CRACKCast E025 – Dyspnea

Rosen’s in Perspective

“Dyspnea”: uncomfortable sensation of breathlessness, “Air hunger”

• Non-specific spectrum from mild disease to severe disease
• May be referred to as different terms

Other terms to know:

Tachypnea − RR > normal >45-60 bpm in neonates; to >18 bpm in adults

Hyperpnea – Greater than normal minute ventilation to meet metabolic requirements

Hyperventilation – Minute ventilation exceeding metabolic demand

-> ABG showing normal PaO₂

+ Uncompensated respiratory alkalosis

+ Elevated pH

Dyspnea on Exertion (DOE) – Dyspnea provoked by physical effort

Orthopnea – Dyspnea in a recumbent position

Paroxysmal Nocturnal Dyspnea (PND) – Sudden SOB at night

Pathophysiology

• Normal breathing controlled by:
  • Centrally by the respiratory centres in the medulla oblongata
  • Peripherally by the chemoreceptors in the carotid bodies
  • Mechanical centres in the diaphragm and skeletal muscles

• Any imbalance in these sites leads to dyspnea – mechanism not fully understood

Perception of dyspnea relates to:

• Increased lung resistance
  • COPD or Asthma
• Increased respiratory drive
  • Severe hypoxemia, acidosis, centrally acting toxins, or CNS events

1) List 10 critical causes of dyspnea

First key question:

• Is the dyspnea cardio-pulmonary OR toxic-metabolic?

CRITICAL CAUSES:

Pulmonary

1. Airway obstruction
   a) Heimlich maneuver & direct laryngoscopy with McGill forceps
2. Pulmonary embolism
3. Non-cardiogenic pulmonary edema
4. Anaphylaxis
5. Respiratory failure
6. Tension pneumothorax +/- flail chest
   a) Severe respiratory distress, hypoxia, hypotension
   b) Decreased breath sounds, oxygen desaturation

 Cardiac

1. Pulmonary edema (due to CHF)
2. Myocardial infarction
3. Cardiac tamponade

Other

1. Toxic ingestions (e.g. organophosphate ingestion)
2. DKA
3. Epiglottitis
4. CO poisoning
5. Acute chest syndrome (e.g. Sickle cell)

CVA / intracranial catastrophe