Podcast #271: Nexus Chest CT Scan Guidelines

Author: Chris Holmes, M.D.

Educational Pearls

  • The nexus chest CT scan rule is based on an 11,000 subject, multicenter study that looked for signs following a trauma that predicted significant findings on subsequent chest CT.
  • Findings that were associated with abnormal chest CT included: abnormal CXR, distracting injury, chest wall, sternal, thoracic spine or scapular tenderness. Furthermore, a mechanism of injury that includes rapid deceleration was also associated.
  • If a patient has none of the above findings, then there is only a small chance that there will be an abnormal chest CT.

References: https://www.mdcalc.com/nexus-chest-ct-decision-instrument-ct-imaging

Podcast #233: CIN AEM Study

Author: Dylan Luyten, M.D.

Educational Pearls

  • Around 30% of patients in the ER receive CT imaging, and the sensitivity of CT imaging may be improved with IV contrast. However, contrast is often withheld for fear of contrast-induced nephropathy.
  • A recent, single-center, retrospective cohort study compared the rates of nephropathy between contrast CT, non-contrast CT, and no CT control patients, and found no differences.
  • This study confirms what many have believed to be true – that the dangers of modern contrast may be overstated. However, the results should be interpreted with caution, as this was a retrospective, single-center study.

References: Hinson, Jeremiah S. et al.. Risk of Acute Kidney Injury After Intravenous Contrast Media Administration. Annals of Emergency Medicine , Volume 69 , Issue 5 , 577 – 586.e4

Podcast #194: Atruamatic ICH

Author: Peter Bakes, M.D

Educational Pearls

  • Intracerebral hemorrhage is an intracranial bleed within the brain tissue or ventricles.
  • Subarachnoid aneurysm causes about 50% of all ICH.
  • Amyloid deposition can lead to ICH in elderly patients.
  • Hypertension is another common cause of atraumatic ICH, commonly leading to pontine, cerebellar, or basal ganglial bleeding. Bleeding in other locations is suggestive of a different etiology.
  • ICH will often present with depressed mental status, but specifically a patient with a systolic BP > 220 is suggestive of hypertensive ICH.
  • CT is the first diagnostic step. CTA should be considered when the bleeding is in an atypical area. Significant edema on imaging can be suggestive of a tumor.
  • Treatment should include hemostatic measures and BP control. Transfuse platelets if necessary and reverse any anticoagulation. BP target is <140 systolic. Monitor ICP if patient has AMS. Neurosurgical intervention is indicated when there is significant expansion of the hematoma with AMS or if the bleed is cerebellar.

References: Sahni R, Weinberger J. Management of intracerebral hemorrhage. Vascular Health and Risk Management. 2007;3(5):701-709. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2291314/

Podcast #186: IV Contrast

Run Time: 2 minutes

Author: Aaron Lessen M.D.

Educational Pearls:

  • Regularly a patient’s creatinine level is an important factor in determining whether a patient will receive IV contrast with a CT because it is thought that contrast can harm the kidneys and could worsen underlying kidney disease.
  • A recent retrospective study compared the rates of worsening kidney problems between patients who received a CT scan with contrast, a CT without contrast, and no CT.
  • The study even included patients with creatinines of up to 4 before excluding patients.
  • The study suggested that there is no difference in the rate of worsening kidney problems between the three groups.

References: http://www.annemergmed.com/article/S0196-0644(16)31388-9/fulltext

Podcast #163: Pregnancy and Radiation

61126a09-45de-45b5-9a33-b18ea86908b6Run Time: 3 minutes

Author: Jared Scott M.D.

Educational Pearls:

  • Pregnancy is a hypercoagulable state and often PE is a concern. When we work up PE in pregnancy the main consideration for harm to the fetus is radiation exposure.
  • The amount of radiation to cause harm to the fetus during pregnancy is thought to be 0.1 Gray.
  • If 0.1 Gray is the same as $100 of radiation then an X-ray = 1/10 of a penny of radiation, a CT PE scan = 25-50 cents of radiation, a VQ scan = 50-75 cents of radiation, and background radiation during the full pregnancy = $5 of radiation.
  • It has been shown that the amount of radiation needed to increase the risk of cancer before age 20 by 1/100 = $10 of radiation – or many, many CT’s and imaging studies.
  • CT scans irradiate both the breast tissue and the thyroid of females, which increases the lifetime risk of breast cancer by 1.5%, which is not an insignificant amount.
  • The VQ scan is the ideal test for PE during pregnancy, but the downside to a VQ scan is that the radioisotope collects in the bladder directly over uterus before it is urinated out, therefore it is not recommended in the first trimester.

Link to Podcast: http://medicalminute.madewithopinion.com/pregnancy-and-radiation/

References: https://www.thoracic.org/statements/resources/pvd/evaluation-of-suspected-pulmonary-embolism-in-pregnancy.pdf