title: Follow-up after asymptomatic penetrating thoracic injury: 3 hours is enough.
abstract: BACKGROUND
  Patients with asymptomatic penetrating thoracic injuries routinely undergo chest radiographs (CXRs) upon emergency department (ED) arrival, and then 6 hours later to exclude delayed pneumothorax (PTX) or hemothorax (HTX). Although previous reports indicate that up to 12% (mean, 3%) of asymptomatic penetrating thoracic injuries are complicated by delayed PTX or HTX, we hypothesized that these events would be detectable after only 3 hours of observation. The purpose of this study was to compare the incidence of delayed thoracic injury at 3 hours and 6 hours using standard CXR.
  
  
  METHODS
  A prospective trial of asymptomatic patients with penetrating thoracic injuries was conducted during 36 months. CXRs were performed upon arrival (supine, AP), and at 3 hours (upright, PA/lateral) and 6 hours (upright, PA/lateral). Patients with either injuries detected on initial CXR or cardiopulmonary symptoms were excluded. Findings from 3 hour and 6 hour CXRs were compared. Assuming a delayed PTX or HTX rate of 3%, the probability of detecting at least one delayed event between 3 hours and 6 hours in 100 patients is 95.25%.
  
  
  RESULTS
  Of 648 patients with penetrating thoracic injuries, 100 patients both met inclusion criteria and completed the study. Patients were predominantly young (32.5 years +/- 13.3 years [mean +/- SD]) men (75% men) with stab wounds (75% stab wounds, 25% gunshot wounds). The mean length of stay for patients discharged from the ED was 8.8 hours +/- 2.6 hours. Although two patients developed a PTX between arrival and 3 hours, none developed after 3 hours. Patient charges, hospital costs, and radiation exposure were calculated for patients in our proposed study protocol, totaling $2802, $189, and 0.08 mSv, respectively.
  
  
  CONCLUSIONS
  No patient in our study population developed a delayed PTX or HTX after 3 hours. Our results suggest that shortening the observation period after asymptomatic penetrating thoracic injuries to 3 hours is safe, cost-effective, minimizes radiation exposure, and may help relieve congested urban EDs.
authors.affiliation: Department of Surgery, Temple University Hospital, 3401 North Broad Street, Philadelphia, PA 19104, USA. mark.seamon@tuhs.temple.edu
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Seamon
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Medina
authors.forename: Paola G
authors.initials: PG
authors.lastname: Pieri
authors.forename: Carol A
authors.initials: CA
authors.lastname: Fisher
authors.forename: John P
authors.initials: JP
authors.lastname: Gaughan
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Bradley
authors.forename: Robert M
authors.initials: RM
authors.lastname: McNamara
authors.forename: Amy J
authors.initials: AJ
authors.lastname: Goldberg
mesh_terms: D000328:Adult; D004636:Emergency Service, Hospital; D005260:Female; D005500:Follow-Up Studies; D006491:Hemothorax / Q000000981:diagnostic imaging / Q000453:epidemiology*; D017721:Hospital Costs; D006801:Humans; D015994:Incidence; D007902:Length of Stay; D008297:Male; D011030:Pneumothorax / Q000000981:diagnostic imaging / Q000453:epidemiology*; D011859:Radiography; D013898:Thoracic Injuries / Q000150:complications* / Q000000981:diagnostic imaging* / Q000628:therapy; D013997:Time Factors; D014950:Wounds, Penetrating / Q000150:complications* / Q000000981:diagnostic imaging* / Q000628:therapy