Syncope as a health risk for soldiers: Influence of medical history and clinical findings on the sensitivity of head-up tilt table testing

Background: Syncope is a relevant health problem in military environments. Reliable diagnosis is challenging. Tilt table testing is an important tool for syncope diagnosis. The aim of this study was to determine whether signs such as prodromal symptoms, co-morbidity, frequency of syncopal events, body length, body mass index, and electrocardiography(ECG) abnormalities can be used to predict the success of tilt table testing at diagnosing syncope.Methods: Data from 100 patients with histories of syncope or pre-syncope, who were diagnosed using head-up tilt table testing, were retrospectively analyzed in a cross-sectional analysis. The diagnostic procedure was based upon a modified version of the Westminster protocol without any pharmacological provocation. Results: Patients showing pathological reaction patterns during tilt table testing suffered from prodromal symptoms, such as dizziness and sweating, significantly more often. The patients reported more injuries resulting from syncopal events and more previous syncopal events, and the prevalence of co-morbidity was greater among patients presenting negative findings during tilt testing. An asthenic-leptosomal physique was not confirmed as a risk factor for syncopal events as is the case for idiopathic arterial hypotension. However, patients with pathological reaction patterns during tilt table testing were significantly taller. This finding was detected for both females and males. No significant predictors were found in the ECG patterns of patients showing syncope during tilt table testing.Conclusions: Frequency of prior syncope and prodromal symptoms, and increased body length with an otherwise good state of health influence the predictive value of tilt table testing for syncope diagnosis. In particular, if these factors are present, tilt table testing should be considered part of the diagnostic algorithm for soldiers with recurrent syncope.

Syncope as a health risk for soldiers-influence of medical history and clinical findings on the sensitivity of head-up tilt table testing

Background:Syncope is a relevant health problem in military environments.Reliable diagnosis is challenging.Tilt table testing is an important tool for syncope diagnosis.The aim of this study was to determine whether signs such as prodromal symptoms,co-morbidity,frequency of syncopal events,body length,body mass index,and electrocardiography abnormalities can be used to predict the success of tilt table testing at diagnosing syncope.Methods:Data from 100 patients with histories of syncope or pre-syncope,who were diagnosed using head-up tilt table testing,were retrospectively analyzed in a cross-sectional analysis.The diagnostic procedure was based upon a modified version of the Westminster protocol without any pharmacological provocation.Results:Patients showing pathological reaction patterns during tilt table testing suffered from prodromal symptoms,such as dizziness and sweating,significantly more often.The patients reported more injuries resulting from syncopal events and more previous syncopal events,and the prevalence of co-morbidity was greater among patients presenting negative findings during tilt testing.An asthenic-leptosomal physique was not confirmed as a risk factor for syncopal events as is the case for idiopathic arterial hypotension.However,patients with pathological reaction patterns during tilt table testing were significantly taller.This finding was detected for both females and males.No significant predictors were found in the electrocardiogram patterns of patients showing syncope during tilt table testing.Conclusions:Frequency of prior syncope and prodromal symptoms,and increased body length with an otherwise good state of health influence the predictive value of tilt table testing for syncope diagnosis.In particular,if these factors are present,tilt table testing should be considered part of the diagnostic algorithm for soldiers with recurrent syncope.

The Changes of Heart Rate Power Spectral Density during Head-up Tilt Test

To study the role of autonomic nervous system in the period of developing syncope induced by head-up tilt test(HUT), we analysed the changes of heart rate power spectral density(HRPSD) in 50 patients with unexplained syncope, including 15 positive patients (Group 1) and 35 negative patients(Group 2), and 15 negative healthy persons(Group 3) in 5 minute periods before and after tilting and 5 minutes before the end of test. HRPSD and their changes in total(T), very low-frequence(VLF), low-frequence(LF), high-frequence(HF) and the ratio of low/high frequence(LF/HF) were similar (P>0.05) 5 minutes before and after tilting among three groups. Five minutes before the end of test, Group 1 had obvious increase of T, VLF, LF and LF/HF while Group 2 and 3 had not such significant changes. There was significant difference(P<0.01) compared Group 1 with Group 2, 3. The results showed that the abnormal regulatory function of autonomic nervous system played an important role in the mechanism of symcope induced by HUT, the positive group had abnormal increase of sympathetic tone and imbalance of sympathetic/parasympathetic neural tone before syncope appeared.

Cardiac index (CI) versus cardio ankle vascular index (CAVI) at different degrees of head-up tilt (HUT) in healthy subjects

The cardio-ankle vascular index (CAVI) is a new index of arterial stiffness that can be measured with a VaSera VS-1000 device. An association between certain arterial stiffness indices and cardiac function has been found but has not yet been validated. The aim of this study was to establish whether any significant relationship exists between cardiac index (CI) and CAVI. Twenty healthy male volunteers with a mean age of 30 ± 5 years and a mean BMI of 23.1 ± 1.1 kg/m2 participated in the study. CO was estimated using a Doppler technique, and CAVI was measured with a VaSeraVS-1000 device. A motorised tilting table was used to achieve head-up tilt (HUT) angles of 0°, 30°and 60°, to modify the peripheral sympathetic outflow. We found that there was a significant inverse correlation between CI and the degree of head-up tilt, ( for 0°and 30°;for 0° and 60°, p for both;for 30° and 60°, ). CAVI showed a significant positive correlation relative with the degree of HUT, ( for 0° and 30°;for 0° and 60°;for 30° and 60°, for all). A significant negative correlation was found between CI and CAVI r = - 0.47, p Additionally, a significant p increase in PVR values was observed for increasing HUT values. In conclusion: An inverse relationship between CI and CAVI was shown;a decrease in cardiac output is associated with an increase in CAVI values at different degrees of HUT. This association provides further insight into the postural link between cardiac output and arterial compliance.

The Changes of Baroreflex Sensitivity During Head-up Tilt Test and Its Clinical Significance in the Patients with Vasovagal Syncope

Objective To study thechanges of baroreflex sensitivity (BRS) during head - up tilt test (HUT) in patients with vasovagal syncope (VS), and to examine the relationship between baroreflex sensitivity and neurohormonal factors. Furthermore, to investigate the effects of the changes of BRS on VS. Methods Forty - two patients with unexplained syncope (Among the 42 patients, there were 22 patients with positive HUT and 20 patients with negative HUT respectively) and 20 healthy volunteers (with negative HUT) underwent passive head - up tilt testing, Ante-cubital vein blood samples were taken before and after HUT, or at syncope. The fasting plasma endothelin , serum nitric oxide (NO), serum NE were measured, the BRS was assessed on the basis of the linear regression slope the RR interval versus systolic arterial blood pressure during the increment in blood pressure after intravenous administration of phenylephrine. Results (1) During the syncope, the BRS significantly reduced in HUT(+) group than baseline. At the end of tilt, the level of plasma ET, serum NO in patients with positive HUT significantly increased compared with baseline or normal controls, and the plasma concentration of NE also had the trend of increase. (2) By multiple regression analysis, a significant negative correlation was found between baroreceptor sensitivity and the plasma ET, NO at the end of HUT in patients with positive HUT, but there was no relationship between BRS and NE. Conclusions During the syncope occure, the BRS in patients with VS decreased significantly compared with normal controls. The abnormal plasma ET, NO concen-tration might contribute to the mechanism of VS.

Deceleration Capacity--A Novel Measure for Autonomic Nervous System in Patients with Vasovagal Syncope on Tilt-table Testing

This study was to investigate the changes of autonomic nerve function and hemodynamics in patients with vasovagal syncope(VVS) during head-up tilt-table testing(HUT). HUT was performed in 68 patients with unexplained syncope and 18 healthy subjects served as control group. According to whether bradycardia, hypotension or both took place during the onset of syncope, the patients were divided during the test into three subgroups: vasodepressor syncope(VD), cardioinhibitory syncope(CI) and mixed syncope(MX) subgroups. Heart rate, blood pressure, heart rate variability(HRV), and deceleration capacity(DC) were continuously analyzed during HUT. For all the subjects with positive responses, the normalized low frequency(LFn) and the LF/HF ratio markedly decreased whereas normalized high frequency(HFn) increased when syncope occurred. Syncopal period also caused more significant increase in the power of the DC in positive groups. These changes were more exaggerated compared to controls. All the patients were indicative of a sympathetic surge in the presence of withdrawal vagal activity before syncope and a sympathetic inhibition with a vagal predominance at the syncopal stage by the frequency-domain analysis of HRV. With the measurements of DC, a decreased vagal tone before syncope stage and a vagal activation at the syncopal stage were observed. The vagal tone was higher in subjects showing cardioinhibitory responses at the syncopal stage. DC may provide an alternative method to understand the autonomic profile of VVS patients.

慢性直立不耐受人群血流动力学模式与缺血性卒中发病风险关系的前瞻性研究

目的:探讨慢性直立不耐受(OI)人群血流动力学模式与缺血性卒中发病风险的关联,为早期评估缺血性卒中的发病提供依据。方法:以多阶段随机抽样的方法抽取吉林省长春市3个街道/乡镇≥40岁638名居民作为研究对象,经颅多普勒(TCD)联合直立倾斜试验(HUTT)评估OI人群血流动力学模式,建立OI研究队列;按血流动力学改变模式将患者分为直立位低血压(OH)组、直立位高血压(OHT)组、体位性心动过速综合征(POTS)组和直立性脑低灌注综合征(OCHOs)组;对入选的研究对象每半年随访1次,随访2年;以首次缺血性卒中发病为观察终点,收集研究对象基线资料和随访期间缺血性卒中发病情况,采用Cox比例风险模型分析与缺血性卒中发病风险关联的因素。结果:121例研究对象符合OI诊断标准,其中OH组80例(66.12%),OHT组35例(28.93%),POTS组5例(4.13%),OCHOs组1例(0.82%);随访期间,总体人群确诊新发缺血性脑卒中事件共43例;在控制相关混杂因素后,以非OI者为参照,OI全人群、OH和OHT患者发生缺血性卒中的风险分别增加1.527倍[风险比(HR)=2.527,95%CI:1.269~5.032,P<0.01]、2.268倍(HR=3.268,95%CI:1.603~6.663,P=0.001)和2.153倍(HR=3.153,95%CI:1.213~8.916,P=0.008)。结论:OI与缺血性卒中发病风险增加有关,其中OH组和OHT组患者发病风险增加尤为明显。

血管迷走性晕厥手术治疗的现状与展望

血管迷走性晕厥作为晕厥中最常见的一种形式,心脏抑制型晕厥患者经随机临床试验证实有效的药物疗法有限,可建议使用永久性起搏器治疗。本文梳理了起搏器治疗血管迷走性晕厥中曲折发展经历并总结了原因,根据指南整理了目前适用于起搏治疗的患者类型以及应用的局限性,心脏神经消融术可能成为血管迷走性晕厥患者的另一种选择,但尚需要大样本随机对照试验证实其安全性、有效性以及适用人群。

直立倾斜试验操作医师累计工作量对血管迷走性晕厥诊断结果的影响性分析

目的:探讨直立倾斜试验操作医师累计工作量对诊断报告结果的影响。方法:回顾性连续纳入中国医学科学院阜外医院自2016年1月1日至2022年12月31日进行直立倾斜试验检查的操作医师和患者资料。根据从本院开展倾斜试验至研究结束这一阶段医师的累计工作量,将医师分为低累计工作量组(累计50~100例)、中等累计工作量组(累计101~350例)、高累计工作量组(累计1000~4000例;无医师累计工作量在351~999例),以及按医师的的性别、学历、职称分别进行分组,分析不同分组内和不同分组间医师倾斜试验报告诊断率的差异。结果:共纳入22名医师操作的6122例患者,22名医师个体之间的阳性、可疑阳性和阴性报告率差异均具有统计学意义(P均<0.001)。中等累计工作量组平均可疑阳性报告率显著高于低累计工作量组和高累计工作量组(3.21%vs.1.09%vs.1.62%,P=0.001),女性医师可疑阳性报告率高于男性医师(2.25%vs.1.07%,P=0.017),本科学历医师可疑阳性报告率高于研究生学历医师(2.46%vs.1.52%,P=0.013),初级职称医师可疑阳性报告率高于中级和高级职称医师(3.40%vs.1.75%vs.2.53%,P=0.024)。多因素Logistic回归分析显示,不论以阴性还是阳性作参照,中等累计工作量均是可疑阳性报告的影响因素(P均<0.05)。结论:不同操作医师个体之间的倾斜试验诊断报告率存在一定差异,中等累计工作量组操作医师更易出具可疑阳性诊断报告。

Age and Sex Distribution of Patients with Vasovagal Syncope Undergoing Head-up Tilt Table Test: 7-Year Audit

To investigate age and sex distribution of vasovagal syncope （VVS） patients undergoing head-up tilt table test （HUTT） at a tertiary hospital. The details of syncope patients who underwent HUTT at our department of cardiac function from January 2004 to December 2010 were reviewed. Of the 1 799 patients who underwent the HUTT, 854 tested positive, of which 558 （65.3%） were women, which were more than the women in the negative group （450, 47.6%） （p〈0.05）. VVS patients showed a bimodal age distribution between 11 and 20 years of age and in the fourth decade. In almost all age groups, mixed response was the highest compared with vasodepressor and cardioinhibitory. VVS patients who underwent HUTT indicate bimodal distribution peaking before the second decade and the fourth decade. The incidence of females was twice that of males before the sixth decade, and old age occupies a small percentage of VVS with no other comorbidities.

年龄和性别对直立倾斜试验诊断血管迷走性晕厥结果的影响

目的：探讨年龄和性别对疑似血管迷走性晕厥（VVS）患者进行直立倾斜试验（HUTT）诊断结果的影响。方法：收集2008-08至2012-12在阜外心血管病医院进行HUTT检查的患者共1 223例,其中男性549例。患者年龄7-79岁,按年龄依次分为≤20岁组、21-40岁组、41-60岁组和〉60岁组。HUTT包括30 min的基础试验阶段和（或）20 min的药物（硝酸甘油）试验阶段。根据阳性患者血压和心电学的变化,VVS分为血管抑制型、心脏抑制型和混合型。结果：HUTT阳性率为51%（624/1 223例）,女性阳性率高于男性（60.1%vs 39.9%,P=0.001）。四组阳性率依次为68.3%、49.1%、48.6%和47.9%。阳性患者中混合型占51.4%（321例）,血管抑制型占28.7%（179例）,心脏抑制型占19.9%（124例）。HUTT阳性类型的分布受年龄因素的影响（男性：χ2=15.65,P=0.016;女性：χ2=18.84,P=0.004）,性别间差异无统计学意义（P〉0.05）。基础试验阶段74.8%的阳性反应出现在试验开始后22.5（17.5-27.5）min,但无年龄性别差异（P〉0.05）;药物试验阶段81.9%的阳性反应出现在试验开始后7.5（5-10）min,女性发生阳性反应的时间比男性提前（7.5 min vs 10 min,P=0.004）,无年龄差异。结论：HUTT诊断VVS的阳性率、阳性分型和发生阳性反应的时间存在年龄和性别差异。

直立倾斜试验诱发晕厥直至出现抽搐症状89例的临床特点及处理

目的：探讨直立倾斜试验（head－up tilt table test，HUTT）诱发晕厥直至出现抽搐症状的临床特点及其处理。方法：2000年9月至2011年8月在中南大学湘雅二医院晕厥专科门诊就诊或住院的不明原因晕厥、头晕、头痛、胸闷等患者进行HUTF检查2377例次，年龄2．00～78．00（18．57±14．39）岁，男1116例次，女1261例次。其中〈18岁（儿童组）1719例次，年龄2．00-17．92（10．88±3．02）岁；≥18岁（成人组）658例次，年龄18．00-78．00（38．66±12．87）岁。总结HU2T过程中诱发晕厥直至出现抽搐症状患者的临床特点及其处理措施。结果：1）2377例次HUTT过程中诱发晕厥直至出现抽搐症状89例（3．74％），其中成人组（62．92％）高于儿童组（37．08％）（X2=87．842，P〈0．01）。2）窦性停搏及心率恢复时间：89例受试者中25例（28．09％）出现窦性停搏，窦性停搏时间3．00～14．60（7．90±3．44）S。HUTf结束后心率恢复时间0．50-37．00（3．05±4．11）min，其中70例（78．65％）在平卧后3min内恢复。3）干预措施：所有受试者完成HuTr后，均通过采取平卧位给氧、神志清醒后喝盒装牛奶等措施后，心率及血压自行恢复，抽搐症状自行消失，未出现死亡病例，仅2例通过静脉给药后生命体征恢复正常。结论：不明原因晕厥、头晕、头痛、胸闷等患者在HuTT中诱发晕厥直至出现抽搐症状者以成人居多，HUTT结束后采取平卧位给氧、神志清醒后喝盒装牛奶等措施，抽搐症状消失，心率和血压可自行恢复正常。HUTF在临床上应用较为安全，可广泛用于包括儿童在内的各年龄人群。

直立倾斜试验对不明原因头晕与晕厥患者诊断比较

目的探讨直立倾斜试验(HUTT)对不明原因头晕与晕厥患者诊断上的差异。方法对头晕组(n=35)进行HUTT检查,并选择同期晕厥组(n=303)的HUTT结果为对照,HUTT采用基础直立倾斜试验(BHUT)及舌下含服硝酸甘油倾斜试验(SNHUT)。结果①头晕组与晕厥组患者在BHUT、SNHUT时收缩压、舒张压、心率比较差异无显著性意义(P>0.05),阳性结果反应类型比较差异亦无显著性意义(P>0.05)。②阳性率:HUTT时头晕组31.43%(11/35),晕厥组42.90%(130/303)。其中BHUT时头晕组28.57%(8/28),晕厥组33.82%(70/207);SNHUT时头晕组42.86%(3/7),晕厥组62.50%(60/96)。阳性率在头晕组和晕厥组比较差异无显著性意义(P>0.05)。两组SNHUT阳性率较BHUT均明显提高(P<0.05)。③出现阳性结果时间:BHUT时头晕组(29.13±11.01 min)仅比晕厥组(23.52±12.80 min)稍长,SNHUT时在舌下含服硝酸甘油后也是头晕组(6.00±3.61 min)比晕厥组(4.98±3.51 min)稍长(P均>0.05)。结论临床上部分不明原因头晕患者由VVS所致,但并不出现晕厥发作,这类患者应重视倾斜试验检查。

不明原因晕厥相关性躯体意外伤害

目的探讨不明原因晕厥相关性躯体意外伤害情况。方法对不明原因晕厥患者（n=351）详细询问病史，包括晕厥发作时躯体意外伤害事件的发生情况，并行倾斜试验（HUTT）检查明确诊断。结果①31例（8．8％）患者有晕厥相关性躯体意外伤害，HUTT阳性患者中19例（11．5％）存在晕厥相关性躯体意外伤害；②晕厥致躯体意外伤害大多较轻，少数患者会发生严重伤害；③发生晕厥相关性躯体意外伤害者男性较多，年龄段以9～13岁居多；④躯体意外伤害患者HUTT反应类型以血管抑制型为主。混合型次之，心脏抑制型最少。结论晕厥相关性躯体意外伤害事件的发生是随机的，大部分患者伤害较轻，个别患者会发生严重意外伤害。强调对不明原因晕厥患者重视HUTT检查。对确诊的血管迷走性晕厥（VVS）患者实施早期干预，将躯体意外伤害事件的发生降至最低限度。

一氧化氮和内皮型一氧化氮合成酶与血管迷走性晕厥发病的关系

目的探讨一氧化氮和内皮型一氧化氮合成酶与儿童血管迷走性晕厥发病的关系。方法血管迷走性晕厥患儿14例(A组),其他原因引起晕厥患儿10例(B组),健康志愿者20例(C组)。于倾斜试验(HUT)前和倾斜不同时间测定A组与B组患儿的血浆一氧化氮(NO)水平,同时对3组儿童进行内皮型一氧化氮合成酶(eNOS)基因G894T多态性检测。结果①A组患儿出现阳性反应时血浆NO水平较平卧时显著升高(76.7±9.6vs 90.0±11.4μmol/L,P<0.05);②A组患儿在症状好转后血浆NO水平较试验前显著降低(82.7±9.2 vs61.5±6.9μmol/L,P<0.01);③B组患儿倾斜时血浆NO水平较平卧时差异无显著性;④A,B两组患儿的血压、心率变化与NO水平无显著相关性;⑤A组患儿eNOS基因G894T突变型基因频率显著高于B组与C组(42.9%vs10%,P<0.05)。结论倾斜体位时血浆NO水平异常升高可能参与了血浆血管迷走性晕厥的发病机制,而其升高水平可能与eNOS基因G894T多态性表达有关。[中国当代儿科杂志,2008,10(4):478-480]

β_1肾上腺素受体基因多态性与小儿血管迷走性晕厥的相关性研究

目的探讨β1肾上腺素受体(ADRB1)基因多态性Arg389Gly与小儿血管迷走性晕厥(VVS)发病的相关性。方法晕厥组为不明原因晕厥(unexplained syncope,UPS)患儿54例,其中男18例,女36例,平均11.8岁;对照组为同期健康体检儿童54例,其中男20例,女34例,平均11.2岁。入选病例均行直立倾斜试验(head-up tilt test,HUTT),根据HUTT结果,分HUTT阳性组即VVS组和HUTT阴性组,各组病例均应用聚合酶链反应PCR和基因测序方法检测ADRB1基因Arg389Gly多态性。结果健康儿童的等位基因Arg389和Gly389的频率分别为73.15%和26.85%,HUTT阳性患儿等位基因Arg389和Gly389的频率分别为66.67%和33.33%,HUTT阴性患儿等位基因Arg389和Gly389的频率分别为85.42%和14.58%;HUTT阳性患儿的Gly389等位基因频率明显高于HUTT阴性组患儿及健康对照儿(P<0.05)。HUTT阳性组共30例(55.6%),其临床分型中心脏抑制型6例(20.0%),混合型9例(30.0%),血管抑制型15例(50.0%),Gly389等位基因频率在各临床分型的分布为66.67%、33.3%和23.33%,心脏抑制型的Gly389等位基因频率高于混合型和血管抑制型(P<0.05)。结论Gly389等位基因频率与VVS有相关性,可考虑作为小儿VVS的候选易感基因,提供临床早期筛查;Gly389等位基因频率与VVS临床分型中的心脏抑制型有相关性,可为其个体化治疗—β受体阻滞剂治疗提供初步的分子生物学理论依据。

血管迷走性晕厥10年临床研究

目的 研究血管迷走性晕厥（VVS）10年临床情况.方法 2000-01～2010-07在我院诊治不明原因晕厥或先兆晕厥患者1782例,根据检查年限分为A组（2000-01～2004-12,n=280）和B组（2005-01～2010-07,n=1502）,根据年龄分为儿童组（〈18岁,n=1180,男450例,女730例）和成人组（≥18岁,n=602,男182例,女420例）.儿童组平均年龄（9.77±3.92）岁,按照年龄段分为4～6岁、7～10岁和11～18岁三个年龄段;成人组平均年龄（40.78±14.05）岁.结果 ①HUTT阳性率：HUTT总阳性率47.7%,其中儿童组和成人组分别为44.3%和54.3%;在儿童和成人中B组较A组均增加（45.7% vs33.3%,61.4% vs33.1%,P〈0.05）.②HUTT阳性率性别比例变化：儿童组和成人组女性均高于男性（32.2% vs12.1%,42.7% vs11.6%,P〈0.05）;在儿童和成人中B组男性和女性均高于A组（分别为12.5% vs9.3%、33.2% vs24.0%,9.8% vs7.3%、51.7% vs25.8%,P〈0.05）.③HUTT反应类型变化：儿童组和成人组血管抑制型〉混合型〉心脏抑制型（P〈0.05）,其中儿童组血管抑制型B组高于A组（33.8% vs19.4%,P〈0.05）;成人组血管抑制型和混合型B组均高于A组（40.1% vs20.5%,18.4% vs9.9%,P〈0.05）.④儿童组HUTT阳性率年龄变化：儿童组11～18岁组〉7～10岁组〉4～6岁组（P〈0.05）.在各年龄段中,4～6岁及11～18岁B组均高于A组（6.2% vs3.9%,23.3% vs21.7%,P〉0.05）,7～10岁组中B组明显高于A组（16.2% vs7.8%,P〈0.05）.结论 VVS患者的阳性率、反应类型在近10年不断发生变化,提示VVS的发生受社会因素、精神因素、生活方式等多种因素的影响.

模拟失重条件下与选择心算关联的脑电位的动态变化

为研究模拟失重对脑功能状态的影响，在１５名正常被试者中比较了头低位倾斜－１０°（ＨＤＴ，模拟失重）和头高位倾斜＋２０°（ＨＵＴ，对照）条件下视觉选择心算的事件关联电位（ＥＲＰｓ），在每种体位的２ｈ期间各进行５套测试。结果表明：靶和非靶闪光信号引起不同的正慢电位；靶信号的正慢电位时程和幅值显著长于和高于非靶信号，尤以后脑区为最；与ＨＵＴ比较，在ＨＤＴ条件下正慢电位的幅值降低，且在第４及第５套记录时更明显。

头高15°倾斜位对肥胖患者全麻苏醒期呼吸功能的影响

目的观察头高15°倾斜位对肥胖患者全麻苏醒期呼吸功能的影响。方法选择择期全麻下行显微耳科手术的肥胖患者80例,男39例,女41例,年龄18~60岁,ASAⅠ或Ⅱ级,BMI≥28kg/m^2。随机分为两组:头高15°倾斜位组(H组)和平卧位对照组(C组)。常规诱导行气管插管,术中麻醉维持采用靶控输注(TCI)丙泊酚2~4μg/ml和瑞芬太尼5~6μg/ml,维持BIS 40~60,术中不追加肌松药,术毕C组采用平卧位,H组采用头高15°倾斜位。记录患者从轻唤睁眼后到达到拔除气管导管标准所需的时间(X),达PACU出室标准所需的时间(Y),拔管后吸入新鲜空气时SpO_2由100%降至92%的时间(Z)和吸入纯氧后SpO_2由92%上升至100%的时间(W)。记录入室时、吸氧3min后、术毕时、气管拔除前及出PACU时的PaO_2、PaCO_2和pH。结果 H组X(14±7)min、Y(45±7)min、W(39±11)s均明显短于C组[(19±6)min,(57±10)min,(51±9)s],Z(335±58)s明显长于C组(245±75)s(P<0.05)。气管拔除前和出PACU前H组PaO_2[(193.4±30.5)mmHg,(82.2±3.4)mmHg]明显高于C组[(169.1±29.4)mmHg,(70.8±4.1)mmHg](P<0.05),其他各时点PaO_2差异均无统计学意义。两组各时点PaCO_2和pH差异无统计学意义。结论头高15°倾斜位可有效促进肥胖患者全麻苏醒期呼吸功能的恢复,安全可行。

美托洛尔治疗儿童血管迷走性晕厥的效果

目的探讨美托洛尔在儿童血管迷走性晕厥(VVS)中的疗效。方法将直立倾斜试验(HUT)阳性的VVS患儿29例随机分为治疗组(n=16,应用口服美托洛尔治疗)及对照组(n=13,应用复合维生素B或谷维素治疗),观察两组患儿临床晕厥发作次数及HUT结果。结果治疗组无发作9例,发作次数减少5例,发作次数增加、无变化各1例;复查HUT 6例转阴。对照组无发作1例,好转5例,发作次数增加3例,无变化4例;HUT 3例转阴。结论口服美托洛尔可有效治疗儿童VVS。