title: Occult pneumothorax in Chinese patients with significant blunt chest trauma: incidence and management.
abstract: BACKGROUND
  Occult pneumothorax (OP) is a pneumothorax not visualised on a supine chest X-ray (CXR) but detected on computed tomography (CT) scanning. With increasing CT use for trauma, more OP may be detected. Management of OP remains controversial, especially for patients undergoing mechanical ventilation. This study aimed to identify the incidence of OP using thoracic CT as the gold standard and describe its management amongst Hong Kong Chinese trauma patients.
  
  
  METHODS
  Analysis of prospectively collected trauma registry data. Consecutive significantly injured trauma patients admitted through the emergency department (ED) suffering from blunt chest trauma who underwent thoracic computed tomography (TCT) between in calendar years 2007 and 2008 were included. An OP was defined as the identification (by a specialist radiologist) of a pneumothorax on TCT that had not been previously detected on supine CXR.
  
  
  RESULTS
  119 significantly injured patients were included. 56 patients had a pneumothorax on CXR and a further 36 patients had at least one OP [OP incidence 30% (36/119)]. Bilateral OP was present in 8/36 patients, so total OP numbers were 44. Tube thoracostomy was performed for 8/44 OP, all were mechanically ventilated in the ED. The remaining 36 OP were managed expectantly. No patients in the expectant group had pneumothorax progression, even though 8 patients required subsequent ventilation in the operating room for extrathoracic surgery.
  
  
  CONCLUSIONS
  The incidence of OP (seen on TCT) in Chinese patients in Hong Kong after blunt chest trauma is higher than that typically reported in Caucasians. Most OP were managed expectantly without significant complications; no pneumothorax progressed even though some patients were mechanically ventilated.
authors.affiliation: Department of Diagnostic Radiology and Organ Imaging, Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, New Territories, Hong Kong, China. leekalok2909@yahoo.com.hk
authors.forename: Ka L
authors.initials: KL
authors.lastname: Lee
authors.forename: Colin A
authors.initials: CA
authors.lastname: Graham
authors.forename: Janice H H
authors.initials: JH
authors.lastname: Yeung
authors.forename: Anil T
authors.initials: AT
authors.lastname: Ahuja
authors.forename: Timothy H
authors.initials: TH
authors.lastname: Rainer
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D002681:China; D004653:Empyema / Q000209:etiology; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D015601:Injury Severity Score; D008297:Male; D008875:Middle Aged; D011030:Pneumothorax / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology / Q000628:therapy; D013902:Radiography, Thoracic; D012042:Registries; D012121:Respiration, Artificial; D012189:Retrospective Studies; D013898:Thoracic Injuries / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology; D013907:Thoracostomy / Q000009:adverse effects / Q000706:statistics & numerical data*; D014057:Tomography, X-Ray Computed; D014949:Wounds, Nonpenetrating / Q000150:complications / Q000000981:diagnostic imaging / Q000453:epidemiology; D055815:Young Adult