This episode of CRACKCast covers Rosen’s Chapter 25, Dyspnea. Dyspnea has a broad differential; to list them all would leave you short of breath. This episode covers an approach to dyspnea and the critical diagnoses to remember for this cardinal presentation.
Shownotes – PDF Here
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
- Airway obstruction
a) Heimlich maneuver & direct laryngoscopy with McGill forceps - Pulmonary embolism
- Non-cardiogenic pulmonary edema
- Anaphylaxis
- Respiratory failure
- Tension pneumothorax +/- flail chest
a) Severe respiratory distress, hypoxia, hypotension
b) Decreased breath sounds, oxygen desaturation
Cardiac
- Pulmonary edema (due to CHF)
- Myocardial infarction
- Cardiac tamponade
Other
- Toxic ingestions (e.g. organophosphate ingestion)
- DKA
- Epiglottitis
- CO poisoning
- Acute chest syndrome (e.g. Sickle cell)
CVA / intracranial catastrophe