Letters to the Editor: Blood Management after Bilateral Total Knee Arthroplasties

Abstract

Reply: We thank Dr. Slappendel and Dr. Dirksen for their interest in our study.2 As mentioned in the manuscript a pneumatic tourniquet was used routinely in all patients having bilateral total knee replacements (TKRs). The tourniquet was inflated on the more symptomatic knee before the skin incision and was released after cementing the implant. After thorough assessment of the patient, the tourniquet was inflated on the other side and a separate team started the second procedure. Releasing the first tourniquet and starting the second TKR before closing the incision of the first knee reduces the overall operation time and offers the possibility to take care of any bleeding vessels before inserting the drains and closing the knee. However, this protocol accounts for a small amount of intraoperative blood loss.2 The average intraoperative blood loss (367.7 mL) in the patients2 is similar to data presented in the literature.7,8 Based on our experience with 461 patients having simultaneous bilateral TKRs, we do not think that predonation of autologous blood is unnecessary and that it is easy to calculate the need for blood transfusions in patients having simultaneous bilateral TKRs. Although there are some protocols to decrease the need for allogenic blood transfusions to almost zero in patients with unilateral TKRs,1,6 blood management in bilateral TKRs seems to be more complex.2,4,5,7,8 The total blood loss after simultaneous bilateral TKRs seems to be as much as 50% greater than the sum of both surgeries in staged bilateral TKRs.3,7 Bould et al3 addressed the issue of blood loss in bilateral TKRs as not simply being double that of a unilateral TKRs. In their study the blood loss in the second knee was increased significantly by what might be explained by a decrease in clotting factors, by effects of the tourniquet, and tissue trauma.3 In a study by Lane et al,8 patients with simultaneous bilateral TKRs had an approximately 17 times greater need for banked blood than patients having unilateral TKRs despite the use of a cell saver and a twofold greater preoperative autologous blood donation in the patients having simultaneous bilateral TKRs. Fick et al5 reviewed 44 patients having bilateral TKRs. Although 95% of the patients received an average of 1059 mL of filtered wound drainage blood and 44% additionally received an average of approximately 1 unit of predonated autologous blood (593 mL), 57% of the patients required allogenic blood transfusions.5 Breakwell et al4 randomized 33 patients having bilateral TKRs to either allogenic blood transfusions alone or the additional use of a postoperative cell saver. Using a postoperative cell saver decreased the need for allogenic blood by 2.5 units, however, these patients still required an average of 3.8 units of allogenic blood.4 Therefore it seems unlikely that using a postoperative cell saver alone will solve the issue of the increased need for allogenic blood transfusions in patients having simultaneous bilateral TKRs. In the Materials and Methods section we stated that: “It was assumed that patients with a postoperative hemoglobin greater than 10.5 mg/dL between postoperative Days 4 to 7 had received too many blood transfusions if they had no medical conditions justifying increased transfusion requirements, such as preexisting coronary artery disease or a history of myocardial infarction,” to reduce the risk of overestimating the transfusion requirements. In the study we focused on reducing the need for allogenic blood transfusions and therefore recommended predonation of 2 units of autologous blood in combination with a postoperative cell saver, knowing that other protocols that rely on allogenic blood transfusions are less expensive. We agree that not mentioning the mean body weight is a weakness of the paper. Friedrich Bottner, MD Hospital for Special Surgery, New York, NY;, and the Department of Orthopaedics,, University Hospital of Muenster,, Muenster, Germany Thomas P. Sculco, MD Hospital for Special Surgery,, New York, NY