Shortness of breath

Introduction

Shortness of breath, or dyspnea, is the subjective sensation of breathing discomfort, often described as breathlessness, difficulty in breathing, or an inability to get enough air. It is one of the most frequent complaints in emergency and primary care, accounting for a large proportion of hospital visits. Dyspnea may be acute (minutes to hours) or chronic (weeks to months) and ranges from benign to life-threatening causes.

Because breathing involves the integrated function of the respiratory system, cardiovascular system, blood, and nervous system, shortness of breath can originate from multiple organ systems. A systematic diagnostic approach is critical to identify the underlying cause.

---

Mechanisms of Dyspnea

Dyspnea results from a mismatch between respiratory drive and the ability of the body to meet that drive. Mechanisms include:

1. Increased respiratory load (airway obstruction, lung stiffness, chest wall restriction).

2. Increased ventilatory drive (hypoxemia, hypercapnia, metabolic acidosis).

3. Neuromechanical dissociation (when the brain perceives more effort than actual ventilation achieved).

---

Etiology of Shortness of Breath

1. Respiratory Causes

• Airway diseases:

  • Asthma.

  • Chronic obstructive pulmonary disease (COPD).

  • Upper airway obstruction (foreign body, tumor, anaphylaxis).

• Parenchymal lung diseases:

  • Pneumonia.

  • Interstitial lung disease.

  • Pulmonary fibrosis.

• Vascular diseases:

  • Pulmonary embolism.

  • Pulmonary hypertension.

• Pleural diseases:

  • Pleural effusion.

  • Pneumothorax.

2. Cardiovascular Causes

• Left-sided heart failure (pulmonary edema).

• Coronary artery disease/angina.

• Arrhythmias (atrial fibrillation, tachycardia).

• Pericardial disease (tamponade, pericarditis).

3. Hematologic and Metabolic Causes

• Anemia.

• Sepsis.

• Metabolic acidosis (diabetic ketoacidosis).

• Thyrotoxicosis.

4. Neuromuscular Causes

• Myasthenia gravis.

• Guillain–Barré syndrome.

• Spinal cord lesions.

5. Psychogenic Causes

• Panic attacks.

• Anxiety disorders.

• Hyperventilation syndrome.

---

Clinical Presentation

• Subjective sensation: Difficulty breathing, air hunger, suffocation feeling.

• Associated symptoms:

  • Wheezing (asthma/COPD).

  • Chest pain (myocardial ischemia, pulmonary embolism).

  • Cough, sputum (pneumonia, heart failure).

  • Orthopnea, paroxysmal nocturnal dyspnea (heart failure).

  • Hemoptysis (pulmonary embolism, lung cancer).

  • Anxiety and palpitations (panic disorder, arrhythmia).

• Acute severe dyspnea: Stridor, cyanosis, use of accessory muscles, inability to speak full sentences → medical emergency.

---

Diagnostic Evaluation

1. History

• Onset: acute vs chronic.

• Triggers: exertion, allergens, lying flat, anxiety.

• Risk factors: smoking, heart disease, lung disease, travel (PE risk).

• Medication history: beta-blockers, opioids (can worsen dyspnea).

2. Physical Examination

• Vital signs: RR, SpO₂, BP, HR, temperature.

• Inspection: Cyanosis, accessory muscle use.

• Chest exam: Wheezes (asthma), crackles (heart failure, fibrosis), absent breath sounds (pneumothorax, effusion).

• Cardiac exam: Murmurs, gallops, JVP elevation, edema.

3. Investigations

• Blood tests: CBC (anemia), BNP (heart failure), D-dimer (PE), ABG (hypoxemia, acidosis).

• Chest X-ray: Pneumonia, heart failure, effusion, pneumothorax.

• ECG: Ischemia, arrhythmias.

• Echocardiogram: Cardiac function.

• CT scan (CT pulmonary angiography): Pulmonary embolism.

• Pulmonary function tests: Asthma, COPD, restrictive lung disease.

---

Management

Management of dyspnea requires both symptomatic relief and treatment of the underlying cause.

---

1. General Emergency Measures

• Airway: Ensure patency, remove obstruction, intubation if necessary.

• Breathing: Oxygen therapy if hypoxemic (target SpO₂ ≥94%, 88–92% in COPD).

• Circulation: Monitor BP, HR; IV access.

• Positioning: Sit upright to ease breathing.

---

2. Etiology-Specific Management

A. Asthma

• Short-acting beta-2 agonists (SABA):

  • Salbutamol (albuterol) 2.5 mg via nebulizer every 20 minutes for 3 doses, then as needed.

• Systemic corticosteroids:

  • Prednisone 40–60 mg orally once daily for 5–7 days.

• Anticholinergics:

  • Ipratropium bromide 500 mcg via nebulizer every 20 minutes for 3 doses.

• Severe cases: IV magnesium sulfate 2 g over 20 minutes.

B. Chronic Obstructive Pulmonary Disease (COPD) Exacerbation

• Oxygen therapy (target 88–92%).

• Salbutamol 2.5 mg nebulized every 20 minutes initially.

• Ipratropium bromide 500 mcg nebulized every 6 hours.

• Prednisone 40 mg orally once daily for 5–7 days.

• Antibiotics if purulent sputum or pneumonia suspected:

  • Amoxicillin–clavulanate 875/125 mg orally twice daily for 5–7 days.

  • Doxycycline 100 mg orally twice daily.

C. Pneumonia

• Empirical antibiotics (adult outpatient, no comorbidities):

  • Amoxicillin 1 g orally three times daily for 5–7 days.

  • Doxycycline 100 mg orally twice daily.

• Severe pneumonia or inpatient:

  • Ceftriaxone 1–2 g IV once daily plus Azithromycin 500 mg IV/PO once daily.

D. Pulmonary Embolism (PE)

• Immediate anticoagulation:

  • Enoxaparin 1 mg/kg subcutaneously every 12 hours.

  • Apixaban 10 mg orally twice daily for 7 days, then 5 mg twice daily.

  • Warfarin (target INR 2–3) overlapped with heparin until INR therapeutic.

E. Heart Failure (Acute Pulmonary Edema)

• Oxygen therapy.

• Furosemide 20–40 mg IV bolus, repeat if needed.

• Nitroglycerin sublingual 0.3–0.6 mg every 5 minutes as needed (avoid if hypotensive).

• ACE inhibitors: Enalapril 2.5–5 mg orally twice daily.

F. Anemia

• Ferrous sulfate 325 mg orally 1–3 times daily.

• Blood transfusion if Hb <7 g/dL (individualized for symptoms).

G. Anxiety / Panic Attack

• Reassurance, breathing techniques.

• Lorazepam 0.5–2 mg orally/IV as needed for acute anxiety.

• Long-term: SSRIs (e.g., Sertraline 50–200 mg orally daily).

---

Precautions and Patient Counseling

• Oxygen therapy should be titrated to avoid hypercapnia in COPD.

• Educate asthma and COPD patients on inhaler technique and adherence.

• Stress smoking cessation in all respiratory diseases.

• Encourage vaccination: influenza, pneumococcal for at-risk patients.

• Heart failure patients should monitor weight and salt intake.

• Anticoagulated patients (for PE, AF) should be counseled on bleeding risks.

---

Drug Interactions

• Salbutamol: Additive tachycardia with beta-agonists, reduced effect with non-selective beta-blockers.

• Ipratropium: May interact with other anticholinergics, increasing dryness and urinary retention.

• Prednisone: Interacts with NSAIDs (GI bleeding risk), CYP3A4 inhibitors.

• Furosemide: Risk of hypokalemia; interaction with digoxin (arrhythmias).

• Warfarin: Numerous interactions (antibiotics, antifungals, NSAIDs, SSRIs).

• Enoxaparin/Apixaban: Additive bleeding risk with antiplatelets (aspirin, clopidogrel).

• Lorazepam: Additive CNS depression with alcohol, opioids, antihistamines.

• SSRIs: Risk of serotonin syndrome with other serotonergic agents (triptans, MAOIs).

---

Prognosis

• Acute reversible causes (asthma exacerbation, pneumonia, anxiety) have good prognosis with timely treatment.

• Chronic conditions (COPD, interstitial lung disease, heart failure) require long-term management; prognosis varies.

• Life-threatening causes (massive PE, tension pneumothorax, severe heart failure) have high mortality if not recognized and treated immediately.