Acute dyspnea

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This page is for adult patients. For pediatric patients, see: acute dyspnea (peds).


Lobes of the lung with related anatomy.

Clinical Features

Emergent Pattern Recognition

Diagnosis Lungs CXR ECG Treatment Contraindicated
Pulmonary Edema Bilateral rales Interstitial fluid Normal/abnormal R/O AMI, lasix, nitrates, ACEi, BiPAP IVF; ?albuterol; ?Beta-blockers
Bronchoconstriction Wheezes Clear/hyperinflated Normal/pulmonary strain Albuterol, atrovent, steroids, consider anaphylaxis (epi) Beta-blockers; ?aspirin
Pneumonia Focal ronchi/decreased breath sounds Infiltrate/effusion Normal IVF, antibiotics Rate control; diuresis
Pulmonary embolism Clear Clear (most) or Westrmark/Hampton hump Normal/S1Q3T3 Anticoagulate/thrombolytics Rate control
Pneumothorax/Hemothorax Unequal Pneumo/hemo Normal Needle thoracentesis/chest tube Rate control
Dysrythmia Clear/pulmonary edema Clear/pulmonary edema Abnormal Type dependent Albuterol; ?IVF
ACS Clear/pulmonary edema Clear/pulmonary edema Normal/abnormal Aspirin; nitrates, anticoagulation, ?beta-blockers, +/- thrombolytics Albuterol; ?IVF

Differential Diagnosis

Acute dyspnea




Pulmonary edema with small pleural effusions on both sides.

Bedside Lung Ultrasound in Emergency (BLUE) Protocol[1]

Algorithm for the Use of Ultrasound in the Evaluation of Dyspnea
  • Landmark study by a French intensivist that described various profiles of specific pulmonary disease found on US[2]
  • Ultrasound approaches include anterior zones and PLAPS (posterior or lateral alveolar and/or pleural syndrome) point, which is located at the posterior axillary line similar to FAST view
  • Predominant A lines anteriorly + lung sliding = Asthma/COPD
  • Multiple predominant B lines anteriorly + lung sliding = Pulmonary Edema
  • Predominant A lines anteriorly + lung sliding + positive DVT = PE
  • Absent anterior lung sliding + anterior A lines + positive lung point = Pneumothorax (PTX)
  • PLAPS findings +/- A or B lines +/- abolished lung sliding = Pneumonia
    • PLAPS describes changes at the PLAPS point, usually related to consolidations and pleural effusions[3]
    • Consolidations may include lung hepatization, shred sign, air bronchograms
      • Note that mirroring (normal) may appear similar to hepatization, but mirroring only shows in specific spots due to specific echogenic windows
    • Pleural effusions are visualized as anechoic/hypoechoic areas with possible spine sign or floating lung sign (sinusoid sign on M-mode)
  • A suggested BLUE protocol guides diagnosis of dyspnea; this should be modified as needed based on clinical presentation
    • Check lung sliding in anterior lung fields ---> check for A and B lines ---> check for PLAPS findings


  • Oxygen
  • Treat underlying cause


  • Depends on underlying diagnosis

See Also


  1. Relevance of Lung Ultrasound in the Diagnosis of Acute Respiratory Failure - The BLUE Protocol
  2. Lichtenstein DA, Mezière GA. Relevance of lung ultrasound in the diagnosis of acute respiratory failure: the BLUE protocol. Chest. 2008 Jul;134(1):117-25. doi: 10.1378/chest.07-2800. Epub 2008 Apr 10. Erratum in: Chest. 2013 Aug;144(2):721. PMID: 18403664; PMCID: PMC3734893.
  3. Lichtenstein DA. Lung ultrasound in the critically ill. Ann Intensive Care. 2014 Jan 9;4(1):1. doi: 10.1186/2110-5820-4-1. PMID: 24401163; PMCID: PMC3895677.