倾斜床模拟推拉动作时受试者的心血管反应及其方法学评价

目的：建立倾斜床模拟推拉动作(push pull maneuver，PPM)模型，并观察其引发的心血管反应性特点。方法：以10名健康歼击机飞行员为被试者，随机进行3次90泣位(head up tilt,HUT)和904立位(hesd down tilt,HDT)体位转换试验，HUT 1 min HDT 10 s HUT 1 min，第2，3次体位转换时HDT的持续时间分别为15s和20s。床体旋转速度为45&;#176;／8s。间隔4s监测一次血压，连续记录心电图。结果：在HDT(-1Gz)期间，各时间心率[-1Gz 0～10s头低位：(60．7&;#177;9．5)次／min,头高位：(85．2&;#177;6．4)次／min；-1Gz 11～15s头低位：(54．4&;#177;6．7)次／min,头高位：(82．7&;#177;4．9)次／min；-1Gz 16～208头低位：(54．1&;#177;7．8)次／min,头高位：(85．1&;#177;5．2)次／min]和血压较基础HUT[(90．7&;#177;70．1)次／min]明显下降(P&;lt;0．05～0．01)。随后HUT时，除11～15s血压外，其余各时间心率和血压较基础HUT明显下降。结论：采用倾斜床可以模拟推拉动作所引起的心血管反应，故其可作为推拉动作模型。     

中老年人症状限制性心电运动试验的心血管反应

目的：探讨症状限制性心电运动试验的心血管反应。方法：依Ｂｒｕｃｅ方案采用活动平板试验。检查者年龄平均５３９±１１３岁，男女比例为２∶１。结果：最大运动时间和最大代谢当量分别为９８９±２７８ｍｉｎ和１０７１±２９２Ｍｅｔｓ；最大心率１５９０±２０４次／ｍｉｎ；最大收缩压２２５±３２ｋＰａ；最大舒张压１１６±１８ｋＰａ。运动后血压均明显降低，以舒张压降低最为明显。可疑冠心病人和体检者的心血管反应类型相似，绝对数值有一定差异。最大运动时ＳＴ段下移最明显，可疑冠心病阳性组ＳＴ段下移大于体检阳性组，两组又都明显大于阴性组（Ｐ均＜０００１）。结论：应采用症状、体征和心电改变确定运动试验终点。运动有一定的降压作用。最大运动时ＳＴ段下移最为明显。运动后常见ＳＴＶ现象，值得进一步研究。     

飞行员运动试验与倾斜试验后心率和血压变化的比较

目的 分析飞行员运动试验与倾斜试验后心率和血压变化的差异,为综合评价飞行员的心血管调节功能提供依据.方法 受试者为20名飞行合格的男性战斗机飞行员,其年龄25～38岁、身高1.67～1.76 m、体重58～82 kg、飞行时间500～2 000 h,分别进行次极量运动试验和倾斜试验.负荷测试前、结束即刻、结束后2 min分别进行心率、血压测量和心电图监测.结果 受试者心率、收缩压、舒张压、脉压分别为①基础:(71.3±11.5)次/min、(17.33±0.98)kPa、(10.67±1.01)kPa、(6.73±0.89)kPa.②运动试验终点:(94.7±12.6)次/min、(21.33±2.03)kPa、(10.79±1.74)kPa、(10.52±2.05)kPa;倾斜试验终点:(81.8±12.4)次/min、(16.13±1.14)kPa、(10.45±1.25)kPa、(5.69±1.13)kPa.③运动试验后2 min:(94.4±9.6)次/min、(18.13±1.41)kPa、(10.45±1.25)kPa、(6.73±1.06)kPa;倾斜试验后2 min:(78.9±9.3)次/min、(15.57±1.34)kPa、(11.09±0.92)kPa、(4.63±1.53)kPa.④两项试验终点和试验后2 min的心率、收缩压、脉压与基础对照比较相差显著(t=2.512～9.518.P<0.01～0.05),而舒张压则相差不显著(t=0.24～2.07,P>0.05);运动试验的心率、收缩压、脉压变化程度均明显超过倾斜试验(t=3.996～8.943,P<0.01).结论 运动试验中主要反映运动时心血管系统的供能水平,而倾斜试验主要反映体位变化时维持心血管系统压力的能力,两种负荷试验结合是评价飞行员心血管功能的有效方法 .     

原发性高血压合并颈椎病患者倾斜后血压和心率的变化

目的 探讨原发性高血压(EH)合并颈椎病患者头高位倾斜后血压和心率的变化及可能机制.方法 EH 49例,根据临床症状,运用X光机、颈椎CT或MRI和椎动脉彩超等检查方法,确诊合并颈椎病23例(合并颈椎病组),不合并颈椎病患者26例(单纯EH组),测定2组患者血压、血脂、血糖,并测定头高位倾斜后的血压、心率.结果 合并颈椎痛组和单纯EH组头高位倾斜后血压变化差异有统计学意义[4(-21～14)mm Hg与-9(-27～-3)mm Hg,H=25.44,P<0.01],心率变化差异有统计学意义[2(-1-14)次/min与5(-2～11)次/min,H=9.30,P<0.01].结论 合并颈椎病患者头高位倾斜后血压不下降与交感神经兴奋可能有关.     

动态血压及其模拟家庭自测血压评价动态动脉硬化指数的方法学简化

目的探讨动态血压及其模拟家庭自测血压评价动态动脉硬化指数（ambulatory arterial stiffness index,AASI）的方法学简化。方法连续入选81例行24小时动态血压监测的患者。AASI的计算：首先根据血压监测所得舒张压与收缩压之间的关系计算出回归斜率,AASI定义为1减去该斜率。AASI2的计算：把动态血压监测数值按收缩压排序,从中选取收缩压的25%及75%分位数,计算出该两个收缩压对应的血压间关系的回归斜率。AASI2定义为1减去该斜率。家庭自测血压的模拟简化（AASI4）：应用24小时动态血压监测期间7：00、12：00、18：00、22：00 4个时间点的血压模拟家庭自测的4次血压。AASI4定义为1减去该4点舒张压与收缩压关系的斜率。Sym-AASI的计算：1-（1-AASI）/r,其中r为动态血压直线回归模型的相关系数。结果 AASI为0.51±0.16,AASI2为0.50（0.24,0.68）,两组比较差异无统计学意义（Z=-1.196,P〉0.05）,两者无相关性（r=0.186,P〉0.05）;AASI4为0.52（0.29,0.71）,与标准AASI差异无统计学意义（Z=-0.480,P〉0.05）,两者无相关性（r=0.123,P〉0.05）;标准的sym-AASI为0.26±0.16,4点sym-AASI4为0.29（0.08,0.47）,两组比较差异无统计学意义（Z=-0.005,P〉0.05）,且两者呈正相关关系（r=0.307,P〈0.01）。Bland-Altman及Mountain plot分析显示标准AASI与AASI2、AASI4不能替换使用,sym-AASI与sym-AASI4不能够替换使用。结论简化AASI2不能替代标准AASI,不能利用1日内家庭自测血压值来简化AASI的计算。     

原发性高血压合并颈椎病患者倾斜后血压和心率的变化

Objective To investigate the change of blood pressure and heart rate in patients of essential hypertension combined with cervical spondylosis in head-up tilt and its potential mechanism. Methods The hypertensive patients were divided into cervical spondylosis group(23 cases) and without cervical spondylosis group (26 cases) by clinical symptom and X-ray machine,CT.MRI and color ultrasonography,then their blood pressure, blood glucose and lipid were measured,and the changes of blood pressure and heart rate were obtained in head-up tilt. Results There was significant difference of blood pressure change between the hypertensive with and without cervical spondylosis(4(-21 ～ 14 mm Hg v. s. -9(-27～-3)mm Hg,P<0. 01),and there was also difference of heart rate change between the hypertensive with and without cervical spondylosis(2(-1 ～14) bpm v. s. 5(-2 ～11) bpm, P < 0. 01). Conclusions There is no decline in blood pressure in the hypertensive with cervical spondylosis in head-up tilt and this might be due to the exciting of sympathetic nerve.     

原发性高血压合并颈椎病患者倾斜后血压和心率的变化

Objective To investigate the change of blood pressure and heart rate in patients of essential hypertension combined with cervical spondylosis in head-up tilt and its potential mechanism. Methods The hypertensive patients were divided into cervical spondylosis group(23 cases) and without cervical spondylosis group (26 cases) by clinical symptom and X-ray machine,CT.MRI and color ultrasonography,then their blood pressure, blood glucose and lipid were measured,and the changes of blood pressure and heart rate were obtained in head-up tilt. Results There was significant difference of blood pressure change between the hypertensive with and without cervical spondylosis(4(-21 ～ 14 mm Hg v. s. -9(-27～-3)mm Hg,P<0. 01),and there was also difference of heart rate change between the hypertensive with and without cervical spondylosis(2(-1 ～14) bpm v. s. 5(-2 ～11) bpm, P < 0. 01). Conclusions There is no decline in blood pressure in the hypertensive with cervical spondylosis in head-up tilt and this might be due to the exciting of sympathetic nerve.     

不同体位和阻力运动对健康人心血管反应的影响

目的：通过在坐位和卧位两种不同体位下,观察健康人进行不同强度抗阻运动时心血管反应及主观感受水平的变化.方法：20名观察对象随机采取坐位、卧位,轻、重两种弹性阻力下,进行每组5min,共4组的右侧伸膝抗阻运动的间歇性运动训练,静止期及每次运动前后均采集观察对象的心率、血压和心率变异性、自觉疲劳程度和焦虑水平等指标.结果：不同体位下的心率（HR）、低频与高频的比值（LF/HF）、高频功率（HFms2）、标准化低频功率（LFn.u.）和标准化高频功率（HFn.u.）差异有统计学意义（P＜0.01）,在体位与阻力的交互作用下这几个指标差异也有统计学差异（P＜0.01）,不同阻力间HR差异有统计学差异（P＜0.01）.卧位下两级阻力间HR差异有统计学差异（P＜0.01）.结论：实验结果提示,体位对心血管反应的影响较明显,而轻阻力负荷下,其阻力差引起的心血管反应差异不明显.各项客观指标对于训练过程中机体的变化灵敏性高于主观感受指标.     

少年篮球运动员对递增负荷运动的心血管反应

目的研究递增负荷运动对篮球运动员心血管反应。方法对12名平均年龄15岁参加业余篮球训练的少年做身体形态主要指标的测量,并在跑台上进行递增负荷运动,测量了每级运动的心率和血压。综合评定少年业余运动员的身体发育和功能水平状况,为训练安排提供科学依据。结果少年篮球运动员身体形态指标优于一般同龄少年,递增负荷运动可增加心血管系统的适应力。结论应定期进行本格检查功能测试,加强医务监督。     

不同角度直立倾斜试验对儿童血管迷走性晕厥诊断的影响

目的探讨不同角度直立倾斜试验(HUTT)对儿童血管迷走性晕厥(VVS)诊断的影响。方法2001-01~2005-12在中南大学湘雅二医院晕厥专科门诊就诊或住院的儿童不明原因晕厥(UPS)患者进行HUTT检查226例次,年龄4~18岁,平均(12.12±3.17)岁,男93例,女133例。倾斜角度在2001-01~2005-05采用70°[n=182,平均(12.19±3.20)岁],在2005-06~2005-12采用60°[n=44,平均(11.82±3.02)岁]。根据临床症状分偶发晕厥(n=66,晕厥发作仅1次)与反复晕厥(n=160,晕厥发作≥1次)。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)。结果倾斜角度、儿童患者性别及试验方式对UPS儿童血流动力学无影响(P>0.05),UPS儿童诊断阳性率及反应类型分布与倾斜角度、儿童患者性别、试验方式及晕厥频次亦无明显关系(P>0.05)。儿童倾斜70°体位感到欠舒适,倾斜60°体位无明显不适感。结论倾斜70°和60°对受试者血流动力学及阳性率无影响,倾斜60°体位较70°感到舒适。推荐临床上在进行儿童HUTT时选择倾斜60°较合适。     

Cardiovascular and microvascular responses to mild hypothermia in an ovine model

Aims

Hypothermia is used for brain protection after resuscitation from cardiac arrest and other forms of brain injury, but its impact on systemic and tissue perfusion has not been well defined. The aim of this study was to evaluate the cardiovascular and microvascular responses to mild therapeutic hypothermia (MTH) in an ovine model.

Methods

Seven anaesthetised, mechanically ventilated, invasively monitored sheep were cooled from a baseline temperature of 39–40 °C to 34 °C using cold intravenous fluids, ice packs and transnasal cooling. After 6 h of MTH, sheep were progressively re-warmed to baseline temperature. Positive fluid balance was maintained during the entire study period to avoid hypovolemia. In addition to standard haemodynamic assessment, the sublingual microcirculation was evaluated using sidestream dark-field (SDF) videomicroscopy.

Results

MTH was associated with significant decreases in cardiac index and left (LVSWI) and right (RVSWI) ventricular stroke work indexes. There was a downward shift in the relationship between LVSWI and pulmonary artery occlusion pressure during MTH, indicating myocardial depression. During MTH, mixed venous oxygen saturation increased, in association with reduced oxygen consumption, but blood lactate concentrations increased significantly. There was a significant decrease in the proportion and density of small perfused vessels. All variables returned to baseline levels during the re-warming phase.

Conclusion

In this large animal model, MTH was associated with decreased ventricular function, oxygen extraction and microvascular flow compared to normothermia. These changes were associated with increased blood lactate levels. These observations suggest that MTH may impair tissue oxygen delivery through maldistribution of capillary flow.     

直立倾斜试验对不明原因晕厥的临床应用

目的探讨直立倾斜试验在不明原因晕厥患者中筛查血管迷走性晕厥的价值。方法对52例不明原因晕厥患者进行直立倾斜试验,严密观察其血压、心率的变化。结果52例患者中阳性30例,占57．7％;基础倾斜试验阳性5例,异丙肾上腺素激发倾斜试验阳性25例;其中,心脏抑制型5例（16．7％）,血管抑制型8例（26．6％）,混合型17例（56．7％）。结论直立倾斜试验能简捷、有效地把血管迷走性晕厥从不明原因晕厥患者中筛查出来,明确诊断,值得临床推广应用。     

试验场地对直立倾斜试验结果的影响

目的 探讨试验场地对直立倾斜试验(HUTT)结果的影响方法对2000-09～2011-08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HUTT检查,共2377例,男11 16例,女1261例,年龄2～78岁,平均年龄(18.57±14.39)岁.根据我院医疗用地总体布局需要,将HUTT检查室进行过两次搬迁.3个直立倾斜试验场地在空间、温度、湿度、窗户面积、工作人员、试验方法等方面均没有变化.HUTT检查场地时间分别为:场地-从2000-09～2007-06(n=579,男224例,女355例),场地二从2007-07-2010-05(n=1114,男577例,女537例),场地三为2010-06-2011-08(n=684.男315例,女369例).比较3个场地HUTT结果的差异.结果 ①受检者在场地一的年龄大于场地二和场地三[(22.72±1.60)岁 vs (17.24±1.38)岁 vs (17.23±1.32)岁.P<0.05],3个场地件别比较差异有统计学意义(x2=26.592,P<0.01).②场地一、二、三的HUTT总阳性率分别为48.87%、52.78%、45.61%,3组比较以场地二最高(x2=8.958,P<0.05).但基础直立倾斜试验(BHUT)在场地一最高(x2=33.139,P<0.01),场地二和场地三差异无统计学意义(x2=0.031,P>0.05).③3个试验场地HUlTr反应类型均以血管抑制型为最高,其次为混合型,3个场地之间比较层异有统计学意义(x2=23.880.P<0.01).但场地二和场地三差异无统计学意义(x2=4.626,P>0.05).结论 单纯场地变化对HUTT结果不产生影响.     

Cardiovascular responses to a hot tub bath.

This study was conducted to determine the cardiovascular effects of 15 minutes of hot tub immersion at 39 degrees C. Five college-age subjects (4 males and 1 female) volunteered to participate in this study. Assessments were made while sitting first in a chair for 5 minutes and then in the hot tub for 15 minutes. Oxygen consumption (VO2) and cardiac output (Q) measurements were made using a Medical Graphics CPX/D metabolic analyzer. Cardiac output was determined at minute 15 using the indirect CO2 rebreathing procedure. The data were analyzed using the analysis of variance with repeated measures, which indicated that at minute 15, heart rate (HR) and Q were increased, which increased VO2. The increase in Q was due to the heart rate (HR) response and the decrease in systemic vascular resistance (SVR). Mean arterial pressure (MAP) and systolic blood pressure (SBP) were decreased while double product (DP) was increased. There were no changes in stroke volume (SV) or arteriovenous oxygen difference (a-vO2 diff). These findings indicate that the HR and Q responses are necessary to the increase in metabolism (VO2). Hot tube use within these time and temperature constraints should reduce concern over hot tub safety in college-age subjects.     

Influence of passive leg movements on blood circulation on the tilt table in healthy adults

Background  

One problem in the mobilization of patients with neurological diseases, such as spinal cord injury, is the circulatory collapse that occurs while changing from supine to vertical position because of the missing venous pump due to paralyzed leg muscles. Therefore, a tilt table with integrated stepping device (tilt stepper) was developed, which allows passive stepping movements for performing locomotion training in an early state of rehabilitation. The aim of this pilot study was to investigate if passive stepping and cycling movements of the legs during tilt table training could stabilize blood circulation and prevent neurally-mediated syncope in healthy young adults.     

Cardiovascular responses to pain and stress in migraine

OBJECTIVE: The purpose of this study was to investigate how migrainous subjects and controls differ in their cardiovascular reactivity and recovery to a cognitive and an acute pain laboratory stressor. BACKGROUND: Prior research suggests that individuals subject to migraine may respond physiologically to pain and stress differently than controls. METHODS: Fifty-two women (26 with migraine and 26 controls) participated in a single laboratory session. Multiple cardiovascular responses to a cognitive (mental arithmetic) and an acute pain (cold pressor task) stressor were recorded with cardiac impedance methods. The cardiovascular responses measured included systolic and diastolic blood pressure, heart rate, cardiac output, stroke volume, and total peripheral resistance. RESULTS: Results indicated that the migrainous participants displayed different cardiovascular recovery patterns for total peripheral resistance, cardiac output, and stroke volume following the termination of the mental arithmetic task. CONCLUSIONS: These results support the hypothesis that individuals with migraine respond physiologically to stress differently than control individuals.     

Cardiovascular and hormonal responses to anaphylactic shock in the pig

Summary. Cardiovascular and hormonal responses to anaphylactic shock were evaluated in anaesthetized pigs sensitized by natural exposure to Ascaris suum as verified by antibodies. In six animals with such antibodies, Ascaris antigen injection produced a plasma histamine increase of 52 (42–196) fold (median and range; P<0.05), while four pigs without such antibodies served as controls with only insignificant increases in histamine. In the anaphylactic group, two of the animals died during the investigation due to cardiovascular collapse. In the sensitized pigs resting heart rate (HR), 104 (86–118) beats min^-1, increased to 204 (164–240) beats min^-1 as mean arterial pressure (MAP) decreased from 94 (83–102) to 45 (31–90) mmHg (P<0.05). In contrast, the non-sensitized pigs maintained the resting HR of 101 (79–113) beats min^-1, as MAP decreased to 50 (41–97) mmHg (P<0–05). In the sensitized group systemic vascular resistance (SVR) fell from 1114 (843–1811) to 990 (588–1173) dyne s^-1 cm^-5 and then increased to 3617 (2593–4166) dyne s^-1 cm^-5, while in the control group there was only a reduction to a minimum value of 730 (458–1307) dyne s^-1 cm^-5 (P<0.05). Thoracic electrical impedance increased only in the sensitized group [from 28.3 (24.7–31.4) to 29.9 (24.0–31.4)], indicating central volume depletion. Plasma catecholamines increased markedly only in the sensitized pigs, and plasma pancreatic polypeptide, vasopressin, aldosterone and renin responses confirmed to those established during central hypovolemia. During anaphylaxis, this study demonstrated cardiovascular responses similar to those established during a major blood loss. However, as indicated by plasma catecholamines, sympathetic activity was many times that previously demonstrated during haemorrhage, and sympathoactivation may explain the marked vasoconstriction noted in the sensitized pigs.     

Renal haemodynamic and sympathetic responses to head-up tilt in essential hypertension

Nine mild-to-moderate hypertensive patients (HT), aged 41 +/- 0.6 years (mean +/- SEM) and nine age-matched normotensive control subjects (NT) were tilted to 60 degrees for 10 min. During tilt, both systolic (S) blood pressure (BP) (p less than 0.01) and diastolic (D) BP (p less than 0.05) increased in HT, but not in NT. At supine rest renal blood flow was higher in HT than in NT and increased by 17% in HT during tilt, while a decrease of 13% was observed in NT (p less than 0.05). Renal vascular resistance was unchanged in HT during tilt, while a significant increase (p less than 0.01) was observed in NT. Arterial plasma noradrenaline increased in both groups (p less than 0.05) during tilt, significantly more in HT than in NT (p less than 0.05). No statistically significant difference was observed between the groups in renal catecholamine uptake or release. Our data indicate enhanced general sympathetic and circulatory responses to tilt in subjects with mild-to-moderate essential hypertension. However, the enhanced haemodynamic and sympathetic responses were not shared by hypertensive kidneys and renovascular resistance remained unaffected by tilt.     

Influence of comorbidities and medication use on tilt table test outcome in elderly patients

BACKGROUND: The tilt table test (TTT) is a useful diagnostic tool in people with unexplained syncope, dizziness, and falls. However, preexisting comorbidities and medications affecting hemodynamic response might affect TTT outcome (i.e. presence or absence of vasomotor syncope). We studied the influence of these compounding factors on TTT outcome. METHODS: One hundred and sixty-four elderly patients with a mean (+/-SD) age of 80.0 +/- 6.1 years (M:F 104:60) underwent TTT. Heart rate and blood pressure were recorded continuously using a noninvasive device (Task Force Monito, CNS systems, Graz, Austria). Predictors of TTT outcome in a backward regression analysis included age, gender, comorbidities (chronic heart failure, hypertension, diabetes, and cerebrovascular disease), and drugs (beta-blockers, angiotensin-converting enzyme inhibitors, calcium channel blockers, diuretics, digoxin, opioids, antidepressants, and nonsteroidal antiinflammatory agents). RESULTS: TTT was positive in 30 patients (18.3%). None of the above factors were a significant predictor of TTT outcome. The use of calcium channel blockers predicted a drop in systolic blood pressure after 2 minutes of TTT (P = 0.048, R(2)= 0.018). However, this was not associated with significant changes in heart rate and did not influence TTT outcome. CONCLUSION: The TTT outcome was not influenced by comorbidities or medications. TTT is a reliable diagnostic tool in a population characterized by significant comorbidities and polypharmacy.