You need an organized, anatomical approach.

Step 1: Consider Differential Diagnosis

  • Upper airway
    • Angioedema
    • Foreign body
    • Abscess
  • Lower airway
    • COPD
    • Asthma
  • Alveoli
    • Pneumonia
    • Pulmonary edema
  • Blood
    • Anemia
    • Acidosis
      • DKA
      • Sepsis (lactic acid)
      • Toxins (salicylic acid)
  • Blood vessels
    • Pulmonary embolism
    • Aortic dissection
  • Heart
    • Myocardial infarction
    • Acute heart failure
    • Cardiac tamponade

Step 2: Examine Anatomically

  • Upper airway
    • Stridor
    • Voice changes
  • Lower airway
    • Wheezing
  • Alveoli
    • Crackles
  • Blood
    • Pallor
  • Heart
    • Dysrhythmia
    • Jugular vein distension (JVD)
    • Edema

Step 3: Testing Plan

  • Common tests
    • Chest x-ray
    • EKG
    • CBC
    • Electrolytes
  • Less common tests
    • Blood gas
    • Troponin
    • BNP
    • D-Dimer

Step 4: Calculate Wells Score and PERC

Additional Reading