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INTRODUCTION

eFAST: extended Focussed Assessment with Sonography in trauma is the sonographic evaluation of the chest and abdomen for pneumothorax, haemothorax, pericardial effusion and intraperitoneal free fluid. As you become more proficient with US, you can also look for pulmonary contusions, aspiration, aortic dissection, intraperitoneal free gas and retroperitoneal fluid.

eFAST is not exclusive to the trauma patient. You can also use these skills to assess the suspected ectopic pregnancy patient, the elderly patient with a low fall and when looking for ascites in liver and right heart failure.

CHEST US VS SUPINE CXR IN TRAUMA

eFAST is highly sensitive and specific for pneumothorax and haemothorax, surpassing the supine CXR (1,2,3,4). US is the investigation of choice for these injuries. There was one recent study (5) which showed that chest US is inferior to supine CXR for traumatic injuries. However, the US was performed by sonographers and read by radiologists. Both of these craft groups have little experience with lung US, whereas emergency physicians have been learning this for the last 20 years!

Except for assessing for a widened mediastinum and the presence of a flail segment (which can be done clinically), there is usually no role for the supine CXR in the initial assessment of the trauma patient when emergency or trauma doctors proficient at eFAST are available (6,7). In a retrospective study, Spering et al (8) showed that mediastinal widening on supine CXR lacks the accuracy to diagnose aortic injury.

US is more accurate than supine CXR for pneumothorax and haemothorax

From Spering et al (5): No significant difference in mediastinal diameter at either the aortic arch or valve level in patients with mediastinal vanscular injury and control patients with no injury

Similarly Vasileiou et al (9) showed that a widened mediastinum had a PPV <1% for aortic injury in 502 trauma patients. On the other hand, without performing a bedside echo and supraclavicular views, a supine CXR is probably the easiest bedside study to exclude a widened mediastinum. So if you are very worried about aortic injury in the unstable patient: go on, do the supine CXR, otherwise just go with US and wait for the CT angiogram which will be much more accurate.

Tailor the eFAST to the mechanism and haemodynamic status

The way you use in eFAST in the injured patient will depend on the mechanism of injury and the patient's haemodynamic status.

LOW MECHANISM OF INJURY - STABLE PATIENT

Many doctors forgo eFAST in these patients because of the low sensitivity of US to detect free intraperitoneal fluid in the normotensive trauma patient quoted in the literature (10,11,12). With a reported sensitivity to detect free fluid in the stable patient as low as 22% (13, 14) US is a RULE IN test only. This is because in the stable patient, the intraperitoneal fluid is likely to be <500ml. Branney et al (15) showed that a median volume of 619ml was required for more that 90% sensitivity. But this does not mean that it isn't useful. I use eFAST in these patients as a risk stratification tool, If I detect pathology on the bedside US, I will expedite or organise further imaging, I will admit the patient to trauma rather than short stay and I will monitor them more closely.

Further, it is these patients you should eFAST to improve your skills. Without the urgency of an unstable patient, you can really improve your technique. Studies show that accuracy increases with greater experience (16).

HIGH MECHANISM OF INJURY - STABLE PATIENT

These patients are going to have a pan scan anyway, however, the eFAST will enable a more accurate assessment of chest injuries than CXR, risk stratification and prioritisation in the case of multiple patients and initiation of targeted management at the bedside prior to CT. For instance, if you see retroperitoneal bleeding you may alert interventional radiology.

HIGH MECHANISM OF INJURY - UNSTABLE PATIENT

In the crashing patient, do not perform chest US: you will just get in the way of the proceduralist who is doing the thoracostomy. Opening the pleural cavity is the priority.

I would start with the subxyphoid view looking for an empty heart (control haemorrhage and push blood products) and a pericardial effusion (initiate ED thoracotomy, alert cardiothoracics).

Following this, look for intraperitoneal free fluid (trauma opstat).

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A complete EFAST

REFERENCES

1. Wilkerson RG, Stone MB. Sensitivity of bedside ultrasound and supine anteroposterior chest radiographs for the identification of pneumothorax after blunt trauma. Acad Emerg Med. 2010 Jan;17(1):11-7

2. Staub LJ, Biscaro RRM, Kaszubowski E, Maurici R. Chest ultrasonography for the emergency diagnosis of traumatic pneumothorax and haemothorax: A systematic review and meta-analysis. Injury. 2018 Mar;49(3):457-466

3. Tian H, Zhang T, Zhou Y, Rastogi S, Choudhury R, Iqbal J. Role of emergency chest ultrasound in traumatic pneumothorax. An updated meta-analysis. Med Ultrason. 2023 Mar 30;25(1):66-71

4.Alrajab S, Youssef AM, Akkus NI, Caldito G. Pleural ultrasonography versus chest radiography for the diagnosis of pneumothorax: review of the literature and meta-analysis. Crit Care. 2013 Sep 23;17(5):R208

5. Santorelli JE, Chau H, Godat L, Casola G, Doucet JJ, Costantini TW. Not so FAST-Chest ultrasound underdiagnoses traumatic pneumothorax. J Trauma Acute Care Surg. 2022 Jan 1;92(1):44-48

6. Lokuge A. Should we ditch the supine chest X ray in early trauma assessment? Australas J Ultrasound Med. 2019 Jun 19;22(4):245-247.

7. Wisbach GG, Sise MJ, Sack DI, Swanson SM, Sundquist SM, Paci GM, Kingdon KM, Kaminski SS. What is the role of chest X-ray in the initial assessment of stable trauma patients? J Trauma. 2007 Jan;62(1):74-8

8. Spering C, Brauns SD, Lefering R, Bouillon B, Dobroniak CC, Füzesi L, Seitz MT, Jaeckle K, Dresing K, Lehmann W, Frosch S. Diagnostic value of chest radiography in the early management of severely injured patients with mediastinal vascular injury. Eur J Trauma Emerg Surg. 2022 Oct;48(5):4223-4231

9. Vasileiou G, Qian S, Al-Ghamdi H, Pace D, Rattan R, Mulder M, Namias N, Dante Yeh D. Blunt Trauma: What Is Behind the Widened Mediastinum on Chest X-Ray (CXR)? J Surg Res. 2019 Nov;243:23-26

10. Miller MT, Pasquale MD, Bromberg WJ, Wasser TE, Cox J. Not so FAST. J Trauma. 2003 Jan;54(1):52-9; discussion 59-60.

11. Stengel D, Leisterer J, Ferrada P, Ekkernkamp A, Mutze S, Hoenning A. Point-of-care ultrasonography for diagnosing thoracoabdominal injuries in patients with blunt trauma. Cochrane Database Syst Rev. 2018 Dec 12;12(12)

12. Smith J. Focused assessment with sonography in trauma (FAST): should its role be reconsidered? Postgrad Med J. 2010 May;86(1015):285-91

13. Carter JW, Falco MH, Chopko MS, Flynn WJ Jr, Wiles Iii CE, Guo WA. Do we really rely on fast for decision-making in the management of blunt abdominal trauma? Injury. 2015 May;46(5):817-21

14.Kornezos I, Chatziioannou A, Kokkonouzis I, et al. Findings and limitations of focused ultrasound as a possible screening test in stable adult patients with blunt abdominal trauma: a Greek study. Eur Radiol2010;20(1):234–238

15. Branney SW, Wolfe RE, Moore EE, Albert NP, Heinig M, Mestek M, Eule J. Quantitative sensitivity of ultrasound in detecting free intraperitoneal fluid. J Trauma. 1995 Aug;39(2):375-80.