Rutherford W F, Panacek E A, Griffith J K, Green J A, Munger M, Bednarczyk E, Miraldi F, Fisher C J
Department of Internal Medicine, Case Western Reserve University, Cleveland, OH.
Crit Care Med. 1989 Dec;17(12):1328-32. doi: 10.1097/00003246-198912000-00017.
Current methods of assessing cerebral blood flow (CBF) are limited in their ability to provide data at the bedside in a timely, inexpensive, and continuous fashion. Since the palpebral conjunctiva is perfused by branches of the internal carotid artery, perfusion of this tissue may reflect global CBF. Conjunctival oxygen tension (PcjO2), PaO2, PaCO2, and pH were measured in ten healthy subjects during normal ventilation and active hyperventilation. CBF was measured simultaneously using positron emission tomography. CBF decreased from an average of 64.3 +/- 15.1 ml x 100 g-1 x min-1 during baseline measurements to 33.2 +/- 8.4 ml x 100 g-1 x min-1 during hyperventilation. The ratio of PcjO2 to PaO2 (the PcjO2/PaO2 index) decreased from 0.53 +/- 0.07 to 0.35 +/- 0.09 in the same time period. The PcjO2/PaO2 index was significantly correlated with CBF (r = .78, p less than .001). We conclude that the PcjO2/PaO2 index may reflect the reduction in CBF induced by hyperventilation in normal humans, and should be investigated further as a method of assessing CBF in other settings which can result in globally reduced cerebral perfusion.
当前评估脑血流量（CBF）的方法在以及时、廉价且连续的方式在床边提供数据的能力方面存在局限性。由于睑结膜由颈内动脉分支供血，该组织的灌注可能反映整体脑血流量。在十名健康受试者正常通气和主动过度通气期间，测量了结膜氧分压（PcjO2）、动脉血氧分压（PaO2）、动脉血二氧化碳分压（PaCO2）和pH值。同时使用正电子发射断层扫描测量脑血流量。脑血流量在基线测量时平均为64.3±15.1ml·100g⁻¹·min⁻¹，在过度通气时降至33.2±8.4ml·100g⁻¹·min⁻¹。同期，PcjO2与PaO2的比值（PcjO2/PaO2指数）从0.53±0.07降至0.35±0.09。PcjO2/PaO2指数与脑血流量显著相关（r = 0.78，p < 0.001）。我们得出结论，PcjO2/PaO2指数可能反映正常人过度通气引起的脑血流量减少，作为评估其他可能导致整体脑灌注减少情况的脑血流量的一种方法，应进一步研究。
