Authors' reply.

Sir,

We are deeply appreciative of the comments of the readers1 regarding our article on the efficacy of tranexamic acid (TEA) in controlling blood loss in patients undergoing bilateral total knee arthroplasty (TKA).2

We agree with their comment that adopting a blood transfusion protocol and employing multiple measures for blood conservation goes a long way in minimizing blood loss and postoperative transfusion requirement. However, preoperative autologous blood transfusion with or without erythropoietin and intraoperative blood salvage using “cell savers” are ways to decrease requirements of allogenic blood transfusion. However for these methods expertise is not readily available at the grass root level. Thus demands of allogenic blood transfusion become really high in patients undergoing bilateral TKA at a single stage. TEA, with its ease of administration, cheaper cost, and safety profile, becomes an important tool in any blood conservation strategy.

The Cochrane review by Henry et al.3 Antifibrinolytic use for minimizing perioperative allogenic blood transfusion; page 7, left hand column, last paragraph, 6th line) itself states that different studies differ on dosage, timing of administration, and number of doses of TEA to be administered. Previous studies have demonstrated a minimum dosage of 10 mg/kg of TEA to obtain the desired antihemorrhagic effect.4 We have used the same dosage in our investigation as in the previous reports; so as to minimize the side effects and found it to be effective in controlling blood loss.

Prior to administration of TEA, the patients were screened preoperatively for any documented history of allergy to TEA; administration of TEA is often done for surgical procedures or for excessive bleeding, and this was the only factor that was taken into account when looking for allergic reactions. None of the patients in our series had a positive history in this regard. No patient developed allergy to TEA during administration in our study.

Patients were also screened for any documented prior history of deep vein thrombosis or history of any hypercoagulable states.

It has been reported that it takes 5–15 min for maximum plasma levels of TEA to be reached after intravenous administration.5 As the time from cementing to release of tourniquet is fairly constant and mostly dependent on the cement curing time, we felt this was a reliable time to administer the drug as it would ensure uniform comparison in all cases. Considering that the mean duration of effect of tranexamic acid is around 3 h, we repeated the dose after this period to prolong the effect of drug to the first 6 h when most bleeding is expected to occur.

A tourniquet was routinely used and a bone plug (to block the femoral medullary cavity after the femoral cuts) was always used to decrease the blood loss. Closure was performed only after adequate hemostasis was obtained after tourniquet deflation. An intra-articular negative suction drain was used in all the cases to measure postoperative blood loss, but no measurement of intra-operative blood loss was done due to the inherent inaccuracies in the methodology.

The subset of patients selected for bilateral TKA represents a population group that is more fit than average, as certain conditions, including anemia do not justify a bilateral procedure. Additionally, the waiting lists of 3 months or more at our institute allowed us to build up any preoperative deficiencies in hemoglobin values, as well as improve nutritional status. The decision to perform a bilateral TKA is not governed by absolute hemoglobin values alone; presence of medical comorbidities, such as diabetes mellitus, bronchial asthma, coronary artery disease, hypertension, and so on, also play a role in the decision-making process. The decision to proceed to the second knee is always clinical. It also depends on the anesthetist's assessment of the patient's ability to withstand the second surgery.

We are highly thankful to the readers for their critical analysis of our work.