title: Air plethysmography: the answer in detecting past deep venous thrombosis.
abstract: OBJECTIVE
  In this study we assessed the accuracy of air plethysmography (APG) as a means of detecting earlier deep venous thrombosis (DVT), in comparison with venography, to develop a preoperative test for patients with varicose veins.
  
  
  METHODS
  In this retrospective analysis of prospectively acquired data, 202 patients referred with the clinical suspicion of chronic venous obstruction (224 lower limbs) and 41 patients (41 lower limbs) who had symptoms and signs suggestive of DVT, but had deep veins that appeared normal on venography, were studied with both venography and APG.
  
  
  RESULTS
  The results of venography were negative for past DVT in 169 legs and confirmed past DVT in 96 limbs. The DVTs were confined to the calf in 19 limbs and were found at popliteal level, more proximal, or both in 77 limbs. A total of 95% of the limbs that had earlier proximal DVT (73 of 77) were identified by means of an APG outflow fraction with occlusion of the superficial veins in the first second (OFs) of less than 28%. This is analogous to the Q wave of the electrocardiogram, which is a means of denoting the presence of myocardial infarction. The specificity rate of the method in the detection of past proximal DVT was 96%, the positive predictive value was 92%, and the negative predictive value was 98%.
  
  
  CONCLUSIONS
  APG is a practical, inexpensive, easy-to-perform, accurate, noninvasive method for the diagnosis of hemodynamically significant (ie, proximal or extensive calf DVT) chronic venous obstruction that could replace venography.
authors: Irvine Laboratory for Cardiovascular Investigation and Research, Division of Surgery, Anesthetics, and Intensive Care, Imperial College School of Medicine, St Mary's Hospital, London, UK. e.kalodiki@ic.ac.uk
authors: E
authors: E
authors: Kalodiki
authors: L S
authors: LS
authors: Calahoras
authors: K T
authors: KT
authors: Delis
authors: C P
authors: CP
authors: Zouzias
authors: A N
authors: AN
authors: Nicolaides
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007866:Leg / Q000098:blood supply*; D008297:Male; D008875:Middle Aged; D010690:Phlebography; D010991:Plethysmography; D011237:Predictive Value of Tests; D012039:Regional Blood Flow; D012189:Retrospective Studies; D012680:Sensitivity and Specificity; D014648:Varicose Veins / Q000175:diagnosis; D020246:Venous Thrombosis / Q000175:diagnosis* / Q000503:physiopathology