ER radiography: Recognizing life-threatening conditions (Proceedings)

Diagnosis of emergency-critical care conditions requires the same attention to good radiographic technique as routine conditions. Otherwise serious errors can result which may seriously affect outcome. Good technique includes making at least two views, correct positioning and obtaining high quality images with adequate detail and contrast. Fortunately special views are infrequently required for critical care work, i.e., the same projections used in routine radiography of a particular anatomic area are usually adequate.

Musculoskeletal System

• Cranial vault fractures

     Computed tomography is the most accurate method of evaluation cranial vault fractures but may not be available in most emergency situations. An alternative is to obtain multiple projections of the head in order to visualize at least three tangents of the cranial vault. Lateral, ventrodorsal/dorsoventral and rostral to caudal views provide tangents across three axes of the head (longitudinal, dorsal and transverse) improving the likelihood of identifying a fracture of the calvarium. Most displaced fractures can be seen with this technique. Knowledge of the location of suture lines of the cranial vault is necessary to avoid misinterpretation.

• Atlantoaxial subluxation

     Trauma of the axis or atlas and hypoplasia of the dens and can lead to displacement of the axis with respect to the atlas, causing compression of the cervical spinal cord. Radiographic diagnosis is dependent on correct interpretation of the lateral projection with the beam centered on the atlantooccipital region. Chemical restraint is not recommended because of the possibility of worsening the patient's condition due to loss of protective reflexes. In addition, a ventrodorsal projection should not be attempted because extension of the head may aggravate atlantoaxial displacement. Radiographic signs include narrowing of the vertebral canal from dorsal displacement of the axis. There is also increased space between the dorsal lamina of the atlas and the rostral aspect of the spinous process of the axis.

• Fracture or luxation of the thoracic and lumbar vertebral column

     As with atlantoaxial subluxation, radiography should begin with lateral projections in patients suspected of having spinal fractures. Close collimation to the vertebral column and use of detail technique are necessary for identifying subtle lesions associated with fracture or luxation. In addition, true lateral positioning with sponges, towels, sandbags, etc. is mandatory to avoid misinterpretation.

• Aggressive versus non aggressive bone lesion-anywhere in the skeleton

     Although not immediately life threatening, aggressive bone lesions must be identified in the ER setting. Radiographic differentiation of aggressive versus non aggressive lesions has be extensively described in the literature

• Long bone and pelvic fractures

     Radiographic classification of long bone fractures is relatively straight forward providing two projections are obtained. In the manus and pes, additional oblique projections are often necessary to avoid missing undisplaced fractures. This especially pertains to the digits where and additional "fan" view should always be made. This is a mediolateral projection with tape applied to digits 2 and 5. Mild tension is applied to place the digits in a "fan" orientation.

• Signs of compound fracture

     o Gas in soft tissues near fracture

     o Defect in skin

Thorax

• Rib fractures

     o Ventrodorsal view essential

• Flail chest

     o Three or more ribs with segmental fractures (strict definition) (http://emedicine.medscape.com/article/433779-overview, 1.20.2010)

     o Paradoxical respiratory motion

• Pneumothorax

     o DV view is superior to VD view

• Pneumomediastinum

     o Can progress to pneumothorax

• Pleural effusion

     o VD view superior to DV view

• Signs of cardiac failure

     o Edema pattern in dog versus cat

          • Dogs tend to have more perihilar and dorsocaudal distribution while cats will have a more random, patchy pattern.

• Cardiac enlargement suggestive of pericardial effusion

     o Globoid shape, may also occur with dilated cardiomyopathy

• Microcardia

     o Hypovolemia

          • Dehydration

          • Hypoadrenocorticism

• Signs of diaphragmatic hernia

Abdomen

• Peritoneal gas (pneumoperitoneum)

     o Look for gas in non dependent areas

• Peritoneal effusion

     o Masks visualization of serosal surfaces.

• Organomegaly—look for displacements

     o Liver

     o Spleen

     o Kidney

     o Urinary bladder (obstructive uropathy

     o Retroperitoneal fluid accumulation (hemorrhage/edema/urine)

• Gastric dilation versus gastric dilation and volvulus

     o Right lateral view is view of choice

          • Fundus and pyloric antrum exchange normal locations

• Small intestinal obstruction

     o First document location of the colon to avoid confusing normal gas filled colon with distended small intestine.

     o Recognized mechanical ileus (obstruction) versus paralytic ileus (atony)

     o With mechanical ileus, normal as well as abnormal intestine is present

• Radiopaque gastrointestinal foreign body