颈内动脉颅外段重度狭窄或闭塞后颅内循环的经颅多普勒超声分析

目的:应用经颅多普勒超声(TCD)对颈内动脉颅外段重度狭窄或闭塞的颅内血流动力学进行分析。方法:采用64层螺旋CT血管造影(CTA)筛查单侧重度颈动脉狭窄或闭塞的患者,用TCD对颅内动脉的血流动力学改变进行评价。结果:(1)重度颈内动脉狭窄或闭塞病变同侧的大脑中动脉平均血流速度和搏动指数均低于对侧。(2)侧支循环开放形成,前交通动脉开放占63.5%,后交通动脉开放占46%,颈内外动脉开放占44%。结论:重度颈内动脉颅外段狭窄或闭塞使同侧半球血流速度下降,侧支循环建立,TCD与CTA从不同角度对颈动脉病变提供诊断治疗依据。     

颈内动脉重度狭窄或闭塞的经颅多普勒超声改变

目的应用经颅多普勒超声(TCD)对颅内动脉狭窄≥70%或闭塞的颅内血管侧支循环进行分析.方法 32例经血管数字减影(DSA)证实为颅内动静脉重度狭窄或闭塞的患者,采用TCD对颅内willis环动脉血管的血流速度、血流方向及脉动指数进行观察.结果 DSA示ICA狭窄≥70%时,TCD可见患侧颈内动脉(ICA)支配的远端颅内血管血流速缓慢,侧支循环开放.表现为前交通动脉开放,后交通动脉开放及颈内外动脉之间的侧支循环开放.结论 TCD通过对颅内血管侧支循环的分析,可评价ICA重度狭窄或闭塞引起的颅内血管血流动力学变化,为临床提供一种无创性检测方法.     

超声对颈内动脉严重狭窄或闭塞时颅内侧支循环情况的评价

目的应用经颅彩色双功超声(TCCS)评价颈内动脉严重狭窄或闭塞时颅内侧支循环的建立情况。方法采用彩色多普勒血流成像筛选单侧颈内动脉严重狭窄或闭塞的患者,用TCCS检测颅内主要动脉的血流动力学变化。结果①有前交通动脉参与的侧支循环与中风发生呈负相关,而眼动脉(OA)参与的侧支循环与中风发生呈正相关。②无症状组及有症状组颈内动脉严重狭窄或闭塞的患者患侧大脑中动脉(MCA)的收缩期峰值流速、搏动指数明显低于健侧及对照组。无症状组患侧OA的收缩期峰值流速、搏动指数与健侧及对照组比较无统计学意义,而有症状组OA的收缩期峰值流速、搏动指数明显低于健侧及对照组。结论TCCS检测颅内主要动脉的血流动力学变化,可以方便地评价颅内侧支循环状态,对颈内动脉严重狭窄或闭塞患者治疗和预后的判断具有重要的临床价值。     

颈动脉连续波多普勒超声评估颅内侧支循环

目的探讨颈动脉连续波多普勒超声评估颅内侧支循环。方法对80例无脑供血动脉狭窄性病变患者,在行颈总动脉压迫试验时采用4 MHz连续波探头检测对侧颈内动脉起始段和同侧椎动脉寰枢段血流速度变化。并对连续波多普勒超声与经颅多普勒超声检测的侧支循环方式结果进行比较。结果颈动脉连续波多普勒超声检出前交通动脉侧支开放76例(95%),经颅多普勒超声检出前交通动脉侧支开放76例(95%)。在受检的160个后交通动脉侧支中,颈动脉连续波多普勒超声检出后交通动脉侧支开放140个(88%),经颅多普勒超声检出132个(83%)。结论颅外动脉连续波多普勒超声结合颈总动脉压迫试验检测颅内侧支循环既安全又方便,其准确率与经颅多普勒超声一致。     

急性颈内动脉闭塞颅内循环的变化及临床意义

目的 分析急性颈内动脉闭塞后颅内血流动力学的变化及临床意义.方法 对68例经影像学检查证实急性单侧颈内动脉颅外段闭塞患者,采用经颅多普勒超声(TCD)检测颅内主要动脉的血流动力学变化.结果 患侧大脑中动脉峰值流速和搏动指数均显著低于健侧(P<0.001).在侧支循环开放中,前交通动脉开放占48.53%(33/68),后交通动脉开放为42.65%(29/68),眼动脉参与的侧支循环占32.35%(22/68),无交通支开放14.71%(10/68).患者颅内侧支循环开放,侧支途径两支以上者、患侧大脑中动脉峰值流速>60 cm/s者,临床预后相对较好.结论 TCD检测颅内主要动脉的血流状况,可以快速方便地评价颅内侧支循环状态,对急性颈内动脉闭塞患者治疗方法选择和预后判断具有重要的临床价值.     

颈内动脉严重狭窄或闭塞患者颅内侧支循环的建立--经颅多普勒超声与数字减影血管造影的对照研究

目的:分析颈内动脉严重狭窄或闭塞时,合并或不合并颅内血管狭窄对侧支循环的影响以及经颅多普勒超声(TCD)与数字减影血管造影(DSA)比较的敏感性和特异性.方法:将DSA检查证实的颈内动脉(ICA)严重狭窄或闭塞患者56例分成两组:单纯ICA病变为组Ⅰ29例;合并颅内血管狭窄为组Ⅱ27例.TCD判断侧支循环的标准:(1)、前交通动脉(ACOA)开放:狭窄同侧大脑前动脉(ACA)反向,对侧ACA血流速增快,压对侧颈动脉后狭窄侧大脑中动脉(MCA)血流速度下降;(2)、后交通动脉(PCOA)开放:同侧大脑后动脉(PCA)及椎基底动脉(VBA)血流速增快;(3)、颈外向颈内侧支循环形成:眼动脉或滑车上动脉反向.结果:全部56例患者ACOA和PCOA的发生率(57.14%和60.71%)明显大于OA(25.0%),(P＜0.01).组ⅡACOA的发生率(37.04%)较组Ⅰ(75.86%)明显下降,(P＜0.01).TCD与DSA比较组Ⅰ的敏感性(96.07%),特异性(94.82%);组Ⅱ敏感性(89.47%),特异性(91.22%),两组比较无显著差异(P＞0.05).代偿血管ACA、PCA、BA的平均血流速(cm/s)分别为(101.0±17.36,91.13±27.75和75.86±24.96)均较无代偿同名血管血流速(61.92±16.84,48.80±13.76和43.69±11.01)明显增快,有显著性差异,P＜0.001.结论:颅内侧支循环以Willis环的前交通动脉和后交通开放为主,合并颅内血管狭窄使前交通动脉的开放明显受损;TCD对颈内动脉闭塞患者颅内侧支循环的判断有良好的敏感性和特异性,合并颅内血管狭窄对侧支循环的判断无明显影响.     

经颅多普勒监测颈内动脉颅外段病变侧支循环建立的准确性研究

目的探讨经颅多普勒(TCD)判断颈内动脉颅外段病变侧支循环开放的准确性。方法选取经DSA确诊的178例颈内动脉颅外段病变患者,将TCD检查结果与DSA检测的侧支循环情况进行对比分析,计算TCD检出各侧支循环开放的敏感性、特异性、假阳性率及假阴性率。结果 178例颅外段病变患者中,TCD检测前交通动脉开放占49.4%,后交通动脉开放占55.1%,颈内外侧支开放占41.6%。TCD诊断前交通动脉开放、后交通动脉开放及颈内外侧支开放的特异性分别为84.6%、87.0%和95.0%,敏感性分别为63.5%、78.3%和88.5%,假阳性率分别为9.1%、20.4%和6.8%,假阴性率分别为51.1%、10.0%和8.7%。重度或闭塞者侧支循环开放率(90.2%)明显高于轻中度狭窄者(72.4%),差异有统计学意义(P0.05)。结论 TCD对颅外段病变侧支循环建立的判断具有较高的准确性,可作为评价侧支循环建立的首选工具。     

经颅多普勒超声评估颈内动脉严重狭窄或闭塞患者的侧支循环代偿能力

目的探讨经颅多普勒超声（TCD）评估颈内动脉严重狭窄或闭塞患者的侧支循环代偿能力。方法对60例一侧颈内动脉严重狭窄或闭塞患者,根据临床上有无脑缺血和神经功能障碍体征,将患者分为症状性严重狭窄或闭塞组（44例）和无症状性严重狭窄或闭塞组（16例）。TCD柃测Willis环和眼动脉的侧支循环通路。结果TCD显示54例前交通动脉侧支开放,31例后交通动脉侧支开放,15例眼动脉侧支开放。3例症状性严重狭窄或闭塞患者未发现侧支循环。无症状性严重狭窄或闭塞患者的大脑中动脉平均血流速度高于症状性闭塞患者（P〈0．01）。结论TCD有助于了解颈内动脉系统动脉严重狭窄或闭塞患者的侧支循环代偿能力,为评估治疗效果和预后提供重要的客观依据。     

颈动脉连续波多普勒超声评估颅内侧支循环

目的探讨颈动脉连续波多普勒超声评估颅内侧支循环。方法对80例无脑供血动脉狭窄性病变患者，在行颈总动脉压迫试验时采用4MHz连续波探头检测对侧颈内动脉起始段和同侧椎动脉寰枢段血流速度变化。并对连续波多普勒超声与经颅多普勒超声检测的侧支循环方式结果进行比较。结果颈动脉连续波多普勒超声检出前交通动脉侧支开放76例（95％），经颅多普勒超声检出前交通动脉侧支开放76例（95％）。在受检的160个后交通动脉侧支中，颈动脉连续波多普勒超声检出后交通动脉侧支开放140个（88％），经颅多普勒超声检出132个（83％）。结论颅外动脉连续波多普勒超声结合颈总动脉压迫试验检测颅内侧支循环既安全又方便，其准确率与经颅多普勒超声一致。     

颈内动脉严重狭窄或闭塞患者颅内侧支循环的建立

目的：分析颈内动脉严重狭窄或闭塞时,登工或不合并颅内血管狭窄对侧支循环的影响以及经颅多普勒超声（ＴＣＤ）与数字减影血管造影（ＤＳＡ）比较的敏感性和特异性。方法：将ＤＳＡ检查证实的颈内动脉（ＩＣＡ）严重狭窄或闭塞患者５６例分成两 ;单纯ＩＣＡ病变为组Ⅰ２９例;合并颅内血管狭窄为组Ⅱ２７例、ＴＣＤ判断侧支循环的标准;（１）前交通动脉（ＡＣＯＡ）开放;狭窄同侧大脑前动脉（ＡＣＡ）反向,对侧ＡＣＡ血流速增     

Determination of creatine kinase isoenzyme MB activity in serum using immunological inhibition of creatine kinase M subunit activity. Activity kinetics and diagnostic significance in myocardial infarction.

This is a new method for the determination of creatine kinase isoenzyme MB activity in serum. The method uses direct activity measurement of creatine kinase B subunit activity after blocking of CK-M subunit activity by inhibiting antibodies. The test takes no longer than 15 min. The method yields an intra-serial C.V. of 2.0-12.9%, and a C.V. from day to day of 5.5%. The detection limit is 3.4 U/l creatine kinase MB. In the 95 cases with proven myocardial infarction several types of creatine kinase MB activity kinetics could be determined. The percentage of creatine kinase MB of peak CK-total is 6-25%, with a mean of 11.1%. The amount of creatine kinase MB with respect to total CK activity after reinfarction is higher than the amount after initial infarction.     

Dissociable correlates of two classes of retrieval processing in prefrontal cortex

Although substantial evidence suggests that the prefrontal cortex (PFC) implements processes that are critical for accurate episodic memory judgments, the specific roles of different PFC subregions remain unclear. Here, we used event-related functional magnetic resonance imaging to distinguish between prefrontal activity related to operations that (1) influence processing of retrieval cues based on current task demands, or (2) are involved in monitoring the outputs of retrieval. Fourteen participants studied auditory words spoken by a male or female speaker and completed memory tests in which the stimuli were unstudied foil words and studied words spoken by either the same speaker at study, or the alternate speaker. On "general" test trials, participants were to determine whether each word was studied, regardless of the voice of the speaker, whereas on "specific" test trials, participants were to additionally distinguish between studied words that were spoken in the same voice or a different voice at study. Thus, on specific test trials, participants were explicitly required to attend to voice information in order to evaluate each test item. Anterior (right BA 10), dorsolateral prefrontal (right BA 46), and inferior frontal (bilateral BA 47/12) regions were more active during specific than during general trials. Activation in anterior and dorsolateral PFC was enhanced during specific test trials even in response to unstudied items, suggesting that activation in these regions was related to the differential processing of retrieval cues in the two tasks. In contrast, differences between specific and general test trials in inferior frontal regions (bilateral BA 47/12) were seen only for studied items, suggesting a role for these regions in post-retrieval monitoring processes. Results from this study are consistent with the idea that different PFC subregions implement distinct, but complementary processes that collectively support accurate episodic memory judgments.     

俯卧位通气对高海拔地区肺复张治疗无效急性呼吸窘迫综合征患者氧合的影响

目的 探讨俯卧位通气对高海拔地区肺复张术(RM)治疗无效急性呼吸窘迫综合征(ARDS)患者的治疗作用.方法 从海拔2260m的地区医院筛选RM治疗无效的41例ARDS患者[平均氧合指数( PaO2/FiO2)较RM前升高＜20％视为RM无效],依不同病因分为肺内源性ARDS组(ARDSp组)和肺外源性ARDS组(ARDSexp组),每组再按信封法随机分为俯卧位组和仰卧位组,即ARDSp俯卧位组(11例)、ARDSp仰卧位组(9例)、ARDSexp俯卧位组(10例)、ARDSexp仰卧位组(11例).在通气前及通气1、2、3、4h监测动脉血氧分压( PaO2)、PaO2/FiO2、静态顺应性(Cst)、气道阻力(Raw)的变化.结果 通气lh时,ARDSexp俯卧位组PaO2/FiO2( mm Hg,l mm Hg=0.133 kPa)即较通气前显著升高(157.4±40.6比129.3±48.7,P＜0.05),并随通气时间延长呈持续增高趋势,4h达峰值(219.1 ±41.1);且ARDSexp俯卧位组通气3h内PaO2/FiO2较其他3组显著增高,另3组间则差异无统计学意义.ARDSp俯卧位组、ARDSexp俯卧位组通气4h时PaO2/FiO2均较相应仰卧位组显著增高(208.8±39.7比127.4±47.1,219.1±41.1比124.9±50.8,均P＜0.05).4组通气前后Cst无显著改变,各组间差异也无统计学意义.ARDSp俯卧位组通气4h时Raw(cmH2O·L-1·s-1)较通气前显著降低(6.8±1.7比10.7±1.8,P＜0.05),且明显低于其他3组;其他3组各时间点Raw组内及组间比较差异均无统计学意义.结论 俯卧位通气作为ARDS机械通气重要策略之一,可以改善RM无效高原ARDS患者的氧合,为抢救患者赢得宝贵的时间.     

Digital imaging among medical facilities

The Department of Veterans Affairs (VA) in the USA operates a network of 172 medical centres which all utilize a hospital information system (HIS) which has been developed and is currently maintained by the VA. During the past several years, an image management and communication module has been developed, installed and clinically utilized at the Washington DC and Maryland VA Medical Centres. This image management and communication system, referred to as the decentralized hospital computer program (DHCP) imaging system, is fully integrated with a commercial picture archiving and communication system (PACS). The system is utilized to capture, archive, and display all images generated within the hospital including radiology, nuclear medicine, pathology, endoscopy, bronchoscopy, and dermatology, intraoperative photographs, ECG data, and a limited number of paper documents. The ultimate goal of the project is to have all patient text and image data available at any clinical workstation to any authorized user anywhere within the network of medical centres. Clinical requirements for an imaging workstation include ease of use, rapid and reliable access to the complete set of patient information, and images which are of acceptable quality to meet the requirements of the user and the subspecialty. Patient confidentiality and data security must be safeguarded at all times. Integration of the images with the remainder of the patient's database was found to be critical to the success of the project. The experience at the Washington and Maryland facilities suggests that an imaging system that is successfully integrated with a hospital information system can provide substantial clinical and economic benefits both within and among medical centres. Clinical acceptance and utilization of the system has been excellent, particularly in diagnostic radiology where DHCP Imaging has been interfaced to a commercial PAC system. Based upon this initial experience, the VA has begun to deploy the system throughout its large network of medical centres.     

Myocardial elastography at both high temporal and spatial resolution for the detection of infarcts

Myocardial elastography is a novel method for noninvasively assessing regional myocardial function, with the advantages of high spatial and temporal resolution and high signal-to-noise ratio (SNR). In this paper, in-vivo experiments were performed in anesthetized normal and infarcted mice (one day after left anterior descending coronary artery [LAD] ligation) using a high-resolution (30 MHz) ultrasound system (Vevo 770, VisualSonics Inc., Toronto, ON, Canada). Radiofrequency (RF) signals of the left ventricle (LV) in longitudinal (long-axis) view and the associated electrocardiogram (ECG) were simultaneously acquired. Using a retrospective ECG gating technique, 2-D full field-of-view RF frames were acquired at an extremely high frame rate (8 kHz) that resulted in high-quality incremental displacement and strain estimation of the myocardium. The incremental results were further accumulated to obtain the cumulative displacements and strains. Two-dimensional and M-mode displacement images and strain images (elastograms), as well as displacement and strain profiles as a function of time, were compared between normal and infarcted mice. Incremental results clearly depicted cardiac events including LV contraction, LV relaxation and isovolumetric phases in both normal and infarcted mice, and also evidently indicated reduced motion and deformation in the infarcted myocardium. The elastograms indicated that the infarcted regions underwent thinning during systole rather than thickening, as in the normal case. The cumulative elastograms were found to have higher elastographic SNR (SNR(e)) than the incremental elastograms (e.g., 10.6 vs. 4.7 in a normal myocardium, and 6.0 vs. 2.4 in an infarcted myocardium). Finally, preliminary statistical results from nine normal (m = 9) and seven infarcted (n = 7) mice indicated the capability of the cumulative strain in differentiating infracted from normal myocardia. In conclusion, myocardial elastography could provide regional strain information at simultaneously high temporal (>/=0.125 ms) and spatial ( approximately 55 microm) resolution as well as high precision ( approximately 0.05 microm displacement). This technique was thus capable of accurately characterizing normal myocardial function throughout an entire cardiac cycle, at the same high resolution, and detecting and localizing myocardial infarction in vivo.     

Clinical Pharmacokinetics of Morphine

Morphine, the most widely used mu-opioid analgesic for acute and chronic pain, is the standard against which new analgesics are measured. A thorough understanding of the pharmacokinetics of morphine is required in order to safely and effectively use this analgesic in a wide variety of patients with different levels of organ function. A MEDLINE search was conducted to identify literature published between 1966 and January 2002 relevant to the pharmacokinetics of morphine. These publications were reviewed and the literature summarized regarding unique and clinically important elements of morphine disposition relative to its parenteral administration (including intravenous, intramuscular, subcutaneous, epidural and intrathecal administration), absorption profile (immediate release, controlled release, and sublingual/buccal, and rectal administration), distribution, and its metabolism/ excretion. Special populations, including infants, elderly, and those with renal/liver failure, have a unique morphine pharmacokinetic profile that must be taken into account in order to maximize analgesic efficacy and reduce the risk of adverse events.