呼吸对右心室充盈的影响及其机制研究

目的研究平静呼吸对三尖瓣血流的影响及其规律,进而探讨呼吸对右心室充盈的影响,为验证呼吸影响心功能机制假说以及利用多普勒超声技术研究右心室舒张功能提供依据。方法20名健康志愿者,采用Sequoia 512彩色电脑声像仪,同步记录三尖瓣血流速度曲线、心电图和呼吸曲线。连续测量5个呼吸周期吸气相和呼气相血流速度及速度时间积分(VTI),取平均值。分别计算吸气相和呼气相三尖瓣舒张早期E波与舒张晚期A波的血流速度比值以及VTI比值。结果三尖瓣舒张早期E波血流速度及VTI在吸气相高于呼气相[(82.35±16.13)cm/s vs(68.62±14.82)cm/s,P<0.0001;(18.25±4.75)cm vs(15.45±4.22)cm,P<0.0001];舒张晚期A波血流速度及VTI在吸气相高于呼气相[(50.62±9.82)cm/s vs(42.25±8.27)cm/s,P<0.0001;(9.81±1.51)cm vs(7.78±1.37)cm,P<0.0001];E波与A波的血流速度比值及VTI比值在吸气相高于呼气相(1.53±0.42 vs 1.42±0.31,P=0.002;1.41±0.30 vs 1.33±0.27,P=0.003)。结论平静呼吸对三尖瓣血流影响具有规律性,这对进一步验证呼吸影响心功能机制假说以及利用多普勒超声技术研究右心室舒张功能提供了重要的资料。     

平静呼吸对左室充盈的影响及其机制的超声心动图研究

目的研究平静呼吸对二尖瓣血流的影响及其规律,进而探讨呼吸对左室充盈的影响,进一步验证呼吸影响心功能机制新假说。方法20例健康志愿者,同步记录二尖瓣血流速度曲线、心电图和呼吸曲线。连续测量5个呼吸周期吸气相和呼气相血流速度及速度-时间积分(VTI),取平均值。分别计算吸气相和呼气相二尖瓣舒张早期E波与舒张晚期A波的血流速度比值以及VTI比值。结果二尖瓣舒张早期E波血流速度及VTI在吸气相低于呼气相(84.28cm/s±15.16cm/s,92.45cm/s±15.96cm/s,P<0.0001;16.27cm±3.70cm,17.73cm±3.91cm,P<0.0001);舒张晚期A波血流速度及VTI在吸气相低于呼气相(51.61cm/s±9.86cm/s,54.21cm/s±11.27cm/s,P<0.0001;9.86cm±1.55cm,10.48cm±2.00cm,P<0.0001);E波与A波的血流速度比值及VTI比值在吸气相低于呼气相(1.69±0.47,1.78±0.52,P=0.001;1.68±0.43,1.75±0.47,P=0.003)。结论平静呼吸对二尖瓣血流影响具有规律性:E波血流速度及VTI、A波血流速度及VTI、E波与A波血流速度比值及VTI比值均在吸气相低于呼气相。在利用二尖瓣血流频谱评价左室充盈时如能结合呼吸变化,则能提供更多信息。进一步验证了呼吸影响心功能机制新假说。     

阻力呼吸对正常人血流动力学的影响及其临床意义研究

目的　研究不同胸腔压力条件下心内各瓣口血流速度的变化 ,进一步验证呼吸影响心功能机制假说 ,为临床无创测定左心室舒张功能提供依据。方法　 3 0名健康志愿者 ,分别测量平静呼吸及不同阻力呼吸时 (胸腔压力变化为 :-4mmHg、-8mmHg 和 -12mmHg)的各瓣口血流速度 ,不同胸压变化时不同呼吸相所测的各瓣口血流速度分别取平均值 ,计算呼吸性血流速度波动指数 (RVI)。结果　各瓣口血流速度在平静呼吸和胸腔压力变化为 -4mmHg时 ,RVI值差别无显著性意义。胸压变化为-8mmHg及 -12mmHg时 ,二尖瓣、主动脉瓣、三尖瓣和肺动脉瓣RVI值分别为 :12 .5 4% ,13 .19% ;6.2 3 % ,8.2 7% ;2 0 .2 7% ,2 4.3 6%和 6.45 % ,7.69%。上述各值与平静呼吸时的RVI值相比 ,差异有显著性意义 (P <0 .0 1或P <0 .0 0 1)。除二尖瓣和肺动脉瓣外 ,其余各瓣口RVI值在胸压变化为-8mmHg 和 -12mmHg 时差别有显著性意义 (P <0 .0 1)。结论　各瓣口RVI随胸压下降幅度增大而增大 ,这为RVI的临床应用、哮喘患者出现奇脉及呼吸影响心功能机制假说提供了依据。     

呼吸对慢性阻塞性肺疾病心脏血流动力学影响的超声心动图研究

目的用超声心动图方法检测慢性阻塞性肺疾病(COPD)患者自然呼吸过程中心脏各瓣口血流速度随呼吸的变化,探讨自然呼吸对COPD患者心功能影响的机制及临床意义。方法采用AcusonSequoia512彩色超声仪记录20例COPD患者和30例健康人自然呼吸时心脏各瓣口血流速度,同步记录心电图和呼吸曲线,计算各瓣口的血流速度呼吸性波动指数(RVI)。结果COPD组与健康对照组均表现为二尖瓣E峰血流速度和主动脉瓣血流速度在呼气相高于吸气相(P<0.001),三尖瓣E峰血流速度和肺动脉瓣血流速度在吸气相高于呼气相(P<0.001)。COPD组心脏各瓣口血流速度RVI较对照组均明显增大[二尖瓣(16.26±8.71)%对(10.53±3.15)%,P<0.03;主动脉瓣(11.61±4.96)%对(4.67±1.79)%,P<0.001;三尖瓣(27.74±8.39)%对(14.89±6.32)%,P<0.001;肺动脉瓣(13.78±4.98)%对(8.55±2.32)%,P<0.001]。结论COPD组与健康对照组自然呼吸时心脏各瓣口血流速度随呼吸时相波动的变化规律一致,但COPD组四个瓣口RVI较健康对照组明显升高,进一步证明了呼吸性胸压变化可以导致心脏各瓣口血流速度变化。该结果对COPD患者肺实质损伤程度的判定以及治疗效果的追踪观察有重要参考价值。     

血管内多普勒超声对Budd-Chiari综合征血流动力学障碍的研究

目的　研究Budd Chiari综合征 (BCS)患者血流动力学 (压力、血流速度及血流量 )障碍及其与正常对照的差异。方法　使用血管内多普勒导丝对 2 7例BCS患者下腔静脉 (IVC)和 (或 )肝右静脉 (RHV )介入治疗(PTA)前后血流速度及血流量的变化进行检测 ,并以 10例正常人的相应数据作为对照。结果　PTA前 ,BCS患者RHV和IVC的平均峰值流速 (APV)明显低于正常组 [RHV :( 5 .0 5± 3.6 9)cm/svs ( 14 .73± 4.5 2 )cm/s ,P <0 .0 0 1;IVC :( 3.0 2± 6 .87)cm /svs ( 2 3.6 7± 5 .38)cm /s ,P <0 .0 0 1]。PTA后 ,BCS患者APV显著增加至正常 ,但与对照组比较差异无显著性意义 [IVC :( 2 4.83± 11.34)cm /svs ( 2 3.6 7± 5 .38)cm/s ,P >0 .1;RHV :( 16 .13± 10 .5 6 )cm /svs ( 14 .73± 4.5 2 )cm/s ,P >0 .1) ] ;而血流量增加更明显 ,和对照组比较差异有显著性意义 [IVC :( 4 914 .79± 937.5 2 )ml/minvs ( 385 6 .96± 376 .92 )ml/min ,P <0 .0 1;RHV :( 90 2 .6 3± 5 12 .37)ml/minvs( 6 13.0 3± 2 0 8.5 6 )ml/min ,P <0 .0 1) ]。结论　BCS存在严重的血流动力学紊乱状态 ,PTA后IVC、RHV血流动力学指标大致恢复正常。     

正常成人颈内静脉多普勒血流频谱分析

目的　利用多普勒超声对正常成人不同年龄段颈内静脉血流动力学进行分析 ,探讨其血流频谱变化与呼吸、心动周期的关系。方法　对随机选取的 12 0名成年健康志愿者沿颈总动脉外侧探测颈内静脉 ,在二维切面的基础上获取其血流频谱 ,测定不同心动周期及呼吸周期中颈内静脉血流动力学指标。结果　在心动周期中 ,颈内静脉血流频谱呈现收缩期S波、舒张期D波和舒张期A波 ;在平静呼吸状态下 ,受检者吸气相和呼气相S波速率分别为 (2 7.17± 19.88)cm/s、(19.0 4± 14 .2 6)cm/s ,D波速率分别为(17.43± 12 .78)cm/s、(12 .70± 10 .57)cm /s ,吸气相速率较呼气相速率快 (均P <0 .0 0 1) ,呼吸周期中A波速率无明显变化 [(6.3 8± 6.3 2 )cm/s、(7.59± 7.42 )cm /s,P >0 .0 5] ;60岁以上组S和D波血流速率较 2 0～ 60岁组血流速度低 (P <0 .0 5)。结论　正常颈内静脉血流频谱由 3个波组成 ,频谱形态随心动周期、呼吸周期呈规律性变化 ;年龄因素影响颈内静脉多普勒血流速率 ;建立了正常成人颈内静脉多普勒血流速率参数的正常值     

心包积液时呼吸对血流动力学影响的超声心动图研究

目的　观察心包积液时呼吸性胸压变化对血流动力学的影响 ,从临床角度验证笔者提出的关于呼吸影响心功能机制新假说 ,提出心包积液时血流动力学改变程度参考指标。方法　 10例大量心包积液患者 ,采用AcusonSequoia 512和 12 8XP/ 10型超声仪 ,同步记录各瓣口血流速率、心电图和呼吸曲线。分别于呼气相和吸气相连续测量 5个呼吸周期的各瓣口血流速率 ,并分别取呼气相和吸气相平均值 ,计算呼吸性血流速率波动指数 (RVI) ,并与 18例健康志愿者的结果进行比较分析。结果　心包积液组二尖瓣(MV)E峰血流速率RVI值和主动脉瓣 (AV)血流速率RVI值均较正常组明显增大 [MV :(14 .57± 7.89) %对 (9.71± 3 .3 9) % ,P <0 .0 5;AV :(11.61± 4.96) %对 (4.67± 1.79) % ,P <0 .0 0 1] ;三尖瓣 (TV)E峰血流速率RVI值和肺动脉瓣 (PV)血流速率RVI值也均较正常组显著增大 [TV :(2 4.97%± 6.19) %对 (14 .82± 3 .70 ) % ,P <0 .0 0 1;PV :(2 3 .93± 10 .12 ) %对 (5.86± 2 .55) % ,P <0 .0 0 1]。结论心包积液时呼吸性胸压变化对心脏各瓣口血流速率影响明显增大 ,RVI值可以作为心包积液和心包填塞严重程度的衡量指标 ;心包腔内压是决定呼吸对血流动力学影响程度的因素之一     

心肌组织多普勒技术结合M型超声评价急性下壁及前壁心肌梗死的右心室功能

目的　应用心肌组织多普勒 (TDI)技术结合M型超声测定三尖瓣环运动评价急性下壁及前壁心肌梗死 (心梗 )患者右心室整体功能。方法　正常对照组 2 5例 ,急性下壁心梗 2 5例 ,急性前壁心梗 2 3例。在标准心尖四腔心观二维图像指引下 ,采用M型超声记录三尖瓣环右室游离壁处运动曲线 ,测量收缩期、舒张早晚期运动幅度 ,采用TDI的频谱多普勒技术记录该处速度曲线 ,测量各期最大运动速度。结果　与对照组相比 ,急性下壁与前壁心梗患者三尖瓣环右室游离壁处收缩期及舒张早期运动幅度显著降低 ,最大收缩速度在下壁心梗显著降低 [(12 .9± 2 .7)cm /svs (15 .9± 2 .6)cm/s ,P <0 .0 1] ,在前壁心梗无下降 [(14 .5± 4.0 )cm/svs (15 .9± 2 .6)cm /s ,P >0 .0 5 ] ,两者舒张早期速度均显著降低 ,分别为 (12±3 .1)cm/s和 (13 .2± 3 .1)cm/s ,舒张早期与晚期速度比值也明显降低。结论　TDI频谱多普勒技术能反映急性心梗导致的右室舒缩功能减低 ,其与M型超声结合测定三尖瓣环运动有利于全面评价心梗后右室整体功能。     

Valsalva动作对评价左室舒张功能三种常用指标的影响

目的研究正常人Valsalva动作后前负荷降低是否引起舒张期二尖瓣口血流频谱、二尖瓣环运动速度及舒张早期左室血流传播速度三种指标变化以及如何变化。方法50例健康人,Valsalva动作前后分别测定舒张期二尖瓣口血流频谱、二尖瓣环运动频谱(DTI)和M型彩色多普勒舒张早期左室内血流传播速度(FPV),并进行Val-salva动作前后对照分析。结果Valsalva动作前后比较,舒张期二尖瓣口血流频谱E峰速度减低〔(80.6±16.3)cm/svs(65.9±13.3)cm/s,P＜0.01〕,A峰速度、E/A比值减低〔(54.2±10.2)cm/svs(49.5±10.4)cm/s和1.51±0.23vs1.37±0.29,P＜0.05),E峰减速时间DT延长〔(0.161±0.031)svs(0.192±0.05)s,P＜0.01〕。侧壁处二尖瓣环运动速度Eal降低〔(18.7±3.8)em/svs(16.3±3.7)cm/s,P＜0.01〕,Aal和Eal/Aal比值无显著变化〔(11.3±2.5)cm/svs(10.5±1.9)cm/s和1.72±0.46vs1.60±0.44,P＞0.05〕,室间隔侧Eas、Aas降低〔(14.7±2.8)cm/svs(13.1±2.4)cm/s和(9.9±1.7)cm/svs(8.8±1.9)cm/s,P＜0.01〕,Eas/Aas比值无显著变化(1.53±0.37vs1.54±0.33,P＞0.05),FPV无显著变化〔(55.87±6.66)cm/svs(55.32±10.22)cm/s,P＞0.05〕。结论作为评价左室舒张功能的指标,二尖瓣口血流易受前负荷影响,舒张期二尖瓣环运动速度与FPV相对不受前负荷影响,但二尖瓣环运动速度这一指标实际应用中更为优越。     

妊高征患者分娩前后肾动脉血流参数变化的多普勒超声研究

目的　利用超声多普勒技术评价妊高征 (PIH)患者分娩前后肾动脉血流动力学变化。方法　重度妊高征患者 2 5例 ,正常妊娠 2 4例 ,彩色多普勒超声引导下利用脉冲多普勒超声检测肾动脉收缩期最大、最小、平均血流速度 (Vs,Vd ,Vm)及阻力指数 (RI)、搏动指数 (PI)等。产后复查。结果　妊高征患者肾动脉血流速度与正常妊娠组(Vs:6 5 33± 18 0 7cm/svs 6 5 0 6± 19 98cm/s;Vd :2 4 90± 7 81cm/svs 2 5 94± 8 6 8cm/s;Vm :44 2 1± 13 91cm/svs 42 18± 10 0 9cm/s)无显著差别 (P >0 0 5 ) ;RI、PI两组间亦无显著差别 (P >0 0 5 ) ;妊高征组及正常妊娠组分娩后上述指标均有不同程度增高 ,但相差不显著 (P >0 0 5 )。结论　妊高征患者肾动脉血流速度及RI与正常妊娠组无显著差别 ,正常妊娠及妊高征患者分娩前后肾动脉血流动力学未发生显著变化。     

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.     

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.     

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.