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Is CT thorax necessary to exclude significant injury in paediatric patients with blunt chest trauma?

Three Part Question

In [paediatric patients with blunt chest trauma] is [CT thorax] necessary to [exclude significant injury]?

Clinical Scenario

A 6-year-old child was brought to hospital as a major trauma having been hit by a reversing car. The actual incident was not witnessed but the tyre tracks across the child's chest and the petechiae on his face and neck give credence to the theory that the car rolled over him. The child has an obvious head injury with a history of a period of consciousness but is haemodynamically stable. After immediate assessment and initial resuscitation you discuss the appropriate imaging with the radiologist. The radiologist agrees to perform a CT of the child's head and neck but declines to do a CT of the child's thorax. He quotes the Royal College of Radiology guidelines that state that for children who have suffered major trauma, CT scans of the thorax are not indicated for the haemodynamically stable child with a normal CXR (https://www.rcr.ac.uk/sites/default/files/publication/BFCR%2814%298_paeds_trauma.pdf). The child subsequently has a normal looking CXR and so you admit him for a period of observation while wondering if a plain film has the sensitivity to rule out significant injury.

Search Strategy

Medline 1946 to April 2015 using the OVID interface.

[exp Thoracic Cavity/ OR exp Thoracic Injuries/ or thoracic.mp. OR exp Radiography, Thoracic/ OR exp Thoracic Vertebrae/ OR exp Thoracic Wall] AND [trauma.mp. or exp “Wounds and Injuries"/] AND [blunt.mp] AND [exp Tomography, X-Ray Computed/ OR computed tomography.mp. OR ct.mp] limit to English language and humans and “all child (0 to 18 years).”

Embase 1988 to 2015 Week 17.

[ct scan.mp. OR exp computer assisted tomography] AND [blunt.mp] AND [thoracic.mp OR chest.mp. OR exp thorax] limited to human, English language and child .

Search Outcome

Two hundred and thirty-seven papers were identified by the Medline search and 116 by the Embase search. No papers were found that directly answered the three-part question but 13 papers were considered relevant to the issues raised.

Relevant Paper(s)

Author, date and country Patient group Study type (level of evidence) Outcomes Key results Study Weaknesses
Manson et al,
1993
Canada		44 children who had CT scan thorax for blunt trauma over 10y period. CXR reviewed prior to CT by radiologists blinded to clinical history and outcomes. Retrospective reviewDetection of thoracic injury.16 children had pneumothoraces, 10 not visible on CXR. 1 aortic injury with widened mediastinum on CXR. 1 tracheal tear with pneumo-mediastinum. 1 pt had tumour, thought to be pulmonary contusion on CXR.Small number of patients.
Sivit et al,
1989
USA		512 pts < 17y with CT scan after blunt abdominal trauma and haemo-dynamic stability presenting between Jan 1983 and July 1988.Retrospective reviewDetection of thoracic injury.170 abnormalities found on CT in 77 patients. 62 had major injuries. CXR underestimated or missed 64 of the 170 abnormalities. Retrospective.
Demetriades et al,
1998
USA		112 patients with blunt deceleration trauma presenting to centre from Oct 1996 to Oct 1999.Prospective observational study.Presence of aortic injury. 9 pts had aortic injury on CT. 42 pts had widened mediastinum on CXR (incl. 5 with aortic injury). 9 had spinal fracture. All detected by CT scan. Small study from single centre.
Lowe et al,
1998
USA		Paediatric trauma patients between 1987 – April 1996 with final diagnosis of aortic injuryRetrospective review. Radiological detection of aortic injury. 7 children identified out of 10,886 patients. All had CXR, 1 unreadable, 1 normal, 3 widened mediastinum, 4 apical capping. CT scans all showed aortic injury.Only looking at patients with positive diagnosis of aortic injury.
Wolfman et al,
1998
USA		664 patients with trauma between August 1991 and July 1992 undergoing CXR and abdominal CT. Retrospective reviewPresence of an ‘occult’ pneumothorax, i.e. visible on CT but not CXR86 pneumothoraces in 70 pts. 44 occult in 36 pts. 17 drained immediately, further 3 required drain insertion due to clinical deterioration.Retrospective. Only reviewed patients with pneumothorax on CT.
Holmes et al,
2001
USA		538 children under 16y undergoing abdominal CT plus chest x-ray after blunt trauma. Blinded radiological report of CXRs where CT showed pneumothorax plus control CXRs. Prospective observational studyPresence of pneumothorax. 25 pneumothoraces present in 20 patients. In 11 patients not visible on CXR. 1 of these patients required chest drain. Only looking at presence of pneumothorax.
Hammad et al,
2009
Saudi Arabia		443 patients undergoing CT scan for blunt thoracic trauma between June 2004 and May 2006.Prospective observational studyPresence of thoracic injury276 had injury on seen on CXR, 412 on CT scan. Of 167 patients with no injury on CXR, 136 had injury seen on CT. CT significantly better at finding pneumothorax, haemothorax, lung contusions, mediastinal emphysema and sternal fractures. 92 patients had clinical management changed on basis of CT scan.
Markel et al,
2009
USA		Pts at level 1 trauma centre undergoing CT scan for blunt trauma. 333 out of 3842 trauma patients. Retrospective reviewDetection of thoracic injury.65 patients had injury found. 42 patients had CXR first, new or additional information found in 30. Only 2 had management changed by CT finding. 6 other patients had interventions, 3 had abnormal CXR, 3 didn’t have CXR.False positive rate for CXR unknown. Small number of patients.
Pabon-Ramos et al,
2010
USA		Paediatric pts with blunt aortic injury 1986 – 2007. CT scans and CXR reviewed in non-blinded fashion. Retrospective reviewDetection of thoracic injury.17 had aortic injury. 11/17 had widened mediastinum, 16/17 had either prominent or indistinct aortic knob.Not blinded. Small numbers.
Holscher et al,
2013
USA		Paediatric trauma pts presenting between Jan 2006 and Dec 2011 who underwent CT chest. 57 pts included. 55/57 also had CXR. Retrospective record reviewPresence of spinal and /or thoracic injuries 82.46% of pts had abnormality on CT; 41.8% had abnormality identified on CXR. 4 pts had spinal fractures on CT not seen on CXR. 7/57 children required intervention for pneumothorax, visible on CXR in 4 cases. Further 12 pts had pneumothorax on CT but no intervention. Retrospective. Small numbers.
Dabees et al
2014
Egypt		30 pts with blunt chest trauma. Prospective observational study.Detection of thoracic injuries26 injuries detected on CT, 17 seen on CXR. CT had significantly higher sensitivity for the detection of chest wall injuries, pleural injuries, parenchymal injuries and mediastinal injuries. 5 vertebral injuries were found with CT of which 1 was visible on CXR but this did not reach statistical significance. Small study from single centre.
Rodriguez et al,
2014
USA		9,905 pts >14y undergoing chest imaging after blunt trauma at 9 trauma centres between Dec 2009 and Jan 2013. 55.4% had CXR only, 42.0% had CXR and CT, 2.6% had CT onlyRetrospective reviewDetection of thoracic injury8.4% pts had injury seen on CXR, 28.8% injury on CT. 15% of pts with CT after normal CXR had injury seen. 1.5% of pts with normal CXR had injury of major clinical significance.Retrospective. Excluded most children.
Hershkovitz et al,
Israel
2014		42 patients with blunt trauma who underwent CT chest and abdomen. Neurologically intact and haemo-dynamically stable with no signs of injury. Prospective observational study.Presence of thoracic injury. 2 pts had lung contusions, 1 rib fracture, 1 pneumothorax, 1 splenic laceration and 1 liver laceration found 2 pts had change in management in that moved to ITU but no pts had surgical intervention.Small study at single centre.

Comment(s)

It is clear that CT scans are more sensitive than plain CXRs for the detection of thoracic injuries; a more difficult question is whether this additional information is clinically important. The risks of missing a significant injury have to be balanced against the risks of the diagnostic procedure.

CT scans involve exposure to ionising radiation causing an estimated life-time risk of fatal cancer of around one in 2500.1 This risk is likely to be higher in children though should be balanced against the estimate that 50% of people born after 1960 in the UK will develop cancer at some point in their lifetime and that 50% of these will be fatal.2 This would mean that a CT thorax would increase an individual's life-time risk of fatal cancer from around 25% to 25.04%. There is also an additional cost of CT compared with plain X-ray although this is may be offset by the ability to discharge patients earlier if the clinician can be confident that significant injuries have been ruled out.

So, what is the risk of a significant injury in a child who has been subjected to trauma but is haemodynamically stable and has a normal CXR? Unfortunately, no individual study provides that answer. Rodriguez et al13 performed the largest retrospective study and found injuries with major significance in 1.5% of the patients with normal CXRs. These injuries were potentially life-threatening and required surgical intervention but it is not known if these patients were haemodynamically stable. Hershkovitz et al6 looked at haemodynamically stable patients who were neurologically intact and had no evidence of chest or abdominal injury and still found one out of the 42 patients had a pneumothorax among other injuries. These patients did not, however, have CXRs performed.

The derivation of a clinical decision rule requires some extrapolation and interpretation of the available evidence. Evidence exists to show that a paediatric patient who has been subject to blunt chest trauma may have clinically important injuries without these being clinically apparent. Evidence also exists to show that CT scans of the thorax have significantly greater sensitivity than plain films in detecting all forms of thoracic injury. Although there is heterogeneity in the published evidence, the overall incidence of injuries requiring intervention would appear to be high enough to outweigh the risks of the radiation exposure particularly in patients where there is a significant degree of suspicion.

Editor Comment

CT – Computed tomography CXR – Chest x-ray Pts - Patients

Clinical Bottom Line

CT scans of the thorax in patients who have presented after trauma find clinically significant injuries that are not clinically apparent and may not show up on a CXR. In paediatric patients with a history of a significant mechanism of trauma and clinical signs of chest injury, a CT scan of the chest would be warranted.

References

  1. Manson D, Babyn PS, Palder S et al. CT of blunt chest trauma in children. Pediatric radiology 1993 23(1), pp.1–5.
  2. Sivit CJ, Taylor GA, Eichelberger MR. Chest injury in children with blunt abdominal trauma: evaluation with CT. Radiology 1989 171(3), pp.815–818.
  3. Demetriades D, Gomez H, Velmahos GC et al. Routine Helical Computed Tomographic Evaluation of the Mediastinum in High-Risk Blunt Trauma Patients. Archives of Surgery 1998 133(10), pp.1084–7.
  4. Lowe LH, Bulas DI, Eichelberger MD et al. Traumatic aortic injuries in children: radiologic evaluation. American Journal of Roentgenology 1998 170(1), pp.39–42.
  5. Wolfman NT, Myers WS, Glauser SJ. Validity of CT classification on management of occult pneumothorax: a prospective study. American Journal of Radiology 1998 171(5):1317-20.
  6. Holmes JF, Brant WE, Bogren HG et al. Prevalence and importance of pneumothoraces visualized on abdominal computed tomographic scan in children with blunt trauma. The Journal of Trauma: Injury, Infection, and Critical Care 2001 50(3), pp.516–520.
  7. Hammad AM, Regal MA. Is Routine Spiral CT-Chest Justified in Evaluation of the Major Blunt Trauma Patients? European Journal of Trauma and Emergency Surgery 2009 35; 31-34.
  8. Markel TA, Kumar R, Koontz NA et al. The Utility of Computed Tomography as a Screening Tool for the Evaluation of Pediatric Blunt Chest Trauma. The Journal of Trauma: Injury, Infection, and Critical Care, 2009 67(1), pp.23–28
  9. Pabon-Ramos WM, Williams DM, Strouse PJ. Radiologic Evaluation of Blunt Thoracic Aortic Injury in Pediatric Patients. American Journal of Roentgenology 2010 194(5); 1197–1203.
  10. Holscher CM, Faulk LW, Moore EE et al. Chest computed tomography imaging for blunt pediatric trauma: not worth the radiation risk. Journal of Surgical Research 2013 184(1), pp.352–357.
  11. Dabees NL, Salama AA, Elhamid SA et al. Multi-detector computed tomography imaging of blunt chest trauma. The Egyptian Journal of Radiology and Nuclear Medicine, 2014 45(4), pp.1105–1113.
  12. Rodriguez RM, Baumann BM, Raja AS et al. Diagnostic Yields, Charges, and Radiation Dose of Chest Imaging in Blunt Trauma Evaluations Academic Emergency Medicine 2014;21(6):644-50.
  13. Cancer Research UK [Online] Lifetime risk of cancer http://www.cancerresearchuk.org/health-professional/cancer-statistics/risk/lifetime-risk (Accessed 26/06/2015)
  14. Hershkovitz Y, Zoarets I, Stepansky A et al. Computed tomography is not justified in every pediatric blunt trauma patient with a suspicious mechanism of injury. American Journal of Emergency Medicine 2014 32(7):697-9.
  15. Public Health England [Online] Patient dose information:guidance. 04 Sept 2008 (Accessed 26th June 2015) https://www.gov.uk/government/publications/medical-radiation-patient-doses/patient-dose-information-