Determining the Cause

Chief Complaint: Wheezing

1️⃣ Start With: Is this an emergency?

Look for red flags suggesting impending respiratory failure:

Inability to speak full sentences
Accessory muscle use
Silent chest
Altered mental status
Cyanosis
SpO₂ < 90% on room air
Rising CO₂ (if available)
exhaustion

If present → Immediate stabilization (oxygen, bronchodilators, steroids, prepare for airway support).

If not → proceed with structured evaluation.

2️⃣ Determine the Pattern of Wheeze

│[ └── Inspiratory or mixed → Consider Vocal Cord Dysfunction or upper airway obstruction]

A. Diffuse, bilateral wheezing

Most common causes:

Asthma (classic in a 20‑year‑old)
Viral bronchitis
Anaphylaxis (look for urticaria, hypotension)
COPD (unlikely at age 20 unless rare exposures)

B. Focal or unilateral wheeze

Think mechanical obstruction:

Foreign body
Mucus plug
Endobronchial tumor (rare at 20, but carcinoid possible)
Localized infection (e.g., pneumonia with airway compression)

C. Wheeze + crackles

Heart failure (cardiac wheeze)
Bronchiolitis
Atypical pneumonia

3️⃣ Use the History to Narrow the Cause

Ask targeted questions:

Asthma clues

Episodic symptoms
Triggers: exercise, cold air, allergens
Personal or family atopy
Nocturnal symptoms

Allergic/anaphylaxis clues

Sudden onset
Exposure to food, drug, insect sting
Rash, swelling, hypotension

Infectious clues

Fever
Cough with sputum
Sick contacts
Recent viral illness

Foreign body clues

Abrupt onset
Choking episode
Persistent unilateral wheeze

Cardiac clues

Orthopnea
Edema
Chest pressure
History of congenital heart disease

4️⃣ Physical Exam Priorities

Work of breathing
Symmetry of breath sounds
Presence of stridor (upper airway obstruction)
Crackles (fluid or infection)
Signs of allergy (rash, swelling)
Cardiac exam (S3, murmurs)

5️⃣ Initial Diagnostic Tests (based on suspicion)

If asthma likely

Peak flow or spirometry (if stable)
Trial of bronchodilator → improvement supports diagnosis

If infection suspected

Chest X‑ray
CBC

If foreign body suspected

Chest X‑ray (may be normal)
Inspiratory/expiratory films
Consider bronchoscopy

If anaphylaxis suspected

Clinical diagnosis → treat immediately

If cardiac cause suspected

CXR
BNP
ECG
Echo if needed

6️⃣ Response to Bronchodilator = Key Diagnostic Clue

A rapid improvement after albuterol strongly suggests asthma or bronchospasm.

No improvement → think:

Foreign body
Mucus plug
Vocal cord dysfunction
Heart failure
Fixed obstruction (tumor, tracheal stenosis)

7️⃣ Special Consideration: Vocal Cord Dysfunction

Common in young adults and often misdiagnosed as asthma.

Clues:

Inspiratory wheeze
Normal oxygenation
Poor response to albuterol
Triggered by stress or exercise

Diagnosis: laryngoscopy during symptoms.

🧠 Putting It All Together: Mini‑Algorithm

Is the patient unstable?      → Yes → Stabilize airway/breathing.      → No → Continue.    Is wheeze diffuse?      → Yes → Think asthma, bronchitis, anaphylaxis.      → No → Think focal obstruction (foreign body, tumor).    Does bronchodilator help?      → Yes → Asthma/bronchospasm.      → No → Foreign body, VCD, cardiac, fixed obstruction.    Are there infectious signs?      → Yes → CXR for pneumonia/bronchiolitis.    Are there allergic signs?      → Yes → Treat for anaphylaxis.    Are there cardiac signs?      → Yes → Evaluate for heart failure.    Still unclear?      → Consider spirometry, CT chest, or bronchoscopy.

START → Wheezing in a 20-year-old

│
├── 2. Characterize the Wheeze
│ ├── Diffuse, bilateral → Go to Branch A
│ ├── Focal/unilateral → Go to Branch B
│ └── Inspiratory or mixed → Consider VCD or upper airway obstruction
│
├── Branch A: Diffuse Wheeze
│ ├── History of atopy, triggers, episodic symptoms?
│ │ ├── YES → Suspect ASTHMA
│ │ └── NO → Continue
│ ├── Recent viral illness? → Viral bronchitis
│ ├── Sudden onset + allergen exposure + rash/hypotension?
│ │ ├── YES → ANAPHYLAXIS (treat immediately)
│ └── Trial of bronchodilator
│ ├── Improves → Bronchospasm (asthma most likely)
│ └── No improvement → Reconsider diagnosis (VCD, cardiac, fixed obstruction)
│
├── Branch B: Focal/Unilateral Wheeze
│ ├── Abrupt onset? Choking episode?
│ │ ├── YES → FOREIGN BODY
│ │ └── NO → Continue
│ ├── Recurrent pneumonia in same area? → Endobronchial lesion (rare but possible)
│ └── Imaging (CXR ± CT) → Look for obstruction, mass, mucus plug
│
├── 3. Evaluate for Mimics
│ ├── Stridor → Upper airway obstruction (laryngeal edema, VCD)
│ ├── Crackles + wheeze → Heart failure, bronchiolitis, atypical pneumonia
│ ├── Normal exam between episodes → Consider VCD
│
├── 4. Initial Diagnostics (based on branch)
│ ├── Peak flow/spirometry → Asthma pattern?
│ ├── CXR → Infection, focal obstruction, hyperinflation
│ ├── CBC → Infection/allergy clues
│ ├── If foreign body suspected → Inspiratory/expiratory films ± bronchoscopy
│ ├── If cardiac signs → ECG, BNP, echo
│ └── If anaphylaxis → Clinical diagnosis; treat immediately
│
└── 5. Reassess After Interventions
├── Improved with bronchodilator → Asthma/bronchospasm
├── No improvement → Foreign body, VCD, fixed obstruction, cardiac
└── Persistent unclear → Consider CT chest, laryngoscopy, or pulmonary consult

END