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Is CPAP Pressure Dangerous?
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zonk Offline

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Post: #1
Is CPAP Pressure Dangerous?
[parts of this thread were copied from our old forum]
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Is CPAP Pressure Dangerous?
Source: Andrew Senske (Supplier #9)
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I was reading a discussion about CPAP pressure on an online CPAP forum the other day and was surprised to read a post from a person claming to be a clinical CPAP expert who suggested CPAP therapy can be very dangerous, and that the wrong pressure setting can lead to a condition known as pneumothorax. This fairly strong assertion wasn't backed up by any data or even by any anecdotal experience, and the poster - who chose to remain anonymous - became somewhat of a victim of the responses of the more level-headed message posters. Of course, the people using common sense along with their own experience pointed out that CPAP therapy is very safe, and asked what all the nonsense was about CPAP-induced pneumothorax.

After reading the messages I decided to look into a couple of issues. First, I wanted to know more about pneumothorax and what causes it. Second, I wanted to know how much pressure - in more commonly understood terms - a CPAP machine really delivers.

A pneumothorax is a pocket of air inside the pleura which causes a collapse of the lung. The pleura is a thin protective covering made up of two layers of tissue filled by fluid. When air enters the pleural cavity, the pressure becomes greater than the pressure inside the lungs, thus causing a partial or full collapse of the lungs. Several things can cause a pneumothorax, and there are three different categories of pneumothorax.

Spontaneous Pneumothorax
A spontaneous pneumothorax is categorized when the cause of the collapsed lung is not trauma. Spontaneous pneumothorax can occur when a weak part of the lung ruptures for whatever reason - including reasons related to lung disorders like chronic obstructive pulmonary disease (COPD) - or when significant pressure changes occur in the lungs.

Traumatic Pneumothorax
A traumatic pneumothorax may be caused by a traumatic injury to the chest and lungs, or by an invasive medical treatment that introduces air into the pleural cavity.

Tension Pneumothorax
Tension pneumothorax is the most serious and dangerous pneumothorax condition, and it describes a pneumothorax in which the tissue through which the air is entering the pleura acts as a valve which prevents air from escaping. Tension pneumothorax can cause an extremely high pressure to occur in the pleura causing the lungs to collapse completely.

So the real question at hand is can CPAP therapy cause a pneumothorax? The aforementioned message poster which claimed this was a potentially very serious consequence of patients adjusting their own pressure settings, believed firmly that unsupervised CPAP therapy can cause a pneumothorax. After the little bit of research I've conducted on the topic it seems to me that just about anything can cause a pneumothorax, including genetic defects, deep sea diving, high altitude flying, getting hit in the chest with a baseball bat, and just sitting idly in a chair (the latter especially if you have some sort of lung disease). In fact, from what I've read, most cases of spontaneous pneumothorax don't occur during physical exertion.

My fairly uneducated hypothesis, then, is that CPAP therapy could potentially (I'm using the word "potentially" very liberally here) induce a pneumothorax, but it would be very unlikely to be the root cause of the pneumothorax. If your lung is going to rupture from CPAP therapy, I'd guess it would probably rupture all by itself, even without CPAP therapy.

The unit of pressure used for CPAP machines is generally centimeters of water or cm H2O. Most people don't really relate too well to that unit of measurement since very few other things we encounter in daily life are described using those units. So I decided to show you all how to convert cm H2O to PSI, or pounds per square inch. Many people in the United States are familiar with the PSI unit of measurement, and as you'll soon see, a CPAP machine delivers a very, very low pressure. All you have to do to see your CPAP pressure setting in terms of PSI is to enter your pressure setting in the text box below, and you'll see the corresponding pressure in PSI. For example, a CPAP machine pressure setting of 8 cm H2O is 0.11 PSI - a low pressure indeed.

cm water (4C):
psi [psi]:
unitconversion.org http://www.unitconversion.org/unit_converter/pressure.html

According to the Encyclopedia Britannica, "pressures within the lungs can be raised to 130 centimetres of water". The human lungs can normally withstand the relatively low and safe pressure settings commonly used in CPAP therapy.

I'd encourage you to talk more with your physician if you're concerned about pneumothorax. In the meantime, you should feel pretty comfortable knowing that CPAP machines don't produce what would be considered to be dangerously high levels of pressure for most CPAP users. And don't forget about the very well-known benefits of CPAP therapy - benefits that far outweigh the dangers of using it. As a matter of fact sleep apnea is a condition that has been shown to be a factor in car crashes, diabetes, pregnancy complications, high blood pressure, and heart disease.

The bottom line for most is that CPAP therapy is not only extremely effective, but it's also very safe.
03-10-2012 02:43 PM
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zonk Offline

Advisory Members

Posts: 7,908
Joined: Feb 2012

Machine: A10 AutoSet
Mask Type: Nasal mask
Mask Make & Model: Activa LT
Humidifier: Integrated /ClimateLineAir
CPAP Pressure: 9/13
CPAP Software: ResScan

Other Comments: CPAP since Nov 2010

Sex: Male
Location: Australia

Post: #2
RE: Is CPAP Pressure Dangerous?
[parts of this thread were copied from our old forum]
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SuperSleeper wrote:
Mr. Senske is a breath of fresh air as far as DMEs are concerned. Seldom does one find the head of a DME so prone to freely offer the 'secrets of CPAP' to customers.

He used to offer Clinician Setup manuals freely on his website for several makes and models, until the CPAP manufacturers set their "legal dogs" after him. He had to remove many of them from his site in order to remain in the "good graces" of the CPAP manufacturers.

It's unfortunate that to remain in business, he was required to keep their "secrets" hidden from end-users.

At least he tried to empower Sleep Apnea patients... for his efforts, I say, Well-done
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archangle wrote:
Here's a better way to visualize CPAP pressure.

20 cmH2O is a very high CPAP pressure, the top limit of most CPAP machines. For those outside the civilized world, 20 cm is 7.8 inches.

Imagine a 20 cm long soda straw, which is actually a fairly short straw. You're drinking a soda with a straw. The cup is almost empty and you're drinking the last bit of soda. At this point, the vacuum in your mouth is 20 cm. Now, imagine that you have a full cup of soda that is 20 cm deep. Put a straw into the cup and let the end of the straw go almost to the bottom of the cup. Now, blow on the straw enough to gently produce a few bubbles. You now have 20 cmH2O pressure in your lungs.

Is anyone afraid you're going to rupture your lungs while playing with your soda?

Now, if blowing bubbles in your soda is 20 cm, can you imagine what the pressure is when you sneeze?

Now to make the idea even stupider, doctors prescribe pressures near 20 cmH2O all the time to their patients. Do they worry about pneumothorax? They often prescribe auto machines with a top pressure of 20 cm, even if the initial pressure is lower. How many patients with prescribed pressures of around 20 cm have developed pneumothorax? Is the self adjusting CPAP user somehow magically more likely to get pneumothorax than the physician prescribed CPAP user?

I will agree with one thing, though. If you're ever diagnosed with lung conditions, or stabbed or shot in the chest, discuss your CPAP with the doctor before you start CPAP again.
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Quote [archangle wrote:I will agree with one thing, though. If you're ever diagnosed with lung conditions, or stabbed or shot in the chest, discuss your CPAP with the doctor before you start CPAP again.]

SuperSleeper wrote:
Good advice, archangle... I'll remember that the next time I'm stabbed or shot in the chest. Wink

Seriously though, good illustration (the straw). Smile
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Steven wrote:
If you are ever stabbed or shot in your chest, I would think that using or not using your CPAP would not be your #1 concern.
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03-10-2012 03:16 PM
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