Autoregulation in a Simulator-Based Educational Model of Intracranial Physiology

Objective.To implement a realistic autoregulation mechanism toenhance an existing educational brain model that displays in real-time thecerebral metabolic rate (CMRO₂), cerebral blood flow (CBF),cerebral blood volume (CBV), intracranial pressure (ICP), and cerebralperfusion pressure (CPP). Methods.A dynamic cerebrovascular resistance(CVR) feedback loop adjusts automatically to maintain CBF within a range ofthe CPP and defines autoregulation. The model obtains physiologic parametersfrom a full-scale patient simulator. We assumed that oxygen demand andarterial partial pressure of carbon dioxide (CO₂ responsivity) arethe two major factors involved in determining CBF. In addition, our brainmodel increases oxygen extraction up to 70% once CBF becomes insufficient tosupport CMRO₂. The model was validated against data from theliterature. Results.The model's response varied less than 9%from the literature data. Similarly, based on correlation coefficients betweenthe brain model and experimental data, a good fit was obtained for curvesdescribing the relationship between CBF and PaCO₂ at a meanarterial blood pressure of 150 mm Hg (R² = 0.92) and 100 mm Hg(R² = 0.70). Discussion.The autoregulated brain model, withincorporated CO₂ responsivity and a variable oxygen extraction,automatically produces changes in CVR, CBF, CBV, and ICP consistent withliterature reports, when run concurrently with a METI full-scale patientsimulator (Medical Education Technologies, Inc., Sarasota, Florida). Once themodel is enhanced to include herniation, vasospasm, and drug effects, itsutility will be expanded beyond demonstrating only basic neuroanesthesiaconcepts.     

A controlled study of Dextran 40: effect on cerebral blood flow and metabolic rates in acute head trauma

A controlled double-blind evaluation of the effects of Dextran 40 at different concentrations on cerebral blood flow (CBF), cerebral oxygen consumption (CMRO₂) and cerebral lactate production (CMRLact) was carried out. We studied 40 patients in coma due to recent head injury. Concentrations of Dextran solution were not significantly related to variations in CBF and metabolic rate over the period of infusion. The lack of effect of the Dextran infusion may be explained by the absence of global brain ischemia in these patients at the time of the study. The very low initital CBF values were a consequence of brain metabolic depression and not a sign of global ischaemia. The rheological benefits of treatment with Dextran 40 in head injured patients should preferably be investigated using techniques which permit detection of local changes in CBF and metabolism.     

Cerebral metabolic rate of oxygen (CMRO2) in pig brain determined by PET after resuscitation from cardiac arrest

Aim

To assess the regional vulnerability to ischemic damage and perfusion/metabolism mismatch of reperfused brain following restoration of spontaneous circulation (ROSC) after cardiac arrest.

Method

We used positron emission tomography (PET) to map cerebral metabolic rate of oxygen (CMRO₂), cerebral blood flow (CBF) and oxygen extraction fraction (OEF) in brain of young pigs at intervals after resuscitation from cardiac arrest. After obtaining baseline PET recordings, ventricular fibrillation of 10 min duration was induced, followed by mechanical closed-chest cardiopulmonary resuscitation (CPR) in conjunction with i.v. administration of 0.4 U/kg of vasopressin. After CPR, external defibrillatory shocks were applied to achieve restoration of spontaneous circulation (ROSC). CBF and CMRO₂ were mapped and voxelwise maps of OEF were calculated at times of 60, 180, and 300 min after ROSC.

Results

There was hypoperfusion throughout the telencephalon at 60 min, with a return towards baseline values at 300 min. In contrast, there was progressively increasing CBF in cerebellum throughout the observation period. The magnitude of CMRO₂ decreased globally after ROSC, especially in cerebral cortex. The magnitude of OEF in cerebral cortex was 60% at baseline, tended to increase at 60 min after ROSC, and declined to 50% thereafter, thus suggesting transition to an ischemic state.

Conclusion

The cortical regions tended most vulnerable to the ischemic insult with an oligaemic pattern and a low CMRO₂ whereas the cerebellum instead showed a pattern of luxury perfusion.     

Effect of cigarette smoking on basal and carbon dioxide stimulated cerebral blood flow in man

Summary. The effect of cigarette smoking on the basal cerebral blood flow (CBF) and on the cerebral hyperemia induced by CO₂ breathing was investigated in healthy human volunteers. CBF was measured with the N₂O-wash-in technique in the basal state and during inhalation of 5% CO₂, before and after smoking of two commercial filter tipped cigarettes. In parallel the (arterial-jugular venous) difference in O₂ content, arterial and jugular venous pCO₂, pulmonary ventilation, heart rate and systemic blood pressure were followed. During smoking there was a 10–15 mmHg increase in systemic blood pressure and a parallel elevation of heart rate (+20 beats/min). Cerebral blood flow increased by about 25%, and cerebral vascular resistance fell about 15%. The cerebral metabolic rate of oxygen (CMRO₂) was elevated by about 30% above control. Inhalation of 5% CO₂ by itself markedly increased CBF and decreased cerebral vascular resistance, while leaving CMRO₂ unaffected. Cigarette smoking did not significantly change either of these effects of CO₂ breathing. From these data it is concluded that cigarette smoking elevates systemic blood pressure and decreases cerebral vascular resistance, and thereby augments basal CBF. This flow-promoting effect of smoking is probably due to an increased cerebral consumption of oxygen. Furthermore, the data demonstrate that smoking does not interfere with the cerebral vascular response to increased arterial pCO₂.     

Development of a combined broadband near-infrared and diffusion correlation system for monitoring cerebral blood flow and oxidative metabolism in preterm infants

Neonatal neuromonitoring is a major clinical focus of near-infrared spectroscopy (NIRS) and there is an increasing interest in measuring cerebral blood flow (CBF) and oxidative metabolism (CMRO₂) in addition to the classic tissue oxygenation saturation (StO₂). The purpose of this study was to assess the ability of broadband NIRS combined with diffusion correlation spectroscopy (DCS) to measured changes in StO₂, CBF and CMRO₂ in preterm infants undergoing pharmaceutical treatment of patent ductus arteriosus. CBF was measured by both DCS and contrast-enhanced NIRS for comparison. No significant difference in the treatment-induced CBF decrease was found between DCS (27.9 ± 2.2%) and NIRS (26.5 ± 4.3%). A reduction in StO₂ (70.5 ± 2.4% to 63.7 ± 2.9%) was measured by broadband NIRS, reflecting the increase in oxygen extraction required to maintain CMRO₂. This study demonstrates the applicability of broadband NIRS combined with DCS for neuromonitoring in this patient population.OCIS codes: (170.3660) Light propagation in tissues, (170.3880) Medical and biological imaging, (170.6510) Spectroscopy, tissue diagnostics     

定量磁化率成像评估高原人脑氧代谢的可行性北大核心CSCD

目的观察定量磁化率成像(QSM)测量高原人脑氧代谢率(CMRO_(2))的可行性。方法纳入高原(高原组)及平原地区(平原组)汉族健康志愿者各34名,测量其血红蛋白(Hb)水平、红细胞计数(RBC)及动脉血氧饱和度(SaO_(2));利用QSM联合3D动脉自旋标记技术,获取静息态下大脑定量磁敏感值,利用后处理软件录入高原地区健康志愿者Hb和SaO_(2),计算全脑白质和灰质的氧摄取分数(OEF)、脑血流量(CBF)、动脉血氧含量(CaO_(2))及CMRO_(2),并与QSM常规方法所测平原组OEF及CMRO_(2)进行比较。结果高原组Hb及RBC均大于(P均<0.05)而SaO_(2)小于平原组(P<0.05);组间CaO_(2)差异无统计学意义(P>0.05)。高原组脑白质及脑灰质OEF高于平原组(P均<0.05);组间CBF及CMRO_(2)差异均无统计学意义(P均>0.05)。结论经校准Hb和SaO_(2)后,QSM技术能更准确地反映高原人在低压、缺氧环境下的脑氧代谢情况。     

Caffeine's effects on cerebrovascular reactivity and coupling between cerebral blood flow and oxygen metabolism

The blood-oxygenation-level-dependent (BOLD) signal is dependent on multiple physiological factors such as cerebral blood flow (CBF), local oxygen metabolism (CMRO₂) and cerebral blood volume (CBV). Since caffeine affects both CBF and neural activity, its effects on BOLD remain controversial. The calibrated BOLD approach is an excellent tool to study caffeine because it combines CBF and BOLD measures to estimate changes in CMRO₂. The present study used the calibrated BOLD approach with 5% CO₂ to determine if a 2.5 mg/kg intravenous injection of caffeine changes the coupling between CBF and CMRO₂ during motor and visual tasks. The results show that caffeine decreases n, the CBF:CMRO₂ coupling ratio, from 2.58 to 2.33 in motor (p = 0.006) and from 2.45 to 2.23 in visual (p = 0.002) areas respectively. The current study also demonstrated that caffeine does not alter cerebrovascular reactivity to CO₂. These results highlight the importance of the calibrated BOLD approach in improving interpretation of the BOLD signal in the presence of substances like caffeine.     

CBF/CMRO2 coupling measured with calibrated BOLD fMRI: sources of bias

The coupling between cerebral blood flow (CBF) and cerebral metabolic rate of oxygen (CMRO2) during brain activation can be characterized by an empirical index n, the ratio of fractional CBF changes to fractional CMRO2 changes. Measurements of n have yielded varying results, and it is not known if the observed variability is due to measurement techniques or underlying physiology. The calibrated BOLD approach using hypercapnia offers a promising tool for assessing changes in CBF/CMRO2 coupling in health and disease, but potential systematic errors have not yet been characterized. The goal of this study was to experimentally evaluate the magnitude of bias in the estimate of n that arises from the way in which a region of interest (ROI) is chosen for averaging data and to relate this potential bias to a more general theoretical consideration of the sources of systematic errors in the calibrated BOLD experiment. Results were compared for different approaches for defining an ROI within the visual cortex based on: (1) retinotopically defined V1; (2) a functional CBF localizer; and (3) a functional BOLD localizer. Data in V1 yielded a significantly lower estimate of n (2.45) compared to either CBF (n=3.45) or BOLD (n=3.18) localizers. Different statistical thresholds produced biases in estimates of n with values ranging from 3.01 (low threshold) to 4.37 (high threshold). Possible sources of the observed biases are discussed. These results underscore the importance of a critical evaluation of the methodology, and the adoption of consistent standards for applying the calibrated BOLD approach to the evaluation of CBF/CMRO2 coupling.     

Effect of supplemental dexmedetomidine in interventional embolism on cerebral oxygen metabolism in patients with intracranial aneurysms

ObjectiveTo investigate the effect of supplemental dexmedetomidine in interventional embolism on cerebral oxygen metabolism in patients with intracranial aneurysms.MethodsNinety patients who underwent interventional embolism of intracranial aneurysms were equally divided into Group A and Group B. In Group A, dexmedetomidine was injected intravenously 10 minutes before inducing anesthesia, with a loading dose of 0.6 µg/kg followed by 0.4 µg/kg/hour. Group B received the same amount of normal saline by the same injection method. Heart rate (HR), mean arterial pressure (MAP), arterial–jugular venous oxygen difference [D(a-jv) (O₂)], cerebral oxygen extraction [CE (O₂)], and intraoperative propofol use were recorded before inducing anesthesia (T₀) and at five time points thereafter.ResultsThe amount of propofol in Group A was lower vs Group B. At all five time points after T₀, HR, MAP, D(a-jv) (O₂), and CE (O₂) in Group A were significantly lower vs Group B, with significant differences for jugular venous oxygen saturation (S_jvO₂) and the oxygen content of the internal jugular vein (C_jvO₂) between the groups.ConclusionDexmedetomidine resulted in less intraoperative propofol, lower D(a-jv) (O₂) and CE (O₂), and improved cerebral oxygen metabolism.     

最大斜率法与去卷积算法在64层螺旋CT脑灌注后处理中的应用比较

目的 比较常用对比剂流率(6 ml/s)下最大斜率法和去卷积算法在64层螺旋CT后处理中的差异.方法 收集32例接受64层螺旋CT头部平扫及灌注成像的患者,分别利用基于最大斜率模型和去卷积模型的灌注软件包进行后处理,在双侧皮质区绘制感兴趣区(ROI),测量CT灌注绝对参数值:脑血流量(CBF)、脑血容量(CBV)、平均通过时间(MTT)和达峰时间(TTP),以患侧参数值与对侧正常参数值的比值为相对参数值.由2位有经验的神经放射医师分别根据各参数伪彩功能图结合双侧灌注参数值盲法做出诊断,以配对t检验进行统计学分析.结果 灌注正常组应用基于两种模型的灌注软件包所得各项参数绝对值差异均有统计学意义(P＜0.01),各相对值差异均无统计学意义(P＞0.05).单侧灌注异常组应用基于两种模型的灌注软件包所得灌注异常侧MTT、CBV绝对值差异有统计学意义(P＜0.01),TTP、CBF绝对值差异无统计学意义(P＞0.05),各参数相对值差异均无统计学意义(P＞0.05).结论 在临床常用注射流率(6 ml/s)下,最大斜率法会低估CBF,其所得MTT、CBV绝对值均明显大于相应去卷积算法所得值.计算相对值不仅能弥补在低注射流率下最大斜率法的不足,而且能消除由不同后处理算法本身所带来的结果差异,能更好地用于定性、定量分析.     

Day-to-Day Test–Retest Variability of CBF,CMRO<Subscript>2</Subscript>, and OEF Measurements Using Dynamic <Superscript>15</Superscript>O PET Studies

Purpose  

We assessed test–retest variability of cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO₂), and oxygen extraction fraction (OEF) measurements derived from dynamic ¹⁵O positron emission tomography (PET) scans.     

MRI 梯度回波T2 加权序列对脑内海绵状血管瘤的诊断价值

目的　通过分析比较自旋回波 (SE)序列和梯度回波T2 WI(准T2 序列T 2 )序列对脑内海绵状血管瘤 (CA)的显示能力 ,以探讨T 2 技术对CA的诊断价值。方法　对 18例CA病人采用SE和T 2 序列进行MRI检查 ,观察两者对CA病灶的检测能力。结果　SE序列共检出 2 3个CA病灶。而T 2 序列则比前者多发现 2 0个CA病灶。T 2 序列能更准确识别邻近蛛网膜下腔的皮层下和缺血灶附近的小CA病灶。结论　CA病人MRI检查时 ,常规SE序列与T 2 相结合 ,能更全面准确地提供诊断信息。     

Effects of hypertonic (3%) saline in rats with circulatory shock and cerebral ischemia after heatstroke

Objective To evaluate the effects of hypertonic (3%) saline in heatstroke rats with circulatory shock, intracranial hypertension, and cerebral ischemia.Design and setting Urethane-anesthetized rats were exposed to a high ambient temperature of 42°C until mean arterial pressure and local cerebral blood flow (CBF) in the corpus striatum began to decrease from their peak levels, which was arbitrarily defined as the onset of heatstroke. Control rats were exposed to 24°C.Measurements and results Extracellular concentrations of glutamate and lactate/pyruvate ratio (cellular ischemia markers), and glycerol (a cellular injury marker) in the corpus striatum of rat brain were assessed by intracerebral microdialysis methods. Striatal PO₂, temperature, and local CBF were measured with a combined OxyLite PO₂, thermocouple, and OxyFlo LDF, respectively. The values of mean arterial pressure, cerebral perfusion pressure, and striatal CBF and PO₂ in rats treated with 0.9% NaCl solution after the onset of heatstroke were all significantly lower than those in normothermic controls. In contrast, the values of intracranial pressure, brain temperature, and extracellular concentrations of glutamate, glycerol, and lactate/pyruvate in the corpus striatum were greater. Intravenous infusion of hypertonic (3%) saline solution either "0" time before the start of heat exposure or right after the onset of heatstroke significantly attenuated the heatstroke-induced arterial hypotension, intracranial hypertension, decreased cerebral perfusion, and cerebral ischemia and damage and resulted in prolongation of survival time.Conclusions Our results strongly suggest that the experimental heatstroke syndromes can be effectively prevented and treated by hypertonic saline.An editorial regarding this article can be found in the same issue ()     

Hypothermia effects on neurovascular coupling and cerebral metabolic rate of oxygen

Neuronal activation is accompanied by a local increase in cerebral blood flow (CBF) and in cerebral metabolic rate of oxygen (CMRO(2)), caused by neurovascular and neurometabolic coupling. Hypothermia is used as a neuroprotective approach in surgical patients and therapeutically after cardiac arrest or stroke. The effect of hypothermia on neurovascular coupling is of interest for evaluating brain function in these patients, but has not been determined so far. It is not clear whether functional hyperaemia actually operates at subnormal temperatures. In addition, decreasing brain temperature reduces spontaneous CMRO(2) following a known quantitative relationship (Q(10)). Q(10) determination may serve to validate a recently introduced CMRO(2) measurement approach relying on optical measurements of CBF and hemoglobin concentration. We applied this method to investigate hypothermia in a functional study of the somatosensory cortex. Anesthetized Wistar rats underwent surgical implantation of a closed cranial window. Using laser Doppler flowmetry and optical spectroscopy, relative changes in CBF and hemoglobin concentration were measured continuously. At the same time, an electroencephalogram (EEG) was recorded from the measurement site. By the application of ice packs, whole-body hypothermia was induced, followed by rewarming. Spontaneous EEG, CBF and CMRO(2) were measured, interleaved by blocks of electrical forepaw stimulation. The Q(10) obtained from spontaneous CMRO(2) changes of 4.4 (95% confidence interval 3.7-5.1) was close to published values, indicating the reliability of the CMRO(2) measurement. Lowering brain temperature decreased functional changes of CBF and CMRO(2) as well as amplitudes of somatosensory evoked potentials (SEP) to the same degree. In conclusion, neurovascular and neurometabolic coupling is preserved during hypothermia.     

Effect of moderate hyperventilation and induced hypertension on cerebral tissue oxygenation after cardiac arrest and therapeutic hypothermia

Aim

Improving cerebral perfusion is an essential component of post-resuscitation care after cardiac arrest (CA), however precise recommendations in this setting are limited. We aimed to examine the effect of moderate hyperventilation (HV) and induced hypertension (IH) on non-invasive cerebral tissue oxygenation (SctO₂) in patients with coma after CA monitored with near-infrared spectroscopy (NIRS) during therapeutic hypothermia (TH).

Methods

Prospective pilot study including comatose patients successfully resuscitated from out-of-hospital CA treated with TH, monitored with NIRS. Dynamic changes of SctO₂ upon HV and IH were analyzed during the stable TH maintenance phase. HV was induced by decreasing PaCO₂ from ∼40 to ∼30 mmHg, at stable mean arterial blood pressure (MAP ∼ 70 mmHg). IH was obtained by increasing MAP from ∼70 to ∼90 mmHg with noradrenaline.

Results

Ten patients (mean age 69 years; mean time to ROSC 19 min) were studied. Following HV, a significant reduction of SctO₂ was observed (baseline 74.7 ± 4.3% vs. 69.0 ± 4.2% at the end of HV test, p < 0.001, paired t-test). In contrast, IH was not associated with changes in SctO₂ (baseline 73.6 ± 3.5% vs. 74.1 ± 3.8% at the end of IH test, p = 0.24).

Conclusions

Moderate hyperventilation was associated with a significant reduction in SctO₂, while increasing MAP to supra-normal levels with vasopressors had no effect on cerebral tissue oxygenation. Our study suggests that maintenance of strictly normal PaCO₂ levels and MAP targets of 70 mmHg may provide optimal cerebral perfusion during TH in comatose CA patients.     

允许性高碳酸血症机械通气对新生猪脑血流的影响

目的 探讨允许性高碳酸血症(PHC)对急性呼吸衰竭新生猪机械通气时脑血流及组织代谢的影响.方法 18只新生猪随机(随机数字法)分为PHC组、标准碳酸血症(NC)组、健康对照组(Control);PHC(PaCO250～60 mmHg)与NC组(PaCO2 35～45 mmHg)以胎粪致急性呼吸衰竭,机械通气;每组6只.应用彩色微球示踪技术,测定脑组织血流速度(CBF),脑组织氧代谢率(CMRO2)、脑组织糖代谢率(CMRGlu)、脑组织乳酸生成率(CLP).结果 NC组新生猪在机械通气6 h,12 h时点CBF较Control组显著降低(P＜0.05);12 h时点CMRGlu及CLP较Control组升高,CMRO2较Control组降低;CBF/CMRGlu及CBF/CLP比值在6 h及12 h均较Control组降低(P＜0.05).NC组CBF/CMRO2与Control组相比,差异具有统计学意义(P＞0.05).PHC组在6 h CBF较Control组降低;12h时点,PHC组CBF与Control组相比,差异无统计学意义;PHC组各时点CMRO2,CMRGlu,CLP与Control组相比,差异均无统计学意义.CBF/CMRGlu及CBF/CLP比值在机械通气6 h,12 h时点,PHC组低于Control组,但与NC组相比,下降程度已减少(P＜0.05);PHC组CBF/CMRO2与Control组相比,差异无统计学意义.结论 急性呼吸衰竭新生猪予正常碳酸血症水平机械通气时,CBF降低,存在脑血流-代谢调节障碍.PHC可减轻CBF下降,改善急性呼吸衰竭新生猪在正压通气时的脑血流-代谢调节障碍.

Abstract：

Objective To investigate the effects of permissive hypercapnia (PHC) strategy used in ventilated newborn swine with respiratory failure on cerebral blood flow (CBF) and tissue metabolism. Method Eighteen newborn swine were randomly (random number) divided into 3 groups (n = 6): PHC, normocapnia (NC) and normal control groups. In PHC (PaCO2 50～60 mmHg) and NC (PaCO2 35 ～ 45 mmHg) groups, newborn swine were ventilated for treating respiratory failure induced by meconium aspiration. CBF was measured by using colored microsphere tracking technique. Cerebral oxygen metabolism rate (CMRO2), cerebral glucose metabolism rate (CMRGlu), and cerebral lactate production (CLP) were measured. Results After ventilation for 6 hours and 12hours, CBF in NC group decreased more significantly than those did in control group, and CMRGlu and CLP increased more significantly than those did in control group. In NC group, CMRO2 decreased more prominently than it did in control group 12 hours later. The CBF/CMRGlu and CBF/CLP ratios in NC group were lower than those in control(P＜0.05). There was no significant difference in CBF/CMRO2 ratio between NC and control groups. After ventilation for 6 hours, CBF in PHC group was lower than those in control group. But after ventilation for 12hours, CBF in PHC group increased and there was no significant difference in CBF between PHC group and control group (P＞O.05). There were no significant differences in CMRGlu, CLP and CMRO2 between PHC group and control group. The CBF/CMRGlu and CBF/CLP ratios in PHC group were lower than those in control, but higher then those in NC group (P＜0.05). There was no significant difference in CBF/CMRO2 ratio between PHC and control groups. Conclusions The reduction of cerebral blood flow and the disturbance of CBF autoregulation disturbance occur in ventilated newborn swine with hypoxemia respiratory failure. PHC may attenuate the reduction in CBF and the disturbance of CBF autoregulation.     

Cerebral blood flow and metabolism in severe brain injury: the role of pressure autoregulation during cerebral perfusion pressure management

Objective: To ascertain if norepinephrine can be used as part of the cerebral perfusion pressure (CPP) management to increase arterial blood pressure (MAP) without causing cerebral hyperemia after severe head injury (HI).¶Design: Prospective, interventional study.¶Setting: Intensive care unit in a university hospital.¶Patients: Twelve severely HI patients; median Glasgow Coma Scale was 6 (range 3–8).¶Interventions: CPP management ( = 70 mmHg). Pressure autoregulation (assessed by norepinephrine infusion) was defined intact if %CPP/%CVR ≤ 2.¶Results: Cerebral blood flow (CBF: Xe¹³³ inhalation technique), jugular bulb oxygen saturation (SjO₂) and transcranial Doppler (TCD) were recorded during the test. Norepinephrine increased CPP by 33 % ( ± 4). Autoregulation was found to be intact in ten patients and defective in two. In the ten patients with preserved autoregulation, CBF decreased from 31 ± 3 to 28 ± 3 ml/100 g/min; in the two patients with impaired autoregulation CBF increased respectively from 16 to 35 and from 21 to 70 ml/100 g/min. SjO₂ did not change significantly from baseline. TCD remained within the normal range.¶Conclusions: During CPP management norepinephrine can be used to increase MAP without potentiating hyperemia if pressure autoregulation is preserved. The assessment of pressure autoregulation should be considered as a guide for arterial pressure-oriented therapy after HI.     

动态CT脑血流灌注测量及临床初步应用

目的 探讨动态CT脑血流灌注测量的临床应用。方法 13名正常成人,5名临床疑有脑缺血患者和2名临床初诊为继发性帕金森病患者进行了动态CT脑血流测量。结果 正常脑灰质血流灌注量为59．3－96．8ml.min^-1,100g^-1,平均76．2ml.min^-1,100g^-1 ;正常脑白质血流灌注量为27．1－43．1ml.min^-1.100g^-1,平均33．9ml.min^-1.100g^-1。5 临床疑有缺血性脑血管病中,4例发现局部脑血流灌注量下降,1例见局部脑血流灌注量增加。2例临床初诊继发性帕金森病中,1例见左侧壳核血流灌注量下降,1例双侧脑血流灌注量未见明显差异,结论 动态CT脑血流灌注测量可以显示正常脑组织以及病变的血液动力学变化。与常规CT检查相结合可同时了解病变的形态学变化和功能变化。     

The peripheral perfusion index and transcutaneous oxygen challenge test are predictive of mortality in septic patients after resuscitation

Introduction

The peripheral perfusion index (PI) is a noninvasive numerical value of peripheral perfusion, and the transcutaneous oxygen challenge test (OCT) is defined as the degree of transcutaneous partial pressure of oxygen (PtcO₂) response to 1.0 FiO_2. The value of noninvasive monitoring peripheral perfusion to predict outcome remains to be established in septic patients after resuscitation. Moreover, the prognostic value of PI has not been investigated in septic patients.

Methods

Forty-six septic patients, who were receiving PiCCO-Plus cardiac output monitoring, were included in the study group. Twenty stable postoperative patients were studied as a control group. All the patients inspired 1.0 of FiO₂ for 10 minutes during the OCT. Global hemodynamic variables, traditional metabolic variables, PI and OCT related-variables were measured simultaneously at 24 hours after PiCCO catheter insertion. We obtained the 10min-OCT ((PtcO₂ after 10 minutes on inspired 1.0 oxygen) - (baseline PtcO₂)), and the oxygen challenge index ((10min-OCT)/(PaO₂ on inspired 1.0 oxygen - baseline PaO₂)) during the OCT.

Results

The PI was significantly correlated with baseline PtcO₂, 10min-OCT and oxygen challenge index (OCI) in all the patients. The control group had a higher baseline PtcO₂, 10min-OCT and PI than the septic shock group. In the sepsis group, the macro hemodynamic parameters and ScvO₂ showed no differences between survivors and nonsurvivors. The nonsurvivors had a significantly lower PI, 10min-OCT and OCI, and higher arterial lactate level. The PI, 10min-OCT and OCI predicted the ICU mortality with an accuracy that was similar to arterial lactate level. A PI <0.2 and a 10min-OCT <66mmHg were related to poor outcome after resuscitation.

Conclusions

The PI and OCT are predictive of mortality for septic patients after resuscitation. Further investigations are required to determine whether the correction of an impaired level of peripheral perfusion may improve the outcome of septic shock patients.     

Effects and mechanisms of catechin for adjuvant arthritis in rats

The present study was carried out to investigate the effects of catechin on adjuvant arthritis (AA) in the rat and its possible mechanisms of action. AA was induced by metatarsal footpad injection with complete Freund’s adjuvant in male Sprague-Dawley rats. The secondary inflammatory reaction was evaluated through assessment of hind paw swelling, polyarthritis index, and pain response. Proliferation of synoviocytes and the activity of interleukin-1 were examined by 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Tumor necrosis factor-α, prostaglandin E₂ (PGE₂), and cyclic adenosine monophosphate levels in synoviocytes were measured by radioimmunoassay. The PGE₂ receptor, EP₂, was analyzed by Western blot analysis. Intragastric administration of catechin (60 and 120 mg/kg) significantly suppressed secondary inflammatory paw swelling, pain response, and polyarthritis index. It also inhibited production of interleukin-1, tumor necrosis factor-α, and PGE₂ and increased cyclic adenosine monophosphate levels in rats with AA. In the immunoblot analysis, catechin could upregulate expression of EP₂ in the synoviocytes of rats with AA. The results showed that catechin reduced secondary inflammation in rats with AA; this outcome reflects its ability to mediate cAMP levels, upregulate expression of EP₂, and inhibit secretion of proinflammatory cytokines in rats with AA.