UMA DAMLE, PGY1 ARTICLE REVIEW: COMPARISON OF FOUR VIEWS TO SINGLE VIEW ULTRASOUND PROTOCOLS TO IDENTIFY CLINICALLY SIGNIFICANT PNEUMOTHORAX

Article e-published in Academic Emergency Medicine in July 2016

BACKGROUND Argument for 1 view Trauma patients generally brought to ED supine and with time in this position, air should collect in the anterior (least dependent) portion of the chest, therefore 1 view in the anterior chest should be able to identify these PTX Argument for 4 views If there are smaller or loculated PTX, 4 views moving laterally to more dependent areas would keep us from missing them and increase sensitivity Also may be able to quantify size of PTX

METHODS Randomized, prospective study on adult trauma patients (meeting state trauma criteria), performed at urban academic ED in a level 1 trauma center US performed by PGY2, 3, & attendings who had performed 25 FAST and 25 chest wall exams reviewed by US faculty Interpreter blinded to chest x-ray result if performed prior to US US & radiology images reviewed again by blinded study author Convenience sample

METHODS Inclusion >18yo Acute traumatic injury going to undergo a chest CT Exclusion Too unstable, requiring care preventing US from being performed, chest tube prior to arrival, pregnant, prisoners Single view longitudinal, midclavicular, 3rd intercostal space 4 views 1 st same as single view, 3 with probe moving inferiorly & laterally

OUTCOME MEASURES Clinically significant = requiring chest tube Clinically insignificant = radiologist’s CT read: “Thin collection of air up to 1cm thick in the greatest slice” or “Seen in fewer than 5 contiguous slices” US +/- based on presence of lung sliding Reference standard = diagnosis PTX on CT chest

ANALYSIS Non-inferiority power calculation To show that a new treatment or exam is not worse than an existing one

RESULTS 50 (36) 32 (26)

RESULTS Large range for confidence intervals

RESULTS: NEEDLE DECOMPRESSION

LIMITATIONS Possibly because they used “tiny apical” PTX within their definition of PTX, sensitivity may have been lower overall and resulted in wider confidence interval Being a convenience sample, may have some selection bias Operator error less likely due to level of experience of examiners

LIMITATIONS May be different in trauma patients transported upright/semi recumbent with PTX positioned differently in chest Difficult to blind a practitioner to chest x-ray result & general clinical presentation in trauma bay The 4 views we use are different from the ones used here vs

DISCUSSION No significant difference between the two exams Both similar in Sensitive for clinically significant PTX Decreased sensitivity for smaller insignificant PTX Both better than chest x-ray Noted that their sensitivity was at low end of other published work, but similar Needle decompression may approximate parietal & visceral pleura focally leading to false negative These patients may benefit from multiple views over single

CONCLUSION As the sensitivity for PTX diagnosis was equivalent with both exams, the consideration of additional time taken for 8 views vs 2 (when examining both lungs) in trauma patients may be the distinguishing factor between these methods.

REFERENCES Helland G, Gaspari R, Licciardo S, Sanseverino A, Torres U, Emhoff T, Blehar D. “Comparison of Four Views to Single View Ultrasound Protocols to Identify Clinically Significant Pneumothorax”. Acad Emerg Med Jul 18 ultrasound-pocus/