Pakulski C
Oddziału Anestezjologii i Intensywnej Opieki Medycznej Wojewódzkiego Szpitala Zespolonego w Szczecinie.
Ann Acad Med Stetin. 1998;44:285-96.
The aim of the work was to demonstrate whether acute hypercapnia (paCO2 > 65 mm Hg) influenced the permeability of blood-brain barrier (BBB). Twelve Chinchilla rabbits which underwent general anaesthesia were randomly divided into 2 groups. The animals were sedated with intravenous administration of pentobarbital, then were subjected to endotracheal intubation and connected to volume-controlled respirator (Zimmermann pump). Artificial ventilation using air/oxygen mixture was applied. Auricular artery, inferior caval vein and aorta were catheterized with a catheter being also placed in the lateral ventricle of the brain. General anaesthesia was supported with continuous intravenous administration of pentobarbital. To maintain normal paCO2 values, the investigation was performed under normal ventilation in control group (5 rabbits). Controlled hypoventilation was applied to achieve an increase of paCO2 in the shortest possible time in the investigated group (7 rabbits). Heart rate (HR), systolic (SAP), diastolic (DAP) and mean (MAP) arterial blood pressure, intracranial pressure (ICP) and cerebral perfusion pressure (CPP) were continuously recorded. Gentamycin was applied as the marker of function of BBB, because it couldn't penetrate into the cerebrospinal fluid after intravenous administration under physiological conditions. BBB function in normal and significantly increased paCO2 was evaluated using gentamycin permeability indexes (QG), defined as gentamycin concentration ratio in the cerebrospinal fluid to serum gentamycin concentration in the same moment of trial. Comparative analysis of the QG index for both groups according to values achieved before the trial and after 1 and 3 hours of experiment indicates the degree of BBB damage. Non-parametric differences significance test according to Kolmogorow-Smirnow was applied for statistical verification of the results. Significance level for the trial was alpha = 0.05.
None of the monitored parameters has changed in the control group. In the group of hypoventilated animals paCO2 values significantly statistically increased and pH values decreased after 1, 2 and 3 hours of the experiment (Fig. 1). In the investigated group increasing paCO2 values were followed by increase of ICP values, which became statistically significant during the third hour of hypercapnia. No statistically significant changes of the CPP values between animals from the control and investigated groups have been noticed. While comparing mean values of the gentamycin permeability index for the investigated group a minimal, statistically insignificant increase of the indexes has been stated during the first hour of hypercapnia. Continuous severe hypercapnia during next two hours caused increase of mean QG value of over 130% (Tab. 1, Fig. 2). That increase remained statistically insignificant as compared to the initial value and also to the estimated one after the first hour of hypercapnia. While comparing QG indexes between control and investigated groups in the given moments of trial it has been stated that mean QG value is statistically significantly higher in animals hypoventilated for 3 hours than in animals which experienced normal ventilation during the whole experiment.
本研究旨在探讨急性高碳酸血症（动脉血二氧化碳分压[paCO₂]＞65mmHg）是否会影响血脑屏障（BBB）的通透性。12只接受全身麻醉的灰鼠兔被随机分为2组。动物经静脉注射戊巴比妥钠镇静后，进行气管插管并连接容量控制呼吸机（齐默尔曼泵）。采用空气/氧气混合气体进行人工通气。于耳动脉、下腔静脉和主动脉插入导管，同时在脑侧脑室也放置一根导管。通过持续静脉注射戊巴比妥钠维持全身麻醉。为维持正常的paCO₂值，对照组（5只兔）在正常通气条件下进行实验。在研究组（7只兔）中采用控制性低通气，以在尽可能短的时间内使paCO₂升高。持续记录心率（HR）、收缩压（SAP）、舒张压（DAP）和平均动脉压（MAP）、颅内压（ICP）及脑灌注压（CPP）。使用庆大霉素作为血脑屏障功能的标志物，因为在生理条件下静脉注射后它不能透过血脑屏障进入脑脊液。通过庆大霉素通透指数（QG）评估正常及显著升高的paCO₂状态下的血脑屏障功能，QG定义为实验同一时刻脑脊液中庆大霉素浓度与血清中庆大霉素浓度之比。根据实验前及实验1小时和3小时后获得的值，对两组的QG指数进行比较分析，以表明血脑屏障受损程度。采用柯尔莫哥洛夫-斯米尔诺夫非参数差异显著性检验对结果进行统计学验证。实验的显著性水平为α = 0.05。
对照组所有监测参数均未改变。在低通气动物组，实验1小时、2小时和3小时后，paCO₂值显著升高，pH值下降（图1）。在研究组，随着paCO₂值升高，ICP值也升高，在高碳酸血症第3小时具有统计学意义。未发现对照组和研究组动物之间CPP值有统计学显著变化。比较研究组庆大霉素通透指数的平均值，在高碳酸血症第1小时指数有最小幅度的、无统计学意义的升高。接下来两小时持续的严重高碳酸血症导致平均QG值升高超过130%（表1，图2）。与初始值及高碳酸血症第1小时后的估计值相比，该升高仍无统计学意义。在实验给定时刻比较对照组和研究组的QG指数，发现通气不足3小时的动物的平均QG值在统计学上显著高于整个实验过程中经历正常通气的动物。
