Lopez-Picado A, Albinarrate A, Barrachina Borja
From the *Araba Research Unit, Araba University Hospital, Vitoria-Gasteiz, Spain; †Bioaraba Research Institute, Vitoria-Gasteiz, Spain; and ‡Department of Anaesthesia & Perioperative Care, Araba University Hospital, Vitoria-Gasteiz, Spain.
Anesth Analg. 2017 Jul;125(1):280-286. doi: 10.1213/ANE.0000000000001992.
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.
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.
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 < .0001). Comparing results of the new and other formulas, we found moderate-to-low agreement (in terms of ICCs) except for that of Camarasa (ICC: 0.992). The limits of agreement with the new formula ranged from -378 to 93 in the case of the comparison with Camarasa's formula and from -2226 to 959 for external blood loss, the difference depending on the magnitude of the estimate to a large extent.
Formulas that take into account both anthropometric and laboratory parameters are useful for evaluating the efficacy of interventions aiming to decrease blood loss but do not ensure that the values obtained are sufficiently accurate for absolute measuring.
可以采用各种不同的干预措施来减少手术失血；然而，对于准确测量围手术期失血量，尚无“金标准”，这使得评估这些干预措施的疗效变得困难。
我们使用了之前一项针对接受全髋关节置换术患者的多中心双盲随机临床试验的数据，在该试验中我们比较了两种氨甲环酸给药方案与安慰剂。我们使用方差分析评估直接测量值（外部失血量）和间接估计值（使用伯克、格罗斯、梅尔库里亚利和卡马拉萨的公式以及我们开发的一个新公式），以比较各研究组之间的估计失血量。此外，使用组内相关系数（ICC）和布兰德 - 奥特曼图来比较每个公式得出的估计失血量。
平均估计外部失血量为909±324毫升，使用格罗斯、伯克和史密斯以及卡马拉萨公式计算的平均失血量估计值分别为1308±555、1091±454和1641±945毫升，而在第2天使用新公式我们得到的值为1511±919毫升。在所有情况下，结果都支持使用氨甲环酸（P <.0001）。比较新公式和其他公式的结果，我们发现除了卡马拉萨公式（ICC：0.992）外，一致性为中到低（就ICC而言）。与新公式的一致性界限在与卡马拉萨公式比较时为 - 378至93毫升，对于外部失血量为 - 2226至959毫升，差异在很大程度上取决于估计值的大小。
考虑人体测量和实验室参数的公式对于评估旨在减少失血的干预措施的疗效有用，但不能确保所获得的值对于绝对测量足够准确。
