title: Incidence, risk factors, and outcomes for occult pneumothoraces in victims of major trauma.
abstract: BACKGROUND
  The supine anteroposterior chest radiograph (CXR) is an insensitive test for posttraumatic pneumothoraces (PTXs). Computed tomographic (CT) scanning often detects PTXs that were not diagnosed on CXR (occult PTXs [OPTXs]). The purpose of this study was to define the incidence, predictors, and outcomes for OPTXs after trauma.
  
  
  METHODS
  Thoracoabdominal CT scans and corresponding CXRs of all trauma patients entered into a regional database were reviewed. Patients with OPTXs were compared with those with overt, residual, and no PTXs regarding incidence, demographics, associated injuries, early resuscitative predictors, treatment, and outcomes.
  
  
  RESULTS
  Paired CXRs and CT scans were available for 338 of 761 (44%) patients (98.5% blunt trauma). One hundred three PTXs were present in 89 patients, 57 (55%) of which were occult; 6 (11%) were seen only on thoracic CT scan. Age, sex, length of stay, and survival were similar between all groups. OPTXs and PTXs were similar in comparative size index and number of images. Subcutaneous emphysema, pulmonary contusion, rib fracture(s), and female sex were independent predictors of OPTXs. Seventeen (35%) patients with OPTXs were ventilated, of whom 13 (76%) underwent thoracostomy. No complications resulted from observation, although 23% of patients with thoracostomy had tube-related complications or required repositioning.
  
  
  CONCLUSIONS
  OPTXs are commonly missed both by CXR and even abdominal CT scanning in seriously injured patients. Basic markers available early in resuscitation are highly predictive for OPTXs and may guide management before CT scanning. Further study of OPTX detection and management is required.
authors.affiliation: Department of Surgery, Foothills Medical Centre, Calgary, Alberta, Canada.
authors.forename: Chad G
authors.initials: CG
authors.lastname: Ball
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Kirkpatrick
authors.forename: Kevin B
authors.initials: KB
authors.lastname: Laupland
authors.forename: Daniel I
authors.initials: DI
authors.lastname: Fox
authors.forename: Savvas
authors.initials: S
authors.lastname: Nicolaou
authors.forename: Ian B
authors.initials: IB
authors.lastname: Anderson
authors.forename: S Morad
authors.initials: SM
authors.lastname: Hameed
authors.forename: John B
authors.initials: JB
authors.lastname: Kortbeek
authors.forename: Robert R
authors.initials: RR
authors.lastname: Mulloy
authors.forename: Stacey
authors.initials: S
authors.lastname: Litvinchuk
authors.forename: Bernard R
authors.initials: BR
authors.lastname: Boulanger
mesh_terms: D000328:Adult; D005260:Female; D006801:Humans; D015994:Incidence; D015601:Injury Severity Score; D007902:Length of Stay; D008297:Male; D011030:Pneumothorax / Q000000981:diagnostic imaging / Q000209:etiology* / Q000401:mortality; D012042:Registries; D012151:Resuscitation; D012307:Risk Factors; D013898:Thoracic Injuries / Q000000981:diagnostic imaging*; D014057:Tomography, X-Ray Computed; D016896:Treatment Outcome; D014949:Wounds, Nonpenetrating / Q000150:complications* / Q000000981:diagnostic imaging