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NEXUS Chest CT Decision Instrument for CT Imaging

Calculators  Respiratory
The national emergency X-ray utilization studies (NEXUS) Chest computed tomography (CT) Decision Instrument for CT Imaging determines if CT imaging can be safely omitted in a blunt trauma patient with thoracic injury
Abnormal chest X-ray
CXR showing any thoracic injury (including clavicle fracture) or widened mediastinum
No 0
Yes 1
Distracting injury
No 0
Yes 1
Chest wall, sternum, thoracic spine, or scapular tenderness
No 0
Yes 1
Rapid deceleration mechanism
Fall from >20 feet/6.1 m or MVA at >40 mph/64.4 km/hr with sudden deceleration.
No 0
Yes 1
Result:

Background

Measured Factor
Risk of significant thoracic injury that requires chest CT imaging
Measured Factor Disease
  • Risk of significant thoracic injury that requires chest CT imaging
Measured Factor Detail
The NEXUS Chest CT Decision Instrument for CT Imaging determines if CT imaging can be safely omitted in a blunt trauma patient with thoracic injury. This helps reduce unnecessary radiation exposure and cost. The calculator is used when chest CT is being considered for further diagnostic evaluation after the patient receives chest X-ray. If there is evidence of thoracic injury, such as abnormal chest X-ray, distracting injury, chest wall tenderness, sternal tenderness, thoracic spine tenderness, scapular tenderness, or rapid deceleration mechanism, major or minor thoracic injury cannot be excluded and further workup including chest CT is recommended.
Speciality
Emergency Medicine Physician
Body System
Respiratory
Measured Factor High Impact
  • Risk of significant thoracic injury that requires chest CT imaging

Result Interpretation

Ranges Ranges
  • Critical High: Answer "Yes" to any criteria | Chest CT imaging is recommended
  • Normal: Answer "No" to all criteria | Chest CT imaging may be safely omitted
  • Normal Adult Male: Answer "No" to all criteria | Chest CT imaging may be safely omitted
  • Normal Adult Female: Answer "No" to all criteria | Chest CT imaging may be safely omitted
  • Normal Geriatric Male: Answer "No" to all criteria | Chest CT imaging may be safely omitted
  • Normal Geriatric Female: Answer "No" to all criteria | Chest CT imaging may be safely omitted
Result High Conditions
  • Risk of significant thoracic injury that requires chest CT imaging
Test Limitations
This calculator should be used to support rather than replace clinical judgment. Moreover, it should not be used to evaluate patients younger than 15 years old.
References: 1

Studies

Study Validation 1
This review looked at 3 prospective multicenter studies over 12 years that derived and validated 3 decision instruments to guide the use of chest x-ray (CXR) and chest computed tomography (CT) in blunt trauma patients. The decision instruments were the national emergency X-ray utilization studies (NEXUS) Chest x-ray,  NEXUS Chest CT-Major, the NEXUS CT-All rule. The NEXUS Chest x-ray consisted of seven criteria (Age > 60 years; rapid deceleration mechanism; chest pain; intoxication; altered mental status; distracting painful injury; and chest wall tenderness) and had a sensitivity of 99.0% and a specificity of 13.3% for detecting clinically significant injuries. The NEXUS Chest CT-Major consists of six criteria (abnormal CXR; distracting injury; chest wall tenderness; sternal tenderness; thoracic spine tenderness; and scapular tenderness) and had  a sensitivity of 99.2% and a specificity of 37.9%. The NEXUS CT-All rule (also known as the NEXUS Chest CT Decision Instrument for CT Imaging) consisted of six NEXUS CT-Major criteria plus rapid deceleration mechanism and had a sensitivity of 95.4% and a specificity of 25.5%. The authors recommended to incorporate these  3 decision instruments into chart templates and electronic medical records in order to safely avoid unnecessary imaging.
References: 2
Study Validation 2
The study evaluated the prevalence and diagnostic performance of the national emergency X-ray utilization studies (NEXUS) Chest computed tomography (CT) criteria. This was a secondary analysis of data on patients in the derivation and validation cohorts of the prospective, observational NEXUS Chest CT study, performed September 2011 to May 2014 in 11 Level I trauma centers. The injury major clinical injury prevalences determined by abnormal chest-x-ray alone were 60.7% (95% confidence interval (CI) 52.2%-68.6%) and 12.9% (95% CI 8.3%-19.4%), respectively, with a sensitivity of 73.7 (95% CI 68.1-78.6) and a specificity of 83.9 (95% CI 83.6-84.2). The injury and major clinical injury prevalences determined by any other single criterion alone other than abnormal chest-x-ray were 16.8% (95% CI 15.2%-18.6%) and 1.1% (95% CI 0.1%-1.8%), respectively. The injury and major clinical injury prevalences determined by two and three criteria other than abnormal chest-x-ray were 25.5% (95% CI 23.1%-28.0%) and 3.2% (95% CI 2.3%-4.4%) and 34.9% (95% CI 31.0%-39.0%) and 2.7% (95% CI 1.6%-4.5%), respectively. The authors concluded that an abnormal chest x-ray was the best sreening parameter for thoracic injury. The presence of any single NEXUS Chest CT criterion other than abnormal chest-x-ray was associated with a low rate of major clinical injury. Finally, rates of injury and major clinical injury increased with the presence of more NEXUS Chest CT criteria.
References: 3
Study Additional 1
This retrospective  study demonstrated the technique of processing computed tomography (CT) images with a custom window blending algorithm that combines soft-tissue, bone, and lung window settings into a single image. Additional aims included assessment of diagnostic performance and comparison of interpretation time for chest CT for thoracic trauma with window blending and conventional window settings. A total of 103 chest CT images with both blended and conventional windows were independently interpreted by two emergency radiologists. Interpretation time and diagnostic performance were compared using the Wilcoxon signed-rank test and McNemar test, respectively. Chest injuries were compared with the national emergency X-ray utilization studies (NEXUS) CT Chest injury severity using the weighted kappa statistic. Interpretation time was faster with the window blending technique (P < .001), with no difference in diagnostic performance. The window blending technique had a sensitivity and specificity of 82.7% and 93.1%, respectively. The conventional windows technique had a sensitivity and specificity of 81.6% and 90.5%, respectively. Major injuries and negative cases determined by the NEXUS CT Chest criteria were correctly identified in all readings. Both window settings techniques resulted in similar injury severity classification . The authors concluded that the window blending technique allowed faster preliminary interpretation with no significant difference in diagnostic performance as compared to the conventional windows technique.
References: 4
Study Additional 2
Minor sternal fracture (SF) is more likely to be diagnosed through the use of chest computed tomography (CT). This study determined the frequency with which SF patients are diagnosed by chest x-ray (CXR) versus chest CT, the frequency of surgical procedures related to SF diagnosis, SF patient mortality and hospital length of stay comparing patients with isolated sternal fracture (ISF) and sternal fracture with other thoracic injury (SFOTI), and the number of cardiac contusions in SF patients. Charts and data of 14,553 SF patients enrolled from January 2009 to May 2013 in the  national emergency X-ray utilization studies (NEXUS) Chest and NEXUS Chest CT studies were analyzed. There were 292 (2.0%) cases diagnosed with SF, and 94% of these SF cases were seen on chest CT only. One patient (0.4%) had a surgical procedure related to SF diagnosis. SF patient mortality was 3.8%, which was not significantly different than the mortality of patients without SF (3.1%). Patients with SFOTI had longer hospital length of stay but similar mortality to patients with ISF (mean difference 0.8%; 95% CI -4.7% to 12.0). Cardiac contusions was detected in 7 (2.4%) of SF patients. The study concluded that most SF cases were seen on CT only and the majority of these cases were associated with low mortality. Cardiac contusions was detected in a low number of SF patients. The authors recommended chest CT evaluation protocols to be included in the SF diagnostic and management guidelines.
References: 5

Authors

Robert Rodriguez, MD, is a professor of clinical emergency medicine, the associate chair for clinical research, and the residency research director at University of California, San Francisco (UCSF) School of Medicine. His research focused on decision instruments for imaging in blunt trauma, critical care in the emergency medicine, infectious disease presentations to the emergency medicine, homeless and immigrant population access and care in the emergency medicine, and defensive medicine
https://emergency.ucsf.edu/people/robert-rodriguez-md

References

  1. Rodriguez RM, Langdorf MI, Nishijima D, Baumann BM, Hendey GW, Medak AJ, et al. Derivation and validation of two decision instruments for selective chest CT in blunt trauma: a multicenter prospective observational study (NEXUS Chest CT). PLoS Med. 2015 Oct 6;12(10):e1001883.
  2. Rodriguez RM, Hendey GW, Mower WR. Selective chest imaging for blunt trauma patients: The national emergency X-ray utilization studies (NEXUS-chest algorithm). Am J Emerg Med. 2017 Jan;35(1):164-170.
  3. Raja AS, Mower WR, Nishijima DK, Hendey GW, Baumann BM, Medak AJ, et al. Prevalence and Diagnostic Performance of Isolated and Combined NEXUS Chest CT Decision Criteria. Acad Emerg Med. 2016 Aug;23(8):863-9.
  4. Mandell JC, Wortman JR, Rocha TC, Folio LR, Andriole KP, Khurana B. Computed Tomography Window Blending: Feasibility in Thoracic Trauma. Acad Radiol. 2018 Sep;25(9):1190-1200.
  5. Perez MR, Rodriguez RM, Baumann BM3 Langdorf MI4 Anglin D5 Bradley RN, et al. Sternal fracture in the age of pan-scan. Injury. 2015 Jul;46(7):1324-7.