Ojaghi 2014.

Study characteristics
Patient sampling	Prospective study
Patient characteristics and setting	Study location: Iran Study period: winter of 2013 Care setting: emergency department of a hospital Mass casualty: no Participants enrolled: 163 Participants included in analysis: 150: 124 men and 26 women Age: not reported Type of injury: multiple trauma, chest trauma Injury severity: ESI1 and ESI2 Haemodynamic stability: not reported Inclusion criteria: patients with severe multiple trauma based on the mechanism of injury, or their history and examination findings of suspected chest injuries, and chest CT scan according to an ATLS algorithm. The mechanisms of injury included: car rollover, being thrown out of the vehicle, frontal impact, compression of the chest with the steering wheel or dashboard, severe side impact, fall, or acceleration/deceleration injury. Exclusion criteria: those who underwent a tube thoracostomy before US due to their unstable clinical situation or for any other reason, such as a lack of access to US at the time of admission
Index tests	Index test: FAST US protocol: participants were evaluated according to the ATLS algorithm, and examination findings were recorded following initial evaluations, an emergency medicine specialist performed chest US to detect pneumothorax and haemothorax. Hardware used: General Electric E200 US with 2 types of probes, namely: a curve probe of 5‐MHz frequency for haemothorax assessment and a linear probe of 6.5‐ to 9‐MHz frequency for pneumothorax assessment Description of imaging technique: US images of the lung are built with air artefacts as the air stops the beam, however this artefact varies when it is in the pleural space. In a normal lung view, pleural movement along the parietal and visceral sides is called lung sliding, which can easily be seen with US. This characteristic is also known as the gliding sign. Moreover, sharp resonance appears during ventilation at the border of the pleura and lung, known as a comet‐tail artefact. Trapped air in the pleural space prevents visualisation of lung sliding signs and comet‐tail artefacts, therefore, based on these findings, pneumothorax can be detected with US. US permits the detection of amounts of loculated pleural fluid as small as 20 mL, which cannot be identified by X‐rays, which are only capable of detecting volumes > 50 mL.
Target condition and reference standard(s)	Target condition: free fluid and air Reference standard: CT (technique specification not reported), CXR Description of technique: assigned radiologists reported both CT scan and portable CXR results, while a specialist performed US. These 2 groups of examiners were unaware of each other’s results. No further specifications of technique were reported.
Flow and timing	Time between US and reference standard: not reported
Comparative
Notes
Methodological quality
Item	Authors' judgement	Risk of bias	Applicability concerns
DOMAIN 1: Patient Selection
Was a consecutive or random sample of patients enrolled?	No
Did the study avoid inappropriate exclusions?	No
		High	Low
DOMAIN 2: Index Test All tests
Were the index test results interpreted without knowledge of the results of the reference standard?	Yes
If a threshold was used, was it pre‐specified?	Yes
Was the qualification of the US operator appropriate?	Yes
Was the US hardware (i.e. generation, manufacturer, probe, etc.) up to date?	Yes
Was the US protocol (i.e. 'classic' FAST) appropriate?	Yes
Are there concerns that the definition or performance of the index test (i.e. POC US of trauma) do not match generally accepted, established, or practiced rules or recommendations?	No
		Low	Low
DOMAIN 3: Reference Standard
Is the reference standards likely to correctly classify the target condition?	Yes
Were the reference standard results interpreted without knowledge of the results of the index tests?	Yes
Was the qualification of the doctors (i.e. radiologists, surgeons, etc.) determining the reference standard appropriate?	Yes
Was the reference imaging standard (i.e. MDCT‐rows (4 to ≥ 256 slices), contrast‐imaging, etc.) up to date?	Unclear
Are there concerns that the definition or performance of the reference tests (e.g. CT, MRI, laparatomy, thoracotomy, autopsy, etc.) do not match generally accepted, established, or practiced rules or recommendations?	No
		Low	Low
DOMAIN 4: Flow and Timing
Was there an appropriate interval between index test and reference standard?	Yes
Did all patients receive the same reference standard?	Yes
Were all patients included in the analysis?	Yes
Did all participants receive a reference standard? (Risk of partial verification bias)	Yes
		Low