没看明白

Interestingly, 500 mL was also the median volume fluid challenge used in the FENICE study(an observational study including 311 centres across 46 countries)[16] whereas a fluid challenge of 250 mL is usually adopted in high-risk surgical patients undergoing goal-directed ther- apy optimisation [31].The use of large volumes for fluid challenge optimisation should be balanced to the detrimental risk of fluid overload [9], primarily if safety limits(i.e., increase in CVP) dynamically indicate fluid non- responsiveness are rarely used [19]. Since fluid challenge volume should be at least 4 mL/kg [32]， smaller fluid challenge volumes may be considered for repetitive tests.

有趣的是，500 mL也是FENICE研究（一项观察性研究，包括46个国家的311个中心）中使用的补液试验中位液体量[16]，而接受目标导向治疗优化的高危手术患者通常补液试验采用250 mL液体[31]。使用大量液体进行补液试验优化时应平衡液体超负荷的风险[9]，尤其当很少使用安全限值( 即 CVP增加 )的动态指标来反应补液试验无响应时。由于补液试验量应至少为4 mL/kg[32]，因此重复补液试验可考虑较小的补液量。

safety limits（主语）are rarely used，dynamically indicate fluid non- responsiveness 定语修饰safety limits？如果是这样，indicate不应该写成indicating吗？