Pleural Effusion Flashcards
1
Q
3 mechanisms of pleural effusion?
A
- increased drainage of fluid into the space
- increased production of fluid by cells in the space
- decreased drainage of fluid from the space
2
Q
What is intrapleural pressure?
A
- neg pressure is created in pleural space as thoracic cage enlarges and lungs recoil during normal inspiration
- negative pressure may be lost if fluid collects in pleural space, making the lung unable to expand fully
3
Q
Normal amt of pleural fluid?
A
- up to 25 ml is normally present, not detectable on conventional radiographs
- pleural effusion: abnorm accum of fluid into pleural space
4
Q
What are the main causes of pleural effusion?
A
- CHF (venous pressure increased - fluid exceeds hydrostatic pressure)
- liver failure ( decreased albumin = decreased oncotic pressure)
- infection
- atelectasis
- cancer
- trauma
5
Q
What is a hemothorax?
A
- blood in pleural cavity
- usually b/c of chest injury
- blood vessel ruptures into pleural space or bulging area into aorta (aortic aneurysm) leaks blood into pleural space
- can occur as a result of bleeding from ribs, chest wall, pleura and lung
6
Q
Diff types of pleural fluid?
A
- transudate: serum w/o protein
- exudate: protein in fluid; infection, inflammation
- empyema: infection - pus accum
- chyle: lymph fluid (milky appearance)
- hemothorax
7
Q
How much fluid needs to be present to be visible on XR? What position can confirm fluid? Other signs on imaging?
A
- 250 ml to be seen on PA CXR
- Lateral decubitus on affected side will almost always confirm fluid
- fluid will sit in Costophrenic angles or fissures
- pleural fluid becomes traped by pleural adhesions, form unusual colelctions along chest wall or in lung fissures - US or CT is uesful to locate loculated or small effusions
- massive pleural effusion: is usually caused by cancer but has been observed in TB and other diseases
- CT scanning is useful in free or loculated pleural fluid
