Chapter 15: Thorax & Lungs

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Welcome back to another Deep Dive.

Today we are opening up the hood and looking directly at the engine room.

The engine room?

I like that description.

It fits.

It feels appropriate, doesn't it?

We're talking about the thorax and the lungs.

This is the machinery that, you know, keeps us oxygenated, keeps the blood moving, and frankly keeps us alive.

And usually does it all on autopilot.

You don't have to tell yourself to breathe.

You just do it.

Thankfully, yes, it is automatic.

But when that automatic system hits a snag or when we as clinicians need to understand what is happening under the hood, the mechanisms become, well,

incredibly complex.

It is a fascinating mix of structure, pressure, fluid dynamics,

and gas exchange.

And sound.

We cannot forget the sound.

A whole lot of strange clicks, wheezes, and thuds.

A symphony of sounds, really, if you know how to listen.

Ah, and that is the catch.

It is.

Most people hear noise.

We want you to hear information.

So that is our mission today.

We are walking straight through chapter 15 of Bates' Guide to Physical Examination and History -Taking.

We're going to try and translate that text into a comprehensive audio guide for students and clinicians.

We're talking anatomy, the art of the interview, and a nitty -gritty of the physical exam, from counting ribs to figuring out why a patient sounds like they're playing an accordion.

And just to be clear from the outset,

everything we discuss today is drawn strictly from that chapter.

We aren't improvising medicine here.

We are unpacking the gold standard of assessment.

Precisely.

But before we put our stethoscopes in help us set the tone.

Why is this exam so critical?

Why can't we just send everyone for a CT scan and call it a day?

Because the chest exam is about more than just technology.

It's about 3D visualization.

You have to understand the anatomy beneath the skin to interpret what you're hearing or feeling.

So it's not just random sounds?

No.

You aren't just listening for a bad sound.

You're building a clinical judgment that directs patient care immediately.

It's about finding the clues that tell you if this is a minor issue or a life -threatening emergency before the machine even warms up.

Okay, let's unpack this.

If we're going to visualize the anatomy, we need a map.

We need to know where we are.

We do.

We call it mapping the chest.

And the text describes the thorax as sort of cage.

It is a cage.

A protective one, but a flexible one.

Anteriorly, that's the front, you have the sternum and the ribs.

Okay.

Laterally, you have more ribs wrapping around.

Posteriorly, the ribs wrap all the way around to meet the thoracic spine.

And the floor of this cage is the diaphragm.

The power source.

Exactly.

The thorax houses the heart and lungs, sure.

But that cage isn't rigid like a jail cell.

It mechanically powers the work of breathing.

But to navigate it, you need landmarks.

You can't just guess.

No, you can't just say the pain is in the upper chest.

That's not specific enough for a medical record, and it's definitely not specific enough to guide

coordinates.

Right.

And the most important coordinate, the north star of the chest exam, is the sternal angle.

Also known as the angle of Louis.

The angle of Louis, yes.

I love that name.

It sounds like a 17th century European aristocrat.

I shall meet you at the angle of Louis.

It does have a regal ring to it, but practically it is your anchor.

So for the listeners, and I want everyone to actually do this right now, unless you're driving,

how do we find it?

Walk us through the physical sensation.

It's surprisingly easy, and it's the key to accurate rib counting.

Start by placing your finger in the hollow curve of the super sternal notch.

That's the dip right at the base of your throat, between your collarbones.

Exactly.

The little dip.

Okay, I'm touching the dip.

It's soft.

Now, move your finger down about five centimeters.

You will feel the bone flatten out, and then you will hit a horizontal bony ridge.

It feels like a little speed bump on the sternum.

I feel it.

Yeah.

Okay.

It's a definite ridge.

That ridge is where the manubrium, the top shield -shaped part of the sternum, joins the body of the sternum.

That joint is the sternal angle.

And why is this ridge so important?

Why can't we just start counting from the top?

Why can't I just find the collarbone and say that's rib number one?

It's a great question, because the first rib is tucked way under the clavicle.

You can't really feel it.

It's hidden.

Okay.

But directly adjacent to that sternal angle, that speed bump, is the second rib.

Always.

It is a constant.

So once you find the angle of Louis, if you slide your finger to the side, you are landing on the second rib.

No question.

Exactly.

And from there, you use a technique called walking down.

Describe that.

Use two fingers.

You find that second rib.

Then you slide down into the soft space below it.

The intercostal space.

Right.

Since the rib was the second rib, the space below it is the second intercostal space.

That makes sense.

The space is named after the rib above it.

Correct.

Then you feel the next bony prominence.

That's the third rib.

Then the third space.

You walk your fingers down in an oblique line, moving away from the sternum slightly as you go down.

Now, I noticed the text mentions a specific challenge here for female patients.

Yes.

In women, breast tissue can completely obscure these landmarks on the anterior chest, making it much harder.

So how do you handle that respectfully and effectively?

You can't just guess.

No, you can't.

The guide suggests either displacing the breast laterally with your left hand while you palpate with your right, or sometimes asking the patient to help move the breast.

Okay.

Alternatively, you can palpate more medially closer to the sternum where the tissue is thinner.

The key is to be gentle but firm enough to find the bone.

Now, let's talk stakes.

You mentioned earlier that these coordinates are vital for clinical procedures.

This isn't just trivia for Not at all.

Give us some examples.

Why does a clinician need to know exactly where the second inner space is versus the fourth?

It is absolutely a matter of life and death in emergency medicine.

Let's take attention pneumothorax.

That's a collapsed lung where air is building up pressure, right?

Yes, and it's crushing the heart and the great vessels.

You need to release that air instantly.

The needle insertion site for emergency decompression is the second intercostal space.

If you go too low, you miss.

If you go too high, you hit structures you don't want to hit.

You need the angle of Louie to find that second rib immediately.

Okay, that is high stakes.

What about the fourth space?

The fourth intercostal space is usually where a chest tube is inserted.

That's a larger tube used to drain blood or fluid.

And if you're looking at a chest x -ray, the fourth rib marks the lower margin of a well -placed endotracheal tube.

If the tube is below the fourth rib, it's too deep.

So these aren't just random numbers.

They are procedural targets.

They are the map.

And here's a critical safety tip from the anatomy section that every student needs to burn into their brain.

Neurovascular structures.

The nerves and blood vessels.

They run along the inferior margin of each rib.

That means they are tucked underneath the bottom edge of the rib.

So if you're sticking a needle in, you never go right under a rib.

Never.

You place the needle just at the superior rib margin.

You ride the top of the rib below the space.

You aim for the top of the rib to avoid the nerves hiding under the rib above.

Exactly.

Ride the rib is the phrase we often use.

It prevents you from slicing an intercostal artery or causing a bleed that can be really difficult to control.

That is a detail you definitely want to remember.

Yeah.

What about the back?

The posterior landmarks.

I assume the angle of Louie doesn't help us much back there.

No, it's a completely different landscape.

The twelfth rib is often your starting point there.

You feel for the bottom most rib, the floating rib and count up.

And the spine.

The spinous processes of the vertebrae are great landmarks.

When you flex your neck, forward chin to chest, the most prominent bone sticking out at the base of the neck is usually C7.

Usually.

What if there are two sticking out?

Good question.

If you feel two, then they are likely C7 and T1.

You can verify this and then count down the vertebrae from there to map findings on the back.

Okay.

Also another visual cue.

The tip of the shoulder blade, the inferior angle of the scapula.

Where does that land?

Usually at the seventh rib or inner space.

So if you hear a crackle right at the tip of the shoulder blade, you know you are around the level of the seventh rib.

It gives you a quick orientation.

Okay.

So we have our vertical map, how high or low we are, but the chest is a cylinder.

We need to know where we are around the circumference.

Correct.

We visualize a series of vertical lines to give us a grid.

On the front, you have the mid -sternal line right down the middle of the chest.

Easy enough.

Then the mid -clavicular line dropping down vertically from the center of the collarbone.

And on the side, under the armpit.

That's the axilla.

So you have the anterior axillary line at the front fold of the armpit, which is the pectoralis muscle.

Right.

Then the mid -axillary line right in the apex or deepest part of the armpit.

And the posterior axillary line at the back fold, the latissimus dorsi muscle.

The text highlights a specific zone here called the triangle of safety.

That sounds ominous and reassuring at the same time.

It's reassuring if you need a chest tube.

This is a region in the mid -axillary line.

The borders are the pectoralis major muscle in the front, the latissimus dorsi in the back, and the nipple line, usually the fourth or fifth inner space at the bottom.

And that's the safe spot.

That triangle is considered the safe position to enter the chest with a tube because you avoid major muscles and breast tissue.

It's a clearer path.

It's like a safe harbor for invasive procedures.

Let's talk about what's inside the cage.

Lungs themselves.

I think most people picture two identical balloons.

And that would be wrong.

They are not identical twins.

No.

Cousins, maybe.

The right lung has three lobes, upper, middle, and lower.

It's divided by two fissures, the horizontal and the oblique.

Three on the right.

And the left lung only has two lobes, upper and lower, divided by just the oblique fissure.

Why the difference?

Why did nature shortchange the left lung?

It's simply a space issue.

The heart sits primarily on the left side of the chest, so the left lung is a bit smaller and lacks that middle lobe to accommodate what we call the cardiac notch.

So the heart gets its own little cutout.

Pretty much.

This affects where we listen, right?

The auscultation geography.

It changes everything.

This is where 3D thinking is crucial.

For instance, if you hear a strange sound in the right upper lung field anteriorly, it's almost certainly the right upper lobe.

Okay, that's straightforward.

But if you're listening laterally in the right middle field.

And to the arm.

Yes.

That could be the upper, middle, or lower lobe, depending on exactly where you are, because of how they stack on top of each other diagonally.

You have to visualize those fissures.

And the text makes a point about the versus the base that surprised me.

That the apex is so high.

Yeah.

Anteriorly, the apex of the lung, the very top tip,

actually rises about two to four centimeters above the clavicle.

It does.

They poke up into the neck, essentially.

Wait, the lungs go higher than the collarbone.

I always thought they were tucked safely inside the ribs.

It's a common misconception.

So if you have a stab wound or a needle stick just above the clavicle, you can actually puncture the lung and cause a pneumothorax.

That is good to visualize.

What about the bottom?

The base?

The base, or lower border, crosses the sixth rib at the mid clavicular line and the eighth rib at the mid axillary line.

Posteriorly, on a deep breath, the lungs can go all the way down to T12.

Now connecting the lungs to the outside world is the tracheobronchial tree.

The plumbing?

The airway.

The trachea splits or bifurcates into the main bronchi right at the level of the sternal angle we talked about earlier.

The angle of Louie strikes again.

It really is the crossroads of the chest.

It is.

Posteriorly, that split is at T4.

Now there is a distinct difference between the right and left bronchus that has huge clinical relevance.

The right main bronchus is wider, shorter, and more vertical than the left one.

Does that shape difference matter?

Hugely.

Think about gravity.

Because the right bronchus is more vertical.

It's almost a straight shot down.

If a patient aspirates something like a peanut or a tooth or vomit, where is it going to go?

It's going to take the path of least resistance down the straight chute.

Exactly.

It falls into the right bronchus.

So aspiration pneumonia is a right -sided problem more often than not, specifically in the right middle or lower lobes.

And I assume the same goes for medical equipment.

Yes, absolutely.

If you insert an endotracheal tube for a ventilator and push it in too far, it's going to slide right into that vertical right bronchus, which means you are only ventilating the right lung.

The left lung gets no air and collapses.

Oh wow.

That's why we listen to both sides immediately after intubation to make sure we haven't essentially turned off the left lung.

Fascinating how geometry dictates pathology.

Before we move to physiology, mention the plurale.

The linings.

The lungs aren't just flopping around against the ribs.

They are covered in a membrane called the visceral pleura, and the inside of the rib cage is lined with the parietal pleura.

In between them.

What's in that space?

It's a potential space with a tiny amount of pleural fluid.

Surface tension.

It keeps the lungs stuck to the wall.

Think of two glass slides with a drop of water between them.

You can slide them, but you can't pull them apart.

Good analogy.

That's how the lungs stay expanded.

But here's the clinical key regarding pain.

The visceral pleura on the lung has no pain nerves.

So the lung itself is numb.

Essentially.

You can cut the lung tissue, and the patient won't feel it there.

But the parietal pleura on the wall, it is richly innervated.

It is extremely sensitive.

So when a patient feels pleuritic pain,

that sharp stabbing pain when taking a deep breath.

It's the parietal pleura.

It's the outer lining that's irritated.

Precisely.

Pleuritis.

Pneumonia reaching the outer wall.

Pulmonary embolism.

That pain comes from the parietal pleura being stretched or inflamed.

Let's look at the machinery in motion.

Section two.

The physiology of breathing.

It's a pressure game.

It is completely.

The primary muscle of inspiration is the diaphragm.

When it contracts, it descends, it moves down.

And that creates space.

It expands the thoracic cavity vertically.

At the same time, the scales and parasternals lift the rib cage.

This increases the volume of the chest.

And Boyle's law takes over.

Volume goes up, pressure goes down.

Exactly.

Intra -thoracic pressure drops below atmospheric pressure, and air rushes in to fill the vacuum.

That's inspiration.

So it's an active process?

Inspiration is active, yes.

Expiration.

Expiration is usually passive.

The diaphragm stops contracting and relaxes.

It rises back up.

The chest wall has elastic recoil, so it snaps back.

The air is pushed out.

But sometimes breathing is hard work when the passive system isn't enough.

Right.

When a patient is in distress or exercising heavily, the diaphragm needs help.

That's when the accessory muscles kick in.

The sternocleidomastoids, or SCMs, in the neck and the scalenes are recruited to aggressively lift the rib cage.

We can see this, right?

This isn't just happening inside.

You can absolutely see it.

If a patient is sitting on the exam table and you see their neck muscle straining and popping out with every breath, that is a sign of significant work of breathing.

It's a warning sign that the autopilot is failing.

Which brings us perfectly to the health history,

the interview, section three.

This is where the detective work begins.

Before you even ask a question, you observe.

As the patient walks in, are they winded?

Can they speak in full sentences?

If they stop every three words to take a breath.

Then something is wrong.

That's a doorway diagnosis clue.

You know before you even sit down that the respiratory system is compromised.

The text lists dyspnea as a major symptom.

Shortness of breath.

But the definition is interesting.

A painless but uncomfortable awareness of breathing.

That's the clinical definition.

But shortness of breath is subjective.

If a marathon runner gets winded walking up one flight of stairs, that's abnormal.

If a sedentary 90 year old gets winded, that might be baseline.

So you can't just ask, is it bad?

No, you have to quantify it.

How do you make it objective?

You ask about function.

How many flights of stairs can you climb before you have to stop?

Can you carry the groceries in from the car?

Can you make the bed?

Real world metrics.

Exactly.

And you have to distinguish it from anxiety.

Anxious patients often describe a smothering sensation, or they feel like they can't take a deep enough breath, even though their oxygen levels are fine.

They might also have paresthesias pins and needles around the lips or hands.

That's from hyperventilation.

Blowing off too much CO2.

Correct.

Then there's wheezing.

Musical respiratory sounds.

That's the key word.

Musical.

It usually indicates partial airway obstruction.

The tube is narrowed so the air whistles.

Like asthma?

Asthma, a foreign body extraction, COPD, exactly.

And cough.

This is a common one.

Everyone coughs.

How do we break it down so it's useful?

Duration is the first cut.

Acute is less than three weeks, usually a viral cold or acute bronchitis.

Subacute is three to eight weeks.

Could be post -infectious or bacterial sinusitis.

And chronic is more than eight weeks.

That's when we think about asthma, reflux, GERD, or chronic bronchitis.

And then the gross part, sputum.

We have to talk about the phlegm.

The color and consistency tell a story.

Walk us through the sputum rainbow.

All right.

If it's mucoid, translucent, white or gray, it's likely viral.

Or maybe cystic fibrosis in a younger patient.

If it's purulent, yellow or green, that points to bacterial pneumonia.

The white blood cells fighting the infection give it that color.

And if it smells bad?

Foul smelling sputum usually means an anaerobic lung abscess.

Basically bacteria that thrive in low oxygen environments and destroy tissue.

It smells like rotting matter because, well, it is.

And if it's thick and sticky?

Thick and tenacious sputum is classic for cystic fibrosis.

Very hard to clear.

The text suggests a way to ask about volume that I found funny but practical.

Teaspoons or cupfuls?

Sounds crude, but it works.

It's hard to estimate, Ambalala, but if a patient says they are coughing up a cupful of sputum a day, that is massive.

That suggests something like bronchiectasis or a lung abscess.

How about blood?

Hemoptysis?

Coughing up blood is always alarming to the patient, and to us.

But you have to verify the source.

Is it actually from the lungs?

Or is it a nose bleed dripping down the back of the throat?

Or is it vomited blood from the stomach?

How do you tell the difference between coughed blood and vomited blood?

Vomited blood is usually darker, maybe mixed with food particles, looking like coffee grounds.

Blood from the lungs is often bright red and frothy because it's mixed with air.

And we define massive hemoptysis as more than 500 mL in 24 hours.

That is an immediate life threat.

Let's touch on chest pain again.

You mentioned the lung tissue itself doesn't hurt.

Right.

So if a patient points to a specific tender spot on the chest wall and says, it hurts right here, and you press it with your finger and they say, ouch, that's it.

You've reproduced the pain.

You've reproduced it.

That's likely musculoskeletal.

Custogendritis.

An inflamed rib cartilage.

And the clenched fist.

The Levine sign.

If a patient clenches their fist over their sternum to describe a squeezing pressure, that is a classic sign of angina heart pain.

It's not the lungs.

One last history item.

Sleep.

Specifically, sleep apnea.

We look for the hallmarks.

Excessive daytime sleepiness, loud snoring,

and witnessed apneas.

That's where the partner says, you stop breathing for 10 seconds at a time and then gasp.

Exactly.

It scares the partner to death.

It's common in obesity.

Patients with retrognathia, which is a recessed jaw, and treatment -resistant hypertension.

Okay, we've talked to the patient.

Now we examine them.

Section four.

Physical examination.

We start with a general survey.

We're back to observation.

Look at the rate, rhythm, depth, and effort of breathing.

What are the numbers we're looking for?

A healthy adult rests at about 14 to 20 breaths per minute.

Tachypnea is rapid breathing, usually defined as over 25 breaths per minute.

And we're looking for signs of distress.

Cyanosis turning blue signals.

Hypopsia.

That's an emergency.

Audible stridor.

A high -pitched whistling sound from the throat that you can hear without a stethoscope means upper airway obstruction.

That is an immediate emergency.

The shape of the chest matters too.

Normally, the chest is wider than it is deep.

The ratio of the AP diameter front to back to the lateral diameter side to side is about 0 .7 to 0 .9.

You are wider than you are deep.

But sometimes the chest gets rounder.

The barrel chest.

The ratio goes over 0 .9.

The chest becomes circular.

We see this in aging, but classically in COPD where the lungs are hyperinflated and push the rib cage out permanently.

Moving to the posterior chest examination.

The patient is sitting up.

Arms folded across the chest.

This is a key trick.

By folding the arms, you swing the scapulae, the shoulder blades, laterally.

It moves the bone out of the way so you can actually hear and feel the lungs, not just the shoulder blade.

Smart.

First step, inspection.

Look for asymmetry.

Does one side move less than the other?

That lag suggests pleural disease or maybe a phrenic nerve issue paralyzing the diaphragm.

Look for retractions of the intercostal muscles that's sucking in of the skin between ribs.

That implies severe asthma or COPD.

The vacuum inside is so strong, it's pulling the skin in.

Next is palpation, touching the back.

We check for tenderness, maybe a broken rib,

and crepitus.

Crepitus is such a visceral word.

What does it feel like?

It feels like bubble wrap popping under the skin, or crunching snow.

It means air has leaked from the lung into the subcutaneous tissue.

It's a crackling sensation under your fingers.

It's strange, but once you feel it, you never forget it.

Then we test chest expansion, lung excursion.

This is the thumb test.

You place your thumbs at the level of the tenth ribs on the patient's back, pinch a little fold of skin between them to give some slack, and ask the patient to inhale deeply.

What should happen?

Your thumbs should move apart symmetrically as the rib cage expands.

If one thumb stays put, and the other moves.

That's unilateral delay.

The side that doesn't move has a problem.

Could be fibrosis, a large pleural effusion, pneumonia, paralysis of that side of the diaphragm.

Now, here's a term that always trips students up.

Tactile fremitus.

Fremitus.

It sounds mysterious, but it's just vibration.

Sound travels through the airway to the chest wall.

How do we test it?

You use the ball of your hand, or the ulnar surface, the pinky side of your hand.

You place it on the patient's back, and ask them to say, 99.

Why 99?

It's a resonant phrase.

It creates a strong, low frequency vibration.

You compare symmetric areas, left side, right side, left side, right side.

And what does the vibration tell us?

This gets into physics.

It does, and this is where intuition fails people.

Most people assume that because air is light, it carries sound best, but in the chest, it's the opposite.

Right, because I think of a soundproof room as being thick and solid.

Think of it this way.

Have you ever talked underwater in a pool?

Sure.

Sound travels incredibly fast and efficiently through water, and even better through solids.

Think of a train coming down the tracks.

You can hear the train through the steel rail, the solid long before you hear it through the air.

Okay, I follow.

Solids conduct vibration.

In a healthy lung, you have millions of tiny air pockets.

Those air pockets disrupt sound waves.

They scatter them, so the vibration feels soft or muffled on the skin.

Okay, so healthy air equals scattered sound equals less vibration.

Exactly.

But if that lung turns into a solid block because of pneumonia, if it fills with pus or fluid, it becomes a solid conductor.

It connects your voice box directly to the chest wall.

The vibration doesn't get scattered.

It shoots straight through.

So when you put your hand on their back and they say, 99, if they have pneumonia.

You feel a buzz that is startlingly strong.

That is increased fremitus.

It means consolidation,

solid lung.

But what if something blocks the sound?

If you have a layer of fluid outside the lung, like a plural effusion or a layer of air outside the lung, a pneumothorax or a really thick chest wall that blocks the vibration from reaching your hand, that is decreased fremitus.

So increased vibration means pneumonia, something solid inside.

Decreased vibration means something is in the way, like fluid or air outside.

Perfect summary.

Section six, percussion,

the drumming of the chest.

This is an art form.

You are turning the chest wall into a drum to see what's underneath.

Describe the technique, because if you do this wrong, you just hurt the patient.

You do.

Hyper -extend the middle finger of your left hand.

That's the pleximeter.

Okay.

Press that finger joint firmly on the surface.

Lift the other fingers off, only that one finger touches.

If the other fingers touch, they dampen the sound.

One finger pressed hard.

Then take your right middle finger, the plexor, and strike the pleximeter.

The motion must come from the wrist.

It has to be brisk and bouncy, like you're testing a hot iron.

Strike and pull back instantly.

If you use your elbow.

You get a thud.

You want a clear note.

And there are five notes to learn.

Let's run through the music of the chest.

Let's start with the extremes.

On one end, you have extreme density.

No air at all.

That's flatness.

Give me a real -world equivalent.

Tap on your thigh right now, that thud.

That's flatness.

Soft, high -pitched, stops immediately.

In the chest, if you hear that, you aren't hitting lung.

You're hitting a massive pleural effusion, or you're tapping on bone.

Okay.

Next.

Dullness.

This is the sound of the liver.

It's got a medium pitch and a thudding quality, but it's not quite as dead as flatness.

If you hear this over the lung fields where there should be air, that is your red flag for pneumonia or a tumor.

Because the air is gone.

Right.

Now move to the middle.

Resonance.

This is the Goldilocks zone.

It's loud, low -pitched, and lasts a bit longer.

This is the sound of a healthy, air -filled lung.

It's hollow, but alive.

Resonance is the goal.

Then we go past normal.

Hyperresonance.

Very loud, lower pitch, like puffing out your cheek and tapping it.

Okay, I can hear that.

This means too much air.

The lung is overinflated like a balloon.

We see this in COPD or pneumothorax.

And the most extreme.

Tympanitic,

loud and musical, like the gastric bubble in your stomach.

If you hear this over the chest, it's a large pneumothorax.

So we ladder this pattern down the back, avoiding the shoulder blades.

And we can also map the diaphragm.

Diaphragmatic excursion.

You percuss down the back until the sound changes from resonant, which is lung, to dull, which is the diaphragm and the structures below.

Okay.

You have the patient exhale and hold mark the spot.

Then inhale deep and hold mark the spot.

You're measuring how far the diaphragm travels.

Yes.

Normal is 3 to 5 .5 centimeters.

If it's high and doesn't move, think effusion or atelectasis.

Second seven.

Oscultation, the main event.

The most important technique.

We are assessing airflow.

Rules of the road.

Diaphragm of the stethoscope.

Mouth open.

Deep breaths.

And please, for the sake of accuracy, on the skin.

No listening through sweaters.

That's a huge pet peeve, I bet.

Never.

It's a fundamental error.

Clothing creates friction noises that sound exactly like crackles.

You will misdiagnose the patient.

We listen in that same ladder pattern.

What are the normal sounds?

Vesicular sounds are soft and low -pitched.

You hear them over most of the lungs.

The key here is that the inspiratory sound lasts longer than the expiratory sound.

It fades away.

Then broncho -vesicular.

Intermediate.

Inspiration equals expiration.

Heard between the scapulae.

And bronchial sounds.

These are loud and harsh.

And curiously, the expiration lasts longer than inspiration.

You hear these over the manubrium, over the big airway.

And the gap.

Yes.

In bronchial breathing, there is often a silent gap between the breath in and the breath out.

Now, here is the clinical pearl.

If you hear those loud, harsh bronchial sounds out in the lung field where it should be soft and vesicular.

That's pathology.

It suggests the air -filled lung has been replaced by fluid or solid tissue.

Solid tissue transmits that harsh sound from the trachea better than air does.

Again, think pneumonia.

The added sounds, the adventitious sounds, these have great names.

They do.

First, crackles, which used to be called rails.

These are discontinuous.

Think dots in time.

Like Velcro ripping.

Yes.

Or hair rubbing together next to your ear.

Fine crackles are soft and high -pitched.

Think interstitial lung disease or heart failure.

Course crackles are louder and lower.

Then there are wheezes.

Continuous sounds.

Dashes in time.

High -pitched and musical.

This is airflow through a narrowed airway asthma, COPD.

And raunchy.

Low -pitched snoring quality.

This usually implies secretions in the large airways.

Often if a patient coughs, raunchy will clear because the phlegm moves.

Ah, so that's a good diagnostic trick.

It is.

Wheezes usually won't clear with a cough.

And stridor.

That high -pitched inspiratory whistle we mentioned.

Upper airway obstruction.

Emergency.

There's one more.

Plural friction rubs.

A coarse greeting sound.

Like walking on fresh snow or rubbing leather together.

It's biphasic herd on inspiration and expiration.

That's the inflamed plural linings rubbing together.

Now earlier we talked about fremitous feeling vibration.

We can also listen for voice vibration.

Transmitted voice sounds.

If you hear abnormal bronchial breathing, you check these.

It's the same physics as fremitous.

First, e -gophony.

Ask the patient to say e.

Normally you hear a muffled e.

But if there is consolidation, like in pneumonia, the sound changes to an a.

Sounds like a goat.

It has a nasal bleeding quality e to a change.

That's e -gophony.

Got it.

Then bronchophony.

Patient says 99.

Normally it's muffled.

If it's loud and clear through the stethoscope, that's bronchophony.

And the last one.

Finally, whispered pectoriloquy.

Ask the patient to whisper 1, 2, 3.

Normally you shouldn't hear it or very faintly.

If it sounds loud and clear, that's positive pectoriloquy.

All pointing to the same thing.

Solid tissue transmitting sound better than air.

Correct.

There are all different ways of confirming the same underlying pathology.

Let's briefly touch on the anterior chest.

Section 8.

Patient is supine.

Arms slightly away from the body.

You inspect for deformities like pectus excavatum, which is a funnel chest, or pectus carinatum, a pigeon chest.

Percussion is interesting here because of the other organs.

Right.

You'll find the dullness of the heart to the left of the sternum, usually in the third to fifth inner space.

On the right, you percuss down to find the dullness of the liver.

And on the left.

On the left, you percuss down to find the timpani, the hollow drum sound of the gastric air bubble.

A quick clinical note from the text.

In COPD, the lungs are so big, so hyperinflated, that they push the liver dullness downward.

Yes.

The diaphragm stays flat and low, so all those landmarks get shifted down.

Section 9.

Special techniques.

These are the extra credit moves that yield big data.

First, the walk tests.

The six -minute walk test.

It's simple.

Measure how far a patient can walk quickly on a flat surface in six minutes.

It predicts clinical outcomes in COPD better than almost anything else.

Then, forced expiratory time.

This is a great bedside test for obstruction.

Ask the patient to take a deep breath and breathe out as fast and completely as possible.

Listen over the trachea.

What's a gut off?

If it takes nine seconds or more for a patient over 60, they are four times more likely to have COPD.

It shows that air is trapped and can't get out.

And finally, the test for a fractured rib.

This one sounds painful.

It is, but it's diagnostic.

AP compression.

You squeeze the chest between the sternum and the spine.

You squeeze the cage front to back.

If the patient feels pain distant from your hands, at the site of the suspected break, that suggests a fracture.

If they only feel pain where you are pushing, it's likely soft tissue injury.

Section 10.

Recording findings.

The text emphasizes being specific.

How do we do that?

Don't just write lungs clear.

Be descriptive.

Thoraximetric.

Good expansion.

Lungs resonant.

Breath sounds vesicular.

No crackles or wheezes.

And for a sick patient.

Increased AP diameter.

Breath sounds distant.

Scattered expiratory wheezes.

Primitus decreased.

Paint a picture so the next doctor knows exactly what you heard and where you heard it.

We're almost at the end.

Section 11.

Health promotion.

We can't talk lungs without talking tobacco.

No, you can't.

It's the leading cause of preventable death.

It's linked to 85 % of lung cancer cases.

Counseling on cessation is the single most important intervention you can do.

But there is screening now.

We have a tool.

Yes.

LECT low -dose computed tomography.

It's the standard.

Chest x -rays don't work for screening.

Who qualifies?

The USPSTF criteria, ages 55 to 80.

A 30 -pack year smoking history.

And they are a current smoker or quit within the last 15 years.

It reduces death by 20%.

It does.

But it has a high false positive rate, so you have to discuss the pros and cons with the patient.

It can lead to a lot of anxiety and further testing.

We also screen for latent tuberculosis.

Usually with the TST, the skin test, or an IGRA, which is a blood test.

We target high -risk groups, foreign -born persons from high -prevalence countries, people in homeless shelters or correctional facilities.

And the goal there is just to prevent it from becoming active.

Exactly.

Latent TB isn't contagious, but we treat it to prevent it from reactivating later in life.

And finally, obstructive sleep apnea, OSA.

We have a tool for this.

The Cetope Bang Questionnaire.

It's an acronym.

Okay, break it down.

S is for snoring.

T is for tired, meaning daytime fatigue.

O is for observed apnea, so someone saw you stop breathing.

P is for high blood pressure.

Okay, Cetope, now bang.

B is for BMI, specifically obesity.

A is for age over 50.

N is for a large neck circumference.

And G is for gender, as it's more common in males.

So if you score high on Cetope, bang.

You likely have OSA and need a sleep study of polysomnography.

Which brings us to the end of the chapter.

We've mapped the cage, watched the breathing, listened to the symphony, and looked for the red flags.

It's a journey from the outside in.

Anatomy, history, inspection, palpation, percussion, auscultation, every step builds on the last.

Before we sign off, I want to leave our listeners with a thought for the text that gave me chills.

It's about the silent chest.

Ah, yes.

In severe asthma, we usually expect loud wheezing.

It sounds terrible.

But sometimes the patient is so tight, so obstructed, that there isn't enough airflow to even make a wheeze.

The chest goes silent.

And that silence is an improvement.

It's imminent respiratory failure.

It is the most dangerous sign.

It's a reminder that sometimes what you don't hear is the most important finding of all.

You have to listen for what's missing.

A sobering but vital lesson.

Thank you for listening to this deep dive into the thorax and lungs.

Keep your ears open and your stethoscope on the skin.

From the Last Minute Lecture Team, thank you and breathe easy.