Tag Archives: imaging

Open book fractures and ultrasound

For me, this is one of those ‘why didn’t I think of that?!’ studies… extending the FAST scan to measure pubic symphyseal widening to detect open-book pelvic fractures. A pubic symphysis width of 25 mm was considered positive; the authors state that this width is considered diagnostic for anterior-posterior compression fracture of the pelvis in the non-pregnant patient.
Since only four of the 23 patients studied had radiological widening, the authors’ conclusions make sense: Further study with a larger cohort is needed to confirm this technique’s validity for diagnosing PS widening in APC pelvic fractures.
A reasonable question might be: ‘so what?’, especially if pelvic binders are routinely applied to polytrauma patients and radiographs are rapidly obtained. However as a retrieval medicine doctor working in remote and austere environments I wonder whether this could be useful to us. Perhaps if combined with this intervention?

BACKGROUND: The focused abdominal sonography in trauma (FAST) examination is a routine component of the initial work-up of trauma patients. However, it does not identify patients with retroperitoneal hemorrhage associated with significant pelvic trauma. A wide pubic symphysis (PS) is indicative of an open book pelvic fracture and a high risk of retroperitoneal bleeding.

STUDY OBJECTIVES: We hypothesized that an ultrasound image of the PS as part of the FAST examination (FAST-PS) would be an accurate method to determine if pubic symphysis diastasis was present.

METHODS: This is a comparative study of a diagnostic test on a convenience sample of 23 trauma patients at a Level 1 Trauma Center. The PS was measured sonographically in the Emergency Department (ED) and post-mortem (PM) at the State Medical Examiner. The ultrasound (US) measurements were then compared with PS width on anterior-posterior pelvis radiograph.

RESULTS: Twenty-three trauma patients were evaluated with both plain radiographs and US (11 PM, 12 ED). Four patients had radiographic PS widening (3 PM, 1 ED) and 19 patients had radiographically normal PS width; all were correctly identified with US. US measurements were compared with plain X-ray study by Bland-Altman plot. With one exception, US measurements were within 2 standard deviations of the radiographic measurements and, therefore, have excellent agreement. The only exception was a patient with pubic symphysis wider than the US probe.

CONCLUSION: Bedside ultrasound examination may be able to identify pubic symphysis widening in trauma patients. This potentially could lead to faster application of a pelvic binder and tamponade of bleeding.

Ultrasonographic determination of pubic symphyseal widening in trauma: the FAST-PS study
J Emerg Med. 2011 May;40(5):528-33

E-FAST for pneumothorax

Some further evidence of the superiority of ultrasound over chest x-ray for the detection of pneumothorax (although it’s not perfect):

INTRODUCTION: Early identification of pneumothorax is crucial to reduce the mortality in critically injured patients. The objective of our study is to investigate the utility of surgeon performed extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax.
METHODS: We prospectively analysed 204 trauma patients in our level I trauma center over a period of 12 (06/2007-05/2008) months in whom EFAST was performed. The patients’ demographics, type of injury, clinical examination findings (decreased air entry), CXR, EFAST and CT scan findings were entered into the data base. Sensitivity, specificity, positive (PPV) and negative predictive values (NPV) were calculated.
RESULTS: Of 204 patients (mean age–43.01+/-19.5 years, sex–male 152, female 52) 21 (10.3%) patients had pneumothorax. Of 21 patients who had pneumothorax 12 were due to blunt trauma and 9 were due to penetrating trauma. The diagnosis of pneumothorax in 204 patients demonstrated the following: clinical examination was positive in 17 patients (true positive in 13/21, 62%; 4 were false positive and 8 were false negative), CXR was positive in 16 (true positive in 15/19, 79%; 1 false positive, 4 missed and 2 CXR not performed before chest tube) patients and EFAST was positive in 21 patients (20 were true positive [95.2%], 1 false positive and 1 false negative). In diagnosing pneumothorax EFAST has significantly higher sensitivity compared to the CXR (P=0.02).
CONCLUSIONS: Surgeon performed trauma room extended FAST is simple and has higher sensitivity compared to the chest X-ray and clinical examination in detecting pneumothorax.

Extended focused assessment with sonography for trauma (EFAST) in the diagnosis of pneumothorax: experience at a community based level I trauma center
Injury. 2011 May;42(5):511-4

UK Radiology guidelines for trauma

The Royal College of Radiologists in the UK has published a guideline document to set standards related to diagnostic and interventional radiology for use by major trauma centres (MTCs) and trauma units (TUs). The standards are:

  1. The trauma team leader is in overall charge in acute care
  2. Protocol-driven imaging and intervention must be available and delivered by experienced staff. Acute care for SIPs must be consultant delivered
  3. MDCT should be adjacent to, or in, the emergency room
  4. Digital radiography must be available in the emergency room
  5. If there is an early decision to request MDCT, FAST and DR should not cause any delay
  6. MRI must be available with safe access for the SIP
  7. A CT request in the trauma setting should comply with the Ionising Radiation (Medical Exposure) Regulations 2000 (IR(ME)R) justification regulations like any other request for imaging involving ionising radiation
  8. There should be clear written protocols for MDCT preparation and transfer to the scan room
  9. Whole-body contrast-enhanced MDCT is the default imaging procedure of choice in the SIP. Imaging protocols should be clearly defined and uniform across a regional trauma network
  10. Future planning and design of emergency rooms should concentrate on increasing the numbers of SIPs stable enough for MDCT and intervention
  11. The primary survey report should be issued immediately to the trauma team leader
  12. On-call consultant radiologists should provide the final report on the SIP within one hour of MDCT image acquisition
  13. On-call consultant radiologists must have teleradiology facilities at home that allow accurate reports to be issued within one hour of MDCT image acquisition
  14. IR facilities should be co-located to the emergency department
  15. Angiographic facilities and endovascular theatres in MTCs should be safe environments for SIPs and should be of theatre standard
  16. Agreed written transfer protocols between the emergency department and imaging/interventional facilities internally or externally must be available
  17. IR trauma teams should be in place within 60 minutes of the patient’s admission or 30 minutes of referral
  18. Any deficiency in consumable equipment should be reported at the debriefing and be the subject of an incident report

Some interesting snippets include:
IV access
Right antecubital access is preferred for contrast administration (left-sided injections compromise interpretation of mediastinal vasculature). However, if arm vein access is not possible and a central line is in situ, it should be of a type that can accept 4 ml contrast/ second via a power injector. This might require local negotiation with emergency department doctors beforehand

Pelvic fracture
If a pelvic fracture is suspected, a temporary pelvic stabilisation (wrap, binder and so on) should be applied before MDCT.
Limb fractures
Rapid immobilisation such as air splints. Only immediately limb conserving manipulations/splinting should be performed prior to CT.
Urinary catheter
All significantly injured patients without obvious contraindications should be catheterised unless this would delay transfer to CT. The catheter should be clamped prior to MDCT.
Standards of practice and guidance for trauma radiology in severely injured patients
Royal College of Radiologists – Full Text Link

FAST in kids has low sensitivity

The abstract says it all – don’t use FAST to rule out significant abdominal free fluid in kids with blunt abdominal trauma. Fine as a rule-in test (for free fluid) though.

Objectives:  Focused assessment of sonography in trauma (FAST) has been shown useful to detect clinically significant hemoperitoneum in adults, but not in children. The objectives were to determine test characteristics for clinically important intraperitoneal free fluid (FF) in pediatric blunt abdominal trauma (BAT) using computed tomography (CT) or surgery as criterion reference and, second, to determine the test characteristics of FAST to detect any amount of intraperitoneal FF as detected by CT.

Methods:  This was a prospective observational study of consecutive children (0–17 years) who required trauma team activation for BAT and received either CT or laparotomy between 2004 and 2007. Experienced physicians performed and interpreted FAST. Clinically important FF was defined as moderate or greater amount of intraperitoneal FF per the radiologist CT report or surgery.

Results:  The study enrolled 431 patients, excluded 74, and analyzed data on 357. For the first objective, 23 patients had significant hemoperitoneum (22 on CT and one at surgery). Twelve of the 23 had true-positive FAST (sensitivity = 52%; 95% confidence interval [CI] = 31% to 73%). FAST was true negative in 321 of 334 (specificity = 96%; 95% CI = 93% to 98%). Twelve of 25 patients with positive FAST had significant FF on CT (positive predictive value [PPV] = 48%; 95% CI = 28% to 69%). Of 332 patients with negative FAST, 321 had no significant fluid on CT (negative predictive value [NPV] = 97%; 95% CI = 94% to 98%). Positive likelihood ratio (LR) for FF was 13.4 (95% CI = 6.9 to 26.0) while the negative LR was 0.50 (95% CI = 0.32 to 0.76). Accuracy was 93% (333 of 357, 95% CI = 90% to 96%). For the second objective, test characteristics were as follows: sensitivity = 20% (95% CI = 13% to 30%), specificity = 98% (95% CI = 95% to 99%), PPV = 76% (95% CI = 54% to 90%), NPV = 78% (95% CI = 73% to 82%), positive LR = 9.0 (95% CI = 3.7 to 21.8), negative LR = 0.81 (95% CI = 0.7 to 0.9), and accuracy = 78% (277 of 357, 95% CI = 73% to 82%).

Conclusion:  In this population of children with BAT, FAST has a low sensitivity for clinically important FF but has high specificity. A positive FAST suggests hemoperitoneum and abdominal injury, while a negative FAST aids little in decision-making

Test characteristics of focused assessment of sonography for trauma for clinically significant abdominal free fluid in pediatric blunt abdominal trauma
Acad Emerg Med. 2011 May;18(5):477-82

Whole body CT in trauma

German trauma patients are more likely to survive if they have a whole body CT rather than selective scans. Or that’s what this paper would have you believe IF you’re happy with the retrospective comparison, multivariate adjustments, and potential confounders. Still, if it helps you get your radiologists to play ball, the reference is…
Effect of whole-body CT during trauma resuscitation on survival: a retrospective, multicentre study
Lancet. 2009 Apr 25;373(9673):1455-61