Department of Surgery, University of Ottawa, Ottawa, ON, Canada.
Ottawa Hospital Research Institute, The Ottawa Hospital - General Campus, 501 Smyth Road, Ottawa, ON, K1H 8L6, Canada.
Can J Anaesth. 2021 Feb;68(2):245-255. doi: 10.1007/s12630-020-01857-4. Epub 2020 Nov 24.
Estimated blood loss (EBL) is an important tool in clinical decision-making and surgical outcomes research. It guides perioperative transfusion practice and serves as a key predictor of short-term perioperative risks and long-term oncologic outcomes. Despite its widespread clinical and research use, there is no gold standard for blood loss estimation. We sought to systematically review and compare techniques for intraoperative blood loss estimation in major non-cardiac surgery with the objective of informing clinical estimation and research standards.
A structured search strategy was applied to Ovid Medline, Embase, and Cochrane Library databases from inception to March 2020, to identify studies comparing methods of intraoperative blood loss in adult patients undergoing major non-cardiac surgery. We summarized agreement between groups of pairwise comparisons as visual estimation vs formula estimation, visual estimation vs other, and formula estimation vs other. For each of these comparisons, we described tendencies for higher or lower EBL values, consistency of findings, pooled mean differences, standard deviations, and confidence intervals.
We included 26 studies involving 3,297 patients in this review. We found that visual estimation is the most frequently studied technique. In addition, visual techniques tended to provide lower EBL values than formula-based estimation or other techniques, though this effect was not statistically significant in pooled analyses likely due to sample size limitations. When accounting for the contextual mean blood loss, similar case-to-case variation exists for all estimation techniques.
We found that significant case-by-case variation exists for all methods of blood loss evaluation and that there is significant disagreement between techniques. Given the importance placed on EBL, particularly for perioperative prognostication models, clinicians should consider the universal adoption of a practical and reproducible method for blood loss evaluation.
PROSPERO (CRD42015029439); registered: 18 November 2015.PROSPERO (CRD42015029439); registered: 18 November 2015.
估计失血量（EBL）是临床决策和手术结果研究中的重要工具。它指导围手术期输血实践，是短期围手术期风险和长期肿瘤学结果的关键预测指标。尽管它在临床和研究中广泛应用，但目前还没有 EBL 估计的金标准。我们旨在系统地回顾和比较在非心脏大手术中用于术中失血量估计的技术，目的是为临床估计和研究标准提供信息。
应用结构化搜索策略在 Ovid Medline、Embase 和 Cochrane Library 数据库中进行检索，检索时间从建库至 2020 年 3 月，以确定比较成人非心脏大手术中术中失血量估计方法的研究。我们总结了两两比较组之间的一致性，包括视觉估计与公式估计、视觉估计与其他方法、公式估计与其他方法。对于这些比较中的每一个，我们描述了 EBL 值较高或较低的趋势、结果的一致性、汇总平均差异、标准差和置信区间。
我们共纳入了 26 项研究，共纳入了 3297 名患者。我们发现视觉估计是最常研究的技术。此外，与基于公式的估计或其他技术相比，视觉技术往往提供更低的 EBL 值，但在汇总分析中，由于样本量限制，这种影响没有统计学意义。在考虑到背景平均失血量的情况下，所有估计技术都存在类似的病例间差异。
我们发现所有失血量评估方法都存在显著的病例间差异，并且各种技术之间存在显著的不一致性。鉴于 EBL 的重要性，特别是对于围手术期预后模型，临床医生应考虑普遍采用一种实用且可重复的失血量评估方法。
PROSPERO（CRD42015029439）；注册日期：2015 年 11 月 18 日。
