钉棒置入与椎间融合修复极外侧型腰椎间盘突出症：远期腰椎稳定性随访

背景：极外侧腰椎间盘突出症是临床上比较少见的一种腰椎间盘突出类型,目前的治疗方法多样,但治疗效果和复发率报道不一。 目的：探讨应用腰椎椎弓根钉棒内固定联合椎间融合器置入椎间融合修复极外侧型腰椎间盘突出症的临床效果。 方法：回顾性分析2006年3月至2009年1月行腰椎椎弓根钉棒系统联合椎间融合器置入椎间融合治疗的19例极外侧型腰椎间盘突出症患者的临床资料,根据目测类比评分标准及Macnab评价标准进行疗效判定,观察治疗后腰椎稳定性,通过数据库文献检索方法评估腰椎椎弓根钉棒内固定联合椎间融合器置入椎间融合修复极外侧型腰椎间盘突出症的效果。 结果与结论：19例患者均得到随访,随访时间13个月-3年。所有患者治疗后即有下肢及腰部疼痛不同程度的缓解,治疗前目测类比评分为（7.3±1.3）分,治疗后为（2.1±0.8）分,差异有显著性意义（P〈0.05）。根据Macnab评价标准,优15例,良3例,可1例,差0例,优良率为95%。所有患者均未发生断钉、断棒及松动现象,所有椎间融合器均达到融合,未发生继发性腰椎管狭窄。提示腰椎椎弓根钉棒系统内固定联合椎间融合器置入椎间融合修复极外侧型腰椎间盘突出症症状缓解快,内固定牢固,可获得良好的腰椎稳定性。     

单枚融合器加椎弓根螺钉治疗腰椎间盘退变性疾病

目的评价应用单枚椎间融合器植骨融合加椎弓根螺钉内固定系统治疗腰椎间盘退变性疾病（DDD）的临床疗效。方法回顾性分析2003年5月至2009年5月采用单枚椎间融合器植骨融合加椎弓根螺钉内固定系统治疗108例DDD患者的临床资料,其中男65例,女43例,年龄36～78岁,平均48.4岁。退变类型：腰椎间盘突出症36例,腰椎管狭窄症42例,退变性腰椎滑脱症22例,退变性腰椎侧凸8例。病变间隙：1个间隙76例,2个间隙28例,3个间隙4例。采用NaKai评定标准判定术后疗效,采用Suk标准评定椎间融合率,观察术后椎体间有无移位,椎弓根螺钉和椎间融合器位置情况。结果手术时间1.5～3.5h,平均2h;术中出血量180～760ml,平均400ml;并发硬膜囊撕裂6例,神经根损伤2例,随访1年～5年8个月,平均2年。按NaKai评定标准判定术后疗效,优72例,良23例,可13例,优良率为88.0%。;术后1年时,按采用Suk标准评定椎间融合率为97.2%;末次随访时无椎间不稳,椎弓根螺钉及椎间融合器均无松动、移位、断裂等。结论 DDD在行后路椎板减压、解除神经根压迫的基础上,采用单枚椎间融合器植骨融合加椎弓根螺钉内固定系统,能很好地恢复腰椎生理曲度,维持椎间高度和节段的稳定。     

单侧椎弓根钉固定结合椎间融合治疗腰椎间盘突出症

背景：脊柱双侧内固定广泛应用于治疗腰椎退行性疾病,但长期随访发现坚强内固定形成的应力遮挡效应会导致融合椎体的骨量丢失以及临近椎体退变加速。目的：观察单侧椎弓根螺钉内固定椎间融合治疗腰椎间盘突出症的临床效果。方法：2006-01/2010-01江苏大学附属武进医院对45例一侧肢体为主要症状的腰椎间盘突出症患者进行经椎间孔后路椎间融合单侧椎弓根螺钉内固定。结果与结论：45例患者均获得随访,随访时间6～24个月。全部切口均一期愈合,未发生切口感染。JOA评分和目测类比疼痛评分两项指标均有显著改善,固定后及末次随访与固前相比,差异有显著性意义（P〈0.01）。45例患者中优36例,良5例,可4例,优良率为91%。6个月后X射线及CT提示椎间融合,椎间融合器无移位,无沉降,内固定无松动、断裂。提示单侧神经减压椎间融合和单侧椎弓根螺钉固定是可行的脊柱外科技术,治疗腰椎间盘突出症可获得满意的临床效果。     

单侧椎弓根螺钉加颗粒骨椎间植骨治疗退行性腰椎不稳的疗效观察

目的观察减压后采用单侧椎弓根螺钉加颗粒骨椎间植骨融合术治疗退行性腰椎不稳症的疗效。方法 1996年6月至2009年10月我科19例退行性腰椎不稳症患者减压后采用单侧椎弓根螺钉内固定加颗粒骨椎间植骨融合。手术前以及末次随访时按日本矫形外科学会(JOA)腰腿痛疗效标准(29分法)进行评价,计算改善率和优良率,并随访观察植骨融合情况。结果术中出血平均160 mL,手术时间平均105 min。随访14~45个月(平均23个月),末次随访时JOA评分与术前比较差异有统计学意义(P<0.05),JOA评分改善率90.7%,优良率94.2%。结论单侧椎弓根螺钉加颗粒骨椎间植骨是治疗轻度退行性腰椎不稳可供选择的较好方法。     

后路钉棒内固定椎间融合治疗复发性腰椎间盘突出症：椎体稳定性评价

背景：腰椎间盘突出症治疗的重要方法是椎间盘切除,但有少部分患者会出现复发现象。 目的：探讨后路椎弓根钉棒内固定联合cage植入椎间融合治疗复发性腰椎间盘突出症后的脊柱稳定性。 方法：选择2007年1月至2011年12月复发性腰椎间盘突出症患者26例,应用后路减压cage植入椎间融合加钉棒系统内固定治疗复发性腰椎间盘突出症进行再手术治疗,观察患者治疗后疼痛症状缓解情况以及腰椎稳定性。通过数据库文献检索的方法分析后路钉棒内固定椎间融合治疗复发性腰椎间盘突出症的椎体稳定性。 结果与结论：26例患者均获得随访,随访时间为12-36个月。所有患者治疗后腰腿痛症状得到有效缓解,椎间融合良好,优良率96.2%。未出现椎弓根螺钉松动、断裂,椎间不融合现象。后路减压cage椎间融合加钉棒系统内固定治疗复发性腰椎间盘突出症,具有症状缓解快、内固定坚强、椎间融合确切等优点,是目前治疗复发性腰椎间盘突出症比较理想的方法。     

椎弓根螺钉系统内固定联合椎间融合器修复腰椎峡部裂性滑脱症:椎间隙高度恢复的评价

背景:峡部裂性腰椎滑脱主要依靠手术治疗,治疗方式多种多样,但其目的是对病变节段进行减压、复位、固定、融合,治疗金标准为生物性融合,而内固定是融合治疗可靠的辅助方法。目的:观察椎弓根螺钉系统内固定联合椎间融合器修复峡部裂性腰椎滑脱症的临床疗效。方法:2010年3月至2013年3月应用椎弓根螺钉系统联合椎间融合器治疗峡部裂性腰椎滑脱症21例,其中Ⅱ度滑脱18例,Ⅲ度滑脱3例。对所有病例进行定期随访,以JOA评分及目测类比评分作为治疗后随访的客观疼痛评价标准,采用Macrab标准评定疗效,根据Prolo指标评价功能恢复,按Lenke标准评估脊柱融合率,通过影像学资料评估滑脱率、滑脱角、骶骨倾斜角和椎间隙后高在治疗前后的改变。结果与结论:21例腰椎峡部裂性滑脱患者均获随访,随访时间12-16个月。所有患者JOA腰腿痛评分及腰腿痛目测类比评分均较治疗前改善,差异有显著性意义(P=0.000)。根据Macrab标准评定,本组优17例,良4例。Prolo活动、症状分级评价治疗前后比较差异有显著性意义(P=0.003)。治疗后腰椎滑脱基本复位,滑脱角明显减少,骶骨倾斜角增大,椎间隙高度基本恢复。提示椎弓根螺钉系统内固定联合椎间融合器是治疗峡部裂性腰椎滑脱症的有效策略之一。     

单枚cage单侧椎弓根螺钉置入内固定治疗退行性腰椎不稳51例

背景:既往多采用双侧显露,双侧椎弓根钉置入固定治疗退行性腰椎不稳,手术风险较大,出血较多,手术时间长,费用高.目的:探讨后路单枚cage单侧椎弓根钉置入内固定治疗退行性腰椎不稳的临床效果.方法:采用后路椎弓根钉及椎间融合器治疗需行内固定融合的退行性腰椎不稳患者51例,男32例,女19例,年龄41～72岁;单节段47例,双节段4例.手术方法均采用单侧显露症状侧椎板及关节突,单侧置入椎弓根钉,经椎间孔入路手术切除椎间盘及软骨终板,植骨后放入单枚cage.根据日本JOA评分法评估术后疗效.结果与结论:术中出血90～430 mL;手术时间单节段为100(85～120)min,双节段为150(120～170)min;术后第二三天即可离床活动.术后有2例患者腰腿痛无好转,复查CT和MRI均未见异常,其中1例经3个月对症处理后腰腿痛减轻,另1例无变化.按日本JOA评分法评定标准,术前JOA评分11(7～13)分,术后1年JOA评分25(18～27)分.94%患者的JOA改善率>50%.51例患者中融合44例,可能融合7例,融合时间为5.4(4.3～7.1)个月.本组未发现椎弓根螺钉松动、拔出、断钉及cage移位.说明单侧椎弓根钉及cage内固定手术方法简单,出血少,手术时间短,对脊柱结构破坏少,是治疗退行性腰椎不稳可供选择的较好方法.     

单侧腰椎弓根螺钉及经椎板关节突螺钉固定与双侧固定的比较

背景：经椎板关节突关节螺钉固定、椎问植骨融合治疗脊柱疾患是一种独特的固定方法,可用于退变性腰椎的融合。目的：比较采用微创经腰椎间孔椎体融合联合单侧椎弓根螺钉及经椎板关节突螺钉固定与常规开放后路腰椎体间融合术联合双侧椎弓根螺钉固定治疗下腰痛疾病的临床效果。方法：纳入2010年6月至2012年6月于武警广东总队医院就诊的腰椎间盘突出伴腰椎轻度不稳患者49例,均采用后路减压椎间融合器植骨内固定治疗。其中24例采用微创经椎间孔椎体融合术联合单侧椎弓根螺钉及经椎板关节突螺钉固定,25例采用常规开放后路腰椎体间融合术联合双侧椎弓根螺钉固定,比较两种固定方法的临床疗效。结果与结论：两种固定方法术后椎体融合率、日本矫形外科协会评分及疼痛目测类比评分改善率差异均无显著性意义（P〉0．05）。可见对无严重不稳的单节段退变性腰椎疾病患者,两种治疗方法的效果相当,均能有效提高椎间融合率,使小关节稳定,解除临床症状,门诊随访满意。但采用微创经椎间孔椎体融合术联合单侧椎弓根螺钉及经椎板关节突螺钉固定的患者手术切口长度、手术时间、术中出血量、术后切口引流液量明显减少（P〈0．05）,说明该方法具有创伤小、操作简单的优势。     

单侧椎弓根钉内固定治疗单节段腰椎间盘突出症疗效比较

目的:探讨单侧椎弓根钉内固定治疗单节段腰椎间盘突出症的临床疗效。方法:我院采用钉棒内固定椎间融合器治疗48例单节段腰椎间盘突出症的患者,其中双侧椎弓根内固定26例(A组),单侧椎弓根固定22例(B组)。比较2种手术患者手术时间、术中出血量、术后住院天数、融合率、手术前后JOA评分的情况,分析其手术方式对治疗效果的影响。结果:术后随访平均17个月,所有患者术后的功能参数均优于术前,B组患者在手术时间、出血量方面优于A组患者,2种手术患者术前JOA差异无统计学意义(P0.05),末次随访时的JOA的差异也无统计学意义(P0.05)。结论:单侧椎弓根钉内固定结合椎间融合术治疗单节段腰椎间盘突出症能够减少手术创伤和手术费用,与同双侧椎弓根钉内固定取得相同的手术效果,适宜于在临床应用。     

空心椎弓根螺钉置入结合小切口后路腰椎融合治疗腰椎间盘突出症

背景：经皮椎弓根螺钉技术的优点在于可有效减少置钉操作对椎旁肌的过度损伤,有利于患者术后的腰背肌功能恢复,其微创技术操作可避免传统开放手术创伤大,出血多等缺陷。可折断U形长尾空心椎弓根螺钉为中空设计,撑开效果良好,内固定后应力强度、压缩时间、弯曲刚度和扭转力学性能均得到临床验证。目的：观察可折断U形长尾空心椎弓根螺钉系统置入结合小切口后路腰椎椎体间融合治疗单节段腰椎间盘突出症的临床效果。方法：纳入2012年1至12月间因腰椎间盘突出症接受可折断U形长尾空心椎弓根螺钉系统置入结合小切口后路腰椎椎体间融合治疗的患者30例。术后随访12个月,通过患者腰腿疼目测类比评分、Oswestry功能障碍指数以及影像学指标评估临床治疗效果。结果与结论：患者术前目测类比评分及Oswestry功能障碍指数分别为（7.3±0.7）分和71.4±7.1;术后第3天分别为（2.9±0.7）分和29.8±3.6,与术前相比差异有显著性意义;至术后12个月时,低水平目测类比评分及Oswestry功能障碍指数未发生显著改变。术后短时间随访发现,病例术后1年椎间融合良好,无内固定失败或感染等并发症发生。提示可折断U形长尾空心椎弓根螺钉系统置入结合小切口后路腰椎椎体间融合治疗腰椎间盘突出症的临床效果良好,椎间融合率高,手术并发症发生率低,创伤小。     

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.