IS Case 565: Bat wing pattern of pulmonary edema
Imaging Sciences URMC 2010
Publication Date: 2011-11-16
Bat wing pattern of pulmonary edema
Pulmonary edema is the accumulation of fluid in the interstitium and alveoli of the lungs. Increased hydrostatic pressure in the capillaries, decreased oncotic pressure or impaired permeability can all cause pulmonary edema. The most common cause of pulmonary edema is cardiogenic. It is a gradual process and usually starts with the transfer of fluid into the interstitium. When the fluid transfer exceeds the capacity of the lymphatics, fluid starts to accumulate in the interstitium. The buildup of fluid eventually causes fluid to fill up the alveoli and affect gas exchange.
The accumulation of fluid initially starts at the bases due to gravity. The fluid at the bases causes vascular flow to be redistributed to the apices and this causes the increased interstitial markings at the apices of the lungs.
“Bat wing” pattern of pulmonary edema refers to centralization of alveolar and interstitial infiltrates with relative sparing of the lateral regions of the lungs, unlike the edema which starts with initial fluid accumulation in the gravity influenced areas. This type of pattern is seen more commonly in edema due to left heart failure or renal disease and the cause for this type of pattern of edema is unknown.
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