Caffeine, extended stress, and blood pressure in borderline hypertensive men

Caffeine increases blood pressure (BP), and its pressor effects are larger in borderline hypertensive (BH) men than in controls. This article extends findings of larger caffeine effects on BP at rest and to brief mental stress in BH to a new analysis of caffeine and prolonged mental stress in BH. In a double-blind, crossover study, 24 male BH (140/90 mmHg < BP < 160/95 mmHg) and 23 normotensive controls who were habitual caffeine consumers (NT; BP < 135/85 mmHg; negative parental history) worked on alternating mental stressors for 35 min after placebo or caffeine (3.3 mg/kg). Caffeine raised systolic blood pressure (SBP) and diastolic blood pressure (DBP) alone and during the extended tasks (all ps < .00001/.00001). BH had larger SBP and DBP increases over all postcaffeine periods (ps < .04/04) and larger DBP rises to the extended tasks after caffeine (p = .007). These combined effects led to undesirably high BPs (> 140/82 mmHg) relative to controls (< 130/75) during the 100 min after caffeine intake. Caffeine taken by BH at times of extended behavioral stress may elevate BP to a clinically meaningful degree. This research was supported by the Medical Research Service of the Department of Veterans Affairs and the National Heart Lung and Blood Institute of the National Institutes of Health, grant numbers HL32050 and HL07640. We thank Barbara McKey and Judith Silverstein for their efforts in data collection and Terrie Thomas for her valuable comments on an earlier version of this article.     

Evaluation of a New Ambulatory Blood Pressure Monitor (Accutracker 102): Laboratory Comparisons With Direct Arterial Pressure, Stethoscopic Auscultatory Pressure, and Readings From a Similar Monitor (Spacelabs Model 5200)

Systolic (SBP) and diastolic (DBP) blood pressure levels generated by a new noninvasive ambulatory monitor, the Accutracker 102, were compared in the laboratory with intra-arterial pressure levels in 12 normotensive men, and with stethoscopic auscultatory determinations in 27 normotensive and hypertensive men and women over a wide range of within-subject pressure variations. In 11 subjects, its performance was also compared with another ambulatory monitor, the Spacelabs Model 5200. Highly positive correlations with both the intra-arterial (median r=+.90 for SBP, +.92 for DBP) and the stethoscopic standards (median r=+.93 for SBP, +.88 for DBP) were obtained using Accutracker's automatic readings (digital readout), while slightly higher correlations were obtained with hand-scoring of recorded data. The Spacelabs BP monitor also yielded readings that were highly correlated with stethoscopic readings (median r=+.83 for SBP, +.77 for DBP), although in 3 of the 11 subjects the Accutracker correlations were substantially higher than the Spacelabs correlations. Despite their generally good tracking of changes in pressure, both ambulatory monitors yielded absolute values in many subjects that differed by 5 mmHg or more from stethoscopic levels. The Accutracker's SBP levels were consistently too high and its DBP levels were occasionally too low, while Spacelabs' SBP and DBP values were too high and too low with equal frequency. However, mean deviation scores for each patient calculated from 5 concurrent ambulatory monitor and stethoscopic readings were shown to yield relatively stable correction factors for use when comparison with clinical standards is desired.     

Peripheral and brachial blood pressure during standardized occupation-related tests in normotensive and mild hypertensive men and women

We investigated the usefulness of peripheral blood pressure (BP) measurement in the assessment of strain in occupational physiology. Our hypothesis was that the brachial and peripheral BP reflect physiologically different events under various occupation-related demands in normotensive (NT) and hypertensive (HT) people. A group of 20 female and 20 male subjects with unmedicated mild hypertension that had been diagnosed by ambulatory blood pressure monitoring [awake time systolic/diastolic BP (BP_s/BP_d) 142.9 (SD 11.3)/86.4 (SD 6.2) mmHg] and 40 NT matched by age and sex [BP_s/BP_d 120.0 (SD 9.8)/75.6 (SD 5.9) mmHg] attended a laboratory session to undertake mental arithmetic tasks, a fingergrip test and submaximal cycle ergometry. Brachial and peripheral BP as well as heart rate were measured using a sphygmomanometer and an continuously automatic blood pressure measuring device on the finger, respectively. The peripheral BP_s was higher than brachial BP_s, BP_d was similar for peripheral and brachial BP except during cycle ergometry. Associations between the levels of brachial and peripheral BP depended on demands and did not explain more than 42% of the common variance. The highest correlations between the two BP methods were observed during habituation, recovery and mental demands, and weak correlations during cycle ergometry. For peripheral BP_s and BP_d we found significant correlations in all phases of the test (r=0.58 to 0.86, P < 0.001), also in ergometry (NT r=0.62, P < 0.001, HT r=0.53, P < 0.001), in contrast to the brachial BP. Peripheral BP differentiated the two BP groups (57.5%–72.5% correctly classified) which had been grouped by daily measurement of brachial BP, but brachial BP was superior in this respect with 65.0%–87.5% being correctly classified. These results supported the suggestion that the combined measurement of peripheral and brachial BP provides complementary information regarding physiological changes in NT and HT in different situations. Accepted: 30 August 1999     

Effects of daily activities and social behavior on blood-pressure elevation

This study examined the effects of daily activities and social behavior on the blood-pressure elevation in 21 normotensives, 20 borderline hypertensives, and 20 sustained essential hypertensives. Blood pressures were recorded over a 24-hr period using an ambulatory monitor while subjects recorded their daily activities and social involvement at each cuff inflation. Results indicated that only a moderate proportion of the blood pressure readings of the two clinical groups exceeded 140/90 mm Hg. Results also suggested that the blood pressures of normotensives were more responsive to changes in physical activity, while the blood pressures of sustained hypertensives were more responsive to social involvement. When group differences emerged on mean blood-pressure elevation, analyses indicated that the two hypertensive groups frequently differed from the normotensive group but rarely from each other. The results suggest that differences in blood-pressure elevation cannot be fully understood without considering behavior and support its continued inclusion in the study of blood pressure.This research was supported in part by National Institutes of Health Grant HL 29795 to Janis H. Crowther and Mary Ann P. Stephens.     

Increased ambulatory arterial stiffness index and blood pressure load in normotensive obese patients

ObjectivesIt has been shown that blood pressure (BP) values measured in obese subjects are higher than the individuals with normal weight, even in normotensive limits. However, data concerning the Ambulatory Arterial Stiffness Index (AASI) and blood pressure load in normotensive obese subjects is lacking. This study was aimed to compare the ambulatory arterial stiffness index and blood pressure load in normotensive obese and healthy controls.MethodsOne hundred normotensive obese and one hundred normal weight subjects were included in this study. All subjects underwent 24-hour ambulatory blood pressure monitoring. Ambulatory arterial stiffness index was calculated from 24-hour ambulatory blood pressure monitoring records. Ambulatory arterial stiffness index was defined as one minus the regression slope of unedited 24-h diastolic on systolic blood pressures. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) load values were calculated from 24-hour ambulatory blood pressure monitoring analysis.ResultsAmbulatory arterial stiffness index of the obese subjects was significantly higher than the healthy controls (0.48±0.2 vs. 0.33±0.11, p<0.001). 24-hours systolic blood pressure and diastolic blood pressure loads were significantly higher in obese subjects. Logistic regression analysis revealed that body mass index (BMI) was an independent predictor for an abnormal ambulatory arterial stiffness ındex (≥0.50) (OR: 1.137, 95% CI: 0.915-1.001, p=0.004).ConclusionBlood pressure load and ambulatory arterial stiffness index are increased in normotensive obese patients. Moreover, body mass index is an independent predictor for an abnormal ambulatory arterial stiffness index. Our results indicate that obese subjects are at higher risk for future cardiovascular events despite normal office BP levels.     

A novel method for non-invasive blood pressure estimation based on continuous pulse transit time: An observational study

Unlike traditional pulse transit time (PTT), continuous PTT (CPTT) can be used to calculate PTT from all samples within the cardiac cycle. It has the potential to be utilized for continuous blood pressure (BP) estimation. This study evaluated the feasibility of CPTT as a non-invasive consecutive blood pressure estimation method in 20 volunteers. The CPTT was calculated with a time delay in all discrete samples of photoplethysmograms measured at two different body sites. BP was then calculated with a regression equation. For comparative evaluation, BP based on PTT was also estimated. Continuous blood pressure was measured using a non-invasive volume clamp BP monitoring device. Four types of BP measurement, systolic BP (SBP), diastolic BP (DBP), mean arterial pressure (MAP), and pulse pressure (PP), were estimated using PTT and CPTT. Correlation coefficients and root-mean-squared-error (RMSE) were used for evaluating BP estimation performance. For estimating SBP, DBP, PP, and MAP, PTT-based BP estimation showed correlations of .407, .373, .410, and .286, respectively, and CPTT-based BP estimation showed correlations of .436, .446, .506, and .097, respectively. With PTT-based estimation, the RMSE between the estimated BP and the baseline BP was 5.44 ± 1.56 mmHg for SBP, 3.14 ± 0.46 mmHg for DBP, 3.66 ± 0.70 mmHg for MAP, and 3.73 ± 1.31 mmHg for PP. The estimated BP using CPTT showed RMSE of 5.36 ± 1.39 mmHg for SBP, 3.02 ± 0.49 mmHg for SBP, 3.44 ± 0.63 mmHg for MAP, and 3.91 ± 1.41 mmHg for PP.     

The Covariation of Blood Pressure and Pulse Transit Time in Hypertensive Patients

To examine the relationship between blood pressure (BP) and pulse transit time (PTT) as measured by the time between the ECG R-wave and an associated peripheral pulse, BP was recorded via a radial artery catheter in 3 hvpertensive subjects who underwent a variety of conditions to alter BP. Overall. 70% of the data was usable. Absolute levels of systolic blood pressure (SBP) but not diastolic blood pressure (DBP) were found to correlate appreciably with PTT. There were significant associations between PTT and both SBP and mean BP but not DBP for direction of BP change. With large SBP changes (> 4 mmHg) an increase in the strength of association occurred in 14 of the 21 conditions across subjects. Overall, PTT did not accurately predict actual BP. PTT and SBP covaried more appreciably in these hypertensives than has been reported for normotensives.     

Sensory effects of baroreceptor activation and perceived stress together predict long-term blood pressure elevations

Activating the arterial baroreceptors in animals has been shown to blunt pain sensation and provide other forms of central nervous system inhibition. This study tested the hypothesis that, among human subjects, a tonic increase in blood pressure (BP) could be a learned response to environmental stressors among subjects in whom the baroreceptor inhibitory mechanism is active. In a sample of 96 healthy, normotensive men and women, amount of pain-reduction produced by baroreceptor stimulation predicted an increase in resting BP 20 months later: the increase was proportional to self-assessed daily life stress. Among the subjects reporting the greatest amount of stress, the pain inhibition effect accounted for more than 80% of the BP variance. These results support the hypothesis that the reduction in perceived stress produced by baroreceptor stimulation may reward learned increases in BP. This research was supported by Deutsche Forschungsgemeinshaft Grant EL 101/3 to Thomas Elbert and National Institutes of Health Grant ROl HL40837 to B. R, Dworkin.     

Laboratory-based blood pressure recovery is a predictor of ambulatory blood pressure

The recovery phase of the stress response is an individual difference characteristic that may predict cardiovascular risk. The purpose of this study was to examine whether laboratory-based blood pressure (BP) recovery predicts ambulatory BP (ABP). One hundred and eighty-two participants underwent a standard laboratory stress protocol, involving a 20-min baseline rest period, and four stressors presented in a counterbalanced order, each followed by a 10-min recovery period. Participants also wore an ABP monitor for 24h during a typical workday. Hierarchical regression analyses showed that BP recovery accounted for significant additional variance for daytime SBP (p<0.001), nighttime SBP (p<0.001), daytime DBP (p<0.001), and nighttime DBP (p<0.001), after controlling for baseline and reactivity BP. Results suggest that persistence of the BP response following stress may be a more salient characteristic of the stress response in understanding its potential impact on longer term cardiovascular regulation.     

Cardiovascular reactivity and positive/negative affect during conversations

Systolic and diastolic blood pressures (SBP, DBP) were measured for 70 college students before, during and after informal dyadic conversations. Participants rated the positive and negative affect they experienced during conversation. SBP and DBP increased significantly from baseline to conversation. Increases in SBP and DBP were associated with more positive affect and unrelated to negative affect. Blood pressure measures taken one week later provided a more useful assessment of resting levels than measures taken before the conversation. Relationships between BP reactivity and positive affect remained significant after controlling for resting levels of BP, amount of talk during conversation, and sex of speaker in hierarchical regression. Blood pressure elevation during social interaction may be associated with involvement or enthusiasm, rather than emotional distress; this association is not simply an artifact of talkativeness. We suggest that cardiovascular reactivity in healthy young adults engaged in nonthreatening conversations may be a widespread phenomenon and not necessarily pathological.     

Social support and hostility interact to influence clinic, work, and home blood pressure in Black and White men and women

The effects of hostility and social support support on clinic, work, and home systolic (SBP) and diastolic (DBP) blood pressures were evaluated in 129 healthy adults. High hostility was related to higher SBP and DBP in Whites; low hostility was related to higher SBP and DBP in Blacks. These relationships were significant for men at home and at work and for women at screening. The relationship between low hostility and higher BP in Blacks was largely due to Black men who reported low hostility plus high anger-in (suggesting suppressed hostility). In contrast, high hostile Black men with high tangible support tended to exhibit lower BP than all other Black men. In White women, high belonging support was related to lower BP, independent of hostility, and low tangible support plus high hostility was related to higher clinic BP. In high hostile subjects, regardless of ethnicity or gender, high appraisal support was related to lower overall BP. These data suggest that the adverse BP effects of hostility and the beneficial effects of social support interact in a complex manner, reflecting contextual, ethnic, and gender specificities.     

Blood pressure effects of long-term stimulant use in disorders of hypersomnolence

Untoward cardiovascular effects have been implicated as a deterrent to long-term central nervous system (CNS) stimulant use in disorders of hypersomnolence. In this study, we reviewed the relationship between blood pressure and long-term stimulant use. Medical records of 54 patients with narcolepsy and idiopathic CNS hyper- somnolence (ICH) were reviewed. The overall mean number of months of follow-up for the entire group was 45.6 (95% CI: 42–49). Both simple linear regression and multiple regression utilizing generalized estimating equations were used to show relationships between blood pressure (BP), time and other covariates. In the simple linear regression model, the average slope of the line of systolic BP (SBP) on time for the entire group was 0.06 (95% CI: -0.09, 0.13) and the line of diastolic BP (DBP) on time was 0.01 (95% CI: -0.05, 0.07). Two multiple regression equations were fitted for the continuous response variables SBP and DBP. Covariates in the model included: time, hypertension, weight at baseline, weight, SBP baseline (SBPBL), DBP baseline (DBPBL), high vs. low dose stimulant therapy and age at starting treatment. For SBP, the covariates weight at baseline, weight and SBPBL were significant (P< 0.05) predictors. For DBP, covariates reaching statistical significance (P< 0.05) included weight and DBPBL. There was no significant change in SBP or DBP over time in either model. Two different statistical models support the conclusion that there was no significant change in SBP or DBP over time in this population.     

Altered cardiovascular/pain regulatory relationships in chronic pain

In healthy individuals, there is an inverse relationship between resting blood pressure (BP) and pain sensitivity. This study examined possible dysregulation of this adaptive relation in chronic pain patients, and tested whether the extent of this dysregulation is a function of pain duration, Continuous resting BP_s were assessed for 5 min after a 5-min rest period in 121 chronic benign pain patients. Unlike the inverse relationship observed previously in normals, mean resting diastolic BP_s during the assessment period were correlated positively with ratings of pain severity. A Pain Duration x Systolic BP i nteraction emerged (p > .05) such that the magnitude of the BP-pain relation was greatest in patients with the longest duration of pain, r(38) = .50, p > .001. A hypothesized progressive alteration in endogenous pain regulatory systems in chronic pain patients was supported. A possible role of endogenous opioid dysfunction in accounting for these alterations is discussed. This investigation was supported by Grant BRSG S07 RR05366-28. awarded to John W. Burns by the Biomedical Research Grant Program, Division of Research Resources, National Institutes of Health. We thank Kathleen Kiselica and Ronald Pawl for allowing access to their patients at the Center for Rehabilitation at Lake Forest Hospital in Lake Forest, IL.     

Family support and cardiovascular responses in married couples during conflict and other interactions

This study examined the relation between perceived support from family and cardiovascular (CV) responses to interaction in 45 married couples, 24 to 50 years old. Gender-specific median splits on Family Support scores from the Brief Social Support Questionnaire defined high versus low support groups. CV responses were obtained from both spouses during baseline and 3 stressors: reading control, conversing about events of the day, and conflict discussion. Men with low support had higher systolic (SBP) and diastolic pressure (DBP) than men with high support or either group of women at baseline and during all task periods (p < .004 and .05). Women with high support did not differ in blood pressure (BP) from women with low support. Men and women with low support had higher vascular resistance indexes (VRI) than those with high support, during all periods (p < .0015), and reported lower dyadic satisfaction and total dyadic adjustment. Because a disproportionate number of non-While participants reported low family support, secondary analyses that included race as a covariate were conducted. Covarying for race did not produce substantial results for any of the measures (SBP,p < .05; DBP,p < .058; VRI, p < .021). Post-hoc analyses were also conducted, in which the marital dyad was considered the unit of analysis. For these analyses, in which both spouses’ perceptions of family support as high or low were considered together, the wife’s perceived support did not influence the husband’s BP, whereas his perceived support did influence his BP (ps < .03). For VRI in both men and women, the spouses’ support level, as well as the participant’s own support level, affected responses (ps < .02). Thus, high family support is associated with both marital and CV benefits for both husbands and wives, although husbands may benefit more.     

Family history of hypertension,exercise training,and reactivity to stress in rats

In this study we sought to assess the role of exercise training on blood pressure (BP) reactivity to tailshock stress in rats with varying family histories of hypertension. Exercise training consisted of swimming 90 min per day in isothermic water for either 2, 6, or 10 months, beginning at 2 months of age. Control subjects were age-matched and did not exercise daily. Rats with either zero (Wistar-Kyoto), 1 (borderline hypertensive), or 2 (spontaneously hypertensive) hypertensive parents were studied. At the appropriate age, femoral artery catheters were implanted and rats were studied at rest and in response to a 20-min stress session. Exercise training reduced basal BP, especially in rats with a positive family history that were exercised for the longest duration. Reactivity to stress was actually significantly enhanced in trained rats. Thus, these data do not support the reactivity hypothesis, but suggest several reasons why the literature has been so inconsistent. The discussion emphasizes the importance of basal, rather than phasic, BP responses resulting from exercise training. Research for this article was supported by National Institutes of Health (NIH) Grant No. HL19680 to James E. Lawler and NIH Grant No. HL34878 to Ronald H. Cox     

Correspondence between laboratory and ambulatory measures of cardiovascular reactivity: a multilevel modeling approach

We examined the correspondence between laboratory measures of cardiovascular reactivity (CVR) and within-person changes in cardiovascular activity during the challenges of daily life, after adjustment for posture, activity, and other effects. Healthy adults (n = 335) were administered laboratory measures of CVR along with 6 days of ambulatory blood pressure monitoring and electronic diary reports. Compared with low reactors, high laboratory systolic blood pressure (SBP) reactors showed larger increases in SBP during periods of high task demand or low decisional control in daily life. High diastolic blood pressure (DBP) reactors showed larger increases in ambulatory DBP during situations rated as both low control and high demand. This multilevel modeling approach may enhance our ability to detect the correspondence between laboratory and ambulatory measures of CVR, and to identify the circumstances under which it may be most clearly observed.     

老年高血压的动态血压监测

对60例老年高血压病患者(Ⅰ期24例,Ⅱ期21例、Ⅲ期15例)、30例健康老年人、30例健康中青年分别进行动态血压监测和比较。结果老年对照组动态血压监测各参数值均明显高于中青年对照组;高血压Ⅰ、Ⅱ、Ⅲ期各组与老年对照组比较各参数值也明显增高。如以老年对照组各项参数的(?)±2s为正常高限,则高血压Ⅰ、Ⅱ、Ⅲ期各组分别有9、13、15项数值超过正常。其中以24小时平均收缩压和舒张压日间平均收缩压和舒张压、夜间平均收缩压和舒张压及血压负荷值等为诊断动态高血压的重要指标。     

Subsistence patterns and blood pressure variation in two rural Caboclo communities of Marajó Island,Pará, Brazil

Blood pressure (BP) increases with age in westernized societies, is higher in men, and is correlated with the body mass index (BMI). Traditional societies present more variable patterns of BP. In 1991, BP and anthropometric data from two “Caboclo” (rural populations of mixed ancestry) groups from Marajó Island, Brazil, were collected: The Paricatuba group, (N = 20;12 women), with a subsistence base of fishing, collection of palm fruits, and traditional gardening; and the Praia Grande group (N = 26; 14 women), where subsistence is based on mechanized agriculture. In Paricatuba, mean BP is 109/74 mmHg in men and 101/70 mmHg in women. There are no significant differences between BP of men and women, and systolic blood pressure (SBP) increases with age. Both SBP and diastolic blood pressure (DBP) are associated with weight, but only DBP is associated with the BMI, while SBP is associated with stature. In Praia Grande, mean BP is 120/76 mmHg in men and 118/70 mmHg in women, with no significant differences between the sexes. In Praia Grande, SBP is higher than in Paricatuba, and both SBP and DBP are associated with age. Compared with urban groups, both Caboclo samples have low BP. Still, differences in BP and body habitus between the two groups support a hypothesis that degree of westernization influences mean levels of BP in rural Amazonian populations. Further, the results also may be interpreted as suggesting that associations of sex, age, and BMI with BP, commonly reported in urban samples, are a byproduct of westernization rather than a result of genetic factors. © 1995 Wiley-Liss, Inc.     

Cardiac vagal control mediates the relation between past depression and blood pressure several years later among young adults

Depression has been associated with high blood pressure (BP). However, the mechanisms of the relation between depression and high BP are unclear. We therefore examined whether impaired cardiac vagal control, indexed as low levels of resting respiratory sinus arrhythmia (RSA), serves as a route from depression to high BP. The sample included 125 subjects with histories of depression (probands), 123 never depressed siblings of probands (high-risk siblings), and 156 controls. Resting RSA was assessed at Time 1 (T1) along with BP when subjects were adolescents (M_age = 16.3 years); systolic and diastolic BP (SBP and DBP) were measured again at Time 2 (T2) when subjects were young adults (M_age = 22.3 years). Linear mixed-effects models were used to examine the group differences in resting RSA and T2 BP outcomes and to test for RSA mediation of the relation between depression (history or being at high risk) and BP. Resting RSA was lower among probands than controls but was similar among high-risk siblings and controls, while the subject groups did not differ in T2 SBP or DBP. Controlling for T1 BP, depression history indirectly affected T2 DBP (but not SBP) through resting RSA. The findings suggest that, although the direct detrimental effects of depression on BP are not yet evident in young adulthood, among those with depression histories, impaired cardiac vagal control appears to serve as a mechanism of elevated DBP.