Imaging in Trauma

Educational Objectives

The goal of this program is to improve the appropriate use of imaging in trauma patients. After hearing and assimilating this program, the clinician will be better able to:

1. Recognize the impact of radiation from computed tomography in trauma patients.
2. Use clinical decision tools to direct the selective imaging of trauma patients.
3. Assess the need for computed tomography based on results from ultrasonography and physical examination.

Summary

Computed tomography (CT) in trauma care: often ordered prior to adequate examination of patient; use clinical decision making skills to determine need for imaging; Korley et al, 2010 — over period of 10 yr, use of CT more than doubled, yet length of stay increased and patient disposition not changed; important to question how much radiation to patient is necessary; trauma patients receive significant amount of radiation

Impact of radiation from CT: concern about potential harm of excessive radiation; impact likely differs based on age of patient; statistics — 1 radiation-induced cancer for every 1000 patients receiving >10 millisieverts; 29,000 future cancers related to CT performed in 2007 (Berrington de Gonzalez et al); risk of leukemia and brain cancer tripled in children exposed to radiation from CT (Pearce et al)

Patients presenting with tachycardia: tachycardia often used as indication or justification for CT in trauma patients; however, anxiety and stress of situation may contribute to tachycardia; in noncritical patients, observe for few minutes (first set of vital signs may not reflect condition) and allow patient time to adjust before re-evaluating; assess trends in vital signs before ordering CT (changes in condition, positive or negative, may influence what imaging indicated)

“Pan scan”: term used when clinician orders CT of head, neck, chest, abdomen, and pelvis for trauma patients; often ordered without thought or appropriate examination; potential advantages — facilitates immediate identification and management of injuries; decreases rate of missed injuries; decreases delays in care; permits safe discharge in more timely fashion; disadvantages — 3-fold increase in use of CT without increase in rate of concerning diagnoses; increases in exposure to radiation, cost, and rate of incidental findings

Consequences of incidental findings: require further work up, and increase cost and potential exposure to radiation; often have no impact on presenting complaint or future health (eg, speaker’s department found 70% of incidental findings had no bearing on current trauma)

Contrast-induced renal failure: 1% of patients who receive intravenous (IV) contrast will develop contrast-induced renal insufficiency; significant, particularly in elderly

“Pan scan” vs selective CT: most studies show no difference in mortality; in 2% to 27% of cases, use of “pan scan” changed course of management, but with few operative consequences; missed injuries — selective CT may reduce number of scans but may miss some injuries (few are critical); many studies show that “pan scans” identify missed injuries (typically nonoperative); clinician must assess own tolerance for missed injuries and decide if more important to diagnose every injury or miss injuries (eg, small rib fracture) with no significant impact on patient care or outcome; summary of data on “pan scans” — increase exposure to radiation; no decrease in mortality; decrease missed injuries (significance unclear); modest decrease in length of stay

Patients with major multisystem trauma: do not send for CT if unstable; reserve multiple selective CT for relatively stable patients when examination of injuries may be limited by, eg, intubation or altered mental status (AMS)

Focused assessment with sonography for trauma (FAST) examination: potential for false-negative results exist; when results positive, beneficial to decision making; when results negative, lack of symptoms and reassuring clinical examination support decision not to order CT

Abdominal trauma: CT of abdomen — <20% demonstrate injury; <3% find injury that requires surgical intervention

Decision making with FAST: patient unstable, FAST results positive — proceed straight to operating room (OR); patient unstable, FAST results negative — determine cause of unstable vital signs; patient stable, FAST results positive — order CT to determine source of injury; patient stable, FAST results negative — for high-risk patients (eg, concerning examination, abnormal laboratory findings, hematuria), order CT; for low-risk patients, observation (can reduce up to 70% of CT)

Pregnant trauma patients: try to avoid CT; 2002 algorithm — uses ultrasonography (US); if patient unstable, perform FAST (if results positive, send to OR; if results negative, evaluate for other causes); if patient stable, perform CT when FAST results positive, but when FAST results negative, patient should not have CT (even with concerning laboratory findings); 2009 algorithm — follow when US not available; recommends against CT in absence of hematuria, hypotension, and abdominal and costovertebral angle tenderness, if GCS >13, hematocrit >29%, and no abnormalities on chest x-ray; reduces use of CT by 50%

Evaluating for chest injuries: chest x-ray — use as initial screening tool; abnormal findings helpful to determine whether further studies needed; however, 7% of patients with aortic injury have normal findings; National Emergency X-Radiography Utilization Study (NEXUS) Chest decision instrument — high risk criteria include age >60 yr, rapid mechanism of deceleration (fall >20 feet, motor vehicle accident >40 miles per hour), chest pain, chest wall tenderness, AMS, painful distracting injury, and intoxication (depends on amount ingested and level of intoxication); chest CT vs x-ray — chest CT detects more injuries than x-ray, but often does not change management of patient; recent study shows that more rib fractures diagnosed using chest CT, with approximately two-thirds of diagnosed rib fractures not identified using chest x-ray (clinical significance unclear); pediatric patients — study in patients <15 yr of age with normal findings on chest x-ray shows no benefit of chest CT; indications for chest CT — abnormal chest x-ray; painful distracting injury; tenderness to chest wall, sternum, or scapula; rapid deceleration injuries; application of these criteria can reduce use of CT chest by 30%

Diagnosing pneumothorax: US superior to supine chest x-ray; performing extended FAST (eFAST) examination (extending US to lung pleura) may be as effective as chest CT for detecting clinically significant pneumothorax

Head trauma: majority of head CT performed return negative findings; most patients with head injury diagnosed with minor head trauma, even in presence of loss of consciousness, brief amnesia, or AMS

Clinical decision instruments: six different sets published in last 10 yr; New Orleans Criteria — problematic; excludes patients with any drug or alcohol intoxication or physical evidence of injury below clavicle; Canadian CT Head Rule — positive level of alcohol permitted, but patients with AMS excluded; high risk criteria for mechanism of injury include pedestrian struck by motor vehicle, ejection from motor vehicle, and fall from >3 feet or >5 stairs; reduces use of CT by 20% to 50%; Pediatric Emergency Care Applied Research Network (PECARN) head trauma prediction rules — in children >2 yr of age, perform CT for AMS, palpable skull fractures, or signs of basilar skull fracture (otherwise, observe); in children <2 yr of age, perform CT for AMS or palpable skull fracture (otherwise, observe and avoid CT); if condition becomes progressively worse, perform CT; can reduce use of CT by 80%

Anticoagulated patients: in study of patients with head injury taking warfarin, second CT after 24 hr of observation found new bleeding in 6%, but all symptomatic; antiplatelet use — in patients receiving antiplatelet medications, risk of hemorrhage at time of initial CT slightly higher, but risk of delayed bleed not increased; for anticoagulated patients with normal findings on initial CT, discharge with precautions or 12 hr period of observation recommended (repeat CT only if changes on examination)

Injuries to cervical spine: CT superior to x-ray for identifying fractures, but not always necessary; if no risk factors present, imaging not indicated; if patient low-risk, perform x-ray of cervical spine; if high-risk (eg, concerning examination, unable to examine, elderly) perform CT; if progressive neurologic symptoms present, obtain MRI

Penetrating wounds to neck: if hard signs present, send straight to OR; if soft signs present, perform CT; if examination negative, imaging not indicated

Readings

Berrington de González A et al: Projected cancer risks from computed tomographic scans performed in the United States in 2007. Arch Intern Med. 169(22):2071-2077, 2009; Korley FK et al: Use of advanced radiology during visits to US emergency departments for injury-related conditions, 1998-2007. JAMA. 304(13):1465-71, 2010; Pearce MS et al: Radiation exposure from CT scans in childhood and subsequent risk of leukaemia and brain tumours: a retrospective cohort study. Lancet. 380(9840):499-505, 2012; Rodriguez RM et al: NEXUS chest validation of a decision instrument for selective chest imaging in blunt trauma. JAMA Surg. 148(10):940-946, 2013; Sadro C et al: Imaging of trauma: part 2, abdominal trauma and pregnancy — a radiologist’s guide to doing what is best for the mother and baby. AJR Am J Roentgenol. 199(6):1207-19, 2012.

Disclosures

For this program, members of the faculty and planning committee reported nothing to disclose.

Acknowledgements

Dr. Colwell was recorded at High Risk Emergency Medicine San Francisco, held May 30 to June 1, 2017, in San Francisco, CA, and at High Risk Emergency Medicine Hawaii, held April 9-13, 2017, on Maui, HI, and presented by the University of California, San Francisco, School of Medicine, and its Office of Continuing Medical Education. For information about upcoming CME conferences from the University of California, San Francisco, School of Medicine, please visit http://meded.ucsf.edu/cme. The Audio Digest Foundation thanks the speakers and the sponsors for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

EM351601

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.