title: Occult pneumothoraces in patients with penetrating trauma: Does mechanism matter?
abstract: BACKGROUND
  Supine anteroposterior (AP) chest radiography is an insensitive test for detecting posttraumatic pneumothoraces (PTXs). Computed tomography (CT) often identifies occult pneumothoraces (OPTXs) not diagnosed by chest radiography. All previous literature describes the epidemiology of OPTX in patients with blunt polytrauma. Our goal was to identify the frequency of OPTXs in patients with penetrating trauma.
  
  
  METHODS
  All patients with penetrating trauma admitted over a 10-year period to Grady Memorial Hospital with a PTX were identified. We reviewed patients' thoracoabdominal CT scans and corresponding chest radiographs.
  
  
  RESULTS
  Records for 1121 (20%) patients with a PTX (penetrating mechanism) were audited; CT imaging was available for 146 (13%) patients. Of these, 127 (87%) had undergone upright chest radiography. The remainder (19 patients) had a supine AP chest radiograph. Fifteen (79%) of the PTXs detected on supine AP chest radiographs were occult. Only 10 (8%) were occult when an upright chest radiograph was used (p < 0.001). Posttraumatic PTXs were occult on chest radiographs in 17% (25/146) of patients. Fourteen (56%) patients with OPTXs underwent tube thoracostomy, compared with 95% (115/121) of patients with overt PTXs (p < 0.001).
  
  
  CONCLUSIONS
  Up to 17% of all PTXs in patients injured by penetrating mechanisms will be missed by standard trauma chest radiographs. This increases to nearly 80% with supine AP chest radiographs. Upright chest radiography detects 92% of all PTXs and is available to most patients without spinal trauma. The frequency of tube thoracostomy use in patients with overt PTXs is significantly higher than for OPTXs in blunt and penetrating trauma.
authors.affiliation: Department of Surgery, Grady Memorial Hospital, Emory University, Atlanta, Ga., USA. ball.chad@gmail.com
authors.forename: Chad G
authors.initials: CG
authors.lastname: Ball
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Dente
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Kirkpatrick
authors.forename: Amit D
authors.initials: AD
authors.lastname: Shah
authors.forename: Ravi R
authors.initials: RR
authors.lastname: Rajani
authors.forename: Amy D
authors.initials: AD
authors.lastname: Wyrzykowski
authors.forename: Gary A
authors.initials: GA
authors.lastname: Vercruysse
authors.forename: Grace S
authors.initials: GS
authors.lastname: Rozycki
authors.forename: Jeffrey M
authors.initials: JM
authors.lastname: Nicholas
authors.forename: Jeffrey P
authors.initials: JP
authors.lastname: Salomone
authors.forename: David V
authors.initials: DV
authors.lastname: Feliciano
mesh_terms: D000328:Adult; D015505:Chest Tubes; D004322:Drainage / Q000295:instrumentation*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D011030:Pneumothorax / Q000000981:diagnostic imaging / Q000209:etiology* / Q000601:surgery; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D013898:Thoracic Injuries / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery; D013907:Thoracostomy / Q000379:methods*; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014950:Wounds, Penetrating / Q000150:complications* / Q000000981:diagnostic imaging / Q000601:surgery