Circadian relations among cardiovascular variables of young adults.

Every 4 hours for 24 hours, 14 clinically healthy young individuals (6 women and 8 men), 26 +/- 4 years of age, measured systolic (S) and diastolic (D) blood pressure (BP) by sphygmomanometer and heart rate by ECG and did impedance cardiography under usual living conditions. Stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were calculated. Time series of SBP, DBP, HR, SV, CO and TPR were analyzed by single and population-mean cosinor. A circadian cardiovascular rhythm is demonstrated by rejection of the zero amplitude assumption in the population-mean cosinor test for SBP, DBP, HR, SV, CO and TPR (P < 0.01). TPR peaks around 0400 (-61 degrees from local midnight), in antiphase with all other variables, their acrophase occurring around 1600 (-240 degrees). A circadian rhythm of statistical significance or of borderline statistical significance is found for all variables except TPR in women. Circadian rhythm characteristics were otherwise mostly similar in men and women with a statistically significant gender difference found by parameter tests only for the MESOR and amplitude of SBP.     

Chronic exercise and its hemodynamic influences on resting blood pressure of hypertensive rats.

Studies with male spontaneously hypertensive rats (SHR) were initiated to determine the hemodynamic relationships associated with the lower resting caudal artery systolic blood pressure (SBP) of endurance-trained SHR populations. After assignment into nontrained (NT, n = 38) and trained (T, n = 38) groups, the T animals were exercised 5 times/wk on a motor-driven treadmill for 12-16 wk at a moderate intensity that ranged from 40 to 70% of their maximum O2 consumption capacity (VO2max). SBP, VO2max, and treadmill run time were determined before the experimental period began and before the animals were instrumented for hemodynamic measurements. At the end of the study, the T rats exhibited significantly lower SBP (NT = 210 +/- 3, T = 200 +/- 3 mmHg) and significantly higher VO2max (NT = 75 +/- 2, T = 83 +/- 2 ml.min-1.kg-1) and run durations (NT = 11.4 +/- 0.4, T = 14.5 +/- 0.3 min). When the animals were anesthetized for insertion of catheters and microprobes for blood pressure and cardiac output (thermodilution) measurements, the T rats had lower values for body mass, heart rate, mean blood pressure, cardiac output, and cardiac index than the NT rats; however, only the body mass and heart rate differences were statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)     

Long-term intake of egg white hydrolysate attenuates the development of hypertension in spontaneously hypertensive rats

This paper evaluates the effect of the long-term intake of a hydrolysate of egg white with pepsin (HEW), with a potent angiotensin converting enzyme inhibitory activity, on the development of hypertension of spontaneously hypertensive rats (SHR). After being weaned, male 3-week-old SHR were randomly divided into five groups that were given until the 20th week of life the following drinking fluids: (1) tap water, (2) non-treated egg white 1 g/kg/day, (3) captopril 100 mg/kg/day, (4) HEW 0.5 g/kg/day, and (5) HEW 1 g/kg/day. From the 20th to 25th week of life, animals from all groups were given tap water. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured weekly in the rats, from the 6th to 25th week of life, by the tail cuff method. Development of hypertension was attenuated in the groups treated with captopril and HEW (P<0.001 vs. the group that drunk tap water). At the 20th week of life, the arterial blood pressure values of the different groups of rats were: tap water (SBP = 219.5 +/- 5.7, DBP = 167 +/- 3.7), non-treated egg white (SBP = 206.4 +/- 1.43, DBP = 166.4 +/- 4.9), captopril (SBP = 131.7 +/- 2.74, DBP = 91.5 +/- 1.62), HEW 0.5 g/kg/day (SBP = 182.9 +/- 4.64, DBP = 127.5 +/- 2.1) and HEW 1 g/kg/day (SBP = 177.7 +/- 4.72, DBP = 120.1 +/- 2.4). SBP and DBP increased in the treated SHR when the corresponding antihypertensive treatment was removed. In spite of this, SBP remained lower in the SHR that had received captopril and HEW than in the SHR of the control groups (P<0.05). The present results suggest that HEW could be used as a functional food with antihypertensive activity.     

Non-invasive blood pressure measurement in Yucatan miniature swine using tail cuff sphygmomanometry

A relatively new non-invasive method using a photo-electric flow sensor in non-heated animals, was evaluated for its accuracy in measuring systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) in 40-90 Kg normotensive and hypertensive Yucatan miniature swine. Directly measured SBP, DBP and electronically averaged MAP were recorded from chronic arterial catheters simultaneously with indirect pressures, cuff pressure and tail blood flow under various conditions. In all of the tests tail cuff SBP estimation averaged within 5% of directly measured SBP. The correlation of the two methods was significant (r = .95, P less than 0.01). Over a 60 to 202 mmHg range of blood pressure induced pharmacologically or due to DOCA hypertension, the tail cuff SBP was within 4-10% of directly measured SBP. The tail cuff method was also used to determine DBP and MAP. DBP determined from the tail cuff record was found consistently to underestimate the direct measured DBP by approximately 17%. The two methods were correlated (r = .87 P less than 0.01). The measured tail cuff MAP generally underestimated the direct MAP by approximately 5%. The correlation of directly measured MAP and tail cuff methods was significant (r = .72, P less than 0.01). These results indicated that this system may be used to accurately assess blood pressure in miniature swine.     

高血压大鼠心肌肥大及逆转过程中相关因素的探讨

目的：探讨在心肌肥大及逆转过程中收缩压(SBP)、舒张压(DBP)、平均动脉压(MAP)、神经肽Y(NPY)等与左心室肥大的关系。方法：血压和心率用生物信号分析系统记录;NPY用放射免疫法测定,用SPSS软件求出了相关系数和回归方程。结果：SBP、DBP、MAP、心肌匀浆中NPY与心系数(LVW／BW)呈正相关,血液中NPY和心率(HR)与心系数不相关。结论：血压升高是导致左室肥大的因素之一,收缩压的影响大于舒张压;SBP、DBP、MAP、心肌匀浆中NPY与心系数(LVW/BW)有相关的趋势。     

Beat-to-beat stroke volume estimation from aortic pressure waveform in conscious rats: comparison of models

Several methods for estimating stroke volume (SV) were tested in conscious, freely moving rats in which ascending aortic pressure and cardiac flow were simultaneously (beat-to-beat) recorded. We compared two pulse-contour models to two new statistical models including eight parameters extracted from the pressure waveform in a multiple linear regression. Global as well as individual statistical models gave higher correlation coefficients between estimated and measured SV (model 1, r = 0.97; model 2, r = 0.96) than pulse-contour models (model 1, r = 0.83; model 2, r = 0.91). The latter models as well as statistical model 1 used the pulsatile systolic area and thus could be applied to only 47 +/- 17% of the cardiac beats. In contrast, statistical model 2 used the pressure-increase characteristics and was therefore established for all of the cardiac beats. The global statistical model 2 applied to data sets independent of those used to establish the model gave reliable SV estimates: r = 0.54 +/- 0.07, a small bias between -8% to +10%, and a mean precision of 7%. This work demonstrated the limits of pulse-contour models to estimate SV in conscious, unrestrained rats. A multivariate statistical model using eight parameters easily extracted from the aortic waveform could be applied to all cardiac beats with good precision.     

心肌梗死患者择期行PCI治疗对左心室重构和收缩功能的影响

目的:研究心肌梗死患者择期行经皮冠状动脉介入(PCI)治疗对左心室重构和收缩功能的影响。方法:选取2009年12月到2014年12月我院收治的心肌梗死择期行PCI治疗的患者60例(研究组),另选同期单纯心绞痛行PCI治疗的患者60例(对照组)。比较治疗前、后两组左心室舒张末期容积(LVEDV)、收缩末期容积(LVESV)、每搏量(SV)、左室射血分数(LVEF)、左室收缩末期压(LVESP)和左心室舒张末压(LVEDP)。结果:治疗后研究组LVEDV、LVESV、SV、LVEF、LVESP和LVEDP均显著优于治疗前,比较差异均具有统计学意义(P0.05),对照组治疗前、后LVEDV、LVESV、SV、LVEF、LVESP和LVEDP比较差异均无统计学意义(P0.05)。结论:心肌梗死患者行PCI治疗具有较好的效果,能显著改善患者的左心室重构和收缩功能。     

Acute volume loading, atrial natriuretic peptide release and cardiac function in healthy men. Effects of beta-blockade

Release of ANP is dependent on right atrial distension and pressure, which in turn are dependent on both venous return and left ventricular function. These two latter parameters are both modulated by beta-receptors. In the present study, the effects of selective beta-blockade vs non-selective beta-blockade on hypertonic volume expansion induced changes in ANP release and systemic hemodynamics were assessed in 8 healthy normotensive male volunteers. On placebo, infusion of hypertonic saline (1200 ml of 2.5% NaCl) caused an intravascular volume expansion of 10-11%, and small non-significant increases in cardiac performance (LVEDV, SV, or CI), but it provoked a 2-fold increase in plasma ANP. Beta-blockade by either atenolol or propranolol blunted the increase in cardiac volume load (reflected by LVEDV) as compared to placebo, but did not affect the ANP response to volume expansion. The increase in ANP correlated closely with the intravascular volume expansion on placebo and to a lesser extent on beta-blockade. In healthy men, therefore, intravascular volume expansion that caused only small changes in cardiac activity, resulted in clear increases in release of ANP. Inhibition of the increase in cardiac volume load by beta-blockade did not interfere with ANP increase, suggesting a role for extra-cardiac receptors in the release of ANP or a change in the pressure/volume relationship.     

Ghrelin as a potential blood pressure reducing factor in obese women during weight loss treatment

BACKGROUND: In animal models ghrelin reduces cardiac afterload and increases cardiac output via receptors in the cardiovascular system. The aim of our study was to evaluate a potential relationship between weight loss treatment, blood pressure and serum ghrelin concentrations in obese women. MATERIAL AND METHODS: A group of 37 obese premenopausal women with no previous history of hypertension (BMI: 36.5 +/- 5 kg/m2) were involved in the study. Blood pressure and serum ghrelin levels were assessed before and after a three-month weight reduction treatment, which consisted of a diet of 1000 kcal/day and physical exercise. Body composition was determined by impedance analysis using Bodystat. RESULTS: Following weight loss (mean 8.9 +/- 4.8 kg) SBP decreased (120 +/- 13 vs. 115 +/- 14 mm Hg, p = 0.01) and serum ghrelin levels increased significantly (66.9 +/- 13.7 vs. 73.9 +/- 15.4 pg/ml; p = 0.005). There were significant correlations between values for ghrelin levels after weight loss and SBP (r = -0.45, p = 0.02), DBP (r = -0.41, p < 0.05), and between Deltaghrelin levels and DeltaSBP (r = 0.52, p = 0.006), DeltaDBP (r = 0.53, p = 0.005). There was a positive correlation between an increase in ghrelin and a decrease in percentage body fat during weight loss (r = 0.51; p = 0.002). CONCLUSION: The results seem to provide evidence that weight loss may decrease blood pressure in obese patients via a ghrelin-dependent mechanism.     

Effects of moderate physical training on blood pressure variability and hemodynamic pattern in mildly hypertensive subjects.

The objective of our study was to compare the cardiovascular effects of moderate exercise training in healthy young (NTS, n=18, 22.9+/-0.44 years) and in hypertensive human subjects (HTS, n=30, 23+/-1.1). The VO(2max) did not significantly differ between groups. HTS of systolic blood pressure (SBP) 148+/-3.6 mmHg and diastolic blood pressure(DBP) 88+/-2.2 mmHg, and NTS of SBP: 128.8 +/- 4 mmHg and DBP: 72 +/- 2.9 mmHg were submitted to moderate dynamic exercise training, at about 50% VO(2max) 3 times per week for one hour, over 3 months. VO(2max) was measured by Astrand's test. Arterial blood pressure was measured with Finapres technique, the stroke volume, cardiac output and arm blood flow were assessed by impedance reography. Variability of SBP and pulse interval values (PI) were estimated by computing the variance and power spectra according to FFT algorithm. After training period significant improvements in VO(2max) were observed in NTS- by 1.92 +/-0.76 and in HTS by 3+/-0.68 ml/kg/min). In HTS significantly decreased: SBP by 19 +/-2.9 mmHg, in DBP by 10.7+/-2 mmHg total peripheral resistance (TPR) by 0.28 +/-0.05 TPR units. The pretraining value of low frequency component power spectra SBP (LF(SPB)) was significantly greater in HTS, compared to NTS. PI variance was lower in HTS, compared to NTS. After physical training, in HTS PI variance increased suggesting a decrease in frequency modulated sympathetic activity and increase in vagal modulation of heart rate in mild hypertension. A major finding of the study is the significant decrease of resting low frequency component SBP power spectrum after training in HTS. The value of LF(SPB) in trained hypertensive subjects normalized to the resting level of LF(SPB) in NTS. Our findings suggest that antihypertensive hemodynamic effects of moderate dynamic physical training are associated with readjustment of the autonomic cardiovascular control system.     

维吾尔族新发2型糖尿病患者肠道 乳杆菌属和多形拟杆菌的定量研究

目的定量研究维吾尔族新发2型糖尿病(T2DM)患者和糖耐量正常(NGT)人群肠道中乳杆菌属(Lactobacillus genus)和多形拟杆菌(Bacteroides thetaiotaomicron)的相对水平。方法严格按照纳入标准、排除标准收集维吾尔族新发T2DM患者96例,NGT 98例。提取所有研究对象的粪便细菌总DNA后,采用16SrDNA基因实时荧光定量PCR(Real-time PCR)对乳杆菌属和多形拟杆菌的水平进行定量检测;运用Pearson相关性分析乳杆菌属与研究对象的BMI、腰围、臀围、收缩压(SBP)、舒张压(DBP)、空腹血糖(FBG)、甘油三酯(TG)、总胆固醇(TC)、高密度脂蛋白(HDL-C)和低密度脂蛋白(LDL-C)的相关性。结果 16SrDNA基因Real-time PCR结果显示:(1)与新疆维吾尔族NGT组相比,乳杆菌属水平在新发T2DM中较低,差异有统计学意义(t=8.557,P=0.000)。但是多形拟杆菌在两组差异无统计学意义(t=0.524,P=0.601);(2)新疆维吾尔族上述人群肠道中乳杆菌属水平与FBG呈负相关(r=-0.334,P=0.000),腰围呈负相关(r=-0.170,P=0.018),TC呈负相关(r=-0.178,P=0.013),TG呈负相关(r=-0.157,P=0.030),收缩压呈负相关(r=-0.255,P=0.000)。结论 Lactobacillus genus水平在肠道中降低可能与2型糖尿病的发病,血糖和血脂代谢有关,其机制需进一步研究探讨。     

Comparison of cardiovascular response to passive tilt in young and elderly men

To test the hypothesis that altered hemodynamic responses to postural changes are associated with aging, cardiovascular responses to head-up tilt (HUT) and head-down tilt (HDT) were examined in 12 healthy young (average age, 24.6 +/- 1.7 years) and 12 healthy elderly (average age, 68.6 +/- 2.2 years) men. Subjects were passively tilted from supine to 30 degrees, 60 degrees, and 90 degrees HUT and HDT. Responses to these perturbations were determined 5 min after tilting with measures of heart rate (HR), blood pressure (SBP, DBP), and echocardiographically determined left ventricular diameter in systole and diastole (LVIDs, LVIDd). In HUT there were no significant age effects. In both young and elderly, SBP decreased significantly (p less than 0.05), and DBP and HR increased significantly. Ejection fraction (EF), mean arterial blood pressure (MABP), and rate-pressure product (RPP) were unchanged in both groups. In HDT, the hemodynamic responses of the young and elderly were in opposite directions and significant age effects were found for SBP, DBP, HR, LVIDs, EF, MABP, and RPP. In HDT, the young appear to increase cardiac output primarily due to an increase in EF and end-diastolic volume (LVIDd), while HR is unchanged and SBP is decreased. MABP is unchanged, suggesting a small decrease in total peripheral resistance. The elderly may increase cardiac output slightly, owing to an increase in LVIDd with no change in EF, and a large increase in HR. Afterload increased markedly, therefore attenuating any increase in cardiac output.(ABSTRACT TRUNCATED AT 250 WORDS)     

三种不同麻醉方式对产妇血流动力学及新生儿的影响

目的;探讨硬膜外麻醉、蛛网膜下腔-硬膜外麻、气管插管全麻三种不同麻醉方式对剖宫产产妇血流动力学及胎儿的影响。方法:纳入行择期剖宫产产妇152例,采用随机表法将其分为硬膜外组(48例)、腰硬联合麻醉组(52例)、气管内插管全麻组(52例)。观察麻醉前正常状态时(T1)、麻醉成功后5 min(T2)、胎儿娩出时(T3)三个时间点产妇SBP、DBP、HR、SV、CO、SVR及胎儿相关指标,包括出生后1 min、5 min Apgar评分、脐动脉血pH、PCO_2、PO_2。结果:硬膜外麻、腰麻-硬膜外联合麻醉、全麻三组间麻醉起效时间有明显统计学差异(P0.05),气管内插管全麻组起效时间最快。三组间在T1时间点SBP、DBP、HR、SV、CO、SVR差异无统计学意义(P0.05)。在T2时间点,硬膜外麻、联合麻醉、全麻三组SBP、DBP、HR、SVR水平均较T1时间点明显降低,差异有统计学意义(P0.05)。T2时间点,全麻组SBP、DBP、HR、SVR水平高于硬膜外、联合麻醉组(P0.05)。T3时间点三组SBP、DBP、HR、SV、CO水平均较T2时间相比差异有统计学意义(P0.05)。T3时间点,全麻组SBP、DBP、SVR高于其他两组,心率低于其他两组,差异有统计学意义(P0.05)。三组间新生儿出生后1 min Apagr、5 min Apgar评分、脐动脉血学pH、PCO_2无统计学差异(P0.05)。三组间脐动脉血PO_2有明显统计学差异(P0.05),气管内插管全麻组脐动脉血PO_2最高。结论:三种麻醉均可以用于剖宫产术,全麻剖宫产术对产妇血流动力学影响最小,起效快,但对胎儿脐动脉血氧浓度有一定的影响。     

Comparison of cardiovascular responses between lower body negative pressure and head-up tilt.

To investigate local blood-flow regulation during orthostatic maneuvers, 10 healthy subjects were exposed to -20 and -40 mmHg lower body negative pressure (LBNP; each for 3 min) and to 60 degrees head-up tilt (HUT; for 5 min). Measurements were made of blood flow in the brachial (BF(brachial)) and femoral arteries (BF(femoral)) (both by the ultrasound Doppler method), heart rate (HR), mean arterial pressure (MAP), cardiac stroke volume (SV; by echocardiography), and left ventricular end-diastolic volume (LVEDV; by echocardiography). Comparable central cardiovascular responses (changes in LVEDV, SV, and MAP) were seen during LBNP and HUT. During -20 mmHg LBNP, -40 mmHg LBNP, and HUT, the following results were observed: 1) BF(brachial) decreased by 51, 57, and 41%, and BF(femoral) decreased by 40, 53, and 62%, respectively, 2) vascular resistance increased in the upper limb by 110, 147, and 85%, and in the lower limb by 76, 153, and 250%, respectively. The increases in vascular resistance were not different between the upper and lower limbs during LBNP. However, during HUT, the increase in the lower limb was much greater than that in the upper limb. These results suggest that, during orthostatic stimulation, the vascular responses in the limbs due to the cardiopulmonary and arterial baroreflexes can be strongly modulated by local mechanisms (presumably induced by gravitational effects).     

Influence of polymorphism of glutathione S-transferase M1 on systolic blood pressure of normotensive individuals

Studies have indicated that systolic (SBP) and diastolic (DBP) blood pressure are multi-factorial traits and significantly heritable. The aims of the present study are to assess whether the glutathione S-transferase M1 (GSTM1) and T1 (GSTT1) genotypes are associated with SBP and DBP of normotensive subjects and to ascertain whether the level of SBP and DBP given exposure to cigarette smoking is modified by the specific genetic polymorphisms of GSTM1 and GSTT1. This cross-sectional study was conducted on 140 subjects (49 females and 91 males) (mean age+/-SD: 38.7+/-14.7). The genotypes were determined using a polymerase chain reaction based method. Individuals were stratified according to the mean values of DBP and SBP, lower than or maximally same as the mean value defines as group I and higher than the mean value defines as group II. The logistic regression analyses were used. The best models fitted by logistic regression analysis for variables were associated with SBP and DBP. For analysis the combination of genotypes, sex, and smoking behavior was used as qualitative variables, and age, body mass index (BMI), and heart rate were used as covariates. Combination of "present-GSTT1, null-GSTM1" genotype (OR=0.001, 95% CI=0.00-0.439, P=0.025), heart rate (OR=1.065, 95% CI=1.018-1.114, P=0.006), and interaction between BMI and combination of "present-GSTT1, null-GSTM1" (OR=1.319, 95% CI=1.058-1.644, P=0.014) was associated with SBP. There was no association between either combination genotypes of GSTs or interaction of genotypes and smoking behavior on DBP. The present results suggest that the GSTM1 gene is one of the candidate genes that alter the baseline of SBP in normotensive individuals.     

Cardiovascular responses to military antishock trouser inflation during standing arm exercise

Military antishock trousers (MAST) inflated to 50 mmHg were used with 12 healthy males (mean age 28 +/- 1 yr) to determine the effects of lower-body positive pressure on cardiac output (Q), stroke volume (SV), heart rate (HR), systolic blood pressure (SBP), diastolic blood pressure (DBP), mean arterial blood pressure (MABP), total peripheral resistance (TPR), and O2 uptake (VO2) during graded arm-cranking exercise. Subjects were studied while standing at rest and at 25, 50, and 75% of maximal arm-cranking VO2. At each level, rest or work was continued for 6 min with MAST inflated and for 6 min with MAST deflated. Order of inflation and deflation was alternated at each experimental rest or exercise level. Measurements were obtained during the last 2 min at each level. Repeated-measures analysis of variance revealed significant increases (P less than 0.001) in Q, SV, and MABP and a consistent decrease in HR with MAST inflation. There was no apparent change in Q/VO2 between inflated and control conditions. There was no effect of MAST inflation on VO2 or TPR. MAST inflation counteracts the gravitational effect of venous return in upright exercise, restoring central blood volume and thereby increasing Q and MABP from control. HR is decreased consequent to increased MABP through arterial baroreflexes. The associated decrease in TPR is not observed, being offset by the mechanical compression of leg vasculature with MAST inflation.     

急性心力衰竭患者就诊时血压心率及血浆BNP水平与心功能的关系分析

目的:探讨急性心力衰竭(AHF)患者就诊时血压心率及血浆脑钠肽(BNP)水平与心功能的关系。方法:选取2013年4月-2014年12月于本院治疗的AHF患者134例,于就诊时测量患者血压、心率、BNP及心脏超声相关指标,分析血压心率及血浆BNP水平与心功能的关系。结果:就诊时SBP水平与左心室舒张末期直径及每搏输出量呈现正相关性(r=0.134、0.238,均P0.05);心率与每搏输出量、左室缩短率以及射血分数呈现负相关性(r=-0.177,-0.231,-0.197,均P0.05);BNP水平与左心室舒张末直径成正相关性,与左室缩短率以及射血分数呈负相关性(r=0.150、-0.247、-0.271,均P0.05)。结论:血压、心率以及BNP是临床诊断、评估AHF的重要指标。     

血液透析血压及其变异性与患者预后的相关性分析

目的:探讨血液透析前后和血液透析过程中血压及其变异性与患者预后的相关性。方法:选取沈阳军区总医院血液透析中心2010年1月1日至2013年12月31日收治的维持性血液透析患者,收集并对比随访期内生存及死亡患者的自然信息及临床资料,评估血液透析过程中患者血压及其变异程度与患者预后的关系。结果:共有269例患者纳入研究,经过4年随访共死亡83(30.86%)例。死亡组年龄显著大于存活组(64.92±13.24岁比49.89±12.86岁,P=0.000),而透析年限显著短于存活组(2.60±2.56年比7.25±4.14年,P=0.000)。死亡组透析前SBP(P=0.001)、DBP(P=0.000)、MAP(P=0.000)均显著高于存活组。两组间透析后SBP、DBP、MAP比较均无显著差异。死亡组△SBP(P=0.026)、△DBP(P=0.001)、△MAP(P=0.001)幅度显著大于存活组。死亡组透析前SBP变异率显著高于存活组(P=0.001);死亡组透析后SBP变异率(P=0.000)、DBP变异率(P=0.014)、MAP变异率(P=0.005)均高于存活组。死亡组每次透析前各时间点间SBP变异率(0.12±0.04 mm Hg比0.09±0.03 mm Hg,P=0.000)与MAP变异率(0.10±0.03mm Hg比0.09±0.03 mm Hg,P=0.001)显著高于非死亡组。结论:维持性血液透析患者透析前血压、透析前后血压改变幅度、透析前后血压变异率、每次透析各时间点间血压变异率等与全因死亡相关。     

Validity of auscultatory and Penaz blood pressure measurements during profound heat stress alone and with an orthostatic challenge

Despite frequent reporting of blood pressure (BP) during profound passive heat stress, both with and without a hypotensive challenge, the method by which BP is measured often varies between laboratories. It is unknown whether auscultatory and finger BP measures accurately reflect intra-arterial BP during dynamic changes in cardiac output and peripheral resistance associated with the aforementioned conditions. The purpose of this investigation was to test the hypothesis that auscultatory BP measured at the brachial artery, and finger BP measured by the Penaz method, are valid measures of intra-arterial BP during a passive heat stress and a heat-stressed orthostatic challenge, via lower body negative pressure (LBNP). Absolute (specific aim 1) and the change in (specific aim 2) systolic (SBP), diastolic (DBP), and mean BPs (MBP) were compared at normothermia, after a core temperature increase of 1.47 ± 0.09°C, and during subsequent LBNP. Heat stress did not change auscultatory SBP (6 ± 11 mmHg; P = 0.16), but Penaz SBP (-22 ± 16 mmHg; P < 0.001) and intra-arterial SBP (-11 ± 13 mmHg P = 0.017) decreased. In contrast, DBP and MBP did not differ between methods throughout heat stress. Compared with BP before LBNP, the magnitude of the reduction in BP with all three methods was similar throughout LBNP (P > 0.05). In conclusion, auscultatory SBP and Penaz SBP failed to track the decrease in intra-arterial SBP that occurred during the profound heat stress, while decreases in arterial BP during an orthostatic challenge are comparable between methodologies.     

Pulse transit time measured from the ECG: an unreliable marker of beat-to-beat blood pressure.

The arterial pulse-wave transit time can be measured between the ECG R-wave and the finger pulse (rPTT), and has been shown previously to have a linear correlation with blood pressure (BP). We hypothesized that the relationship between rPTT, preejection period (PEP; the R-wave/mechanical cardiac delay), and BP would vary with different vasoactive drugs. Twelve healthy men (mean age 22 yr) were studied. Beat-to-beat measurements were made of rPTT (using ECG and photoplethysmograph finger probe), intra-arterial radial pressure, PEP (using cardiac bioimpedance), and transit time minus PEP (pPTT). Four drugs (glyceryl trinitrate, angiotensin II, norepinephrine, salbutamol) were administered intravenously over 15 min, with stepped dosage increase every 5 min and a 25-min saline washout between agents. All subjects in all conditions had a negative linear correlation (R2 = 0.39) between rPTT and systolic BP (SBP), generally constant between different drugs, apart from four subjects who had a positive rPTT/SBP correlation with salbutamol. The 95% limits of agreement between measured and rPTT-predicted SBP were +/-17.0 mmHg. Beat-to-beat variability of rPTT showed better coherence with SBP variability than it did with heart rate variability (P < 0.001). PEP accounted for a substantial and variable proportion of rPTT (12-35%). Diastolic (DBP) and mean arterial BP (MAP) correlated poorly with rPTT (R2 = 0.02 and 0.08, respectively) but better with pPTT (rPTT corrected for PEP, R2 = 0.41 and 0.45, respectively). The 95% limits of agreement between measured and pPTT-predicted DBP were +/- 17.3 mmHg. In conclusion, the negative correlation between rPTT and SBP is generally constant, even with marked hemodynamic perturbations. However, the relationship is not reliable enough for rPTT to be used as a surrogate marker of SBP, although it may be useful in assessing BP variability. DBP and MAP cannot be predicted from rPTT without correction for PEP. The significant contribution of PEP to rPTT means that rPTT should not be used as a marker of purely vascular function.