Sorry for the extended absence. Personal life a bit crazy right now. I had this written almost two months ago now. I’m realizing this chest X-ray series keeps growing. I was hoping to wrap it up but the article kept getting longer, so I will do one more lung pathology article covering congestive heart failure after this and it will be very important so stay tuned. Also, I’m going to experiment with vlogging when we move into fluoro next. I’ve never tried barium after all these years and will make that my first post. Okay, for this lecture let’s go over atelectasis and pneumothorax.
Atelectasis refers to collapsed lung tissue. This can result from obstruction of the airway. The lung tissue that would normally be aerated by that airway then collapses. I think it can be best understood as lung that can’t inflate because the airway is blocked. Simple analogy: blow up a balloon normally and then try doing it while pinching the neck. The neck of the balloon is blocked and can’t be inflated just like lung tissue. Take a look. Do you see the atelectatic lung?
This one was kind of subtle and can be harder to detect. The right upper lobe is totally collapsed and this is the normal appearance for right upper lobe atelectasis. The right upper lobe collapses upward and medially towards the mediastinum at the center of the chest. So, what causes the airway to collapse?
An airway can become blocked on the inside (intrinsic compression). The most common cause in a hospital-based setting is mucous plugging. Your airways have tiny hairs the propels all the junk in the air upwards out of your lungs that you unknowingly swallow or hock up as a lugie (yuck!). If the stuff becomes too thick or your body is not well enough to do its job, the mucous can form thick tubular plugs and block the airways far out near the end of the airways, which would be like the tips of an upside down tree with the trunk being the trachea branching into two main offshoots where the tips where the leaves grow being the terminal bronchioles that get intrinsically compressed (filled) with mucous preventing the necessary air exchange. It is essentially suffocating from your own thick secretions. In this situation, a pulmonologist may perform bronchoscopy with lavage (washing) and aspiration (vacuum out the junk), aptly called pulmonary toilet (double yuck!).
When we pinched off the neck of the balloon, that was blocking it from the outside (extrinsic compression). Tumors can grow and compress airways causing atelectasis. The tumors can be subtle hiding in the mediastinum and hila being very small but knocking out the airway leading to lobar atelectasis and collapse. Another common cause of extrinsic compression causing atelectasis is pleural effusion, which is the accumulation of fluid in the chest cavity. This occurs commonly with heart failure and infections or inflammation of the chest. Even a small amount of fluid causes some degree of lung compression, obviously increasing with the more fluid in the chest cavity taking up the space where the lung is normally aerated.
Intrinsic (mucous plugging) and extrinsic (tumor) compression are two can’t miss reasons for atelectasis because they need medical and potentially surgical treatment. However, atelectasis by itself is a normal physiologic process. Unless you are exercising, odds are at work, relaxing on the couch, or sleeping in bed, your lungs are not fully expanded, in which case some of your lungs are atelectatic. This will be seen at the bottom of the lungs on chest X-ray and CT scans in a dependent location. For all the patients’ reading this blog, don’t panic! A little information is a scary thing. Many “normal” chest X-rays can have some atelectasis at the bases. This does not mean you have cancer!!!
Pneumothorax, pronounced New-Moe-Thor-Axe, is an air leak in your chest. Your chest wall has a lining called the pleura. The outside of your lung lobes has a lining too, which is what keeps the tissue encapsulated so you can hold it rather than a glob of goo. Between the chest wall lining (pulmonary pleura) and your lung lobes lining (visceral pleura), there is a negative pressure/a vacuum. This keeps your lungs from completely collapsing between breaths.
Balloon experiment #2: Blow up an empty balloon. It takes a big breath to get the initial inflation. Now let it deflate half way and blow it up again. With the balloon partially inflated it is much easier to blow up. Same as your lungs. If your lungs collapsed all the way each time, it would be a lot harder and take a lot more energy and effort to breathe.
So a hole in the lining of your pulmonary pleura will cause a loss in the normal vacuum/negative pressure that keeps your lung partially inflated all the time. You can see how this could be bad. The most common reasons for a pneumothorax include trauma (broken ribs cutting and puncturing the pulmonary pleura), iatrogenic (healthcare provider causes) from biopsy or supportive blood vessel catheter placement (central lines), and on occasion can be congenital (born with a problem). Congenitally it is often discovered during adolescence with competitive sports. The individual often has tiny airsacs (blebs) near the top of the lungs (pulmonary apices) that pop and cause a pneumothorax.
So we talked about it ad nauseum, but how do you detect it? Sometimes is grossly obvious, like the featured image for this article. But more often it can be quite subtle. A radiologist looks for the lack of pulmonary marking extending to the periphery of the lung coupled with a thin pleural line. Do you see it?
Try the magnification view. While this can be very subtle as well, it is the clinical information provided by healthcare provider referrers and the radiologic technologists performing the exam inputting the relevant clinical information that aides in detection. Sure we look for it in every trauma, every lung biopsy, and every known central line placement. It is the attempted central lines and the adolescent athlete that felt or heard a pop and developed acute shortness of breath where we could use the clinical help.
Again, sorry for the prolonged absence, but life gets really busy at times. Send me comments. It keeps me motivated!