高浓度七氟醚诱导对髓核摘除术患者脑血流速度的影响

目的观察吸入高浓度七氟醚(8%)诱导时大脑中动脉血流速度的变化。方法椎间盘突出择期行髓核摘除的患者24例,年龄35~55岁,ASAⅠ或Ⅱ级,依诱导方式的不同随机均分为两组,8%七氟醚吸入组(S组)和靶控输注(TCI)丙泊酚-瑞芬太尼组(P组)。记录诱导前(T0)、诱导后1 min(T1)、2 min(T2)、3 min(T3)时的脑血流平均速度(Vmean)、MAP及HR。结果 T1时S组Vmean明显快于T0时及P组(P<0.05),P组各时点Vmean变化差异无统计学意义。结论 8%七氟醚吸入诱导可使脑血流速度加快,尤以诱导后1 min最明显。     

应用SPECT研究地氟醚麻醉对人脑血流分布的影响

目的研究吸入不同浓度地氟醚麻醉下健康志愿者脑血流(CBF)分布的动态变化。方法选择9名志愿者,每位志愿者分别在清醒、吸入0.5和1.0MAC地氟醚后采用单光子发射计算机断层成像(SPECT)仪进行扫描,观察地氟醚麻醉下人局部脑血流(rCBF)的动态变化。结果全脑CBF计数在清醒时为127.5±23.1,吸入0.5MAC地氟醚麻醉后全脑CBF计数为130.8±25.4,吸入1.0MAC地氟醚后为128.8±22.9,三组间比较差异无显著意义;额叶、顶叶、颞叶、枕叶、中脑、小脑、丘脑、海马、基底核、扣带回和舌回等脑区rCBF计数差异也均无显著意义。结论在保持PETCO2和MAP稳定且在正常范围时,吸入地氟醚麻醉不影响人脑内血流量的分布。     

Simultaneous laser-doppler flowmetry of canine spinal cord and cerebral blood flow: Responses toPa_{CO_2 } and blood pressure changes

We observed the relative changes of both spinal cord blood flow (local SCBF) and local cerebral blood flow (local CBF) using independent laser-Doppler flowmeters (LDF) in 12 dogs under N₂O(50%)-O₂-enflurane(1.0%) anesthesia. The dorsal surface of the lumbar spinal cord and the parietal surface of the brain were partially exposed. Two fine LDF probes were placed between the exposed surfaces and the dura maters at each site. Both local SCBF and local CBF decreased simultaneously with hyperventilation and increased with hypoventilation within several seconds. The local SCBF responses to Pa_{CO 2} changes were similar in direction and degree as those of the local CBF. Autoregulation of local SCBF to arterial blood pressure (ABP) changes was abolished, though that of the local CBF was still recognized in a blunted fashion within a mean ABP range of 50 to 150mmHg.(Sadanaga M, Kano T, Hashiguchi A, et al.: Simultaneous laser-Doppler flowmetry of canine spinal cord and cerebral blood flow: Responses to Pa_{CO 2} and blood pressure changes. J Anesth 7: 427--433, 1993)     

异氟醚和异氟醚/N2O麻醉时的脑血流CO2反应性

目的 比较颅脑手术中相同ＭＡＣ（１．３ＭＡＣ）的异氟醚和异氟醚／Ｎ２Ｏ麻醉时的脑血流ＣＯ２反应性。方法 选择ＡＳＡⅠ￣Ⅱ级颅内肿瘤病人行择期开颅手术２０例,随机分为两组：异氟醚组（Ⅰ）：吸入１．５％异氟醚、空气、氧气;异氟醚／Ｎ２Ｏ组（Ｎ）：吸入０．８％异氟醚、（６０￣６５）％Ｎ２Ｏ、氧气,每组１０例。在ＰａＣＯ２为５．３ｋＰａ、３．７ｋＰａ时分别抽取动脉、颈内静脉球部血行血气分析。根据Ｆｉｃｋ公     

腹腔镜胆囊切除术中二氧化碳气腹对脑血流的影响

目的 观察腹腔镜期间二氧化碳气腹对患者脑血流的影响。方法 选择行腹腔镜胆囊切除术患者３０例,ＡＳＡⅠ～Ⅱ级、于气腹前、气腹后１０、３０ｍｉｎ分别采取桡动脉血管颈内静脉血,测定ＰａＯ２、ＰａＣＯ２、ＳａＯ３、颈内静脉血氧分压（ＰｉｖＯ２）和血氧和度（ＳｕｖＯ２）等值。结果与气腹前比较,气腹后１０ｍｉｎ、３０ｍｉｎ的ＳｕｖＯ２、颈内静脉血氧含量（ＣｕｖＯ２）和ＰａＣＯ２无显著性增加（Ｐ〈０．０１）,脑     

硬膜外阻滞对剖宫产胎儿脐血流的影响

目的 观察剖癌产术硬膜外阻滞时对胎儿脐血流的影响。方法 采用多普勒超声仪,探头频率３．５ＭＨｚ,麻醉前测脐静脉,脐动脉,直径。记录ＵＡ收缩期峰值速度,舒张期最低速度 ,平均速度,算出Ｖｍａｘ及Ｖｍｉｎ之比,搏动指数及阻力指数。脉冲多普勒取样线与脐动脉长轴夹角θ≤２０度     

围术期经颅多普勒超声提供的麻醉信息

背景单深度经颅多普勒（transcranial doppler,TCD）技术是脑血流动力学的一种检查方法,具有实时、易操作、可连续监测等优点,可于麻醉过程中监测脑血流速度的改变、血栓的形成,并为术中脑保护提供信息。目的介绍近年TCD在围术期的应用及进展。内容综述不同手术围术期TCD可以提供的麻醉相关信息,如血流速度、脉搏节律变化、血管狭窄及血栓、判断颅内压等。趋向TCD用于围术期脑血流监测具有许多优势,其应用前景广阔。     

Comparison of changes in cerebral blood flow and cerebral oxygen saturation measured by near infrared spectroscopy (NIRS) after acetazolamide

Summary The present study compares the change of cerebral blood flow and HbO₂ measured by near-infrared spectroscopy (NIRS) after administration of 1000 mg acetazolamide intravenously. CBF studies in 21 patients with ischaemic cerebrovascular disease were performed routinely with the¹³³Xenon technique. Additionally the local HbO₂ was recorded by NIRS. A rest study was followed by a second study after the administration of 1000 mg acetazolamide. In 18 patients we observed an increase of 30.8% of CBF and 4.7% of HbO₂, 3 patients showed a decrease of CBF and 2 patients a simultaneous decrease of HbO₂. We did not find a correlation between the absolute values of CBF and HbO₂ at rest or after stimulation. However, a positive correlation (r=0.71, p < 0.05) between the change of CBF and HbO₂ could be detected. Assuming a threshold value of normal CBF reactivity of 30% and 4% HbO₂ reactivity we found for NIRS a sensitivity of 0.88 and a specificity of 0.75.The results demonstrate that changes of CBF can be detected with NIRS and the algorithm of the used monitor is able to calculate the intracranial part of the signal. So, NIRS can be used as non-invasive screening method to test the cerebrovascular reserve capacity.     

Cerebral blood flow in minor cerebral contusion

Seventeen patients with minor cerebral contusion were selected from a series of patients with head injuries of various severity, who had undergone repeat evaluations of the regional cerebral blood flow. The mean global flow (expressed as mean global initial slope index) on early examination was found to be significantly lower, compared with that recorded in healthy volunteers. A tendency towards the recovery of higher flow values was apparent in repeat evaluations that were performed several weeks after the injury. Interhemispheric asymmetries of flow were a common occurrence, with lower perfusion and reduced attenuation values on computed tomography scans being, however, in good agreement only in approximately half of the cases.     

New measurement of hepatic blood flow by xenon CT system: an animal study with PGE1

BACKGROUND: A new Xenon computed tomography (CT) system was developed to measure both hepatic arterial and portal venous tissue blood flow (HATBF/PVTBF) non-invasively. Despite its clinical trial, the effect of prostaglandin E1 (PGE1) on hepatic hemodynamics is not well investigated. In a rabbit model, we evaluated the accuracy of this system by comparing it with the electromagnetic blood flowmeter (EMBF), the pharmacological effect of PGE1 on the fractional hepatic hemodynamics. MATERIALS AND METHODS: Seven NZW-rabbits were used. Serial abdominal CT scan was obtained every min before and during the 4 min inhalation of the Xenon gas, followed by 5 min administration of oxygen air. From these images, HATBF and PVTBF were separately calculated with a special new imaging system. We also used EMBF during laparotomy, and directly measured the hepatic arterial and portal venous flow with or without PGE1 administration. RESULTS: Xenon CT showed HATBF of 18.4 +/- 4.5 (ml/min/100 g) and PVTBF of 69.4 +/- 15.0, was almost identical with those of EMBF (19.8 +/- 5.7 and 67.2 +/- 19.1, respectively). After PGE1 administration, Xenon CT showed 22.9 +/- 4.6 and 76.5 +/- 20.5, while those with EMBF were 21.0 +/- 6.5 and 84.7 +/- 21.6, respectively. There were significant correlations (P < 0.01) in total HTBF, HATBF, and PVTBF between results of Xenon CT and EMBF. CONCLUSIONS: Xenon CT with a newly developed imaging system enables us to measure the fractional hepatic tissue blood flow in rabbits, differentially and accurately. Venous administration of PGE1 increased total hepatic blood flow, mainly affecting the portal blood flow.     

Pulsatile flow improves cerebral blood flow in pediatric cardiopulmonary bypass

The objective of this study was to evaluate the effect of pulsatile flow on cerebral blood flow (CBF) in infants with the use of a mild hypothermic cardiopulmonary bypass (CPB). Thirty infants scheduled for open heart surgery were randomized to the pulsatile group (Group P, n = 15) and nonpulsatile group (Group NP, n = 15). In Group P, pulsatile perfusion was applied during the aortic cross‐clamping period, whereas nonpulsatile perfusion was used in Group NP. The systolic peak velocity (Vs), the end of diastolic velocity (Vd), the mean velocity (Vm), and the pulsatility index (PI) and the resistance index (RI) of the middle cerebral artery were measured by a transcranial Doppler (TCD) ultrasound after anesthesia (T1; baseline), at the beginning of CPB (T2), 10 min after aortic cross‐clamping (T3), 3 min after declamping (T4), at the cessation of CPB (T5), and at the end of the operation (T6). During T3 and T4, the Vs in Group P was significantly higher than in Group NP. However, there were no statistically significant differences between Vd and Vm. The PI and RI in Group P were also higher than those in Group NP (both P < 0.05). During T5, Vd and Vm were higher in Group P (P < 0.05), whereas there was no difference in Vs. Additionally, PI and RI in Group P were significantly lower than those in Group NP (P < 0.05). However, there was no difference during T6. Pulsatile perfusion may increase CBF and decrease cerebral vascular resistance in the early period after mild hypothermic CPB.     

猫脑缺血时脑不同部位脑血流与氨基酸的变化

目的 比较缺血时猫脑不同部位脑血流、氮基酸的变化并研究两者之间的关系。方法 利用激光多普勒血流计，持续监测猫脑不同部位（颞叶、枕叶）在脑缺血时脑皮层表面的血流变化；利用微透析技术，测定相同位置细胞间隙中的氨基酸变化。结果 在阻断猫大脑中动脉（MCA）后，颞叶和枕叶部位的脑血流迅速下降，分别为正常值的21．44％和23．61％，并在2h内缓慢下降；微透析液中谷氨酸浓度迅速增加，可达到正常值的80余倍。结论 缺血时猫颞叶和枕叶的脑血流与谷氨酸浓度变化相同，差异无统计学意义。     

Local cerebral blood flow and partition coefficients measured in cerebral astrocytomas of different grades of malignancy

Local cerebral blood flow and local partition coefficients were measured in patients with different grades of malignant cerebral astrocytomas (n = 5) who inhaled 35% stable xenon during computed tomography scanning. Results were compared with those in age-matched normal subjects (n = 5. Mean values for local cerebral blood flow in the gray matter in patients with astrocytomas were decreased throughout the tumor mass and surrounding brain that was apparently free of tumor. Patients with highly malignant glioblastoma multiforme (astrocytoma grade IV; n = 2) showed more variable values for local cerebral blood flow and local partition coefficients compared to those with astrocytomas of lower grades (grades I-II; n = 3). Local partition coefficients in gray matter invaded by grade IV astrocytoma were significantly higher than those in gray matter invaded by grade I-III astrocytomas. Local cerebral blood flow and local partition coefficients in the brain tissue surrounding grade IV astrocytomas were reduced to a greater extent than those in more benign tumors.     

Local cortical cerebral blood flow and response to carbon dioxide during anesthesia in patients with moyamoya disease

Purpose. The CO₂ reactivity of cortical cerebral vessels and local cortical blood flow (l-CoBF) were evaluated during anesthesia in patients with moyamoya disease who were undergoing revascularization surgery. Methods. Using laser–Doppler flowmetry, the CO₂ reactivity of cortical cerebral vessels and l-CoBF were measured continuously in five patients at the local surgical field of the middle cerebral artery (MCA) territory. Results. Local-CoBF values obtained during the normocapnic condition varied from site to site of gyrus in the MCA region (0–73 ml · 100 g⁻¹·min⁻¹). Local-CoBF was maximal at 39–43 mmHg of the PaCO₂ range, and decreased above and below this range. The response of l-CoBF to CO₂ was larger at the sites where the maximal level was obtained during normocapnia. In two patients, l-CoBF decreased by about 50%, and remained law even 40 min after administration of acetazolamide. Conclusion. In patients with moyamoya disease, l-CoBF values obtained during the normocapnic condition varied from site to site of gyrus, and not only hypocapnia but also hypercapnia decreased l-CoBF within the MCA region. Received for publication on May 29, 1998; accepted on January 26, 1999     

硝普钠在冠状动脉搭桥手术中对脑血流速度的影响

目的 研究硝普钠在冠状动脉搭桥手术中对脑血流速度的影响及在提高大脑供血供氧方面的意义。方法 选择ASAⅡ～Ⅲ级,择期行冠状动脉搭桥手术的患者24例。麻醉诱导后行桡动脉和颈内静脉穿刺置管,颈内静脉留置管放于颈静脉球部。分别在心肺转流(CPB)前(T_1)、CPB初期泵入硝普钠前(T_2)及泵入硝普钠10min后(T_3)三个时相监测下列指标:(1)使用彩色多普勒超声(TCD)测定大脑中动脉的血流速度(CBFV),并计算其搏动指数(PI)和阻力指数(RI);(2)动脉及颈静脉球部血气(SaO_2,SjvO_2),并计算出氧摄取率(COE);(3)平均动脉压(MAP);(4)中心静脉压(CVP)。结果 CPB期间应用硝普钠后,尽管MAP从(65.8±10.8)mmHg降为(47.5±4.8)mmHg(下降27.8％),但大脑中动脉的血流速度由(40.8±6.8)cm/s升高至(43.9±7.6)cm/s(上升7.6％)(P<0.01),搏动指数和阻力指数也有明显下降(P<0.01),而COE未见明显差别(P>0.05)。结论 体外循环期间硝普钠的血管扩张效应尽管在一定程度上降低MAP,但由于脑血管阻力降低、脑血流加速而增加全脑血流量,对脑代谢无不良影响。     

Precerebral arterial blood flow pattern in intracranial hypertension with cerebral blood flow arrest

Summary A pulsed echo Doppler flowmeter was used to confirm cerebral flow arrest in patients with intracranial hypertension resulting in a cerebral perfusion pressure of zero or close to zero. The cerebral angiograms showed non-filling. The term brain tamponade is used for this condition. The patients had a mean arterial blood pressure at the time or recording ranging from 70 to 160 mmHg. Under these conditions the transcutaneous recording of internal carotid artery flow velocity immediately distal to the carotid bifurcation showed a reverberating flow pattern with marked pulsations. The forward flow in systole was counterbalanced by the retrograde flow during diastole resulting in a net flow of zero. This flow pattern is basically caused by a combination of intracranial vascular obstruction, the arterial blood pressure at the site of measurement, and finally the compliance of the distal arterial segment as well as the intracranial compliance. This noninvasive method is of potential value in the determination of intracranial flow arrest.     

腹腔镜下妇科肿瘤切除术中二氧化碳气腹对患者脑血流的影响

目的 观察妇科肿瘤患者腹腔镜手术期间二氧化碳(CO2)气腹对患者脑血流的影响.方法 选择妇科肿瘤行腹腔镜手术的患者40例,美国麻醉医师协会(ASA)分级Ⅰ～Ⅱ级,无心、脑系统疾病,于气腹前、气腹后头低臀高位20 min分别采取桡动脉和颈内静脉血,测定动脉血氧分压(PaO2)、动脉血二氧化碳分压(PaCO2)、动脉血氧饱和度(SaO2)、颈内静脉血氧分压(PjvO2)和颈内静脉血氧饱和度(SjvO2)等值.结果 气腹前SjvO2为(66±7)％,气腹后20min的SjvO2为(84±6)％,颈内静脉血氧含量(CjvO2)气腹前为(9.4±1.6)％,气腹后20 min为(11.6±1.8)％,PaCO2气腹前为(4.2±0.4) kPa,气腹后20 min为(5.3±0.4) kPa,均显著增加(P＜0.01),脑动静脉血氧含量差(Ca-jvDO2)气腹前为(5.1±1.2)％,气腹后为(2.4±0.9)％,显著减少(P＜0.01).结论 妇科肿瘤患者腹腔镜手术期间,CO2气腹对脑循环产生显著影响,脑血流(CBF)显著增加,Ca-jvDO2明显减少.这种变化提示可能存在脑细胞缺氧.     

Effect of ketanserin on cerebral blood flow autoregulation in healthy volunteers

Summary The effect of a clinically relevant dose of ketanserin (10 mg as a bolus followed by an infusion of 6mg/h) on cerebral blood flow (CBF) and CBF autoregulation was examined in 12 healthy volunteers. Changes in CBF were estimated by the cerebral arteriovenous-oxygen saturation difference method, while mean arterial blood pressure (MABP) was increased by norepinephrine and decreased by ganglionic blockade (trimethaphan camphosulphonate) combined with lower body negative pressure one hour after the infusion of ketanserin. During ketanserin infusion, MABP fell insignificantly by 2.5 mmHg (6 to –2), while CBF rose insignificantly by 5 ml/100 g/min. Autoregulation was preserved in all volunteers. CO₂-correction factors from 0 to 4.6% CBF/0.1 kPa were used. The lower limit of CBF autoregulation was 82 mmHg (80–86) with an SE of 3 mmHg (1–5) similar to a previous control group of healthy volunteers. Aside from a major decrease in MABP in one subject, no adverse side effects were observed.The present study shows that CBF autoregulation is maintained during ketanserin infusion.     

Pediatric physiologic pulsatile pump enhances cerebral and renal blood flow during and after cardiopulmonary bypass

Controversy over benefits of pulsatile flow after pediatric cardiopulmonary bypass (CPB) continues. Our study objectives were to first, quantify pressure and flow waveforms in terms of hemodynamic energy, using the energy equivalent (EEP) formula, for direct comparisons, and second, investigate effects of pulsatile versus nonpulsatile flow on cerebral and renal blood flow, and cerebral vascular resistance during and after CPB with deep hypothermic circulatory arrest (DHCA) in a neonatal piglet model. Fourteen piglets underwent perfusion with either an hydraulically driven dual-chamber physiologic pulsatile pump (P, n = 7) or a conventional nonpulsatile roller pump (NP, n = 7). The radiolabeled microsphere technique was used to determine the cerebral and renal blood flow. P produced higher hemodynamic energy (from mean arterial pressure to EEP) compared to NP during normothermic CPB (13 +/- 3% versus 1 +/- 1%, p < 0.0001), hypothermic CPB (15 +/- 4% versus 1 +/- 1%, p < 0.0001) and after rewarming (16 +/- 5% versus 1 +/- 1%, p < 0.0001). Global cerebral blood flow was higher for P compared to NP during CPB (104 +/- 12 ml/100g/min versus 70 +/- 8 ml/100g/min, p < 0.05). In the right and left hemispheres, cerebellum, basal ganglia, and brainstem, blood flow resembled the global cerebral blood flow. Cerebral vascular resistance was lower (p < 0.007) and renal blood flow was improved fourfold (p < 0.05) for P versus NP, after CPB. Pulsatile flow generates higher hemodynamic energy, enhancing cerebral and renal blood flow during and after CPB with DHCA in this model.     

Losartan increases renal blood flow during isoflurane anesthesia in sheep

BACKGROUND: Inhaled anesthetics cause a transient reversible depression of renal function by direct renal effects or indirectly by changes in neurohumoral systems or cardiovascular performance. When the sympathetic nervous activity is decreased during anesthesia, other vasoactive systems like vasopressin (AVP) and particularly the renin angiotensin system (RAS) are of importance for blood pressure maintenance. Little is known about how the renal circulation is affected by angiotensin receptor blockade during isoflurane anesthesia. METHODS: The study was performed on isoflurane anesthetized sheep equipped with flow probes (placed around a femoral and a renal artery) and a pulmonary artery catheter. During stable conditions the sheep were given one or more of the following substances: isotonic saline (NaCl); losartan (LOS) 10 mg x kg(-1); prazosin (PRAZ) 0.2 mg x kg(-1) and a vasopressin V1-receptor antagonist (AVP-a) 10 microg x kg(-1). RESULTS: LOS and AVP-a did not affect mean arterial pressure (MAP), whereas PRAZ lowered MAP significantly (from 98+/-12 to 65+/-7 mmHg). Renal blood flow (RBF) increased after LOS treatment (148+/-34 to 222+/-33 ml x min(-1)). The other substances were without effect on RBF. Femoral blood flow remained unchanged after all treatments. CONCLUSION: We conclude that the sympathoadrenal system is still the major determinant for blood pressure maintenance during isoflurane anesthesia in sheep. The apparently increased activity of the renin angiotensin system in this situation causes a reduction in renal blood flow, which is counteracted by angiotensin II AT1-receptor blockade.