title: Abnormal echogenic findings detected by transesophageal echocardiography and cardiorespiratory impairment during total knee arthroplasty with tourniquet.
abstract: BACKGROUND
  In patients undergoing total knee arthroplasty, intraoperative pulmonary embolic events are rare, and most occur following tourniquet deflation. This embolization can be observed using transesophageal echocardiography. However, the authors have encountered sudden decreases in arterial oxygen partial pressure while a tourniquet is still inflated. Therefore, the current investigation was designed to detect emboli during the tourniquet inflation phase and to identify the composition of the echogenic material.
  
  
  METHODS
  Forty-six patients were randomly assigned to undergo total knee arthroplasty without (control, n = 24) or with a tourniquet (n = 22). Hemodynamic monitoring, blood gas analysis, and continuous transesophageal echocardiography were performed during the total knee arthroplasty procedure. Right jugular blood specimens were collected whenever echogenic material was seen in the atrium.
  
  
  RESULTS
  In the tourniquet group, embolic events occurred in 27% of patients during femoral reaming and in 100% after tourniquet deflation. In the control group, emboli were detected in 54% of patients during femoral reaming. Most of the patients exhibited cardiopulmonary impairment after severe echogenic embolism, even while the tourniquet was inflated (two patients). None of the blood samples aspirated from the central catheters contained detectable material.
  
  
  CONCLUSIONS
  This prospective study showed that embolic events occurred during total knee arthroplasty, even while a tourniquet was inflated. An inflated tourniquet does not completely prevent pulmonary emboli.
authors.affiliation: Department of Anesthesiology, Nippon Medical School, Tokyo, Japan. n-kato@mva.biglobe.ne.jp
authors.forename: Nobuya
authors.initials: N
authors.lastname: Kato
authors.forename: Kazuhiro
authors.initials: K
authors.lastname: Nakanishi
authors.forename: Shinichi
authors.initials: S
authors.lastname: Yoshino
authors.forename: Ryo
authors.initials: R
authors.lastname: Ogawa
mesh_terms: D000368:Aged; D019645:Arthroplasty, Replacement, Knee / Q000009:adverse effects*; D017548:Echocardiography, Transesophageal; D005260:Female; D006439:Hemodynamics; D006801:Humans; D007431:Intraoperative Complications / Q000209:etiology*; D008297:Male; D008875:Middle Aged; D011655:Pulmonary Embolism / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology; D012119:Respiration; D014111:Tourniquets