DIP Episode 407 - Pulmonary Pathophysiology Series 6

Welcome everyone. This is episode 407 of the Divine Intervention Podcasts. Into these podcasts we continue the Pomonaille Pathophysiology series. This is going to be series six. And if you're taking your USMLA exams any time within the next few days, you may be interested in the few courses I have coming up. I have the NBME Test Digging Strategies class coming up tomorrow from 5 to 7 30 PM Pacific Standard Time. I've had tons of people take this class. Tons of people have done really well. Raise their Europe Cuban percentages, increase the NBME scores, increase the real exam scores. And then I also have a 20-hour review courses. Don't take it please all through next week except when there's going to be Monday to Saturday except Wednesday from 5 to 9 PM Pacific Standard Time on June. I decided to put those times because I imagine it would work well with a lot of people's schedules. So the course is going to be really helpful for anyone taking these exams. I think it's something I'm going to be going to find to be profoundly helpful. I'm going to meet from 5 to 9 PM Pacific Standard Time on June. And then on the 18th of this month I have a Bio Statistics Board camp. I've gotten a lot of very positive feedback from it from both of the exams and he said, oh divine. Most of the Bio Star Solutions I saw my test. I could easily crush them because of the class that I took with you. So it's going to be on the 18th of this month from 5 to 9 PM Pacific Standard Time.

If you're interested, shoot me an email and I'll give you some more information. All these classes are over June. And the Bio Stats Board camp applies to step 1 to step 3. The other classes apply more to step 2, seek-and-step 3 and complex level 2 and 3. The Testic Nist Strategy's class specifically applies to step 2, seek-and-step 3. Okay, although many people that take the cumulus exams and adjust really doing Q-Banks find you to be supremely helpful. So let's go ahead and dive into homonology. So yesterday, two days ago, I believe I did a episode 4 or 6, right? Give a small dose of pulmonary physiology. Again, today I'm going to give a larger dose than that. I imagine. But again, I'll try not to make this too long so that you can have time to sit with these concepts and understand them. Right? So now today, one thing I really want to focus on, focus on pressures. On a focus on our viola pressures and on a focus on pure pressures. Many people might at least struggle with this. But if you just be attention and follow along, you'll see that this is really not as hard as it seems. So again, when we finished our podcast last time, one thing we ended up on was, oh, whenever you see in a text or in a resource or whatever, then referring to the pressures within the audio line as being zero. They are choosing that zero as basically being at most pressure. So 760 millimeters of mercury is zeroed out to become zero. Okay?

So anything above 760 will be positive, intraveolar pressure, anything below 760 will be a negative intraveolar pressure. So just think of a number line where 760 is choosing as a big charge zero point. If you keep that in mind, then a lot of this is going to fall in place nicely for you. So let's talk about viola and plural pressures and how they relate to each other. So many of us know we have such a thing as the plural. Obviously, the plural is the space between the visceral and parietal plural. It's the space between the visceral and parietal plural. Usually there's nothing there. Except maybe just a little liquid. If you have a ton of liquid there, that's a plural fusion right there. If you have a ton of air, that's a pneumothorax. So the thing is this plural space, should always have a negative pressure. So since I'm saying you should always have a negative pressure. It means in other words, the pressure inside that plural space should be less than 760 millimeters of mercury because we chose that 760 as a zero point, right? And the thing is as you inspire, as you're bringing air into your lungs, those intraplural pressures get even more negative. It's really, really key to understand this thing. Now, you have viola. So I've talked about the plural. The plural pressures are pretty much always negative, right? And they're going to get more negative with inspiration. Now, let's look at you have viola. Again, let's stick things separately and then we'll integrate them.

So they have viola in your other hand, they can switch pressures a lot, right? They can have pressures that could be zero, that's 760 millimeters of mercury. They could have pressures that could be negative, that's some value less than 760 millimeters of mercury, or they could have values that could be positive, that's some value that's over 760 millimeters of mercury, right? And all these switches happen as the lungs are switching between inspiration and expiration, right? Now, one principle that'll help you really understand inspiration and expiration is that the lung will always move in the direction of a pressure gradient. I'll say that the lung will always move in the direction of a pressure gradient. So the lung is going to move in the direction of high pressure to low pressure. It's going to from high pressure to low pressure. So if you think about it, when you have a negative plural pressure, right? I told you that, oh, your introplural pressure is always negative. Well, the negative plural pressure that you have, right, is less than the pressure that exists in the alveoli. That's literally what makes it possible for your lungs to expand. So, say, for example, your alveoli is even at zero pressure, but your plural is at some negative pressure. Well, a negative pressure is, we've said we've defined this something less than 760. Zero pressure of design defined is something that is E760. So there is a difference.

The pressure inside the alveoli is bigger than the pressure in the plural. So the lungs are going to expand in that direction. That's what makes it possible for the lungs to expand, from that high pressure to low pressure, right? Into the plural space. So the lung will expand into the plural space-dreaming inspiration, right? And the thing is, obviously, as the lungs expand into the plural space, right, that's going to increase the volume inside the, inside the alveoli, right? Because think about it, the alveoli, they are crumpled together initially. When they expand, right, the pressure in that alveoli is going to go down because volume is going up. This is just simple boils, where you probably learn from general chemistry in college, right? Volume and pressure are inversely related. As the volume of the alveoli goes up, the pressure inside the alveoli is going to come down, right? So if you think about it, if the pressure within the alveoli, so we're talking about inspiration now, the pressure within the alveoli goes down, right? As a result of that original expansion of the alveoli into the plural cavity, that's going to reduce the pressure again within the alveoli. If you reduce the pressure within the alveoli, then it's going to be some number that is less than 760. It's going to be less than atmospheric pressure. So basically, that's going to create a pressure gradient between the outside world and the longer of your life.

Since the longer of your life is now a lower pressure system because it's expanded, it's increased volume and lowered its pressures. It's a lower pressure system. So oxygen wants to flow down from the atmosphere, which is at a higher pressure, 760, than the alveoli, which is now at some negative pressure, which is now at some lower pressure. So this will draw into the long-term inspiration. Now, the thing is, as areas get into the logs, that pressure gradient will slowly be eliminated, because over time, when flow happens from a high pressure situation to a low pressure situation, pressure is going to start building up in that low pressure situation until it equalizes the pressure from the high pressure situation that things are coming from. So essentially, as areas get into the logs, the pressure gradient will slowly be eliminated until it becomes very similar to atmospheric pressure until it becomes zero again. Once that happens, inspiration is going to stop. Now, one tip bit I want you to take away from all of this is that it is very, very high to know that the maximum gradient for inspiration exists midway through the respiratory cycle. I'll see that again. It is very, very high to know that the maximum gradient for inspiration exists midway through the respiratory cycle. Now, let's look at exhalation. In exhalation, it's literally the reverse of everything we've just said. The pressure on your purer is going to get less negative than B-slides.

It's going to still be negative, but it's going to be less negative than it's used to. Let's say, oh, normally it's negative six, but then it's going to become negative two. Obviously, negative two is bigger than negative six. So the pressure in the purer is going to get less negative than B-slide. Because it's less negative than B-slide, it's going to create a gradient that shrinks the logs, that reduces the long volumes. And again, as the volume of the logs go down, boils low, volume and pressure, and firstly, the volume of the logs go down. The pressure inside the logs are going to go up. The pressure inside the alveoli are going to go up. The pressure is going to increase past zero. It's going to be some number that is past zero, some positive number, some number that is graded and 760 millimeters of mercury. So if it's some number that is graded and 760 millimeters of mercury, that means, oh, inside the alveoli, we have more higher pressures than outside in the outside world, because the outside world has air and a constraint pressure of 760. So since this is higher than the atmospheric pressure, the intraveolar pressure is higher than the atmospheric pressure, air is going to move out of the logs, down its gradient, to the outside world, until we immediately meet the gradient and the pressure in the long schools back to zero.

So again, your logs are basically in this switcher root process, where the intraveolar pressures get negative when you're inspiring so that air can come in. And then the intraveolar pressures, you know, when they're negative, negative, negative, and air comes in until it gets to zero, then there's no more gradient for flowing inspiration will stop. Right? And then the intraveolar pressures will then switch a rule and become more positive than atmospheric pressure. So air will flow out of the logs, right? Down the pressure gradient from high intraveolar pressures to the normal atmospheric pressure that exists in the outside world, until the intraveolar pressure gets back to zero and then acceleration, exploration pretty much stops. Really, that's the way a lot of these things move. Right? So now let's talk about pluriponary mechanics. Let's look a little bit because some people are probably wondering, like, why are pluripresures negative? Like, why? What creates these negative intraveolar pressures? We have pluripresures negative at baseline. Well, let's explain. The thing is, on the normal circumstances, right? There's always going to be air in your logs, right? There's always going to be air molecules in your logs. Now, the thing is, these air molecules have attractive forces between them. Right? Those attractive forces, those air molecules kind of get emerged to each other. Is what causes the natural tendency of the lungs to be pulled inward? Right?

But again, we've already said that, oh, the chest wall likes to spring outward, but the lung likes to pull in words just because of the attractive forces between those air molecules that are within the avial line. Right? Now, the thing is, if we're looking at the intraveolar space, right? The space within the aviales, right? Literally, because of those air molecules, the lungs can spring downward, can collapse in words, but the chest wall is kind of pulling out words, right? But, you know, you have something, you have those counterbalancing forces kind of balancing each other out. Right? So that's why you can have an intraveolar pressure of zero, right? Because again, the chest wall is pulling out words. It's counterbalancing those attractive forces between the air molecules within the avial line. That's pulling the avial line inward, that's pulling the lung in words. But the thing is, think about it. Think about the plural space. The plural space technically should not have air molecules within it. We have air molecules that's an emotorax, right? So it has no air molecules within it. So it has literally no inward force available to counterbalance the outward chest wall force. So because it has no inward force, because there's no air in it, there's no air, there are no air molecules that are trying to get married to each other. Right? It cannot counterbalance the outward chest wall force. Right? So the chest wall essentially wins the battle, right?

And that's what establishes the negative pressure, because it's almost like, oh, the intraplural space cannot, it doesn't have any tug of work and give with chest wall. So it's almost like the chest wall wins the battle. That's what establishes the negative pressure that exists in the plural space. Right? So again, like I said, if air is admitted into the plural space, that's like a new emotorax. Then that negative pressure that exists in the plural cavity that helps the lung expanding inspiration is gone. Right? So the lungs are going to start collapsing inwards like a lot. Right? That's going to be bad. Right? That's why many times we have an emotorax, your lungs are going to shrivel up. Right? Because that negative intraplural space, intraplural pressure is gone. Right? Hopefully you know that if a person has an emotorax, they are two kinds. There is the one that has him with dynamic significance that's the tension in the thorax. Obviously for that one, you're going to do a needle decompression first. That's what's also known as a needle thoracostomy. That will convert the tension to an open emotorax. And then an open emotorax, right? For that, you can do a, you can place a chest tube. Remember, an example chest tube is tube thoracostomy. Notice every thing I've said here is thoracostomy, not thoracotomy. Thoracotomy is where you literally make an incision in a person's chest wall. Thoracostomy is where you introduce like a tube into a person's chest wall.

That's a very subtle point. But it's a very important point. The NB means they are very famous for making this play on words on exams. There's something you just kind of want to be, want to be mindful of. Okay. So hopefully you understand all of this. Right? Hopefully you understand all of this. So let's go ahead and talk about compliance. Right? Let's talk about compliance. Again, another thing that people might TV struggle with. Right? The thing is, first thing I want to say is compliance and elastance inversely related. As your compliance goes up, your elastance is going to calm down. As your elastance goes up, your compliance is going to calm down. Right? So compliance, what is it? It's basically a measure of long stiffness. Right? It's a measure of long stiffness. Right? Compliance is measured as volume of repressure. It's measured as volume of repressure. Right? So obviously, along that is very compliant for a small pressure change, the volume is going to change a lot. Right? So very compliant long, very happy to record a large increase in volume or a large change in volume with a small change in pressure. Right? So it makes it easy for you to move in and out of this kind of long, you know, because the longs, just low pressure boom, we're just blowing up very well in terms of volume. Right? That that's where it does nothing to work very hard here at all. Right? But you have a non-compliant long. A non-compliant long is a long that has low compliance. Right?

It's going to record very small changes in volume for very large changes in pressure because that long is too stiff. So you're putting a pressure change, you get a much, you get a very small change in volume. Right? Because the longs are too stiff. Right? So in this case, your diaphragm has to work really, really hard to move the same amount of air in and out of the long. Right? To move the same amount of air in and out of the long. Right? So that your longs can work well. Like literally your longs are just, your diaphragm is just going to be working harder. It's going to tie out quicker in those circumstances. Right? I just kind of think of it this way. Let's see, you're living the lifestyle of the region famous, like you have a home in the Hamtons, and you have a Lamborghini, and a Maserati, and the Rose Royes, and everything. Right? And let's say, oh, you had this job that paid you a million dollars an hour. Right? But then let's say, you know, weird stuff happens in life, and you're not starting to earn ten bucks an hour. Right? The thing is, if you're trying to maintain the same lifestyle as you were doing on a million dollars an hour, you have to work many more hours at that ten dollar an hour job to meet and meet. Right? That's like less compliance. Right? So because your income is less compliant, you've got to work much harder. Right? So that's maybe like a nice, easy analogy to think about compliance. Right?

So again, for a compliant long, small pressure change brings a large volume change for a non-compliant long, large pressure change brings a very small volume change. Right? It brings a very small volume change. So what are some things that can affect the compliance of the longs? Well, some things that can affect the compliance of the longs. First, you know, if you, you can decrease long compliance. How can you decrease long compliance? It decrease long compliance, whenever there's more stuff added inside the Alveol line. Right? So inside, think of the Alveol line as a bag. If you put more stuff inside it, you're going to have a decrease long compliance. So let's say you have like fluid inside the longs, pomeridima, or you have consolidation within the longs, pneumonia. Those things all decrease compliance. Right? So again, if you put something inside the actual bag that's the Alveol line, don't crush your compliance. And that thing that can also decrease your compliance is where you add more stuff to the walls of the Alveol line. Right? So say for example, a presence like Polyn-Refi-Broses, or they have interstitial long disease, there's more stuff in the wall of the Alveol line. Right? That's going to cause it to be less compliant. Now, the thing is you also, so let's maybe look at it from a perspective of what can increase long compliance. Right? So the things that increase long compliance is when you take stuff from the walls of the Alveol line. Right?

So remember like if a presence in Fesima and they have all these produces, all right, we have our phone and touch-tripsing deficiency, all these produces that are literally chewing up the parankham of your lungs, you're literally taking stuff away from the walls of the Alveol line. When you take stuff away from the walls of the Alveol line, the Alveol line is going to be more compliant. Right? That's why in Fesima, enough phone and touch-tripsing deficiency, those people have more compliant lungs. Now, the thing is it's pretty high to know that your long compliance increases as you get older, okay? Your long compliance increases as you get older. Now, as we wrap up today, it's just another final quick rule I want to talk about that I think will really help people. And that's the concept of EE Gridients, right? So it's a simple rule because you see people when it comes to EE Gridients, they memorize like this long-large list of stuff, which is many times not necessary at all, right? So they're like, oh, define how do I remember causes of hypoxia with an increased EE Gridients versus causes of hypoxia with a normal EE Gridient. Here's the rule. When they have a problem that is native to the long, when they have a problem that is within the longs, your EE Gridients will always be increased.

So if, for example, your hypoxic and the problem, the reason for how you hypoxia is because of a long problem, pneumonia, pulmonary fibrosis, COPD, whatever, you're going to have an increase in your EE Gridient. Whenever you have hypoxia that is for a reason that is outside of the longs, your EE Gridient is going to be normal. For example, if your hypoxic because you overdose on opioids, your respiratory rate is going to go down, right? There's no theorem with your longs, you just took too much opioid. That's going to cause hypoxia, but that hypoxia is going to be associated with a normal EE Gridient. If you really keep this rule in mind, you'll be very solid from an EE Gridient perspective. So I think again, hominology is kind of technical, so I'm going to go ahead and stop here because I want to go into a new topic, but I will address that in a future podcast. So again, I'd offer one on one tutoring for all the USMEL exams, step one to three, all the complex exams, complex one to three, except OMM, I do not tutor to OMM. And then I also offer review courses, a 20-hour review course for step two and step three and complex two and three, an MBA me testing strategy scores that many people have taken and want to be supremely helpful. And then a biosatistics book that runs for four hours. And then I have this podcast on Apple podcasts, on Google podcasts, I know Spotify, at least the most recent one, 150.

If you want everything from episode one to 407, then you need to go on the website, divineinterventionpodcasts.com. If you actually subscribe with your Word Press account, you get an email notification whenever I make a new podcast. And then I have a You Tube channel, divineintervention, USMEL podcasts and videos. It's the place where I post all the videos I make and all the podcasts that I'll be making a lot additions to the You Tube channel within the next few days. In fact, I probably need to do something today when I'm finalizing everything. So just go on there and subscribe so that you can get access to these updates. It's called divineintervention, USMEL podcasts and videos. And then many of you that listen to this podcast, normal Christian, so I've always talked about life lessons and I will continue to talk about life lessons. In fact, I will discuss a life lesson today. But I have a website that I've said aside, just full life lessons from a Bible-based perspective. It's called divineinterventionlifelessence.com. I make two podcasts that I post every week, usually like on Fridays and Sundays. Right now, I believe we have almost 104 of thereabouts episodes. So if you're a person that loves my life lessons, looking for a biblical perspective on things, I use a biblical perspective to address a life lesson. Most of the podcasts are like 10 to 20 minutes long. I actually have an Apple podcast. They've voted to it. It's called the divineintervention life lessons podcast.

So you know, just check that out. I think you're going to find it to be super, super helpful. So what's my life lesson today? My life lesson today is don't treat what is long term for what is short term. I feel like this is something that many people make mistakes with and then it kind of ends up costing them very dearly in life. People love to focus on something that is very short term. Right? They'll choose the short term instead of making the wise choice of the long term. What do I mean by that? Right? Say for example, a person is you're marriage to somebody, right? You told this person you love them everything. And then you see this person that oh, you're like, oh, this extra marital affair, right? Oh, cheating with their spouse with this person. That cheating, right? It's many times it's going to be a short term thing that oh, yeah, you enjoy it for a very short while. Right? You've essentially treated your marriage, your kids, everything for the short term. Right? That's not always the smartest thing to do. If I got you these many times, never the smart thing to do. Right? So just going to be careful of that. I mean, if you want to apply that to a prospective or medical student, right? Like, enjoying the present where you're not studying for your USML exams, nothing. You're just kind of coasting through your classes, whatever. You're not doing any studying, your party in hard. I'm not saying you should all relax. I'm not saying you shouldn't spend time on social media.

I'm not saying you shouldn't watch TV, right? But you're making an active choice in the present to take some instant gratification. When you're taking a standard vacation, you're going to be the president of the future, right? You see people they get to the, they get a period, they're not prepared, nothing. And then they're like, panic, panicking, panicking, panicking, panicking, right? That's not the kind of life you want to live. Right? Remember when I was in my first years of med school at Hopkins, right? You know, studying pretty hard. And there were sacrifices that we made. Was I watching as much TV as I'm actually don't get me wrong. I'm actually watching a pretty decent amount of TV. No, they think about it. But I was making a choice to be prudent every single day, at least most days. Right? So when the USML time came out long, I didn't have to struggle as hard as many other people struggled to study for the exam. Like literally weeks before I even got into my day to get a period for step one, I was just scoring above the national average. Right? So again, it's just very helpful to just be wise and be prudent in the present. Right? Like think long term. Whenever you're making decisions, don't make decisions based on the sport of the moment. Don't make decisions based on temporary things you see. Right? Like, you know, there's this biblical example of Issa and Jacob. An issa literally treated his entire future just because he was hungry in the present. Right?

That hunger, if you have probably held his belly and looked around, even if he's for six hours, you would have found some other food instead of training his birthright. So it's just important. Just be wise. You know, delayed gratification is a thing. It's a very helpful thing for many people's destinies. So I'm going to go ahead and stop here. I'll see you in episode 408. Have a wonderful rest of your day. If you're interested in sending out for any of the courses, just shoot me an email through the website. I'll give you some more information. Thank you. God bless you. Bye for now.

It must be negative, as the outward force of the chest wall counterbalances the inward attractive forces of the lung parenchyma.

Alveolar volume increases, which causes alveolar pressure to decrease (Boyle's Law).

Air always moves down a pressure gradient (from high pressure to low pressure).

It measures the lung's stretchability; high compliance means large volume change with small pressure change.

Thoracotomy is making an incision into the chest wall; thoracostomy is introducing a tube through the chest wall.

Midway through the respiratory cycle.

The outward force of the chest wall counterbalancing the inward attractive forces of the lung parenchyma.

Compliance decreases because adding material inside the alveolar "bag" makes it stiffer and harder to inflate.

The negative pressure gradient is lost, allowing the lungs to collapse inward due to elastic recoil.

Lung compliance increases as a person gets older.

Normal, because the problem is outside of the lungs.

Needle decompression (needle thoracostomy).

The outward force of the chest wall counterbalancing the inward attractive forces of the lung parenchyma.

Compliance decreases because adding material inside the alveolar "bag" makes it stiffer and harder to inflate.

The negative pressure gradient is lost, allowing the lungs to collapse inward due to elastic recoil.

Lung compliance increases as a person gets older.

Normal, because the problem is outside of the lungs.

Needle decompression (needle thoracostomy).