Müller Thomas, Löhle Matthias, Schubert Harald, Bauer Reinhard, Wicher Carola, Antonow-Schlorke Iwa, Sliwka Ulrich, Nathanielsz Peter W, Schwab Matthias
Institute of Laboratory Animal Science, Friedrich Schiller University, D-07740 Jena, Germany.
J Physiol. 2002 Mar 15;539(Pt 3):957-67. doi: 10.1113/jphysiol.2001.012590.
We validated laser Doppler flowmetry (LDF) for long-term monitoring and detection of acute changes of local cerebral blood flow (lCBF) in chronically instrumented fetal sheep. Using LDF, we estimated developmental changes of cerebral autoregulation. Single fibre laser probes (0.4 mm in diameter) were implanted in and surface probes were placed on the parietal cerebral cortex at 105 +/- 2 (n = 7) and 120 +/- 2 days gestational age (dGA, n = 7). Basal lCBF was monitored over 5 days followed by a hypercapnic challenge (fetal arterial partial pressure of CO(2), P(a,CO2): 83 +/- 3 mmHg) during which lCBF changes obtained by LDF were compared to those obtained with coloured microspheres (CMSs). Mean arterial blood pressure (MABP) was increased and decreased using phenylephrine and sodium nitroprusside at 110 +/- 2 and 128 +/- 2 dGA. Intracortical and cortical surface laser probes gave stable measurements over 5 days. The lCBF increase during hypercapnia obtained by LDF correlated well with flows obtained using CMS (r = 0.89, P < 0.01). The signals of intracortical and surface laser probes also correlated well (r = 0.91, P < 0.01). Gliosis of 0.35 +/- 0.06 mm around the tip of intracortical probes did not affect the measurements. The range of MABP over which cerebral autoregulation was observed increased from 20-48 mmHg at 110 dGA to 35 to > 95 mmHg at 128 dGA (P < 0.05). Since MABP increased from 33 to 54 mmHg over this period (P < 0.01), the range between the lower limit of cerebral autoregulation and the MABP increased from 13 mmHg at 110 dGA to 19 mmHg at 128 dGA (P < 0.01). LDF is a reliable tool to assess dynamic changes in cerebral perfusion continuously in fetal sheep.
我们验证了激光多普勒血流仪（LDF）用于长期监测和检测慢性植入仪器的胎羊局部脑血流量（lCBF）急性变化的能力。使用LDF，我们估计了脑自动调节的发育变化。在妊娠105±2天（n = 7）和120±2天（n = 7）时，将单纤维激光探头（直径0.4 mm）植入顶叶大脑皮层并将表面探头放置在其表面。在5天内监测基础lCBF，随后进行高碳酸血症激发试验（胎儿动脉血二氧化碳分压，P(a,CO2)：83±3 mmHg），在此期间将LDF获得的lCBF变化与彩色微球（CMS）获得的变化进行比较。在妊娠110±2天和128±2天时，使用去氧肾上腺素和硝普钠升高和降低平均动脉血压（MABP）。皮质内和皮质表面激光探头在5天内给出了稳定的测量值。LDF获得的高碳酸血症期间lCBF增加与使用CMS获得的血流密切相关（r = 0.89，P < 0.01）。皮质内和表面激光探头的信号也密切相关（r = 0.91，P < 0.01）。皮质内探头尖端周围0.35±0.06 mm的胶质增生不影响测量。观察到脑自动调节的MABP范围从妊娠110天时的20 - 48 mmHg增加到妊娠128天时的35至> 95 mmHg（P < 0.05）。由于在此期间MABP从33 mmHg增加到54 mmHg（P < 0.01），脑自动调节下限与MABP之间的值从妊娠110天时的13 mmHg增加到妊娠128天时的19 mmHg（P < 0.01）。LDF是一种可靠的工具，可连续评估胎羊脑灌注的动态变化。
