三维斑点追踪技术评价不同左室构型尿毒症患者左室收缩功能的应用价值

目的 探讨三维斑点追踪（3D-STI）技术评价肾移植前不同左室构型尿毒症患者左室整体收缩功能的临床应用价值。方法 将85例拟行肾移植术的尿毒症患者根据不同左室构型分为4组：左室构型正常组19例（LVN组）,左室向心性重构组24例（LV-CR组）,左室向心性肥厚组19例（LV-CH组）和左室离心性肥厚组23例（LV-EH组）,另选24例同期体检的健康成人为正常对照组。测量并比较各组左室整体圆周应变（GCS）、整体径向应变（GRS）及整体纵向应变（GLS）的差异。绘制受试者工作特征（ROC）曲线分析各应变参数评估尿毒症患者心肌重构的价值。随机选择15例患者,采用Bland-Altman法分析GLS、GRS、GCS在观察者内和观察者间的一致性。结果 与正常对照组比较,尿毒症各组GLS均减低,LV-CH、LV-EH组GRS、GCS均减低（均P<0.05）;与LVN组比较,LV-CH、LV-EH组GLS、GRS、GCS均减低（均P<0.05）;与LV-CR组比较,LV-CH组GLS、GCS及LV-EH组GLS、GCS、GRS均减低（均P<0.05）;与LV-CH组比较,LV-E...     

三维斑点追踪成像定量评价青年尿毒症患者肾移植术后早期左心室整体应变

目的 应用三维超声斑点追踪成像(3D-STI)定量评价青年尿毒症患者肾移植术后早期左室整体应变。方法 选取成功行肾移植的青年尿毒症患者31例(肾移植组)及年龄性别相仿的健康志愿者 31例(对照组),正常对照组与肾移植组(术前、术后1月、术后3月)分别行常规超声心动图检查及3D-STI指标测量;比较各组左室整体纵向收缩期峰值应变(GLS)、左室整体径向收缩期峰值应变(GRS)、左室圆周收缩期峰值应变(GCS)和左室面积收缩期峰值应变(GAS)的差异。结果 术前肾移植组GLS、GCS、GRS、GAS低于正常对照组(P<0.05),术后一月,GLS较术前无显著差异,GCS、GRS、GAS较术前降低(P<0.05),术后三月,GLS、GCS、GRS、GAS较术前比较均升高(P<0.05)。术后三月GCS、GRS较正常对照组间无显著差异,GLS、GAS小于正常对照组(P<0.05)。结论 1、GLS、GAS是尿毒症患者心肌受损的敏感指标,GRS、GCS是维持尿毒症患者心功能的主要因素;2、青年尿毒症患者肾移植早期心脏结构和功能得到有效改善。     

三维斑点追踪成像技术评价不同左心室构型高血压患者左心室收缩功能

目的 探讨三维斑点追踪成像(3D-STI)技术评价不同左心室构型高血压患者左心室收缩功能的价值。方法 随机抽取原发性高血压患者90例和30名健康志愿者(N组),根据Ganan分类方法将原发性高血压患者分为正常构型组40例(Ⅰ组)、向心性重构组20例(Ⅱ组)、向心性肥厚组15例(Ⅲ组)及离心性肥厚组15例(Ⅳ组)。采用3D-STI技术获取左心室整体纵向收缩期峰值应变(GLS)、径向收缩期峰值应变(GRS)、圆周收缩期峰值应变(GCS)、面积收缩期峰值应变(GAS)及左心室射血分数(LVEF),并分析各组间参数的变化规律。结果 GAS随着左心室重构程度加重呈逐渐递减趋势(P<0.05),Ⅰ组GAS峰值小于N组(P<0.05);Ⅱ、Ⅲ组GLS峰值低于N、Ⅰ组(P<0.05);Ⅱ组GRS峰值高于其余各组(P<0.05);Ⅳ组GLS、GRS、GCS、GAS峰值均低于其余各组(P<0.05)。左心室GLS、GCS、GAS、GRS与LVEF相关(r=-0.42、-0.50、-0.58、0.41,P均<0.05)。结论 3D-STI技术为分析不同左心室构型高血压患者的心肌形变提供了新方法。     

三维斑点追踪技术评价阻塞型睡眠呼吸暂停低通气综合征伴高血压患者左心室整体收缩功能

目的 应用三维斑点追踪（3D-STI）技术评价阻塞型睡眠呼吸暂停低通气综合征（OSAHS）伴高血压（HT）患者左心室整体收缩功能。方法 OSAHS 40例,分为单纯OSAHS组20例和OSAHS+HT组20例;另选择20名健康正常人作为正常对照组。行常规超声心动图检查,采集左心室心尖四腔三维全容积图像,存储图像并应用3D-STI分析软件在线分析,计算左心室整体纵向收缩峰值应变（GLS）、左心室整体径向收缩峰值应变（GRS）、左心室整体圆周收缩峰值应变（GCS）及左心室整体面积收缩峰值应变（GAS）。结果 与正常对照组相比,OSAHS组 左心室GLS、GRS、GAS减低（P均<0.05）,OSAHS+HT组左心室GLS、GRS、GCS、GAS均减低（P均<0.05）。与OSAHS组比较,OSAHS+HT组 左心室GLS、GCS、GAS均减低（P均<0.05）。结论 OSAHS合并HT患者存在左心室收缩功能受损。3D-STI能早期、准确有效地评估其左心室整体收缩功能改变。OSAHS患者心脏结构及功能变化独立于HT而单独存在,二者同时存在时改变加重。     

三维斑点追踪成像技术评估右心双腔间隔起搏对左心室功能的影响

目的 应用三维斑点追踪成像（3D-STI）评估右心双腔间隔起搏对左心室功能的影响。方法 对42例右心双腔间隔起搏患者（起搏器组）和37名健康志愿者（对照组）行3D-STI检查,于心尖四腔切面图像获得左心室总体纵向峰值应变（GLS）、总体周向峰值应变（GCS）、总体径向峰值应变（GRS）、总体面积峰值应变（GAS）及左心室总体拧转（GTw）和左心室整体扭转（GTs）值。比较2组间三维应变参数,并分析GTw、GTs与GLS、GCS、GAS及GRS的相关性。结果 与对照组相比,起搏器组左心室GLS、GCS、GAS、GRS及GTs均明显减低（P均<0.05）;2组间GTw差异无统计学意义（P>0.05）。对照组GTs与GCS和GRS呈正相关（r=0.45、0.40;P均<0.05）,与GAS、GLS无相关性（P均>0.05）;GTw与GLS、GCS、GAS、GRS均无相关（P均>0.05）。起搏器组GTw、GTs与GLS、GCS、GAS、GRS均无相关（P均>0.05）。结论 右心双腔间隔起搏可损害左心室心肌形变能力,致左心室整体收缩功能隐匿性减低。     

三维斑点追踪技术定量评价2型糖尿病患者左室收缩功能成珍珍 刘勇

目的 应用超声三维斑点追踪成像技术（3D-STI）定量评价2型糖尿病（T2DM）患者左心室整体收缩功能的早期改变。方法 选取50例左心室收缩功能正常（LVEF≥50％）的T2DM患者（DMA组）,30例左心室收缩功能减低（LVEF＜50％）的T2DM患者（DMB组）以及42例健康志愿者（NC组）。应用三维斑点追踪成像技术测量左心室的整体收缩期峰值纵向应变率（GLS）、径向应变率(GRS)、圆周应变率(GCS)以及面积应变率（GAS） 结果 与NC组比较,DMA GLS、GCS、GAS显著减低,而GRS显著增高(P ＜0.05);DMB组GLS、GCS、GAS均显著减低(P＜0.05）,而GRS无差异(P ＞0.05）。且DMB组GLS、GCS、GRS、GAS均较DMA组显著减低（P＜0.05）。 结论 3D-STI可用于检测T2DM患者早期左室收缩功能的异常,是评估糖尿病患者早期心肌病变可靠方法。     

超声二维斑点追踪技术评价心力衰竭患者二维整体应变

目的 探讨二维整体峰值应变指标在不同程度心力衰竭患者中的变化特征.方法 35例心肌梗死合并心力衰竭患者按照左心室射血分数(LVEF)分为轻度(14例)、中度(13例)及重度(8例)心力衰竭三组.28名健康受试者为正常对照组.应用二维斑点追踪技术分别测量收缩期左心室的纵向峰值应变(LS)、径向应变(RS)和圆周应变(CS),分别计算三种应变的平均值作为左心室整体纵向应变(GLS)、整体径向应变(GRS)及整体圆周应变(GCS);同时应用常规二维超声测量LVEF和左心室容积(LVEDV)等,比较各组间整体二维应变和心功能,分析GLS、GRS、GCS在不同心力衰竭组中的变化及其与LVEF的关系.结果 轻、中、重度心力衰竭组分别与正常对照组相比较,GLS、GRS、GCS差异均有统计学意义(P＜0.01);三组心力衰竭组间相比,随着LVEF的减低GLS明显减低,三组心力衰竭组间GLS差异有统计学意义(P＜0.05);重度心力衰竭组GCS明显低于轻度、中度心力衰竭组(P<0.05);但轻度与中度心力衰竭组间GCS差异无统计学意义(P＞0.05);三组心力衰竭组之间GRS差异无统计学意义(P＞0.05).相关分析显示GLS与LVEF呈高度相关(r=-0.65,P<0.01)、GCS与LVEF有一定的相关性(r=-0.55,P<0.01).结论 GLS、GRS、GCS在不同程度的心力衰竭组中变化不同,GLS与LVEF的变化关系密切.GLS、GRS、GCS的变化可能反映了心肌收缩功能不同程度的损伤.     

三维斑点追踪成像技术评估心房功能性二尖瓣反流患者左心室功能

目的：应用三维斑点追踪成像技术(3D-STI)探讨心房功能性二尖瓣反流(AFMR)患者的左心室功能,并探讨其临床应用价值。方法：选取82例心房颤动患者,根据其有无AFMR分为单纯房颤组48例和心房AFMR组34例,另选取同时期40例健康志愿者作为对照组。应用3D-STI获取心肌整体纵向应变(GLS)、整体圆周应变(GCS)、整体径向应变(GRS)和左心室整体扭转角度峰值(LVP_tw),比较上述参数在各组之间的差异。绘制3D-STI各参数评价AFMR隐匿性左心室功能受损的ROC曲线,确定GLS、GCS、GRS及LVP_tw对AFMR患者左心室功能受损的诊断效能。结果：与对照组相比,单纯房颤组GLS、GCS、GRS均降低,差异均具有统计学意义(P均<0.05);与对照组、单纯房颤组比较,AFMR组GLS、GCS、GRS、LVP_tw均降低,差异均具有统计学意义(P均<0.05)。ROC曲线分析显示,GLS、GCS、GRS和LVP_tw诊断AFMR患者左心室功能受损的曲线下面积分别为0.884、0....     

三维斑点追踪成像技术评价2型糖尿病患者左心室整体应变

【摘要】目的 运用三维斑点追踪成像技术（3D-STI）测定左心室整体心肌变化,评价2型糖尿病（T2DM）患者的左心室整体心肌的收缩功能。方法 选取2型糖尿病患者81例,依据左心室射血分数（LVEF）分为收缩功能正常组（n=46例）和左心室收缩功能减低组（n=35例）,另入选35例健康志愿者作为对照组。使用3D-STI技术测定左心室收缩期短轴整体峰值环向应变（GCS）、径向应变（GRS）、长轴纵向应变（GLS）、面积应变（GAS）及左室扭转（LVTW）,并与健康对照组比较。结果 与对照组相比,患者组的GLS、GAS和LVTW均有显著减低(P＜0.05);左心室LVEF减低组的GAS和LVTW均低于LVEF正常组,差异有统计学意义（P＜0.05）。左心室GAS和GLS同LVEF呈负相关（r分别为﹣0.81和﹣0.62）。 结论3D-STI能准确测定T2DM患者的左心室整体应变,其中GLS、GAS等参数具有一定的临床实用价值。     

美托洛尔对肥厚型心肌病患者左心室收缩功能影响的三维应变研究

目的探讨肥厚型心肌病(hypertrophic cardiomyopathy,HCM)患者应用美托洛尔短期治疗前、后左心室收缩功能的变化。方法 HCM患者27例(HCM组),均给予酒石酸美托洛尔治疗,分别于治疗前及治疗3个月后行超声心动图检查,应用三维斑点追踪(three-dimensional speckle tracking imaging,3D-STI)技术测量左心室心肌收缩期整体纵向应变(global longitudinal strain,GLS)、左心室整体圆周应变(global circumferential strain,GCS)以及左心室整体径向应变(global radial strain,GRS),应用脉冲多普勒测量左心室流出道最大瞬时压差(left ventricular outflow tract pressure gradient,LVOT-PG)等参数,并与同期30例体检健康者(对照组)进行比较。结果 HCM组治疗前GLS[(-17.6±2.7)%]低于对照组[(-22.1±4.9)%],GRS[(102.7±33.8)%]及GCS[(-30.2±2.5)%]较对照组[GRS为(86.7±34.1)%,GCS为(-23.5±3.2)%)]增强(P0.05),LVOT-PG[68.0(27.0,109.0)mm Hg]高于对照组[5.1(3.2,7.8)mm Hg](P0.05);治疗3个月后,HCM组GLS[(-16.9±3.8)%]与治疗前比较差异无统计学意义(P0.05),GRS[(93.7±31.5)%]、GCS[(-27.1±2.8)%]、LVOT-PG[34.0(17.0,69.0)mm Hg]较治疗前降低(P0.05),但HCM组治疗后LVOT-PG仍高于对照组(P0.05),GRS、GCS仍较对照组增强(P0.05)。结论美托洛尔可降低HCM患者LVOT-PG以及左心室GRS、GCS,3D-STI技术可为HCM治疗效果的评价提供新的方法。     

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.     

手转胎头术失败的原因与分娩结局临床分析

目的 探讨手转胎头术失败的原因与分娩结局.方法 选择2008年1月至2010年12月于我院住院分娩的持续性枕横位、枕后位产妇198例,根据行手转胎头术后结果分为成功组126例、失败组72例.比较两组分娩结局,对比分析失败原因.结果 失败组胎儿体质量≥3500 g的发生率[76.4％(55/72)]明显高于成功组[31.7％(40/126)],差异有统计学意义(x2=30.177,P=0.001)、失败组宫缩乏力发生率[58.3％(42/72)]高于成功组[38.1％ (48/126)],差异有统计学意义(x2=7.569,P=0.006)、失败组骨盆临界或轻度狭窄发生率[38.9％ (28/72)]高于成功组[23.8％(30/126)],差异有统计学意义(x2 =5.030,P=0.002)、失败组手转胎头时机不当(宫口开大＜6 cm、胎头位于坐骨棘上及宫口开大8～10 cm、胎头位于坐骨棘下≥2 cm)发生率[61.1％(44/72)]高于成功组[38.9％(49/126)],差异有统计学意义(x2=9.084,P=0.003).失败组母儿并发症(产后出血、产褥病率、胎儿窘迫、新生儿窒息)发生率高于成功组(x2 =9.586,P=0.002、x2=9.334,P=0.002、x2=5.910,P=0.015、x2=5.240,P=0.022)、失败组剖宫产发生率[72.2％(52/72)]明显高于成功组[34.1 ％(43/126),x2=26.641,P=0.001)].结论 手转胎头术能使难产变顺产,降低剖宫产率,减少母儿并发症,但须积极预防、处理导致手转胎头术失败的原因,对矫正失败后继续矫正及试产应慎重.     

Evidence-Based Pain Management and Palliative Care in Issue Four for 2009 of The Cochrane Library

ABSTRACT

The Cochrane Library of Systematic Reviews is published quarterly. Issue 4 for 2009 contains 4027 complete reviews, 1906 protocols for reviews in production, and 11447 one-page summaries of systematic reviews published in the general medical literature. In addition, there are citations of 600,000 randomized controlled trials, and 12,200 cited papers in the Cochrane methodology register. The health technology assessment database contains over 7500 citations. This edition of the Library contains 90 new reviews, of which 19 have potential relevance for practitioners in pain and palliative medicine.     

Wie zuverlässig sind Angaben zu nichtentzündlichen ausgedehnten Schmerzen?

ZusammenfassungFragestellung Es wurde geprüft, wie sich der Differenziertheitsgrad zweier Schmerzmessmethoden auf Angaben zur Ausgedehntheit klinischer Schmerzen auswirkt. Zugleich wurde der Referenzzeitraum variiert, über den die Patienten berichten sollten.Methode Erfasst wurde der Einfluss zu Lasten der Befragungsdifferenziertheit durch den Vergleich zweier Körperschema-Bildvorlagen. Drei Referenzzeiträume (Schmerz aktuell, letzte Woche, letztes halbes Jahr) wurden vorgegeben.Ergebnisse Patienten mit ausgedehnten Schmerzen gaben bei differenzierter Befragung um so mehr Schmerzen an, je weiter die Schmerzen zurück lagen und je größer der Berichtszeitraum war. Patienten mit gelenknahen Schmerzen gaben bei hoch differenzierter Befragung weniger ausgedehnte Schmerzen in der Vergangenheit an als bei globaler Einschätzung. Patienten mit Rückenschmerzen berichteten bei differenzierter Befragung zum aktuellen Schmerz über weniger ausgedehnte Schmerzen als bei globaler Befragung.Schlussfolgerung Die Angaben zur Schmerzausdehnung variieren vor allem bei Patienten mit ausgedehnten Schmerzen in Abhängigkeit von der Differenziertheit der Befragung. In diesen Fällen ist die Wahrscheinlichkeit erhöht, dass sich die Beschwerdesymptomatik zumindest teilweise erst in der Reaktion auf die situativen Befragungsbedingungen konstituiert und daher nicht auf andere Befragungsbedingungen generalisiert werden kann.