这两个词啥意思？

When investigators seek to show the superiority of a particular approach, a usual-care comparator is generally thought to be better than the creation of a contrasting protocol. But what is usual care, and is it the same everywhere? The amount of intravenous fluid that was received by the patients in the standard-care group in this trial was substantially less than that observed in previous national and international trials of early, goal-directed resuscitation involving patients with septic shock and in cohort studies.The results of work completed previously by the authors that suggested benefit from a more restrictive fluidmanagement strategy might have changed clinical practice in northern Europe sufficiently that this trial was unable to answer the question it set out to address.

当研究者试图显示特定治疗方法的优效性时，通常认为常规治疗对照方法优于创建对比方案。但什么是常规治疗，各地是否一样？本研究中，标准治疗组患者静脉输液量远低于既往国家和国际研究（涉及脓毒性休克患者的早期目标导向复苏）和队列研究中观察到的量。作者之前完成的工作结果表明，从更严格的液体管理策略中获益，可能已充分改变了北欧的临床实践，因此本研究无法回答其提出的问题。

usual-care comparator？

contrasting protocol？