Determination of Perioperative Blood Loss: Accuracy or Approximation?.

BACKGROUND: Various different interventions can be used to reduce surgical blood loss; however, there is no "gold standard" for accurately measuring the volume of perioperative blood loss, and this makes it difficult to assess the efficacy of these interventions. METHODS: We used data from a previous multicenter double-blind randomized clinical trial in patients undergoing total hip arthroplasty in which we compared 2 regimens for administering tranexamic acid versus placebo. We assessed direct measures (external blood loss) and indirect estimates (using the formulas of Bourke, Gross, Mercuriali, and Camarasa and a new formula we have developed) using analysis of variance to compare estimated volumes of blood loss among the study groups. In addition, intraclass correlation coefficients (ICCs) and Bland-Altman diagrams were used to compare the estimated volumes of blood loss obtained with each formula. RESULTS: The mean estimated external blood loss was 909 +/- 324 mL, and the mean estimates of blood loss calculated using the formulas of Gross, Bourke and Smith, and Camarasa were 1308 +/- 555, 1091 +/- 454, and 1641 +/- 945 mL, respectively, whereas we obtained a value of 1511 +/- 919 mL with the new formula at day 2. In all cases, the results favored the use of tranexamic acid (P

http://ift.tt/2ouYL09