DIP Episode 406 - Pulmonary Pathophysiology Series 5

Okay, welcome. My name is Divine. This is episode 406 of the Divine Intervention Podcasts. In today's podcast, we're going to be continuing the Pomanary Path of Physiology series. This is actually going to be series five. It's going to be series five. And really today it's going to be short because I'm going to focus on some technical stuff. I want to make sure that you actually get it. I actually understand it. It's going to be called, you know, we're going to be talking about a lot of volumes and things like that again. For those that have been listening to this since the series one, my goal has been to just go over a poem in a way that you actually understand it because poem is some of the has some of the hardest arguably. Cardiac Physio don't get me wrong. It's a little hard. Renov Physio is a little hard but really nothing in my opinion holds a candle to poem just from an understanding perspective. You don't find it explained very well outside us either. So again, you see I've kind of broken it up into into bits and pieces. If you really follow those bits and pieces, you you'll feel very good about poem. A series one is episode 392 series two is episode 393 series three is episode 397 and then series four is episode 402. So this is going to be series five, which again is episode 406. And as I do, if you're taking your step two or step three or complex level two or three exams, any time to have a few courses that's going to help you out.

I actually have the courses the series of courses starting this week have an MBA me test against tradition scores. It's going to be taking place on Friday from five to seven thirty p.m. Pacific standard time that's seven to ten thirty Eastern. I mean seven to nine thirty. So wait, hope something to my math right. So five to seven thirty p.m. Pacific standard time. Right. So that's going to be eight to ten thirty p.m. Eastern standard time. It's going to be on zoom. And then I have a twenty hour and that course is more for step two and step three. Then I have a twenty hour review course that's going to be taking place from Monday to Saturday next week. It's basically, it basically applies to complex two and three and step two and three. It's going to be from five to nine p.m. Pacific standard time on Monday, Tuesday, Thursday, Friday and Saturday. And then we'll have a biostatistics review. Biostat's asking a one that is taking the exam recently almost very few of the questions you see are going to be plugged in chalk. Most of them are going to be straight up kind of do you actually understand the concept? So if you want a course, it's a four hour course is from five to nine p.m. Pacific standard time on the 18th of this month. This is for step one, step two, step three. It's of course you're going to be profoundly helpful.

If bio stats, if you want to get, if you want to understand bio stats and not just have it be a bunch of formulas to you, that's of course you want to attend. There's a lot of reward problems that we have that will just help you see right through most of the bio stats situations you'll see on your exam. Okay. So let's jump into a discussion of Paul, right? So long volumes are important to understand, right? And probably the best easy one to start with is the title volume. The thing is you see some people they try to memorize like the diagrams and what not. And don't get me wrong. There's nothing wrong with that. Obviously you can do whatever you want to do. But at the end of the day, the thing that's really going to help you is if you understand it, you can kind of work it out in your mind. So what's the title volume? The title volume basically is the amount of air that comes into and out of your lungs with each quiet breath. So just like you sitting chilling breathing or sleeping chilling breathing the amount of air getting in getting out getting in getting out. That's your that's your title volume. But the thing is after you blow out a title volume, you can still blow out some more air. That extra air is what is called the expatory reserve volume. So you can blow out extra. That's the expatory reserve volume. But the thing is after you've blown out your expatory reserve volume, they still some air in the lungs. That air in the lung is what's called your residual volume.

Okay. It's what's called your residual volume. So again, remember, title volume is what you breathe in and out with just normal breathing, no more respiration, right? But if you blow out some after you've blown out a title volume through blood more, that's your expatory reserve volume, right? But there's still going to be some blow oxygen in the lungs, some air in the lungs. That's going to be a reserve volume. I mean, sorry, residual volume. Now, let's look at title volume from the other perspective of breathing in, right? Again, you're breathing in normally in and out in and out in and out in and out. When you breathe in just a normal breath, you'll just breathe in a title volume. But you have the ability to breathe in more air. That more air you can breathe in is what's known as the inspiratory reserve volume. You see, it's very analogous to the expatory reserve volume, but that's just the other end of the coin. And you may have heard of the term long capacity. Whenever you hear of a long capacity, it's a combination of at least two different volumes. You need to opt to more volumes to get a long capacity, right? So like, for example, total long capacity is all your long volumes added together. All of your long volumes added together will give you a total long capacity. Your vital capacity is basically your total long capacity minus your residual volume. So it's almost your like, you're like, hmm, you know what?

If I completely blow out all the air possible, like I can't know from my lungs, I'll be left with, I'll be left with residual volume. If you breathe in to like your max, max, max capacity, that's stuff you're breathing in above your residual volume is your vital capacity. Obviously, your vital capacity is a mixture of a bunch of volumes. And don't forget that your inspiratory capacity is your title volume plus your inspiratory reserve volume, right? Your title volume plus your inspiratory reserve volume and your functional residual capacity, which is a pretty high volume to know, is basically your zero volume plus your expiratory reserve volume. Okay? So title volume plus inspiratory reserve volume is your inspiratory capacity. And then your FR, which is your functional residual capacity is your residual volume plus your expiratory reserve volume. Again, every now and then you see these things on the exams, the things you want to make sure that you know, but I think one thing that may help is to really drill in and ask ourselves, what in the world does functional residual capacity mean? Basically, functional residual capacity is the volume of air left behind in the lungs after you've taken a quiet breath. To really get this down, it's really helpful to think of the lungs as being one system. Think of your lungs as being one system, right? And your lungs are set to be at rest.

This one system of your lungs, we can say that they are at rest when the lung volume is at the functional residual capacity, where your lung volume is at FRC. And if you really think about it, we say that a system is at rest when the forces in one direction counterbalance the forces in the opposing direction. Just think of it as a push and pull. If you've been pushed in one direction and being pulled in the opposite directions, then it's almost like if and if both forces cancel out each other, then you're pretty much going to be at rest. You're pretty much going to be at rest. So in the case of the lungs, these two equal, but opposite forces are one, the inward pull of your lung itself and then two, the outward pull of your chest wall. Okay? So your lungs are set to be at rest when your lung volume is at FRC. To be at rest, it means the forces in one direction, most much of the forces in the opposing direction. Just think of it in a logical physics line light. So the two forces we're referring to in the lungs that kind of keep everything at rest is one, the inward pull of the lung itself and two, the outward pull of the chest wall, the outward pull of the chest wall, counterbalancing the inward pull of the lung. Now, it is super, super, super high you to understand that your lung naturally wants to collapse while your chest wall naturally wants to spring outward. I'll see that again. The normal orientation of your lung is to collapse inward.

The normal orientation of your chest wall is to spring out, is to expand outwards, to spring outwards. That's a very important concept to keep in mind. You see it's going to play a ruling this podcast and also in just future pulmonary pathophysiology podcast that I make. So let's discuss a few more things and then again we'll bring in some, we'll bring in some integrations. This time goes on. Again, I will try to keep this podcast short because I feel like the stuff in this podcast is something you have to sit down and really think about. So I need really short in this and just make another one fairly, fairly soon that just continues our ideas just to kind of keep things going. But I don't want to give you a large dose of hard stuff on at once. That's probably not ideal. Okay. Now, what is your ventilator rate? If you ever hear a question on the NBM, it's like what in the world is a ventilator rate? Well, basically, your ventilator rate is simply the product of the volume of air to inspire with each breath. Right? So basically your title volume multiplied by your respiratory rate. Right? Remember, usually the normal respiratory rate is between like 12 to 18 or 20 beats per minute, breaths per minute, right? Not beats per minute, beats per minute, it will be the heart. But you know, 12 to, sorry, between 18 and 20 is pretty normal. Now, the thing is it is not all the air that comes into your lungs that participate in gas exchange, right?

Many of us have heard of this term dead space. Again, let me really break it down and make it clear and obvious to you. It's not all the air that comes into your lungs that participate in gas exchange. If he did, oh, that would be super awesome. But there are also some benefits to not all of that air participation in gas exchange. So the thing is about 30% of the air that comes in, it does nothing. And the thing is the airway regions that deal with this 30% are things we call dead space. And this dead space includes a few things, right? Like the key critical airsization, no, are your upper respiratory tract, you know? So like from your nose, all the way to your terminal bronchial, right? Basically the conduct in zone of your airway. And then some portions of your lung apex, okay? So your long, some portions of your lung apex and the conduct in zone of your airway, right? So from the nose, basically, to the terminal bronchial, these things contribute to dead space. Now, there are two kinds of dead space, right? So the conduct in zone again, from your nose to your terminal bronchial, it gives rise to something that we call the anatomic dead space, the anatomic dead space. It's pretty much always there. Now, the apex of your lungs are the things that are known as the functional dead space. So again, there are two kinds of dead spaces and then there is an that dead space term I will describe. But there's an atomic dead space is called an atomic because it's always there.

You know, I would hope that you have an airway, right? So from the nose or the way to the terminal bronchial. And then the apex of the lungs, the episodes of the lungs, and known as the functional dead space. The thing is, they're usually there, but in some situations, you can make them not be dead space anymore, especially like in the situation of exercise. When you exercise, you begin to recruit like a lot of your out of your life in the apcs of the lungs and they no longer are dead space. So your anatomic dead space is always going to be dead space. But your functional dead space, aka the apcs of the lungs, they can be dead space most of the time. But in certain situations, you can recruit them to no longer be dead space. That's why they are called functional dead space. Many times you recruit them in the setting of exercise. So I said I would describe one more dead space term. What is that one more dead space term? Is this term called physiological dead space? Physiological dead space is basically the addition of your anatomic dead space and your functional dead space. If you add those two together, you basically have your physiologic dead space, your anatomic dead space and your functional dead space. It's about 150 milliliters, right? So like 0.15 liters, right? And again, your dead space can be modulated. It can increase or decrease in certain circumstances. These are all very good examples of scenario-based questions they can give on exams.

And the thing is, we're going to analyze those things as we go along in this Poinert Pathophysiology series. Now, one other thing I want to discuss, really for this podcast, I just want to hit out a few, like just disparate public physiology things. And then again, we'll start making integrations in future in future podcasts. But let's talk about the relationship between volume and pressure in the lungs. Many of us have heard of the term compliance. That, ooh, C is equal to V over P, right? So like compliance is equal to volume of a pressure, right? And obviously, elastance is the inverse of that. So elastance is pressure over volume, right? So as compliance goes up, elastance goes down, right? So the long compliance and the long elastance there, they're inversely related. Now, the thing is, if you look at the volume pressure relationship for the lungs, as you add more volume to the lungs, the pressure in the lungs go up. As you add more volume to the lungs, the pressure in the lungs go up. So the thing is, many times, if you're describing a volume pressure relationship with the lungs, as one is going up, the other goes up, right? So the volume is going up, the pressure goes up. I mean, if you think about it from a balloon perspective, if you keep blowing up balloon, over time, the walls of the balloon will expand, they'll become taught, they'll become distended, because as volume is going up, pressure is going up.

But the thing is, you need to remember this, a balloon cannot descend forever, right? A balloon cannot really descend forever. You know, it will hit a maximum, the extension at which point, you know, very small increases in volume will be accompanied by very large increases in pressure, right? So think about it as you're blowing up that balloon. Initially, it blows up really easily. You know, volume is going up, pressure is going up almost in linear fashion. But as you've, after you've blown that balloon for a while, one, it will require, even with just a very small change in volume of the balloon, you're blowing just a little air. The balloon pressure goes on very significantly, just with a small volume change, just with a small volume change, right? Just with a small volume change. And notice, when the balloon has been distended significantly, it requires more work from you to blow that balloon, even further. It requires more work from you to blow that balloon, even further, right? So the thing is, you can essentially derive some principles from this. Your lungs become less compliant when you conduct respiration at high volumes. I'll say that again, your lungs become less compliant when you conduct respiration at higher volumes, at higher volumes, at higher volumes, right? Because again, the work of breathing is just harder. That's why you see people that have COPD, for example, right?

People that have really bad COPD, where they have like long hyperinflation, their lungs are operating at high long volumes. So those people's lungs are not going to be very compliant. They're not going to be able to go from, they're not going to be able to increase the pressure in the lungs significantly. I mean, like any, any volume increase will be accompanied by a very big, massive pressure increase, right? Obviously, you don't want to blow the lungs. That's how those people get like these are ruptured vapicoblabs and they can get like a pneumothorax and things like that, right? So it's very high to know that the lung is less compliant when you conduct respiration at higher volumes. I'll say this again, because this point is extremely important. It is extremely important. Your lungs become less compliant when you conduct respiration at higher volumes. This is why the work of breathing is really big and people that have COPD. That's something that's pretty high to know, for example, okay? That's something that is extremely, extremely high to know for exams, okay? It's extremely high to know for exams. So again, just to make sure I really hit the snail on the head. Your lung is at rest when it's at functional residual capacity, right? The pressure, the alveolar pressure, literally the pressure within your alveolar is going to be zero within your alveolar. I'm not talking about within your plur, we'll talk about plurial pressures in another podcast.

I feel like this podcast has even gotten pretty intense already, right? So just, I'm just going to end with this thought. And then we will dig deeper at the next, we will literally dig deeper in the next podcast. Well, when you're at FRC, as I said, the alveolar your lungs wanting to collapse inward is balanced perfectly by your chest walls desire to expand outward. That's it, okay? And the pressure inside your alveoli, I'm not talking about plurial pressures, the pressure inside your alveoli when your lungs are FRC is zero. Now, this pressure of zero is actually time-termout. It's actually equivalent to atmospheric pressure. It's more like a pressure of 760. It's more of a pressure of 760. Basically, that's, it's almost like we just zero out the pressures. We just say, you know what, if an intra-alveolar pressure of zero exists, then we're talking about atmospheric pressure, which is roughly 760 millimeters of mercury. Okay, we set that 760 as a zero point. So if, for example, you have any pressures over 760 inside the alveoli, right? Then that's a positive, that's like a positive non-zero pressure. But we'll talk about those some more with regards to breathing, right? Because I think one thing that may be very helpful and that's almost certainly going to be the next podcast.

We'll talk about things that are related to, oh, what happens to your alveolar pressures when you're inspiring, what happens to your plural pressures when you're inspiring, you see all these pressure ingredients and see how the lungs expand or contract as a result of that. So I think I'm going to go ahead and stop here. Again, I do offer one or one tutoring for all the USML exams. Step one, all the way to step three, complex level one to three. I just don't tutor for women. I don't tutor for women. And then I offer review courses for step two and step three and complex level two and three. I talked about them at the beginning of this podcast. And then I have these podcasts on Apple podcasts, Google podcasts, Spotify. If you subscribe, you get the most recent 150 podcasts on any of those platforms. But if everything from episode one, all the way to this corner, episode 406, you want to go ahead and get on the website, divininterventionpodcasts.com. And then I also have a You Tube channel. It's called Divine Intervention, USM Ly podcast and videos. That's where I post the videos that I make. Again, like I said, I'm going to be making some changes to that very, very soon. It's something that I'm currently working on. And then I also have a new website called Divine Intervention Ly Flessence.com. It's a website that has an attached podcast. It's an Apple podcast. It's called the Divine Intervention Life Lessence Podcast. But basically, many of you know I'm a Christian.

I use a, I discuss a problem that's faced by many people and attend a 20-minute podcast. I add about 12 them every week. And I use a biblical perspective to describe the problem and how to solve that problem. And then I also help with ER As applications, rec letters, personal statements, mocking reviews. Again, I've worked with many people that are now attendants, they're now residents in competitive programs all over the country, dermatology, ortho, ENT, IM, family medicine, peds, psych, gendered radiology, and asthesia. I've worked with people from many different disciplines. So if you're interested in many of those things, just shoot me an email through the website and I can give you some more information. So thank you for listening to me today. Again, this is a shorter podcast. But again, many of the principles from this podcast will play into the next podcast. So have a wonderful rest of your day. God bless you. Thank you.

The amount of air that enters and leaves the lungs during quiet, normal breathing.

Residual Volume (RV).

FRC = Residual Volume (RV) + Expiratory Reserve Volume (ERV).

Anatomic Dead Space (Upper airways/Conduction zone) and Functional Dead Space (Alveolar apices).

When the lung volume is at FRC, where the inward pull of the lungs is perfectly balanced by the outward pull of the chest wall.

Compliance decreases because the tissues become stretched and less able to expand further without massive pressure increases.

$C = V/P$ (Compliance equals Volume over Pressure).

The elastic recoil of the lung tissue itself.

Inspiratory Reserve Volume (IRV).

Alveolar pressure is zero, meaning it is equivalent to atmospheric pressure (760 mm Hg).

Anatomic Dead Space + Functional Dead Space.

They have decreased compliance because they are operating at high lung volumes.

$C = V/P$ (Compliance equals Volume over Pressure).

The elastic recoil of the lung tissue itself.

Inspiratory Reserve Volume (IRV).

Alveolar pressure is zero, meaning it is equivalent to atmospheric pressure (760 mm Hg).

Anatomic Dead Space + Functional Dead Space.

They have decreased compliance because they are operating at high lung volumes.