Correspondence

Fat Embolism Syndrome

N Engl J Med 1994; 330:642-643March 3, 1994

Article

To the Editor:

Pell and colleagues (Sept. 23 issue)1 used transesophageal echocardiography to visualize echogenic masses in a patient undergoing fixation of a femoral fracture with an intramedullary nail. They assumed these masses were embolic fat on the basis of the postoperative development of the fat embolism syndrome in their patient.

Although there is ample evidence to support the diagnosis of fat embolism syndrome, the echogenic material seen with echocardiography may not be fat. Current clinical echocardiographic techniques do not permit the characterization of tissue: any material whose density differs from that of blood can produce echoes. Without analysis of a concomitant sample of venous blood, the identity of the material producing the echoes seen by Pell et al. remains speculative.

During joint-replacement surgery, transesophageal echocardiography will reveal both small (<1 mm in diameter) and large (1 to 5 mm in diameter) echogenic masses coincident with tourniquet release and knee manipulation2. Although the images may arise from thrombus, air, fat, marrow content, or large particles of methylmethacrylate cement, blood withdrawn during the procedure demonstrates thrombus, not fat2,3. We have observed identical echogenic masses with transesophageal echocardiography during femoral reaming for total hip replacement.

The echogenic material observed by Pell and colleagues may represent fresh thrombus rather than fat. Fracture of the long bones releases thromboplastin, which activates coagulation and may produce fresh thrombus4. Like fat, fresh thrombus deforms readily and could pass through a patent foramen ovale. The patient described in their report remained immobile for 11 days before undergoing surgery. With only subcutaneous heparin prophylaxis, deep-vein thrombosis could have developed, with subsequent surgical manipulation dislodging the thrombus.

Parsimony suggests that all echogenic masses imaged during orthopedic surgery have a common source and composition. However, until further investigation produces more definite identification of these materials, these masses cannot be ascribed to fat or thrombus. Although fat embolism syndrome clearly developed in their patient, the intraoperative echogenic masses could have included thrombi as well.

Jonathan L. Parmet, M.D.
Jan Horrow, M.D.
Henry Rosenberg, M.D.
Hahnemann University, Philadelphia, PA 19102

4 References

1. 1

   Pell ACH, Hughes D, Keating J, Christie J, Busuttil A, Sutherland GR. Fulminating fat embolism syndrome caused by paradoxical embolism through a patent foramen ovale. N Engl J Med 1993;329:926-929
   Full Text | Web of Science | Medline

2. 2

   Parmet JL, Berman AT, Horrow JC, Harding S, Rosenberg H. Thromboembolism coincident with tourniquet deflation during total knee arthroplasty. Lancet 1993;341:1057-1058
   CrossRef | Web of Science | Medline

3. 3

   Ereth MH, Weber JG, Abel MD, et al. Cemented versus noncemented total hip arthroplasty -- embolism, hemodynamics, and intrapulmonary shunting. Mayo Clin Proc 1992;67:1066-1074
   Web of Science | Medline

4. 4

   Gossling HR, Pellegrini VD Jr. Fat embolism syndrome: a review of the pathophysiology and physiological basis of treatment. Clin Orthop 1982;165:68-82
   Web of Science | Medline

To the Editor:

Pell and colleagues describe a case of fulminating fat embolism syndrome demonstrated by transesophageal echocardiography in a patient undergoing intramedullary fixation of a femoral-shaft fracture. The report provides substantial insight into the pathophysiology of this syndrome. One of the advantages of transesophageal echocardiography in this setting was the early detection of embolic material in the right heart after the insertion of a guide wire into the medullary cavity at a point when the patient had no signs of hemodynamic or pulmonary impairment. Further manipulation of the medullary cavity resulted in massive embolism, as demonstrated by transesophageal echocardiography. Medullary manipulation was temporarily stopped. The patient's condition deteriorated during the following 20 minutes, and he required resuscitation. Despite strong evidence of embolic phenomena, the procedure was then continued and a medullary nail inserted. We wonder whether the authors considered abandoning the procedure altogether or using a different surgical approach, such as open osteosynthesis or external fixation, thus avoiding extensive intramedullary manipulations. In our view, a vena caval filter 1 could have been inserted at the first echocardiographic evidence of embolism, before the intramedullary nail was placed.

M. Haller, M.D.
G. Schelling, M.D.
Ludwig-Maximilians University, 81366 Munich, Germany

1 References

1. 1

   Rohrer MJ, Scheidler MG, Wheeler HB, Cutler BS. Extended indications for placement of an inferior vena cava filter. J Vasc Surg 1989;10:44-50
   CrossRef | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: Parmet and colleagues are correct in stating that current echocardiographic techniques do not allow the characterization of tissue, and it is possible that the embolic material seen in our patient included thrombus masses. Nevertheless, we believe that the clinical and pathological evidence suggests that embolism of fat predominated. Numerous discrete embolic masses (>1 cm in diameter) and large quantities of smaller echogenic debris appeared continuously within the heart for more than 20 minutes during the orthopedic procedure. Despite the duration and intensity of the embolism, there was no evidence of venous thrombosis in the leg veins or pulmonary arteries at autopsy, and widespread microvascular fat embolism was observed. Furthermore, the perioperative clinical course was entirely consistent with the presence of the fat embolism syndrome. Fat emboli can be detected in the femoral vein during reaming procedures,1 and although blood samples were not obtained from this patient, we have found an increase in the fat content of blood samples obtained from the right atrium during echocardiographically detected embolism2. The role of other factors, including thromboplastin, fresh thrombus, platelets, complement, and leukotrienes, in the pathogenesis of the fat embolism syndrome is uncertain, but it is of interest that large thrombus-coated fat emboli have been described in experimental studies3. Embolic material is commonly detected with transesophageal echocardiography during orthopedic procedures,2 but frequently its presence appears to have no adverse sequelae. Further research is required to determine whether specific characteristics such as the size, intensity, or duration of embolism are predictive of subsequent events. If transesophageal echocardiography does prove valuable in identifying subjects with massive, life-threatening embolism, then the use of alternative therapeutic strategies, as suggested by Haller and Schelling, might be considered. However, we are uncertain whether the insertion of a vena caval filter would prevent embolic material from reaching the heart and lungs, since fat emboli are thought to be readily deformable,4 which accounts for their passage across the pulmonary capillary bed or through a patent foramen ovale as in our patient.

Alastair C.H. Pell, M.R.C.P.
Western Infirmary, Glasgow G11 6NT, United Kingdom

James Christie, F.R.C.S.
Royal Infirmary, Edinburgh EH3 9YW, United Kingdom

4 References

1. 1

   Manning JB, Bach AW, Herman CM, Carrico CJ. Fat release after femur nailing in the dog. J Trauma 1983;23:322-326
   CrossRef | Web of Science | Medline

2. 2

   Pell ACH, Christie J, Keating JF, Sutherland GR. The detection of fat embolism by transoesophageal echocardiography during reamed intramedullary nailing: a study of 24 patients with femoral and tibial fractures. J Bone Joint Surg Br 1993;75:921-925
   Web of Science | Medline

3. 3

   Wenda K, Ritter G, Wittich N, Erbel R. Monitoring during noncardiac surgery. In: Erbel R, Khandheria BK, Brennecke R, Meyer J, Seward JB, Tajik AJ, eds. Transesophageal echocardiography: a new window to the heart. Berlin, Germany: Springer-Verlag, 1989:291-2.
   

4. 4

   Mode of action of the emboli. In: Sevitt S. Fat embolism. London: Butterworths, 1962:58-70.
   

Citing Articles (4)

Citing Articles

1. 1

   Ramesh K. Sen, Sujit K. Tripathy, Vibhu Krishnan. (2011) Role of corticosteroid as a prophylactic measure in fat embolism syndrome: a literature review. MUSCULOSKELETAL SURGERY
   CrossRef

2. 2

   Stavros Gourgiotis, Stavros Aloizos, Christos Gakis, Nikolaos S. Salemis. (2011) Platypnea-orthodeoxia due to fat embolism. International Journal of Surgery Case Reports
   CrossRef

3. 3

   I VINCENTIROUQUETTE, H DAVID, M BORNE, B DEBIEN, B PATS. (1998) Intérêt de l'IRM dans l'embolie graisseuse cérébrale. Annales Françaises d’Anesthésie et de Réanimation 17:3, 278-280
   CrossRef

4. 4

   J ESTEBE. (1997) Des emboles de graisse au syndrome d'embolie graisseuse. Annales Françaises d’Anesthésie et de Réanimation 16:2, 138-151
   CrossRef