title: Overdiagnosis of pulmonary embolism: evaluation of a hypoxia algorithm designed to avoid this catastrophic problem.
abstract: BACKGROUND
  We observed a substantial increase in the incidence of pulmonary embolism (PE) after total joint arthroplasty (TJA) when multidetector computerized tomography (MDCT) replaced ventilation-perfusion (V/Q) scans as the diagnostic modality of choice. We questioned whether this resulted from the detection of clinically unimportant PE with the more sensitive MDCT and in 2007 instituted a hypoxia protocol to enhance the detection of PE.
  
  
  OBJECTIVE
  We determined whether this new hypoxia protocol increased the specificity of our workups for suspected clinically important PE in the immediate postoperative period without affecting patient morbidity and mortality.
  
  
  METHODS
  We compared the frequency of MDCT, V/Q scan and total investigations, incidence of PE, and overall mortality rates in the 3 years prior (January 2003 to December 2006) and 2 years after (January 2007 to November 2009) the implementation of the algorithm.
  
  
  RESULTS
  After instituting the protocol, we observed a trend toward a decrease in the number of patients worked up for PE (4.6 to 4.0 per 100 TJAs, 13.5% decrease). At the same time, there was an increase in the percent of positive findings of PE per workup for PE (23-33 positive PEs per 100 patients, 40.5% increase). All-cause mortality rates decreased for the 30-day period (3.1 to 1.4 per 1000 TJAs, 53.5% decrease) and the 90-day period (5.0 to 2.6 per 1000 TJAs, 48.3% decrease).
  
  
  CONCLUSIONS
  With the implementation of this algorithm, the specificity of our management of postoperative hypoxia and suspected clinically important PE improved without affecting patient morbidity or mortality.
authors: The Rothman Institute of Orthopedics at Thomas Jefferson University Hospital, 925 Chestnut Street, Philadelphia, PA 19107, USA.
authors: Brian S
authors: BS
authors: Winters
authors: Mark
authors: M
authors: Solarz
authors: Christina L
authors: CL
authors: Jacovides
authors: James J
authors: JJ
authors: Purtill
authors: Richard H
authors: RH
authors: Rothman
authors: Javad
authors: J
authors: Parvizi
mesh_terms: D000465:Algorithms; D019643:Arthroplasty, Replacement / Q000009:adverse effects* / Q000401:mortality; D016009:Chi-Square Distribution; D003430:Cross-Sectional Studies; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000628:therapy; D015994:Incidence; D055420:Perfusion Imaging; D015143:Philadelphia / Q000453:epidemiology; D011237:Predictive Value of Tests; D011379:Prognosis; D015397:Program Evaluation; D011655:Pulmonary Embolism / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000628:therapy; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D013997:Time Factors; D014057:Tomography, X-Ray Computed; D014692:Ventilation-Perfusion Ratio