Friday, April 11, 2014

Chest x-ray - mnemonics - Pulmonary edema

Chest x-ray - mnemonic - Pulmonary oedema

Cardiogenic Pulmonary oedema chest x-ray findingAlveolar edema (bat's wing or butterfly)

These are pulmonary opacities seen in bilateral perihilar areas. Outer third of the lung usually spared in pulmonary edema.

Kerley B lines

Kerley B lines are short (1-2 cm) horizontal linear shadows, perpendicular to the pleura, seen close to costo pherenic angles caused by thickened interlobular septae, due to accumulation of fluid (transudate). Other than pulmonary edema rare causes of kerley B lines are lymphangitis carsinomatosis, sarcoidosis, viral and mycoplasmal pneumonia.

 Pulmonary oedema chest x-ray findingCardiomegaly

In normal individuals cardio thoracic ratio(CTR) is less than 50%. CTR is the maximum transevers diameter of the heart divided by the greatest internal diameter of the thoracic cage. In cardiomegaly CTR is more than 50%.

Dilated prominent upper lobe vessels

In a patient with congestive heart failure, the pulmonary capillary wedge pressure rises  and the upper zone veins dilate and are equal in size or larger than lower zone pulmonary veins, also termed as cephalization.In normal individuals, the lower zone pulmonary veins are larger than the upper zone veins due to gravity.

Pleural effusion

Thia is due to increase hydrostatic pressure in pulmonary vasculature so it is a transudate.

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