| JOURNAL HOME | CME HOME | THIS MONTH | PAST ISSUES | ETOC | COLLECTIONS |
| AUTHORS | REVIEWERS | EDITORIAL BOARD | FEEDBACK | RSS | HELP |
| ||||||||||||||
| ||||||||||||||
|
|
|
|
||||||||||||
|
||||||||||||||
Royal National Orthopaedic Hospital, Stanmore, Brockley Hill, Middlesex, UK
To the Editor:
We read with interest the paper by Horlocker et al. (1) investigating coagulation testing during spinal fusion surgery. This is a thorough study that has direct relevance to our practice, but we have some reservations in drawing conclusions from it.
Allocating groups for investigation by relying solely on recorded surgical impressions of bleeding could have lead to unrepresentative data sampling. Further to this, in the group "without increased bleeding" only 5% of patients had intraoperative activated partial thromboplastin time or prothrombin time measured and only 2% had a platelet count recorded. Data relating to other factors relevant to coagulation, such as temperature and timing of blood product administration, are unavailable. This, combined with the heterogeneity of patient factors and surgical procedure, makes comparison and robust analysis difficult to perform.
A more complete data set for the "normal" group would be of great interest, as the relationship between laboratory coagulation tests and surgical blood loss remains complex. Indeed, a normal range for perioperative patients does not exist, as laboratory indices are mostly based on healthy volunteers.
This is an important area of research that, as the authors state, needs further prospective investigation. Retrospective studies do have a valid role in clinical research, but we believe that there are times when the available information is inadequate to answer the questions posed.
References
Department of Anesthesiology, Mayo Clinic, Rochester, MN
In Response:
We would like to thank Drs. Cooper and McLeod for their thoughtful letter. Although allocation of groups based on recorded surgical impressions of bleeding could lead to unrepresentative data sampling, observation of the surgical field is the first and most important determinant of the need for transfusion of non-red blood cell products (1). When increased surgical bleeding, defined as recurrent bleeding despite adequate use of electrocautery and suture or decreased clot formation within the field is noted, coagulation tests are performed to confirm the existence of a coagulopathy and to determine which non-red blood cell products are needed to correct the disorder. Conversely, routine assessment of coagulation studies in the absence of a clinical clotting abnormality would have limited usefulness. This later point also explains why only 5% of patients in the group without increased bleeding had coagulation tests performed. We agree that prospective studies are needed to further define the mechanisms of coagulopathy and the role of coagulation testing during major spine surgery. Our retrospective analysis provides direction on which coagulation tests may be most useful in the development of evidence-based guidelines for blood component therapy.
References
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|
