Shortness of Breath: She Looked Fine a Minute Ago

Lecture Notes

The first thing to do when presented with a chief complaint is to develop a critical differential. For shortness of breath the critical differential diagnosis is:

  1. Pneumonia
  2. Pneumothorax
  3. ACS
  4. CHF Exacerbation
  5. Asthma/COPD
  6. PE

After developing your differential diagnosis you will want to walk over to your patient and assess what degree of respiratory distress they are in

Spectrum of respiratory distress

The following bits of information can be used to determine what degree of respiratory distress your patient is in:

  • RR
  • Sao2
  • Are there signs of retractions or accessory muscle use?
  • How many words is your patient able to speak in a sentence?

Remember that this is a spectrum. So the patient may not fall into a hard category but may instead be in mild to moderate or moderate to severe respiratory distress.

In the video, CHF is given as a brief example. To learn more about CHF exacerbation check out our video on CHF Exacerbation.

While you are initially resuscitating your patient based on what degree of respiratory distress they are in, you will want to simultaneously order some labs and imaging studies. This will be based on your critical differential diagnosis.

Consider ordering the following labs:

  • CBC - to make sure the patient is not anemic
  • BMP - to check for acidosis, electrolyte abnormalities
  • EKG - to assess for STEMI
  • Troponin - to assess for AMI or demand ischemia.
  • +/-D Dimer - to assess for PE. Use PERC rule or Well’s criteria to determine who to get d-dimer on


  • Chest Xray: to ensure that the patient does not have pneumonia or pneumothorax
  • CT PE : Based on D Dimer + Well’s Criteria Algorithm for Dyspnea

Full article and algorithm on Dyspnea can be found at /

Full article and algorithm on Dyspnea can be found at

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