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Correspondence  |   August 2003
Significance of a Tourniquet to Prevent Thromboembolism during Total Knee Arthroplasty as Assessed by Transesophageal Echocardiography
Author Affiliations & Notes
  • Claudia Stöllberger, M.D.
    *
  • Krankenanstalt Rudolfstiftung, Wien, Austria.
Article Information
Correspondence
Correspondence   |   August 2003
Significance of a Tourniquet to Prevent Thromboembolism during Total Knee Arthroplasty as Assessed by Transesophageal Echocardiography
Anesthesiology 8 2003, Vol.99, 512. doi:
Anesthesiology 8 2003, Vol.99, 512. doi:
To the Editor:—
In their article, Kato et al.  1 report about intraoperative transesophageal echocardiographic findings in 46 patients who underwent total knee arthroplasty, randomly assigned with or without a tourniquet around the thigh. The authors looked for abnormal echogenic findings in the right atrium during the tourniquet inflation phase, and they sought to identify the nature and composition of the echogenic material. During femoral reaming and insertion of the prosthesis, echogenic signals were detected in the right atrium of 27% patients with and 54% patients without a tourniquet. No blood samples, aspirated from the right atrium, contained nonphysiologic material in either the tourniquet or the nontourniquet group.
Although we agree with the conclusions that an inflated tourniquet does not completely prevent pulmonary emboli, we have concerns regarding the following points in the article:
  • What is the morphologic substrate of the abnormal echogenic findings? We know from previous studies 2–4 that air, bone cement, cold blood, fat, fresh venous thrombus, and “bone dust” have been aspirated from the right atria of patients with abnormal echogenic findings.

  • How do the authors explain the discrepancy between the abnormal transesophageal echocardiographic findings and the impossibility of aspirating nonphysiologic material from the right atrium? Was it only the diameter of the catheter? Were artifacts excluded?

  • Did the authors find differences between patients who did and did not show echogenic findings regarding the clinical characteristics or duration of operation or tourniquet inflation?

  • Why did the authors look only for pulmonary embolism and not for venous thrombosis? It has been shown that tissue thromboplastin from bone marrow leads to systemic activation of the clotting cascade, lesions of the venous endothelium, and thrombogenesis. 5 A recent study 6 in patients after hip arthroplasty found that the incidence of deep-vein thrombosis was associated with abnormal intraoperative echogenic findings.

  • When looking for pulmonary embolism, why did the authors rely on perfusion scans, which are known to have a low specificity? Why did they not measure pulmonary artery pressure or use helical computed tomography?

  • In how many patients did the authors observe a crossing of echogenic abnormalities from the right into the left atrium? Because a patent foramen ovale is assumed to have a prevalence of 27%, such a transition must be expected, at least in some patients.

  • Were causes other than pulmonary embolism excluded as being responsible for the observed cardiorespiratory impairment?

  • Did the authors consider that an activation of the clotting cascade could simply derive from the compression of muscle, fibrous tissue, and fat by the tourniquet?

  • What are the clinical relevance and practical implications of the study? Is it necessary to provide a more intense prophylaxis of venous thromboembolism? Should we continue the use of tourniquet-inflation during total knee arthroplasty?

In conclusion, we agree with the authors that we should be aware of acute pulmonary embolism during total knee arthroplasty. The important questions, however—which measures should be undertaken to prevent it and how transesophageal echocardiography can be useful in this situation—remain unanswered.
References
Kato N, Nakanishi K, Yoshino S, Ogawa R: Abnormal echogenic findings detected by transesophageal echocardiography and cardiorespiratory impairment during total knee arthroplasty with tourniquet. A nesthesiology 2002; 97: 1123–8Kato, N Nakanishi, K Yoshino, S Ogawa, R
Pell AC, Christie J, Keating JF, Sutherland GR: The detection of fat embolism by transesophageal echocardiography during reamed intramedullary nailing: A study of 24 patients with femoral and tibial fractures. J Bone Joint Surg (Br) 1993; 75: 921–5Pell, AC Christie, J Keating, JF Sutherland, GR
Berman AT, Parmet JL, Harding SP, Israelits CL, Chandrasekaran K, Horrow JC, Singer R, Rosenberg H: Emboli observed with use of transesophageal echocardiography immediately after tourniquet release during total knee arthroplasty with cement. J Bone Joint Surg (Am) 1998; 80: 389–96Berman, AT Parmet, JL Harding, SP Israelits, CL Chandrasekaran, K Horrow, JC Singer, R Rosenberg, H
Hayakawa M, Fujioka Y, Morimoto Y, Okamura A, Kemmotsu O: Pathological evaluation of venous emboli during total hip arthroplasty. Anaesthesia 2001; 56: 571–5Hayakawa, M Fujioka, Y Morimoto, Y Okamura, A Kemmotsu, O
Koessler MJ, Pitto RP: Fat and bone marrow embolism in total hip arthroplasty. Acta Orthop Belg 2001; 67: 97–109Koessler, MJ Pitto, RP
Pitto RP, Hamer H, Fabiani R, Radespiel-Troeger M, Koessler M: Prophylaxis against fat and bone-marrow embolism during total hip arthroplasty reduces the incidence of postoperative deep-vein thrombosis. J Bone Joint Surg (Am) 2002; 84: 39–48Pitto, RP Hamer, H Fabiani, R Radespiel-Troeger, M Koessler, M