Asthma vs COPD

The reversible one vs the one that gave up trying

A 55-year-old with 30 pack-years presents with chronic dyspnea and wheezing. PFTs show FEV1/FVC < 0.7. After albuterol, FEV1 improves by 8%.

Asthma or COPD?

The Core Split

These two diseases both cause airflow obstruction and wheezing. That's where the similarity ends. Flip between tabs · notice how different the stories are.

⚡ ASTHMA
🫁 COPD

Clinical Images

Spirometry flow-volume curves
📷 PFTs: obstructive vs restrictive patterns · tap to expand

Who Gets It

Young. Often childhood onset. Atopic history · eczema, allergic rhinitis, food allergies. Family history of asthma. The kid who couldn't run the mile in gym class.

What's Happening

Eosinophilic inflammation → bronchial hyperreactivity → airway smooth muscle spasm → reversible obstruction. The airways are twitchy, not destroyed.

The Key Feature

REVERSIBLE. Give albuterol → FEV1 jumps ≥12% AND ≥200mL. The airways open back up because the walls are still intact. They're just spasming.

Triggers

  • Allergens (dust, pollen, dander)
  • Exercise (especially cold air)
  • Infections (viral URI)
  • NSAIDs (aspirin-exacerbated respiratory disease)
  • Emotional stress

Treatment Backbone

Inhaled corticosteroids (ICS) are the controller. SABA for rescue. Step up with LABA + ICS combo. The goal is no symptoms · and that's actually achievable.

Who Gets It

Older smoker. Usually 40+ with significant smoking history. The guy who smoked a pack a day for 30 years and now can't climb stairs.

What's Happening

Neutrophilic inflammation → protease-antiprotease imbalance → alveolar wall destruction (emphysema) + mucus gland hypertrophy (chronic bronchitis). The architecture is permanently damaged.

The Key Feature

IRREVERSIBLE. Give albuterol → FEV1 improves <12% or <200mL. The obstruction is structural. You can't relax a wall that's been demolished.

Subtypes

  • Emphysema · "pink puffer." Thin, pursed-lip breathing, barrel chest, hyperinflated lungs. Destroys alveolar walls → ↓ surface area
  • Chronic bronchitis · "blue bloater." Overweight, cyanotic, productive cough ≥3 months/year for 2+ years. Mucus glands take over

Treatment Backbone

LAMA (tiotropium) is the first-line controller. Add LABA. ICS only added for frequent exacerbations (≥2/year). Smoking cessation is the ONLY thing proven to slow decline. O2 if PaO2 ≤55.

Feature-by-Feature

One screen. All the differences. Lead with what's DIFFERENT, not what's shared.

⚡ Asthma
🫁 COPD
Age
Young (childhood-20s)
>40, smoker
Reversibility
Yes (≥12% + 200mL)
No (<12%)
Inflammation
Eosinophils
Neutrophils
FEV1/FVC
Normal between attacks
<0.7 always
Symptoms
Episodic, triggered
Persistent, progressive
CXR
Usually normal
Hyperinflation, flat diaphragms
1st-line controller
ICS
LAMA
Prognosis
Can achieve full control
Progressive decline
Key history
Atopy, allergies, eczema
Pack-years, occupational exposure
DLCO
Normal
↓↓ (destroyed alveoli)

The Villains

Three airway disorders. Each one presents differently and demands a different fight. Tap a card to flip it.

Asthma airway illustration NIH Asthma Airway
Centrilobular emphysema histology Emphysema
COPD chest x-ray hyperinflation Barrel Chest
Spirometry obstructive vs normal Spirometry
⚡
Asthma
Reversible. Eosinophilic. Twitchy.
tap to flip

Asthma

Who: Young, atopic. Eczema, allergies, family history.

Cell: Eosinophils. IgE-driven Th2 inflammation. Mast cells fire, IL-5 summons eos.

Key: REVERSIBLE. FEV1 improves ≥12% AND ≥200mL post-albuterol.

Triggers: Allergens, cold air, exercise, NSAIDs, viral URI.

Rx: ICS (controller) + SABA (rescue). Step therapy up to ICS/LABA combo.

PFTs: Normal between attacks. FEV1/FVC normalizes post-bronchodilator.

🫁
COPD
Irreversible. Neutrophilic. Structural.
tap to flip

COPD

Who: Smoker, >40. Pack-years do the damage. A1AT deficiency = young non-smoker.

Cell: Neutrophils. Protease-antiprotease imbalance → alveolar destruction.

Key: IRREVERSIBLE. FEV1/FVC <0.7 always. Bronchodilator response <12%.

Subtypes: Pink puffer (emphysema, low BMI, hyperinflated) vs Blue bloater (chronic bronchitis, hypercapnic, edematous).

Rx: LAMA first. Add LABA. ICS only if ≥2 exacerbations/year. O2 if PaO2 ≤55. Smoking cessation = only proven mortality benefit.

🌀
ACOS
Asthma-COPD Overlap Syndrome
tap to flip

ACOS (Overlap)

Who: Older patient with asthma history who smoked, OR young smoker with partially reversible obstruction.

Spirometry: FEV1/FVC <0.7 (like COPD) but also shows ≥12% reversibility (like asthma). Both criteria met.

Inflammation: Mixed eosinophilic + neutrophilic. The two diseases collide.

Board trap: Boards test clean patterns. Only call ACOS when they explicitly give BOTH disease features. If it looks like COPD, call COPD. If it looks like asthma, call asthma.

Rx: ICS + LABA (treat both components). More exacerbations, worse outcomes than either alone.

PFT Flow-Volume Loops

The shape of the expiratory limb tells you the diagnosis. Click a pattern to examine it.

Volume Exhaled (L) → Flow Rate (L/s) 0 Exp. Insp. PEF FEV1 FEF 25-75 FVC
Board Pearl
1FEV1 / FVC < 0.7 = obstructive (asthma or COPD).
2FVC reduced + FEV1 / FVC normal (> 0.7) = restrictive. Confirm with TLC < 80% predicted.
3Scooped expiratory limb = obstructive. Small but normal-shaped loop = restrictive.
4FEF 25 to 75 drops first in early small-airway disease (asthma, early COPD), before the FEV1 / FVC ratio crosses below 0.7.
Normal Obstructive Restrictive
All Three Patterns
NormalWide loop, rapid peak, linear decline
ObstructiveWide loop, concave / scooped expiratory limb
RestrictiveNormal shape, but smaller overall

Boards shortcut: scooped = obstructive. Small = restrictive. Normal = neither. Click each button for the full breakdown.

Normal
FEV1 / FVC> 0.70
FVCNormal
TLC80 to 120% predicted
ShapeRapid rise to PEF, then linear decline

The reference shape. Airways open fully, peak flow is high, exhalation is unrestricted. Memorize this first. Everything else is a deviation from it.

Obstructive (Asthma / COPD)
FEV1 / FVC< 0.70 (diagnostic cutoff)
FVCNormal or slightly reduced
TLCNormal or increased (air trapping)
Key shapeScooped / concave expiratory limb
Asthma vs COPDAsthma: reversible post-bronchodilator

The concave scoop = small airways collapsing mid-exhalation, cutting off flow before the lungs are empty. FEF 25 to 75% is the most sensitive marker. In asthma, the curve normalizes with bronchodilator. In COPD, it does not.

Restrictive (Fibrosis / Sarcoid)
FEV1 / FVCNormal or elevated (> 0.70)
FVCReduced
TLC< 80% predicted (gold standard)
ShapeNormal proportions, compressed loop

Stiff lungs cannot expand, so TLC and FVC are both reduced. But once you start exhaling, airway patency is intact: FEV1/FVC stays normal or elevated. TLC below 80% predicted is the gold standard diagnostic criterion.

Memory Hooks

🔑
Reversibility is the whole game. Tap for the hook →
Asthma is a rubber band · stretches and snaps back. COPD is a broken rubber band · once it snaps, you can't unsnap it. Albuterol tests which one you're holding.
🔑
First-line controllers are backwards. Tap →
Asthma = ICS (the Inflammation is the problem · calm it down). COPD = LAMA (the Lungs are structurally locked · force them open). ICS doesn't fix broken walls. LAMA doesn't fix twitchy muscles. Match the drug to the damage.
🔑
The cell tells you the disease. Tap →
Eosinophils = Early onset, Episodic → Asthma. Neutrophils = Never going back, Nicotine damage → COPD. The inflammatory cell IS the diagnosis.
🔑
Pink puffer vs blue bloater. Tap →
Pink puffer (emphysema): hyperventilates to compensate → stays pink but exhausted. Thin because all that breathing burns calories. Blue bloater (chronic bronchitis): stops trying to compensate → CO2 retention → cyanosis. Overweight because NOT burning extra calories breathing. The body's coping strategy determines the phenotype.

The Algorithm

Board vignette drops. Patient is wheezing. Walk through it.

Step 1: How old is the patient?
Child / young adult (<40)
Older adult (>40)

Elimination Rounds

Five patients walk in wheezing. Don't give them the wrong inhaler.

Board Questions

Read every explanation, not just the correct answer.

Q1 of 8
A 45-year-old with a 25 pack-year history presents with FEV1/FVC of 0.64. After albuterol, FEV1 improves by 9%. What is the most appropriate first-line controller medication?
A. Inhaled corticosteroid (fluticasone)
B. Long-acting muscarinic antagonist (tiotropium)
C. Short-acting beta-agonist PRN only
D. Oral prednisone taper
Q2 of 8
Which PFT finding BEST distinguishes asthma from COPD in a patient with FEV1/FVC of 0.65?
A. Decreased FEV1
B. Decreased FVC
C. Bronchodilator reversibility (FEV1 improves ≥12% AND ≥200mL)
D. Decreased DLCO
Q3 of 8
A 28-year-old with childhood eczema presents with episodic wheezing worsened by cat exposure. Baseline spirometry is normal. What test would confirm airway hyperreactivity?
A. High-resolution CT chest
B. Methacholine challenge test
C. Serum eosinophil count alone
D. Exhaled nitric oxide (FeNO)
Q4 of 8
A 32-year-old non-smoker presents with lower-lobe panacinar emphysema on CT. He has chronic liver disease. What should be tested first?
A. Sputum culture for TB
B. Sweat chloride test for cystic fibrosis
C. Alpha-1 antitrypsin level and Pi genotyping
D. Pulmonary function tests only
Q5 of 8
A COPD patient has had 3 exacerbations in the past year despite LAMA + LABA. Blood eosinophil count is 420 cells/mcL. What should be added?
A. Roflumilast (PDE4 inhibitor)
B. Inhaled corticosteroid (ICS)
C. Theophylline
D. Oral azithromycin prophylaxis
Q6 of 8
A 70-year-old with COPD on home oxygen has SpO2 of 96%. He becomes somnolent and confused. His SpO2 is now 99%. What is the most likely mechanism?
A. Paradoxical bronchospasm from high-flow oxygen
B. Over-oxygenation blunted hypoxic drive, causing CO2 retention
C. Pulmonary embolism causing hypercapnia
D. Hypoxic vasoconstriction released, causing shunting
Q7 of 8
A child uses their albuterol 4 days per week and wakes up coughing twice per month. What asthma step is appropriate and what drug should be started?
A. Step 1 (intermittent) · SABA PRN only
B. Step 2 (mild persistent) · low-dose ICS as daily controller
C. Step 3 (moderate persistent) · low-dose ICS plus LABA
D. Step 4 (severe persistent) · medium-dose ICS plus LABA
Q8 of 8
Which is the ONLY intervention proven to reduce mortality in COPD patients with PaO2 at or below 55 mmHg?
A. Tiotropium (LAMA)
B. Pulmonary rehabilitation
C. Long-term supplemental oxygen (at least 15 h/day)
D. Triple inhaler therapy (ICS + LABA + LAMA)
← ABG Interpretation RESP Portal
Board-Style Walkthrough

Board-Style Walkthrough

Original board-style vignettes. Shuffled, never-repeat, full explanations for every choice.