Fritschka E, Ferguson J L, Spitzer J J
Circ Shock. 1980;7(3):333-42.
This study was performed to determine if autoregulation of regional cerebral blood flow (rCBF) occurs in conscious dogs with ventriculocisternal perfusion (VCP) during moderate hypotension. Six dogs were perfused for 360 minutes using mock cerebrospinal fluid (CSF). A 120-minute control period was followed by 180 minutes of moderate hemorrhagic hypotension (mean arterial pressure (SAP) 60-80 mm Hg). The lost blood (approximately 40% of the calculated blood volume) was retransfused after 300 minutes of perfusion, and an additional 60 minutes of observation concluded the study. The rCBF was measured at 120, 240, and 360 minutes of perfusion using labeled microspheres of 15 mu diameter. Cardiac output (CO) was 2.8 +/- 0.41 liters/min at 120 minutes, decreased to 1.4 +/- 0.10 liters/min after hemorrhage, and rose after retransfusion to 2.2 +/- 0.13 liters/min. The percentage of cardiac output (%CO) received by the brain was 1.8 +/- 0.37% at 120 minutes, 3.8 +/- 0.44% at 240 minutes, and 2.2 +/- 0.22% after retransfusion (P < 0.05). There was no significant change in rCBF during hypotension. The regional cerebral blood flow was, however, significantly elevated in the thalamus, mesencephalon, pons, and medulla after retransfusion indicated a local alteration of set point in the plateau of the autoregulatory curve. Cerebral venous pH (measured in internal maxillary venous blood) decreased significantly during hemorrhage to 7.25, while cerebral arteriovenous difference of oxygen and A-VpH increased significantly during hemorrhage. Thus, autoregulation of total cerebral blood flow (CBF) during acute moderate hypotension remains intact during VCP at a rate of 0.2 ml/min using a perfusate of a constant pH and, hence, CSF-pH appears not to be of major significance for the autoregulation of CBF in moderate hypotension.
本研究旨在确定在中度低血压期间，脑室脑池灌注（VCP）的清醒犬是否存在局部脑血流量（rCBF）的自动调节。6只犬使用模拟脑脊液（CSF）灌注360分钟。120分钟的对照期后是180分钟的中度出血性低血压（平均动脉压（SAP）60 - 80 mmHg）。灌注300分钟后回输丢失的血液（约占计算血容量的40%），并额外观察60分钟结束研究。使用直径15μm的标记微球在灌注120、240和360分钟时测量rCBF。120分钟时心输出量（CO）为2.8±0.41升/分钟，出血后降至1.4±0.10升/分钟，回输后升至2.2±0.13升/分钟。脑接受的心输出量百分比（%CO）在120分钟时为1.8±0.37%，240分钟时为3.8±0.44%，回输后为2.2±0.22%（P<0.05）。低血压期间rCBF无显著变化。然而，回输后丘脑、中脑、脑桥和延髓的局部脑血流量显著升高，表明自动调节曲线平台期设定点的局部改变。出血期间脑静脉pH（在内颌静脉血中测量）显著降至7.25，而出血期间脑动静脉氧差和A - VpH显著增加。因此，在使用恒定pH灌流液以0.2毫升/分钟的速率进行VCP期间，急性中度低血压期间全脑血流量（CBF）的自动调节保持完整，因此，CSF - pH在中度低血压中对CBF的自动调节似乎没有重大意义。
