title: Digital photoplethysmography in the diagnosis of suspected lower limb DVT: is it useful?
abstract: OBJECTIVE
  to determine the role of digital photoplethysmography (D-PPG) in the diagnosis of deep-vein thrombosis (DVT), in comparison to the "gold standard" of either contrast ascending venography (ACV) or colour-flow duplex imaging (CFDI).
  
  
  METHODS
  prospective study of 100 hospital inpatients (103 legs) referred to the X-ray department for ACV or CFDI with clinically suspected lower limb DVT in a district general hospital. Each patient was assessed by either ACV or CFDI, and D-PPG.
  
  
  RESULTS
  thirty-seven limbs were found to have DVT as demonstrated by ACV or CFDI. All patients with a venous refilling time (RT) of greater than 20 s and venous pump (VP) of greater than 35 had a normal ACV or CFDI. Using RT of less than 21 s as the optimal cut-off point, D-PPG achieved a sensitivity of 100%, negative-predictive value of 100%, specificity of 47% and positive-predictive value of 51%. By using VP of less than 36 as the optimal cut-off point, a sensitivity of 100%, a negative-predictive value of 100%, a specificity of 35% and positive-predictive value of 46% were achieved.
  
  
  CONCLUSIONS
  these results validate the use of portable D-PPG as a useful screening tool for the diagnosis of clinically suspected lower limb DVT. A positive test requires further confirmation by one of the "gold standard" methods, whereas a negative test effectively excludes DVT.
authors.affiliation: Department of Surgery, Wrexham Maelor Hospital NHS Trust, Croesnewydd Road, Wrexham, LL13 7TD, U.K.
authors.forename: Y K
authors.initials: YK
authors.lastname: Tan
authors.forename: A F
authors.initials: AF
authors.lastname: da Silva
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010690:Phlebography; D017156:Photoplethysmography / Q000379:methods*; D011446:Prospective Studies; D012680:Sensitivity and Specificity; D014463:Ultrasonography; D020246:Venous Thrombosis / Q000175:diagnosis*