Chapter 14: Dyspnea Assessment & Clinical Evaluation

Welcome to Last Minute Lecture.

This free chapter overview is designed to help students review and understand key concepts.

These summaries supplement not replaced the original textbook and may not be redistributed or resold.

For complete coverage, always consult the official text.

It's 2 a .m.

in the ER.

You walk into room 4 and you see a patient sitting on the edge of the bed.

They aren't speaking.

They're gripping the rails like their life depends on it.

You can see it in their eyes, that primal, absolute terror of, I cannot get enough air.

That look.

It's unmistakable.

It's the look that stops every clinician in their tracks.

Today we are talking about dyspnea.

And honestly, looking at the service material from Chapter 14 of Advanced Health Assessment and Clinical Diagnosis in Primary Care, I think this might be the single most high -stakes symptom in primary care and emergency medicine.

It's definitely up there because unlike sore throat or a twisted ankle, dyspnea is existential.

It's the body's alarm system going haywire.

But here's the thing that the text points out immediately, which I think puts up a lot of students initially.

Dyspnea is fundamentally subjective.

It is.

And that's a crucial distinction we have to make right at the start.

We are trained to look for objective signs to hypnea, low oxygen saturation, wheezing.

The numbers.

Exactly the numbers.

But the definition of dyspnea provided in the chapter is the patient's perception of air hunger.

It is the sensation of labored breathing.

You can have a patient with an oxygen saturation of 98 percent who is screaming internally that they can't breathe and their experience is valid dyspnea.

Which puts the clinician in a tough spot, right?

You have to decode this subjective feeling.

The text actually breaks this air hunger down into three specific categories of true dyspnea.

I love this breakdown because it helps you filter the noise and figure out where the signal is coming from.

It's a great mental model.

The first bucket the text describes is increased awareness of normal breathing.

OK, so what does that mean in practice?

Think of the classic panic attack patient.

The mechanics are working perfectly.

The pump is fine.

The pipes are clear.

The gas exchange is happening.

But the brain is hyper aware and signaling suffocation.

So the hardware is fine, but the software is glitching.

Exactly.

Then you have the second bucket, which is probably what we see most often in acute settings.

Increased work of breathing.

This is a mechanical failure.

This is physics.

Pure physics.

Either the airway is narrow, like trying to breathe through a coffee stir in asthma,

or the lung is stiff and won't expand, which we see in conditions like pneumonia or pneumothorax.

The body is fighting massive resistance just to move the same volume of air.

OK, so that's bucket number two.

And the third.

That's the abnormalities in the ventilatory system itself.

This is where the lungs might be structurally OK, and the airway is open, but the pump is broken.

The bellows.

The bellows just won't open.

We're talking neuromuscular disorders, chest wall abnormalities, or diseases of the muscles themselves.

So before we even touch the stethoscope, we're asking ourselves, is this anxiety?

Is this a plumbing problem where the pipes are clogged?

Or is the pump itself breaking?

That is the roadmap.

And usually when we see this in a diseased state, the text says it signals pulmonary or cardiac pathology.

It's almost always harder lungs until proven otherwise.

So let's get into the diagnostic reasoning.

The chapter lays this out chronologically, starting with the history and looking at the text, there is a massive bold warning right at the beginning of the history section.

The golden rule.

Is this an emergency?

We aren't asking about family history or allergies yet.

No, not at all.

The text is very, very specific here.

Severe dyspnea is a medical emergency.

If you don't treat it immediately, you are looking at respiratory failure and death.

So before you start your nice, polite interview, you assess the adequacy of the airway.

You establish ventilation, identify the threat, neutralize the threat, then ask questions.

Precisely.

Once they are stable, then you search for the cause.

But in that initial triage moment, you're looking for specific cues.

And the biggest clue the chapter gives us is the onset.

The speed of the train matters.

It matters immensely.

If a patient tells you I was fine at breakfast and then boom, I couldn't breathe, or I was just walking to the mailbox and it hit me, that is a flashing red light.

Acute onset almost always signals a catastrophic physiological event.

What are we worrying about with acute onset?

What's on that list?

The text lists the big five life threats associated with acute onset.

Aspiration of a foreign body, anaphylaxis, pulmonary embolism, pneumonia, and left ventricular dysfunction, which is essentially acute heart failure or flash pulmonary edema.

Okay, so sudden onset equals danger because the body hasn't had time to compensate.

Now talk to me about the pediatric side of this.

Because a two -year -old isn't going to look at you and say, excuse me, I experienced an acute onset of shortness of breath at 1 ,400 hours.

They definitely won't, no.

In children younger than three years, the text says you have to be a detective.

You have to rely on observation.

You're looking for tachypnea fast breathing.

You're looking for retractions, where the skin sucks in between the ribs, stridor, nasal flaring.

But there is one sign the text highlights that I think is brilliant.

Which one is that?

Feeding difficulty.

You have the fascinating point in the reading.

Why is feeding such a red flag for breathing?

It seems disconnected at first.

It's all about the suck -swallow -breathe coordination.

For an infant, eating is a complex neurological dance.

It takes a lot of coordination.

If an infant is air -hungry, their brain prioritizes breathing over eating.

It has to.

It has to.

They literally cannot pause their breathing long enough to swallow safely.

So a mother telling you he won't take the bottle or he gets sweaty and stops when he tries to nurse is often the first sign of respiratory failure, not a stomach issue.

That is a critical clinical pearl.

Won't eat equals can't breathe.

Now sticking with the scary stuff in pediatrics, let's talk about upper airway emergencies.

The text highlights two major ones, epiglottitis and foreign body aspiration.

Let's start with acute epiglottitis.

This is the stuff of nightmares for any commission.

It's usually caused by haemophilus influenza.

It's a bacterial infection that causes the epiglottis, that little flap that protects your windpipe, to swell up massive.

And the presentation is very specific, right?

The textbook picture.

It's rapid, sudden onset.

The key signs, the text lists are drooling, dysphonia, which is trouble speaking, dysphagia, trouble swallowing and a high fever.

But clinically, you look at the child's behavior, they look toxic.

And they adopt a specific posture?

The tripod position.

The child looks anxious.

They sit up and lean forward with their jaw open.

They are physically trying to align their airway to get air past that swollen lump.

It's a position of desperation.

It is.

And there is a huge warning in the text about examining these kids.

A, do not do this role.

A massive one.

I saw that.

What is it?

If you suspect epiglottitis, you see the drooling, the muffled voice, the tripoding.

Do not lay them down and do not try to inspect the throat with a tongue depressor.

Because you might poke the bear.

Worse.

Much worse.

That manipulation can trigger a vagal response or a spasm of the laryngeal muscles.

Because the airway is already so swollen that spasm can cause total occlusion.

You could cause a complete airway obstruction right there in the exam room.

Wow.

You keep them calm.

You keep them upright.

And you get an airway expert, an anesthesiologist, or an ENT immediately.

Okay, noted.

Hands off the throat if they're drooling and tripoding.

What about foreign body aspiration?

This is the classic toddler playing on the floor scenario.

Or for adults, the text calls it the steakhouse syndrome.

Usually someone eating solid food, often combined with alcohol consumption.

The history here is usually sudden choking or coughing, isn't it?

Sudden onset coughing or wheezing without any prior cold or runny nose.

If a healthy kid is playing with Legos and suddenly turns blue and starts coughing, it's a foreign body until proven otherwise.

Moving down the anatomy to lower airway emergencies, the text mentions status asthmaticus and anaphylaxis.

Status asthmaticus is an asthma attack that isn't breaking.

It's progressive bronchospasm that doesn't respond to the usual pharmacologic interventions like albuterol.

It just keeps getting worse.

And there's a specific concept here that I found really interesting and scary.

The concept of the silent chest.

This is one of those clinical paradoxes where better actually means worse.

Usually with asthma, you expect to hear wheezing.

That's the sound of air squeezing through tight tubes.

It's turbulent.

Like blowing through a whistle.

Exactly.

But if you listen to an asthmatic in severe distress and you hear nothing, no wheezing, that is ominous.

Because the whistle isn't broken, there's just no air blowing through it.

That's it.

The obstruction is so severe or the patient is so fatigued that they cannot move enough air to create the turbulence that makes the sound.

The absence of wheezing can be worse than the presence of wheezing.

It means the patient is on the verge of respiratory arrest.

So silence is not golden,

okay, and anaphylaxis.

This is a systemic allergic reaction.

Insect bites, peanuts, shellfish, you'll see flushing, generalized periudas, which is just itching, and anxiety.

The text notes a correlation that I think is really useful for triage.

And what's that?

The faster the symptoms appear after exposure, the more severe the reaction usually is.

If they eat a peanut and collapse in 30 seconds, you are in big trouble.

Okay, so those are our immediate life threats.

But the history -taking also has to cover specific risk factors.

The text groups these into trauma, PE, chronic disease, and some really interesting neuromuscular causes.

Let's look at trauma first.

The big worry here is a pneumothorax, a collapsed lung.

The text mentions this can happen from blunt trauma, like a car accident or fall.

But it emphasizes that it can also be spontaneous.

Spontaneous, as in just walking down the street.

Yes.

It happens most frequently in young, tall, thin people, often males, during strenuous activity.

Suddenly, a bleb or a small blister on the lung ruptures, air leaks into the chest cavity and the lung collapses.

Sudden shortness of breath, sudden sharp pain.

Okay, now let's talk about the great masquerader, pulmonary embolism, or PE.

Why does the text give it such a dramatic nickname?

Because it refuses to follow the rules.

The symptoms can be incredibly vague, but the outcome is deadly.

The classic presentation described is acute distress, pleuritic chest pain, pain that stabs you when you take a deep breath, maybe bloody sputum and fever.

But the text mentions a specific feeling patients have, and this goes back to the subjective nature of dyspnea.

The sense of impending doom.

It sounds almost melodramatic, doesn't it?

I feel like I'm going to die.

It does, but biologically it's a survival reflex.

When you throw a clot into the pulmonary artery, you are blocking blood flow to the lungs.

You create a massive dead space.

You are breathing air in, but there is no blood to pick up the oxygen.

So it's a VQ mismatch, ventilation without perfusion.

Exactly.

The brain senses the sudden drop in oxygen delivery and the strain on the right heart, and it triggers a massive catecholamine surge adrenaline, cortisol.

This manifests as pure, unadulterated terror.

If a patient looks you in the eye and says, something is wrong, I think I'm dying, and their lungs sound clear, you listen to them.

You take that very seriously.

Very seriously.

Now to catch a PE, we have to know the risk factors.

The text references Virch's triad effectively.

This is classic pathology.

Right.

Three factors that lead to clots.

First, venous stasis, blood that sits still clots.

So we ask about bed rest, sitting for a long time like a long international flight.

That's the classic one people know.

It is.

Two, hypercoagulability.

Is the blood thicker than normal?

We ask about family history of clotting, lupus, or antiphospholipid syndrome.

And three, vessel injury.

Recent surgery, fractures, especially leg fractures, where the marrow can release fat emboli or cause trauma to the veins.

And medications play a huge role here, too.

The text calls this out specifically.

Huge oral contraceptives, especially if the woman also smokes and is over age 35.

That combination skyrockets the risk of clots.

Also, estrogen replacement therapy and tamoxifen.

So a very thorough medication history is key.

Okay, let's pivot to the chronic disease history.

This helps us differentiate the acute from the chronic on acute.

What are we looking for?

COPD is a big one.

You're looking for a history of progressive shortness of breath, a morning cough, and clear to yellow sputum.

It's a slow burn.

And then there is heart failure.

Yes.

With heart failure, the key history questions are about body position.

This is where gravity comes into play.

We ask about orthopnea.

Does the breathing get worse when they lie flat?

When you lie down, fluid redistribution increases the load on the heart.

If the heart is weak, it backs up into the lungs.

So these patients sleep on three pillows or in a recliner just to breathe.

And there's another one.

PND.

Right, paroxysmal nocturnal dyspnea, or PND.

Do they wake up suddenly in the middle of the night gasping for air?

That's fluid that has slowly accumulated in the lungs overnight, finally reaching a critical point.

And for kids with heart failure, since they aren't sleeping on three pillows?

It's subtle.

Poor feeding, again, that's a recurring theme.

And specifically, diaphoresis sweating on the forehead or upper lip while eating.

Eating is exercise for a baby.

If they break a sweat doing it, their heart might be failing.

That is fascinating.

Now, the section that really surprised me was the neuromuscular causes.

These are the hidden history clues.

The text lists some very specific, somewhat odd questions we need to ask.

This is the Sherlock Holmes part.

You have to ask about honey.

Honey.

You're asking a parent about honey.

You have to.

If an infant has eaten honey, you have to think about infant botulism.

Honey can contain Clostridium botulinum spores.

In babies, their gut flora isn't mature enough to handle it.

The toxin causes a descending paralysis.

Signs are constipation, a weak suck, and a floppy baby.

That muscle weakness eventually hits the diaphragm, causing respiratory failure.

I had no idea honey was dangerous for infants.

That's a huge public health point.

It's why pediatricians say no honey before age one.

Another one the text mentions, farm residents.

Living on a farm.

How is that a risk factor?

Exposure to organophosphate insecticides.

These chemicals essentially poison the junction between the nerve and the muscle.

They can cause a myasthenia -like syndrome.

It paralyzes the respiratory muscle.

Wow.

And what about paint?

Lead poisoning.

Flaking paint or dust in older homes.

It affects the central nervous system and can depress the respiratory center in the brain.

And finally, immunizations.

Which feels like it should be a standard question, but is so important here.

Always check.

Lack of polio or tetanus shots.

Tetanus can cause tetany -rigid paralysis of the respiratory muscles.

Polio causes flaccid paralysis.

We don't see them often, thankfully.

But in an unvaccinated population, they have to be on your radar.

Incredible.

So the history gives us the clues.

Now we have to verify them with our hands and eyes.

Let's move to section two.

The focused physical examination.

This is where we use our senses.

Inspection, palpation, percussion, auscultation.

It starts with general appearance, and we are back to posture.

We talked about tripoding for epiglottitis, but the text mentions it for COPD2.

Why does tripoding actually help?

What are the mechanics?

It's about anchoring the shoulder girdle.

Normally, your pectoral muscles move your arms.

But if you lock your arms on your knees, if you fix the insertion point, those muscles can reverse their action.

They pull against the fixed arms to lift the rib cage up.

So they are turning their arms into a scaffold to hang their lungs from.

Exactly.

They are recruiting accessory muscles to physically expand the chest wall because the diaphragm is tired and flattened.

And in infants, they can't tripod.

Look for hyperextension of the neck.

They tilt their head back to open the airway.

It's often called the sniffing position.

It aligns the axis of the airway to reduce resistance.

The text also mentions level of consciousness as a respiratory sign, which can be easy to miss.

Yes.

Restlessness and confusion are often the early signs of hypoxia.

The brain is the first organ to complain about low oxygen.

If a nice cooperative patient suddenly becomes agitated, combative, or confused, check their oxygen before you call security.

That's a fantastic point.

Now we inspect the chest itself.

We are looking for deformities.

The text lists a few restrictive conditions.

Right.

These are structural issues that physically stop the lungs from expanding.

You've got kyphosgoliosis, that curvature of the spine.

It compresses the lungs and increases the work of breathing.

And then the two pectus deformities.

Exactly.

Pectus excavatum, or funnel chest, where the breastbone is sunken in, and pectus carinatum, or pigeon chest, where the breastbone sticks out.

Interestingly, the text links pigeon chest to asthma or cystic fibrosis.

And there's a specific sign called Harrison -Sulci.

What's that?

Those are grooves at the bottom of the rib cage, the sub -custal margin.

They are caused by chronic diaphragmatic traction.

Basically, the diaphragm has been pulling so hard for so long, like in rickets or chronic airway disease, that it creates a permanent groove in the soft bone of the chest wall.

Let's talk about retractions again.

We see the skin sucking in.

But explain the physics here.

Why does the skin suck in?

Think of the chest as a vacuum chamber.

To get air past a blockage, like a narrowed bronchiole, the diaphragm has to pull down hard.

This creates massive negative pressure inside the chest.

That pressure is so strong relative to the outside air that it literally collapses the soft tissue inward.

It's imploding the soft spots.

Exactly.

And the text notes a progression.

It usually starts low sub -custal below the ribs.

But as the obstruction gets worse, and the negative pressure requirement gets higher, the retractions move up.

When you see super sternal retractions, the skin sucking in right at the base of the neck above the clavicle, that is a patient generating massive force just to move a tiny amount of air.

That is late -stage distress.

That's a sign you are minutes away from collapse.

Absolutely.

Let's talk about the respiration assessment, specifically the timing, the IE ratio.

Normal breathing has a ratio.

Exhalation should take about twice as long as inhalation, a one to two ratio.

But in COPD, because they have trouble getting air out, they have air trapping, that ratio changes.

Exhalation becomes four times as long, a one to four ratio.

They are struggling to empty their lungs through collapsed airways.

And then there are the named patterns, chain stokes and cousmal.

Chain stokes is a weird one.

It's a rhythmic cycle.

Breathing gets deeper and faster than slower and shallower than a period of apnea where they stop breathing, and then it starts all over again.

It's caused by a delay in the feedback loop between the lungs and the brain.

It's classic in severe heart failure or neurological disease.

And cousmal.

Cousmal breathing is deep, rapid, gasping breathing.

This isn't a lung problem, it's a blood problem.

The body is trying to blow off CO2 to fix metabolic acidosis like in diabetic ketoacidosis or DKA.

They're literally panting to fix their pH.

Okay, moving to sounds we can hear without a stethoscope.

Stridor versus wheezing.

How do we tell them apart?

Stridor is a high -pitched, harsh sound caused by narrowing in the upper airway.

It sounds terrifying, like a seal bark.

Wheezing is high -pitched and musical, usually from the lower respiratory tract, like an asthma.

But the text gets granular on stridor.

Inspiratory versus expiratory.

And this helps you locate the blockage.

Inspiratory stridor usually means the obstruction is supraglottic above the vocal cords, like with epiglottitis.

You hear it when they pull air in.

Expiratory or biphasic stridor, where you hear it on both in and out, suggests the obstruction is at the glottis or below it, subglottic.

That is usually more significant because the airway is narrower there to begin with.

And the voice gives clues, too.

Yes.

A muffled voice, that classic hot potato voice, suggests supraglottic swelling.

There's a lump in the throat dampening the sound.

A hoarse voice suggests the problem is right at the vocal cords or just below them, subglottic.

Okay, let's get hands on.

Palpation and percussion.

First, tracheal deviation.

We are sticking our finger in the notch above the sternum.

Right.

The trachea should be midline.

If it shifts, it's being pushed or pulled.

The most critical one is attention pneumothorax.

The buildup of air pressure on one side pushes the heart and trachea away to the healthy side.

That is a late and very bad sign of a life -threatening emergency.

Next is tactile fremitus.

This is where we have the patient say, 99, while we feel their chest vibrations with the ulnar side of our hand.

How does this work?

What's the science?

This is all about density.

Sound travels better through solid or fluid than it does through air.

Think about putting your ear to a railroad track.

You hear the train better through the steel than through the air.

That's a great analogy.

So if the fremitus, the vibration, is decreased, it means there is more air or a barrier blocking the sound.

This happens in asthma, emphysema because of air trapping, or pneumothorax because of the air outside the lung.

Okay.

But if the fremitus is increased, it means the sound is traveling through something solid.

This points to consolidation, like in pneumonia.

The solid, fluid -filled infection conducts the vibration perfectly from the bronchus to your hand.

Got it.

Fluid solid equals more vibration.

Air equals less vibration.

And percussion follows the same physics.

Similar principle.

You tap on the chest like a drum.

Dullness, a thud sound, means you are tapping over fluid or solid.

Think pneumonia or a plural effusion.

Hyperresonance, a booming drum -like sound, means there's too much air.

Think COPD or a pneumothorax.

There's an evidence -based practice box right here in the text regarding plural effusion.

What did the research show?

What are the high -yield maneuvers?

It reviewed eight different physical exam techniques.

And the verdict was that dullness to percussion and tactile fremitus are the most useful findings to detect a plural effusion.

They are surprisingly sensitive if done correctly.

So the classics still work.

Okay, finally, we put the stethoscope in our ears.

Oscultation.

Let's run through the lung sounds.

Crackles or rails?

Crackles sound like Velcro being pulled apart or hair rubbing near your ear.

They are discontinuous popping sounds.

Physiologically, this is fluid or mucus causing the small airways to stick together.

And then they pop open when you inhale.

And the text differentiates them by timing.

Right.

Timing matters.

Early inspiratory crackles are often associated with COPD.

Mid -to -late inspiratory crackles are more likely heart failure or fibrosis.

And wheezing.

What are we listening for there?

That whistling sound.

If it's a fixed -kitch wheeze where it sounds the same every time in the same spot, that usually means a localized problem.

A tumor pressing on a bronchus or a peanut stuck in there.

It's a single fixed obstruction.

And if it's not fixed?

If it's a varying pitch or polyphonic where it sounds like a weird orchestra of different notes all over the chest, that usually means asthma.

Multiple airways of different sizes are constricted creating all these different notes.

What about raunchy?

Raunchy are deep, coarse snoring sounds.

This is mucus in the large airways flapping around.

Often you hear this in bronchitis or pneumonia.

The key differentiator is that raunchy often clears or changes if the patient coughs and moves the mucus around.

Crackles do not clear with coughing.

And the friction rub.

A grating squeaking sound.

Like leather rubbing together.

That indicates pleuritis.

The lining of the lung is inflamed and it's rubbing against the lining of the chest wall with each breath.

The text also mentions voice transmission tests.

These are the tests with the funny names.

Brontophony, egophony, whispered bectoryloquy.

Right, and these are all to confirm consolidation.

Like pneumonia, they rely on that same principle.

Solid transmit sound better than air.

So for bronchophony, they say 99.

Normally it's muffled.

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

And egophony.

They say E.

Normally you hear E.

If it sounds like I, that's the classic E to A change.

It's because the consolidation filters out the lower frequencies of the sound.

And finally, whispered bectoryloquy.

They whisper a word.

Usually you can't hear it well.

If you hear the whisper clearly, that's a positive sign for consolidation.

Before we leave auscultation, the text says we have to check the heart too.

Yes.

If heart sounds are muffled, think COPD.

The lungs are so overinflated with air that they physically cover the heart.

You're listening through a pillow of air.

And listen to gallops.

An S3, or ventricular gallop, is a key sign of heart failure.

It's the sound of blood splashing into a distended non -compliant ventricle.

An S4, an atrial gallop, signals a stiff, stressed heart, often from chronic hypertension.

Section 3 is brief but important.

Extremities and systemic signs.

Let's talk about color.

Cyanosis.

Blue discoloration.

And you have to know the difference.

Central cyanosis is blue lips or mucous membranes.

This is serious.

It means low arterial oxygen.

The blood leaving the heart isn't carrying enough O2.

And peripheral.

Peripheral cyanosis is blue fingers or toes.

This can be low oxygen, but it can also just be cold or vasoconstriction.

So central is a much more ominous sign.

And the text reminds us for dark -skinned patients, check the mucous membranes inside the mouth or the conjunctiva.

They might appear gray or ashen instead of blue.

Good point.

And clubbing.

The loss of the angle at the nail bed.

It looks like the end of a drumstick.

This is a sign of chronic hypoxia, lung cancer, cystic fibrosis.

But here's an important distinction the text makes.

Clubbing is not usually seen in asthma.

If an asthmatic has clubbing, you have to look for something else.

Maybe a coexisting malignancy.

And there's a clue in the timing of the clubbing too, right?

Yes.

If clubbing develops rapidly over weeks, you should suspect infective endocarditis.

Last systemic sign.

Edema.

Swelling.

Usually in the legs.

It's a classic sign of right heart failure.

But in infants, don't just look at the legs.

Look for periorbital edema puffy eyes.

Feel for an enlarged liver hepatomegaly.

The litter acts as a reservoir for backed up blood in infants.

Okay, we've examined the patient.

Now we order tests.

Section 4.

Laboratory and diagnostic studies.

Starting with the simple one.

Pulse oximetry.

What are the norms we need to know?

For adults, greater than 95 % is generally considered normal.

The text breaks it down more specifically for pediatrics.

95 to 98 % is normal.

90 to 95 % is mild hypoxia.

And less than 85 % is severe hypoxia.

Imaging.

Chest x -ray versus CT scan.

The chest x -ray is the workhorse.

It's cheap, it's fast, and it gives you the big picture.

It's essential for pneumothorax, pneumonia, and foreign bodies.

A little tip from the text.

For foreign bodies, get inspiratory and expiratory views.

A foreign body might act as a ball valve letting air in but not out.

So on the expiratory view, the blocked lung stays inflated while the other empties.

And the CT.

The CT, specifically a CTPA or CT angiogram, is the gold standard for a pulmonary embolism.

Spirometry.

This measures lung function.

How do we differentiate obstructive versus restricted disease with this?

It's all about the FEV1, the forced expiratory volume in one second.

For obstructive disease like asthma or COPD, think of a kinked garden hose.

You can't get air out quickly.

So the FEV1 is low and the ratio of FEV1 to the total volume, the FTC, is also low.

And restricted.

For restrictive disease like fibrosis or pneumonia, think of a smaller water tank.

You can't get as much air in.

The total volume, the FTC, is low.

But the water you do have flows out fast.

So the ratio of FEV1 to FTC might actually be normal or even high.

That makes sense.

And finally, blood work.

D -dimer and hemoglobin.

The D -dimer is a degradation product of a blood clot.

Basically, it's debris.

It is a fantastic rule -out test.

If it's normal, you can essentially rule out a PE.

But if it's high, it doesn't confirm a PE.

It could be high from inflammation, surgery, pregnancy.

But it means you need to look further with imaging.

So a negative is very helpful.

A positive is not.

And always check hemoglobin and ematocrit.

Check for anemia.

If you don't have enough red blood cells to carry oxygen, you will feel short of breath even if your lungs are perfect.

Also, look for polysathemia, which is high red blood cells.

This happens in chronic hypoxia.

Like with COPD, the body tries to compensate by making more blood cells to capture every last molecule of oxygen.

We have gathered all our evidence.

Now we go to the courtroom.

Section 5.

Differential diagnosis.

The text splits this into emergent, the life threats, and non -emergent.

Let's rapid fire the emergent conditions one more time to lock them in for our listeners.

Let's do it.

Pulmonary embolus.

Dyspnea plus chest pain plus risk factors.

The text mentions using the Wells score to assess probability.

Number 2.

Foreign body.

Sudden onset, stridor, and often a unilateral wheeze because it's stuck in one bronchus.

OK.

Anaphylaxis, angioedema, so swollen face and tongue,

hypotension, and bilateral wheezes.

Pneumothorax.

Sudden sharp pain, absent breath, sounds on one side, and maybe that tracheal shift if it's a tendon pneumo.

And the distinction between epiglottitis and croup.

The text has a specific comparison here that's really useful.

It does.

Drooling, toxic appearance, snow cough, high fever.

Sit them up, don't touch the throat.

This is a bacterial emergency.

Seal bark cough, that seal -like sound, and variable distress.

Yeah.

Usually viral, it sounds loud and scary, but the child usually looks much less toxic than the epiglottitis kid.

And the last couple of emergencies.

Status asthmaticus.

History of asthma, that silent chest, or severe wheeze, and maybe pulses paradoxus, which is a big drop in blood pressure when they breathe in.

And finally, botulism, the honey ingestion, descending paralysis, wheat cray.

Got it.

Now the non -emergent chronic subacute conditions.

These are the bread and butter of primary care.

COPD.

Smoker.

Barrel chest, that increased AP diameter.

Distant breath sounds.

Hyper resonance because of all that trapped air.

Heart failure.

Wet lungs, so basilar rails or crackles.

An S3 gallop.

JVD, the distended neck veins.

And peripheral edema.

Anemia.

Power.

Tachycardia.

Dyspnea on exertion.

The key is that the lungs sound totally clear, but the patient is winded from walking to the exam room.

Asthma when it's not in status.

Recurrent episodes.

Clear precipitating factors, like cats, pollen, or exercise.

And it responds well to bronchodilators.

Pneumonia.

Devered mener.

A productive cough, often with green or rust -colored sputum.

And all those consolidation signs we talked about.

Dolness to percussion.

Egophany.

Increased fremitus.

And finally, psychogenic or hyperventilation syndrome.

This is often a diagnosis of exclusion, isn't it?

It is.

You have to rule out everything else first.

The key symptoms are puerial numbness, tingling around the mouth, and tingling in the fingers.

Or paresthesias.

This happens because hyperventilation blows off too much CO2.

Causing a respiratory alkalosis.

That changes calcium binding in the blood, leading to the tingling.

And there's a key difference in the history.

Right.

The symptoms don't improve with rest, unlike most heart or lung causes.

In fact, anxiety -related dyspnea often gets worse at rest.

Because they have nothing to do but focus on their breathing, which makes it worse.

Wow.

We have covered a massive amount of ground.

From the subjective feeling of air hunger to the specific physics of a crumbling lung.

Let's wrap this up with our ITRO.

What is the main takeaway for the students listening?

I think the mission is clear.

History is 80 % of the battle.

If you ask the right questions about the onset, the triggers, the risk factors, you usually have a very good idea of the diagnosis before you even touch the patient.

The physical exam is there to confirm your suspicion.

And that golden rule.

And never forget the golden rule.

Airway first.

Identify the emergency, then find the cause.

Thank you so much for joining us on this deep dive into dyspnea.

To all the nursing and NP students out there, we know how much you have to memorize.

We hope this audio summary helps you crush your next exam.

And more importantly, take better care of your patients.

This has been the Last Minute Lecture Team.

You've got this.

Good luck in clinicals.

See you on the next deep dive.