Flow Volume Spirometry

00:01 Okay. So where we are here with our flow volume spirometry is well, just a recap, in the middle is normal. Bottom loop represents inspiration. I want you to begin at residual volume, you should always have a little bit of volume in your lung.

00:20 The bottom half represents inspiration. What does it mean when you get to the top, where you have maximum volume in your lung? That’s called TLC. Okay, obviously the top half we spend time with, that’s your exhalation.

00:32 Take a look at the right, that’s my pathology in restrictive, isn’t it? Which one? You tell me. The red looks normal, that loop is now shifted to the right, that’s the pathology.

00:45 So, take a look at your exhalation do you see a scalloped pattern? Nope. What about the peak flow? Diminished and it’s moved to the right, so tell me about the total lung capacity of the normal which is the red at 6 compared to total lung capacity of the restrictive lung at approximately 3. Obviously decreased, right? Tell me about the FVC.

01:12 It is decreased. What about FEV1/FVC ratio? Never decreased, either normal or elevated.

01:20 In current day practice with restrictive lung disease here’s the algorithm that you want to be quite familiar with. Now, to begin with a couple of abbreviations that you’ll come across quite commonly and the names that you want to be able to interchange readily at a given time. We have diffused parenchymal, a.k.a interstitial lung disease abbreviated accordingly. With DPLD or diffused parenchymal lung disease, interstitial. Known causes maybe drugs. What drugs that we talked about already? Those drugs included things like bleomycin, busulfan and company. Known causes include maybe perhaps rheumatoid arthritis.

02:03 Do not forget that, that’s a big one for us, you’ll see later.

02:06 Next, what else are we going to do? Well, we take a look at something called Idiopathic or now better yet called another type known as interstitial pneumonia and we’ll take this category ladies and gentlemen and we’re going to dissect the heck out of it, you’ll see. Before we get there though, let’s take a look at few others. Granulomatous, so what does that mean to you? Think of sarcoidosis huh? Sarcoidosis type of diffused parenchyma would be non-caseating granuloma. So, create yourself this type of flowchart, algorithm in your head so that you’re able to perfectly place yourself accordingly, we need to in terms of differentials. Other forms, well something like lymphangioleiomyomatosis, you have Langerhans cell type of issues and eosinophilic type of pneumonia. Okay now with eosinophilic pneumonia you’ll find that discussion to be quite interesting. For example you’ve heard of Löffler, good.

03:04 Next, well we will going ahead and take this IIP which is idiopathic interstitial type of pneumonia, and then we will further divide this. The non-familial type is the most common where 80% of your patients will then be presenting as non-familial.

03:24 With non-familial we would then break this into, chronic fibrosing, acute fibrosing and smoking related.

03:30 Let’s take a look. If it’s chronic fibrosing, it’s idiopathic pulmonary fibrosis, this is the one that you have seen quite often in your medical education but truly ladies and gentlemen I beg of you to at least give yourself an organization pattern when dealing with diffused parenchymal type of restrictive lung disease. Chronic fibrosing. If it’s the gene associated with it that’s now been found, it’s mucous, think of it that way.

04:03 So you have MUC and then I don’t know how to do this but you have to memorize, 5B. Okay, I can only take you so far. Next, what if it’s acute type? Well, we have something here called cryptogenic organizing type of pneumonia and also we have acute interstitial pneumonia. Cryptogenic becomes important to us. I'll have a few words for you as we go through that differential. And smoking related. If it’s smoking related respiratory bronchiolitis, interstitial lung disease and something called desquamating interstitial pneumonia. Now, in these I have then bolded common conditions that then you should know as far as your everyday practice and obviously on your boards of any type.

04:53 Continue. Okay, so interstitial lung disease well for the most part a term falling out of favour for diffuse lung disease which is good. The entire lung is being affected mostly in the interstitium though. Wide variety of causes, we’ve walked through a bunch of differentials. Generally all are characterized by parenchymal, hence in the previous flowchart we looked at diffuse parenchymal lung disease as being the common theme. Now, this type of parenchymal lung disease involvement seen on radiology or in pathology and this of course give you the restriction type of pulmonary function test.

05:29 Separate airway disease obviously from obstructive. Not all diffused lung disease produce restrictive physiology so keep that in mind.