critically low levels?

Initially, hemorrhage is a volume problem [18]. With ongoing massive bleeding, coagulation will be increasingly compromised. Regardless of its primary cause, every bleeding will result in coagulopathy if no early intervention is successfully applied. Yet not all coagulation factors will be equally influenced. Even for the singular specialty of PPH, it was shown that coagulopathy is not observed in all women who suffer obstetric hemorrhage and cannot be predicted solely by blood loss. Additionally, different etiologies cause different disturbances in coagulation [21]. However, fibrinogen, the most abundant coagulation factor, is the first to reach critically low levels in severe bleeding events [5].

最初，出血是一个容量问题。随着大出血的持续，凝血功能会越来越差。无论主要原因，若未成功地早期干预，每次出血都会导致凝血障碍。然而，并不是所有的凝血因子都会受到同样的影响。即使对于单纯PPH(产后出血)的特殊情况下，也未在所有产科出血的患者中观察到凝血病且不能仅通过失血量来预测是否会发生凝血病。此外，不同的病因导致不同的凝血障碍。然而，纤维蛋白原（最丰富的凝血因子），在严重出血时首先达到临界低水平。

critically low levels?临界低水平 还是 极低水平？临界低水平就是略低于正常水平吧？