Hyperinflation of lungs

sam thomas · Post by **sam thomas** » Fri Mar 28, 2008 6:12 am

Who can we ask medical questions at cpaptalk.com. For example
Will high pressure cpap cause lung hyperinflation?

Sam Thomas st2166@sccoast.net

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Slinky · Post by **Slinky** » Fri Mar 28, 2008 7:04 am

I would guess SAG or Dr Barry Krakow.

BarryKaraoke · Post by **BarryKaraoke** » Fri Mar 28, 2008 8:57 am

A CPAP machine does not (and will not) "inflate" your lungs...it will hardly inflate a beach ball.

The actual PSI (pounds per square inch) of a CPAP machine is very, very low and not to be confused with your pressure setting (centimeters of water). They are two very different things.

The highest pressure of most CPAP machines (20) is actually only 0.28 psi. Not very good for inflating things!

Goofproof · Post by **Goofproof** » Fri Mar 28, 2008 10:05 am

Not a danger unless someone has removed your rib cage. Jim

ozij · Post by **ozij** » Fri Mar 28, 2008 11:43 am

Slinky wrote:I would guess SAG or Dr Barry Krakow.

SAG is the member called StillAnotheGuest

Dr. Barry Krakow is the memeber called BarryKrakowMD. Not to be confused with the member who took on a similar name.

O.

DME Daddy · Post by **DME Daddy** » Fri Mar 28, 2008 3:27 pm

I measured a good sneeze at something over 80cm or over three times what a cpap can do. No, not very scientific but it does show that cpap pressures are modest at best.

split_city · Post by **split_city** » Sat Mar 29, 2008 8:04 am

BarryKaraoke wrote:A CPAP machine does not (and will not) "inflate" your lungs...it will hardly inflate a beach ball.

The actual PSI (pounds per square inch) of a CPAP machine is very, very low and not to be confused with your pressure setting (centimeters of water). They are two very different things.

The highest pressure of most CPAP machines (20) is actually only 0.28 psi. Not very good for inflating things!

I would have to disagree with this. CPAP does increase lung volume quite effectively. Heinzer et al (2006) demonstrated that 13cmH20 CPAP increased lung volume by ~770mL which is greater than an average tidal breath.

Furthermore, O'Donoghue et al (2002) showed that lung volume increased by ~1.1L following the application of 10cmH20 in a group of COPD patients.

The compliance of the lungs is relatively high above resting lung volume i.e. doesn't take much pressure to increase lung volume.

Increasing lung volume helps to prevent upper airway collapse. The increase in lung volume brought upon by CPAP, is one reason why the airway remains patent. This is in addition to the direct splinting effect that CPAP has on the airway.
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GreenIce · Post by **GreenIce** » Sat Mar 29, 2008 10:09 am

split_city, is there any studies about prolong CPAP high pressure on lungs ?

I am concerned of any side effects of high pressures.

DME Daddy · Post by **DME Daddy** » Sat Mar 29, 2008 10:29 am

This is old news really. In two plus decades of cpap, there has been no documented cases of otherwise healthy individuals being harmed by prolonged cpap use. Many patients that have been on cpap over twenty years are going strong.

gasp · Post by **gasp** » Sat Mar 29, 2008 10:49 am

Goofproof wrote:Not a danger unless someone has removed your rib cage. Jim

LOL - I forgot how funny you are!

BarryKaraoke · Post by **BarryKaraoke** » Sat Mar 29, 2008 10:55 am

split_city wrote:I would have to disagree with this. CPAP does increase lung volume quite effectively.

Of course it increases lung volume and splints open the airway...it wouldn't be effective treatment if it didn't do this.

The point, is that a CPAP machine is not going to somehow "over inflate" your lungs to the point of damage/rupture, as the OP fears.

Snoredog · Post by **Snoredog** » Sat Mar 29, 2008 11:16 am

split_city wrote:
BarryKaraoke wrote:A CPAP machine does not (and will not) "inflate" your lungs...it will hardly inflate a beach ball.

The actual PSI (pounds per square inch) of a CPAP machine is very, very low and not to be confused with your pressure setting (centimeters of water). They are two very different things.

The highest pressure of most CPAP machines (20) is actually only 0.28 psi. Not very good for inflating things!
I would have to disagree with this. CPAP does increase lung volume quite effectively. Heinzer et al (2006) demonstrated that 13cmH20 CPAP increased lung volume by ~770mL which is greater than an average tidal breath.

Furthermore, O'Donoghue et al (2002) showed that lung volume increased by ~1.1L following the application of 10cmH20 in a group of COPD patients.

The compliance of the lungs is relatively high above resting lung volume i.e. doesn't take much pressure to increase lung volume.

Increasing lung volume helps to prevent upper airway collapse. The increase in lung volume brought upon by CPAP, is one reason why the airway remains patent. This is in addition to the direct splinting effect that CPAP has on the airway.

BarryKaraoke · Post by **BarryKaraoke** » Sat Mar 29, 2008 12:06 pm

Snoredog wrote:And I disagree with Barry's comment on pressure, it IS centimeters in water as measured with a manometer. PSI is NOT used for any measurement with these machines what so ever.

You missed my point. The original poster fears that HIS LUNGS WILL OVER INFLATE by using a CPAP machine. I was merely pointing out that even 20 CENTIMETERS OF WATER is still a very, very low pressure. This isn't my opinion...it is a measurable fact. My reference to PSI was used as a COMPARISON as the average person does not encounter this unit of measure in there day to day lives, yet most know and understand PSI.

There is an interesting article on the risks of "Pneumothorax" using CPAP HERE.

From the article:

"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.

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 bottom line...fear of possible lung hyper-inflation should not keep someone from continuing CPAP therapy. Agreed?

Snoredog · Post by **Snoredog** » Sat Mar 29, 2008 12:27 pm

BarryKaraoke wrote:
Snoredog wrote:And I disagree with Barry's comment on pressure, it IS centimeters in water as measured with a manometer. PSI is NOT used for any measurement with these machines what so ever.
That was my point. The original poster fears that HIS LUNGS WILL OVER INFLATE by using a CPAP machine. I was pointing out that even 20 CENTIMETERS OF WATER is a very, very low pressure. PSI was used as a COMPARISON as the average person has no normal application for this unit of measure, yet most understand PSI.

SnoreDog & Split_City: Are you both then answering the original poster with a YES? That there IS a risk of "Lung Hyperinflation" with CPAP? Or merely arguing over semantics?

BarryKaraoke · Post by **BarryKaraoke** » Sat Mar 29, 2008 12:31 pm

Snoredog wrote:Considering the length of time CPAP therapy has been implemented (more than 20 years) hyperinflation of the lungs does not appear to be a problem, so the answer to the original poster would be "No".

Exactly. That was all I was getting at. A fear of lung "hyper inflation" should not keep you from using your CPAP machine.

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