Routine early post-operative dosage of hemoglobin does not impact transfusion rate after total knee arthroplasty (TKA)
Resumen
INTRODUCTION
Post-operative hemoglobin determination after total knee arthroplasty (TKA) is considered essential to detect significant post-operative anemia and to determine whether autologous blood transfusion (ABT) is indicated. The primary objective of the study was to determine whether this assay performed the first post-operative day provided clinically useful information for the possible indication of ABT when modern blood saving procedures were used. The hypothesis tested was that there was a significant relationship between the Hb level on the first post-operative day and the necessity of post-operative ABT
MATERIAL – METHODS
An observational prospective study was carried out. 101 patients operated on for elective TKA between October 2017 and October 2020 were selected; The mean preoperative Hb level was 13.9 ± 1.2 g/dl (range, 11.3 to 17.7 g/dl). Hb levels were systematically collected on the first post-operative day, and subsequently if required. The need for post-operative ABT, its motivation and timing were noted. The possible occurrence of secondary complications occurring up to 90 days after the procedure was noted. The primary criterion was the need for post-operative ABT. The relationship with the Hb level on the first post-operative day was analyzed; the sensitivity, specificity, predictive and negative values of a Hb level on the first post-operative day of less than 8 g/dl on the need for ABT were calculated.
RESULTS
Five patients 5% received ABT during the early postoperative phase: two in view of the Hb level on the first postoperative day, and three later. The mean Hb level on the first post-operative day was 11.7 ± 1.3 g/dl (range, 7.0 to 17.1 g/dl). The mean Hb loss was 2.2 ± 1.1 g/dl. Ninety-five patients (94%) had Hb levels on the first post-operative day greater than 8 g/dl; one was transfused immediately and three later. Six patients (6%) had Hb levels on the first post-operative day of less than 8 g/dl. Only one was transfused immediately. There was no significant relationship between post-operative ABT and Hb level on the first post-operative day. The sensitivity of the Hb level on the first postoperative day to predict ABT was 20%, the specificity 95%, the positive predictive value 17% and the negative predictive value 96%. The analysis of the ROC curve does not find a relevant threshold
CONCLUSIONS
Knowledge of Hb levels on the first post-operative day after TKA did not provide useful information for the management of possible post-operative anemia and the indication of ABT. The systematic determination of hemoglobin on the first post-operative day after TKA does not seem to be a useful factor in the management of the patient when a modern blood saving protocol is followed, including normalization of pre-operative Hb and use of tranexamic acid.
