped quite a bit, according to my wife, who said I was spending a lot less time gasping for air every night.

In May, I got fed up waiting for the DME. I asked the sleep center to prescribe a self-pay AirSense 11 Auto I found at sleeplay.com, they did so, and I bought it. Pressure was set to 12, EPP to 3, 10 minute ramp up, per the prescription. After a couple of false starts with masks that didn't work well, I found a good one, which I've been using ever since. I stay in bed with the mask on and the machine running for at least 8 hours a night. According to OSCAR, for the 48 days I stayed on the factory settings, I was averaging an AHI of 3.6, with 11 of those days over 5.0.

After reading some of the really informative stuff on this forum and elsewhere and watching SleepHQ videos, I got into the clinician menu and started experimenting. After a week or so, I settled on a setting of 12 minimum, 20 maximum, EPR 3, no ramp up, and I now have 50 days on that, with an average AHI 0.4, a high (one night) of 1.0, and a number of nights with either 0.0 or with just one or two CAs and no OSAs or hyponeas. Most nights the pressure stays between 12 and 13,5 or so, with the 99.5% never higher that 17.6. Most importantly, I'm sleeping more hours than I've been able to sleep in many years (7 to 7.5 most nights), most mornings I wake up feeling refreshed, and I'm no longer fighting drowsiness all day long.

In short, I consider myself lucky to be one of those for whom CPAP therapy worked pretty much from the start.

Now for the question. Two weeks ago I had my follow-up appointment with the sleep center, with an AP-RN who works for the large medical practice that operates the center. She reviewed the SD card results that I provided. I told her what I had done with the pressures, and she was upset that I had messed with the clinician menu and changed the recommended settings. I pointed out to her the significant improvement in AHI. Her response was anything under 5 is an acceptable AHI, which makes the higher maximum unnecessary, and that there's no real advantage to an AHI under 1. Then she said that the reason she was recommending going back to 12 fixed was that higher pressures can damage the heart.

I've done quite a bit of reading about CPAP, and I've never come across that claim. Is there any truth to it?

[Rubicon]

Absolutely!

[Rubicon]

Once you start hitting about 25 cmH2O.

Very high pressures start to impinge upon the capillary bed, and blood starts to back up behind right heart and accumulate in the periphery.

"Damage" is a strong word, but circulatory balance does get a little askew.

[Rubicon]

OTOH, if one has emphysematous blebs, a more serious side effect would be having one of those rupture and you end up with a pneumo. That's bad.

[Rubicon]

I've done quite a bit of reading about CPAP, and I've never come across that claim.

Search "high levels of PEEP" and some stuff will pop up.

[Rubicon]

Most nights the pressure stays between 12 and 13,5 or so, with the 99.5% never higher that 17.6.

Another concern would be if you're dehydrated and on high pressures all night, if you suddenly pull off your mask and jump out of bed you'll probably pass out.

[LSAT]

I would disregard everything Rubicon posted...
I would continue with the 12/20 settings.
The NP at the Sleep Center is wrong...under 5 is acceptable to some...Under 1 is better
If your 95% is 17 there is no problem with max 20.
Continue to monitor your therapy by using Oscar software.

[babydinosnoreless]

My sleep study in Nevada recommended 19-24 as a starting pressure. My doctor in Arizona set my pressure at least that high. I couldn't sleep and changed it myself. Was ready for them to yell at me when I went to my follow up. If they noticed I had changed it they didn't say anything.

Personally I would dump the doctor and get a second opinion. If its not supposed to be that high why the heck would they make machines that go that high ? And why would two sleep professionals in two different states prescribe it that high if it was going to damage my heart ?

[ChicagoGranny]

Her response was anything under 5 is an acceptable AHI,

I bet she doesn't use CPAP. If you sleep 7 hours and have an AHI of 4.5 (That's under 5.), you are awakened rudely 31 times in that 7 hours. That ain't good for your heart nor any other body part.

Carry on.

[Rubicon]

I would disregard everything Rubicon posted...
I would continue with the 12/20 settings.

Well now I'm confused. 12/20 has nothing to do with what I posted as the "worry point".

And why should you disregard "everything"?

[earlvillestu]

Personally I would dump the doctor and get a second opinion.

Easier said than done, unfortunately. Where I live the options for medical care that accept my insurance are very limited. I'd really like to dump my PCP, who is hyper-concerned about my LDL and wants to put me on a statin, in spite of all the evidence that for me the statin would be more likely to do harm than good. But no can do, unless I want to drive 50 miles every time I need routine care.

[Dog Slobber]

I'd really like to dump my PCP, who is hyper-concerned about my LDL and wants to put me on a statin, in spite of all the evidence that for me the statin would be more likely to do harm than good.

Create a paper, and submit your findings to a peer-reviewd medical journal.

You'll be rich and famous.

[earlvillestu]

I'd really like to dump my PCP, who is hyper-concerned about my LDL and wants to put me on a statin, in spite of all the evidence that for me the statin would be more likely to do harm than good.

Create a paper, and submit your findings to a peer-reviewd medical journal.

You'll be rich and famous.

Unfortunately, the evidence has already appeared in peer-reviewed medical journals, multiple times, so I guess I'll never be rich or famous. But my PCP isn't impressed by evidence and sticks with the conventional wisdom promulgated by the statin manufacturers and accepted uncritically by the American medical establishment. I'd love to continue that conversation, but don't think this is the time or place.

[Janknitz]

For the most part, CPAP has very positive effects on people with either congestive heart failure or emphysema and is very commonly used in both conditions, which are often concomitant with sleep apnea.

There is a very small and RARE subset of people for whom too much pressure can present a danger. Do you have severe emphysema with blebs (essentially blisters on your lungs) or severe congestive heart failure? If not, there's no need to worry. The major danger you face from CPAP is dropping it on your toe.

There is a difference between "adequate" treatment and "optimal treatment". Adequate is less than 5 AHI, optimal is less than 1 (some say only 0 is optimal). Consider, with an AHI of 5, if you sleep 8 hours, you stop breathing at least 40 times in that 8 hour period. The So-called "normal population" that is used as comparison isn't so "normal" in the first place, and it's not a very good thing to stop breathing that often in an 8 hour period. Anyone with some critical reasoning can understand that only once every few hours is far better.

So I wouldn't worry unless you are a rare bird with severe lung or heart disease, and as I'm someone in your shoes, I certainly want optimal treatment.

And you sound like you are able to make intelligent analysis of the data on statins in primary prevention too. Few people appreciate the difference between actual and relative data, and any critical thinking seems to go out the window the minute the words "cholesterol" and "heart attack" are used in the same sentence.

[Rubicon]

There is a very small and RARE subset of people for whom too much pressure can present a danger.

Cool, but my point is that the group becomes significantly higher at CPAP >25 cmH2O.

However, to your point, there aren't any machines that could provide that pressure, nor would anybody in their right mind order it or experiment with it.

Let me add another one while we're at it. The esophageal sphincter would lose patency at 25-28 cmH2O so you'd blow the stomach up like a (insert metaphor here).

Anyway, that high level CPAP (referred to as PEEP in the critical care world) will decrease cardiac output is an undebatable fact. I can produce innumerable references and explanation like this practice parameter:

https://ccforum.biomedcentral.com/artic ... 186/cc3877

In patients with acute lung injury, high levels of positive end-expiratory pressure (PEEP) may be necessary to maintain or restore oxygenation, despite the fact that 'aggressive' mechanical ventilation can markedly affect cardiac function in a complex and often unpredictable fashion. As heart rate usually does not change with PEEP, the entire fall in cardiac output is a consequence of a reduction in left ventricular stroke volume (SV).

During my (simultaneous) time in the critical care world, cardiac output would be monitored as PEEP was upwardly titrated. And every now and then someone would crash. Oh well, crank up the dopamine. Can always go on dialysis if the kidneys get fried.

Interestingly, an ARDS patient would be more tolerant of high level PEEP than a normal patient. Rationale to follow.

Anyway2, yes high levels of PEEP/CPAP can be dangerous, but not at the levels that are seen in routine OSA treatment.

Unless you're hypovolemic.

Ever wonder why they take blood pressure (or should) at least a couple of times during CPAP titrations?