Daboussi A, Fourcade O
Département d'anesthésie-réanimation, hôpital Purpan, CHU de Toulouse, place du Docteur-Baylac, 31059 Toulouse cedex 09, France.
Ann Fr Anesth Reanim. 2006 Jul;25(7):729-34. doi: 10.1016/j.annfar.2006.03.010. Epub 2006 May 11.
The ischemic threshold is reached when the availability of oxygen in the cerebral tissue does not cover oxygen requirement. For a patient sedated, with constant PaO(2) and haemoglobin, the cerebral blood flow (CBF) global and local is the essential factor to maintain such a balance. At a cellular level, ischemia occurs when the CBF is below 20-25 ml/min. However, this threshold probably varies with the patient and also within the normal or perilesional tissue. A cerebral perfusion pressure (CPP) of 60 mmHg, recommended for a cerebral perfusion allowing a sufficient CBF for normal brain, does not prevent ischemia. Monitoring aimed to control parameters of the aerobic metabolism (PtiO(2), SjO(2) and microdialysis) and to detect the ischemic threshold allows to adapt the CPP to each patient and continuously.
当脑组织中的氧供应无法满足氧需求时，就会达到缺血阈值。对于一名处于镇静状态、动脉血氧分压（PaO₂）和血红蛋白恒定的患者，全脑和局部脑血流量（CBF）是维持这种平衡的关键因素。在细胞水平上，当脑血流量低于20 - 25毫升/分钟时会发生缺血。然而，这个阈值可能因患者不同而有所差异，并且在正常组织或病灶周围组织中也会有所不同。为了实现能为正常大脑提供足够脑血流量的脑灌注而推荐的60毫米汞柱的脑灌注压（CPP），并不能预防缺血。旨在控制有氧代谢参数（脑组织氧分压（PtiO₂）、颈静脉血氧饱和度（SjO₂）和微透析）并检测缺血阈值的监测，能够使脑灌注压根据每个患者的情况进行持续调整。
