Egans ch. 21 pt.2

Four tissue densities you can see on a chest radiograph

Air-absorbs little energy and looks dark or black

Fat-absorbs less energy than bone or tissue and looks darker than the tissue, light gray

Tissue-absorbs a larger amount and looks medium gray

Bone-or metal is nearly white

Three indications for a chest radiograph for outpatient

severe persistant cough

unexplained dyspnea

hemoptysis

Three indications for a chest radiograph for inpatients

ET placement

Confirm placement of PAC of central line

sudden increase in peak pressure on vent

Explain "LAG" in reference to the chest x-ray

Lag refers to symptoms like fever and cough preceding radiograph changes by 12 to 24 hour. As the patient gets well, the reverse is true

The two basic ways to shoot a plain chest film

PA- film in front, energy behind; PA=posterior to anterior

AP- film in back, energy in front (portable films)

What might happen to the heart in an AP film

It might appear enlarged

If PA films are so much better in quality, why do most of our patients have AP chest x-rays

Portables are easier to do on a critically ill patients

What structures offer clues to help identify whether the patient's position is straight or rotated

Compare the position of the ends of the clavicles(anterior structure) to that of the spinous processes (posterior structure)

What appearance of the vertebral bodies suggests underexposure

Lack of visualization of the vertebral bodies through the heart shadow

What effect does underexposure have on the appearance of lung tissure

the lungs appear whiter and maybe misinterpreted as congestion or infiltrates

The pleura appear at the edge of the chest wall (although the pleura themselves are usually difficult to see) What are two major pleural abnormalities detected on the chest film

pleural effusion

pneumonthorax

CT

Computed tomography

What the advantage does CT over regular radiographs

CT allows you to image areas of the chest that are hard to see on the radiograph, like the medistinum

What is CT angiography used for

to better visualize blood vessels

HRCT

High-resolution CT

Explain the concept of "slices" and what this technique is good for showing

Emphysema, intersitual lung disease, and bronchiectasis might be better visualized under high resoultion due to the thinner clearer slices

MRI

Magnetic resonance imaging

What type of tissue in the chest is imaged with MRI technique

shows soft tissue well, like blood vessels

What is the costophrenic angle

The angle between the diaphragm and the chest wall

Describe how you recognize the presence of fluid in the pleural space; what dose that angle look like

the pleural meniscus sign, you lose the sharp edge

Which view is most sensitive for detecting pleural fluid? How is the patient positioned to obtain this view

The lateral decubitus view. The patient is positioned so they are lying on the side with the suspected effusion

When is sonography (ultrasound) indicated in the evaluation of pleural abnormalities

Identifying small and loculated pleural effusions, and separating fluid from solid tissue abnormalities.

Sonography can also be used to guide pleural drainage procedures

What other imaging procedure may be helpful

computed tomography (CT)

Air in the pleural space is always abnormal. Name three common causes of this condition

Iatrogenic-biopsy

rupture of the bleb

barotrauma

What breathing maneuver will help identify a small pneumothorax on a chest film

upright chest film obtained during exhalation

Tension pneumothorax is immediately life threatening. Name at lease two radiographic signs of tension pneumothorax

inferiorly displaced hemidiaphragm

mediastinum shifted away from the effects side

What is the treatment for tension pneumothorax

immediate decompression with a chest tube