Pulmonary edema

Pulmonary edema is a broad descriptive term and is usually defined as an abnormal accumulation of fluid in the extravascular compartments of the lung 1.

The clinical presentation of pulmonary edema includes:

  • acute breathlessness
  • orthopnea
  • paroxysmal nocturnal dyspnea (PND)
  • foaming at the mouth
  • distress

One method of classifying pulmonary edema is as four main categories on the basis of pathophysiology which include:

Broadly causes can be classified as cardiogenic and non-cardiogenic:

The causes of non-cardiogenic pulmonary edema can be recalled with the following mnemonic: NOTCARDIAC.

The chest radiograph remains the most practical and useful method of radiologically assessing and quantifying pulmonary edema 3,4.

Features useful for broadly assessing pulmonary edema on a plain chest radiograph include:

There is a general progression of signs on a plain radiograph that occurs as the pulmonary capillary wedge pressure (PCWP) increases (see pulmonary edema grading). Whether all or only some of these features can be appreciated on the plain chest radiograph, depend on the specific etiology 1. Furthermore, pulmonary edema is usually a bilateral process, but it may uncommonly appear to be unilateral in certain situations and pathologies (see unilateral pulmonary edema). 

Interstitial pulmonary edema is most commonly demonstrated by the following CT signs 7:

  • ground glass opacification
  • bronchovascular bundle thickening (due to increased vascular diameter and/or peribronchovascular thickening)
  • interlobular septal thickening

Alveolar edema is demonstrated by airspace consolidation in addition to the above findings.

Pleural effusions are a frequent accompanying finding in cardiogenic/hydrostatic pulmonary edema.

The appearance of pulmonary edema is defined as a function of the perturbation of the air-fluid level in the lung, a spectrum of appearances coined the alveolar-interstitial syndromes. 

As subpleural interlobular septa thicken among air-filled alveoli, they create a medium in which incident ultrasound waves will reverberate within, creating a short path reverberation artifact.  Referred to as B-lines, these are pathological when more than three appear, garnering the title lung rockets, and consistent with thickened interlobular septa. When spaced 7 mm apart they correlate with radiographic interstitial edema and when 3 mm apart with ground glass opacification. When surrounding alveoli become fluid-filled, the resultant interface assumes a tissue-like pattern. The tissue-like sign and shred sign are pathognomonic 10

General imaging differential considerations include other causes of diffuse airspace opacification:


Article information

rID: 16256
System: Cardiac, Chest
Synonyms or Alternate Spellings:
  • Pulmonary edema
  • Lung oedema
  • Lung edema
  • Acute pulmonary oedema
  • Oedema of the lungs
  • Oedema of lungs
  • Edema of the lungs
  • Edema of lungs

ADVERTISEMENT: Supporters see fewer/no ads

Cases and figures

  • Case 1: high altitude pulmonary edema
    Drag here to reorder.
  • Case 2
    Drag here to reorder.
  • Laryngospasm-indu...
    Case 3: laryngospasm induced - post obstructive
    Drag here to reorder.
  • Case 4
    Drag here to reorder.
  • Case 5
    Drag here to reorder.
  • Case 6
    Drag here to reorder.
  • Case 7: re-expansion edema
    Drag here to reorder.
  • Case 8: near drowning
    Drag here to reorder.
  • Case 9
    Drag here to reorder.
  • Case 10
    Drag here to reorder.
  • Case 11: with bat's wings
    Drag here to reorder.
  • Case 12: cardiogenic pulmonary edema
    Drag here to reorder.
  • Case 13
    Drag here to reorder.
  • Case 14: neurogenic pulmonary edema in a child
    Drag here to reorder.
  • Case 15: cardiogenic APO
    Drag here to reorder.
  • Case 16: APO due to ciguatera toxicity
    Drag here to reorder.
  • Case 17: cardiogenic pulmonary edema
    Drag here to reorder.
  • Case 18: APO
    Drag here to reorder.
  • Case 19
    Drag here to reorder.
  • Updating… Please wait.

     Unable to process the form. Check for errors and try again.

     Thank you for updating your details.