PRACTICE guidelines are systematically developed recommendations that assist the practitioner and patient in making decisions about health care. These recommendations may be adopted, modified, or rejected according to clinical needs and constraints.

Practice guidelines are not intended as standards or absolute requirements. The use of practice guidelines cannot guarantee any specific outcome. Practice guidelines are subject to revision as warranted by the evolution of medical knowledge, technology, and practice. They provide basic recommendations that are supported by analysis of the current literature and by a synthesis of expert opinion, open forum commentary, and clinical feasibility data.

This update includes data published since the “Practice Guidelines for Blood Component Therapy” were adopted by the American Society of Anesthesiologists (ASA) in 1995; it also includes data and recommendations for a wider range of techniques than was previously addressed.

实践指南是系统制定的建议，帮助执业医师和患者做出医疗保健决策。可根据临床需求和限制采纳、修改或拒绝这些建议。

实践指南并非标准或绝对要求。使用实践指南不能保证任何特定结果。根据医学知识、技术和实践的演变，实践指南将进行修订。它们提供了基本建议，得到了当前文献分析以及专家意见、公开论坛评论和临床可行性数据综合的支持。

该更新包括自1995年美国麻醉医师学会 (ASA) 通过“血液成分治疗实践指南”以来发表的数据；还包括数据和比之前讨论的更广泛的技术建议。