Friday, August 23, 2013

What is Pulmonary Fibrosis?

The word "pulmonary" means lungs and the word "fibrosis" means scar tissue -- just like the scars you might have on your skin from previous injuries or surgeries. So, in its simplest sense, pulmonary fibrosis (sometimes called PF) means scarring in the lungs. But many people use the term PF to describe a family of over 100 diseases that affect the walls of the air sacs* of the lung. This larger family of diseases is called "interstitial lung disease" or ILD. While in many cases of ILD, scar tissue is present in the air sacs, there can also be inflammation or other changes to this delicate lung tissue. The details depend on which kind of PF you have (more on this later).

There are four consequences to the build-up of scar tissue or inflammation in the lungs. Doctors use these consequences to recognize that someone has PF.



  • Stiff lungs. Scar tissue and inflammation make your lungs too stiff. Stiff lungs are hard to stretch, so your breathing muscles have to work extra hard just pull air in with each breath. Your brain senses this happening, and it lets you know there’s a problem by triggering a feeling of shortness of breath while exerting yourself. Also, stiff lungs hold less air (they shrink up a bit). Doctors take advantage of this to diagnose and track the disease by using breathing tests (called Pulmonary Function Tests) that measure how much air your lungs can hold. The more scar tissue or inflammation your lungs have, the less air they will hold.
  • Low oxygen levels in the blood. I will spend a whole posting on this later on. The short story is that oxygen has a hard time traveling from the insides of your air sacs to the inside of the blood vessels in the lung because scar tissue and inflammation make the lungs less efficient. For many people living with PF, oxygen levels are only reduced a little bit while resting, but their oxygen levels drop quite a bit during exertion. The brain can sense these low oxygen levels, triggering shortness of breath. Doctors will check your oxygen levels to see if they drop after walking  -- a clue that PF might be present. Doctors also often prescribe oxygen to be used through a nasal cannula or a facemask during exertion and sleep for those with moderately advanced PF. As PF progresses, oxygen may be needed 24 hours a day.
  • "Crackles" Your doctor may have told you that you she heard "crackles" in your lungs. "Crackles" (also called "rales") are heard in a variety of lung diseases because they are typically present with any type of problem affecting the air sacs (such as PF, pneumonia, or pulmonary edema from heart failure). Some people with PF don't have crackles, but most do.
  •  Abnormal CAT scan. Scar tissue and inflammation can often be seen on a CAT scan. (A "CAT" scan is also called a "CT" scan -- same thing). Healthy lung tissue looks nearly black on a CAT scan. Scar tissue and inflammation both appear grey or white. Many forms of PF look similar on a CAT scan to the untrained eye, but subtle findings on CAT scans are critically important when trying to identify which type of PF you have.
On the one hand, these four consequences are very helpful since they tell us that someone has PF.  On the other hand, it takes a lot more work to figure out which one of the 100+ types of PF you might have. And the truth is that most docs don't have the time to figure this out. More on this in a subsequent post.

*the air sacs of the lung are also known as "alveoli"

14 comments :

  1. Thanks for laying it out this way. So much of what I find is written in such a way I feel like I need to go to med-school to understand it. This is also good information that I can pass onto my husband who at this point is convinced he has been misdiagnosed. Sigh...

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    1. Thanks so much for your comments on my blog! More content to come!

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  2. Thank you so much for the information you have posted. I am an RN and the evidence based research available appears to require a PhD. My husband experienced a hospital admission for hypoxia and was sent home on 02 24/7. His HRCT failed to show s/sx of PF, so he was told to lose weight. We have a second opinion scheduled at DUKE in 2 weeks and hopefully will get a more detailed workup to see what is causing the hypoxia. Even with weight loss, he is started to desat with activity while 02.
    I will follow your blog with great interest as you explain this disease to us.
    Thanks

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  3. Duke is a terrific place. Best of luck with the evaluation there.

    Dr. Lederer

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  4. Crackles. While in the local (Newmarket) hospital in March for an exacerbation, I volunteered to allow student nurses to listen to the "unique" sounds of PF. The instructor then offered to let me listen to my own lungs. When one listens to a conch shell, they say you are actually hearing your own circulatory system echoing in the shell. Well, I finally realized that late at night when the house was very quiet, and I had my earplugs in and reading in bed, I was actually hearing the crackles in my breathing.

    What I was wondering though is there a difference in the crackles (rales) from PF versus the sounds from pleurisy? My previous Primary Care Physician diagnosed me with pleurisy during the previous decade based on both the type of pain and the sounds but also during the previous decade in both 2005 and 2008 I underwent pulmonary including PFTs and cardiac investigation because of shortness of breath and excessive coughing. And just a couple of weeks ago, I again experienced for about 4 days the same pain that was present when diagnosed with pleurisy. Coincidentally, or not?, the pleurisy has been on my right side and it is my right lung that is more markedly affected by IPF (my IPF diagnosed was confirmed last Sept via VATS biopsy with UIP pattern).

    Any insight would be helpful.

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  5. Thanks for sharing your experience. It's very hard for me to comment on anyone's individual experience. What I can say is the pleurisy is typically painful, whereas pulmonary fibrosis typically does not cause pain. It is possible to have both pleurisy and pulmonary fibrosis, but only your doctors can sort that out for you. Best of luck with everything.

    David

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  6. Hi everyone, it's my first pay a visit at this site, and post is in fact fruitful in favor of me, keep up posting these types of articles.

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  7. David,
    Is there any chance of "crakles'' can help with the diagnostic of some ILD forms?

    Pam.

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  8. Hi Pam,

    Crackles are very helpful in identifying if Pulmonary Fibrosis (ILD) is present or not. Many (but not all) people with PF have crackles. The absence of crackles can clue us into certain forms of PF -- one example is pulmonary sarcoidosis, which typically doesn't have crackles. There are other sounds we can here that can also be helpful in figuring our which kind of PF someone has. An example is the "squeak" which -- you guessed it -- sounds like a squeak. We hear squeaks when someone's PF involves the airways.

    Bottom line; Crackles are helpful to identify the presence of PF (most of the time). Crackles are only helpful in figuring out which kind of PF is present in a small fraction of people with PF.

    David

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  9. I have crackles and squeak not all the time, but a lot of it. Like reading your articles, even though I have had ILD 12 years, you explain it better than anyone.

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  10. I have crackles and squeak not all the time, but a lot of it. Like reading your articles, even though I have had ILD 12 years, you explain it better than anyone.

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    1. Thanks, Lisa. Very happy to know my blog is helping you and others.

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    2. Very informative, thank you very much! Please keep posting

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  11. Can anyone tell me anything regarding "telemeres" Is there a medication or treatment to prolong the life of telemeres and would it help PF if there was.












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