Blood Pressure In Daily Life Research Articles

First-in-human study for evaluating the accuracy of blood pressure measurement using the ring-type device with a photoplethysmography

Abstract Background Early diagnosis of hypertension and optimal blood pressure (BP) control are important for prevention of cardiovascular morbidity and mortality. The 24-hour BP is better predictive of cardiovascular outcome than the office BP. However, conventional non-invasive BP measurement by sphygmomanometer has limitations in obtaining continuous BP and its variability in daily life. Recently, a ring-type BP measuring device, CART-I Plus (Sky Lab Inc, South Korea) without a cuff has been developed. Purpose This study was a prospective, single arm, first-in-human pivotal trial to evaluate accuracy of blood pressure measurement by the new device. Methods The ring-type smart wearable blood monitoring device measures photoplethysmography signals from the proximal phalanx and transmits the data wirelessly to the connected smartphone, to monitor the BP (Figure 1). A cuff was worn on arm to check the reference BP by auscultation, while the test device was worn on the finger of the opposite arm to check the test BP simultaneously. Measurements were repeated for up to three sets each on the left and right arms. The primary outcome measure was mean error and standard deviation of BP differences between the test device and the reference readings. Results The final analysis included 89 subjects, 47% of whom were male, with a mean age of 40.1 years. We collected 526 sets of systolic BP (SBP) and 513 sets of diastolic BP (DBP), with ranges of 80 to 175 mmHg and 43 to 122 mmHg, respectively. In sample-wise comparison (Figure 2), the mean error between the test device and the reference was 0.16 ± 5.90 mmHg (95% limit of agreements [LOA] -11.41 to 11.72) in SBP and -0.07 ± 4.68 (95% LOA -0.26 to 9.10) in DBP. The test device showed a good correlation with the reference for SBP (r=0.94, p<0.001) and DBP (r=0.95, p<0.001). In subject-wise comparison, the test device showed a good correlation with the reference for SBP (r=0.98, p<0.001) and DBP (r=0.98, p<0.001), with a mean error of 0.17 ± 3.67 mmHg (95% LOA -7.04 to 7.7) in SBP and 0.02 ± 3.21 mmHg (95% LOA -6.27 to 6.31) in DBP. Conclusion The new ring-type BP measuring device had a good correlation for SBP and DBP with minimal bias compared with a auscultation method. It has the potential to provide accurate BP in daily life.

Contactless and continuous blood pressure measurement according to caPTT obtained from millimeter wave radar

Continuous measurement of blood pressure (BP) is very important for assessing the health of the cardiovascular system. In this paper, a new system is first-time established to contactlessly and continuously measure BP according to the central-artery pulse transit time (caPTT) which is acquired from the neck and chest areas simultaneously with single millimeter wave (mmWave) radar. The two signals are separated by beam-component focusing and then BP is estimated by regression fitting. The correlation of the PTT’s variation measured by radar and contact device is verified by data from 16 subjects. The effectiveness of BP estimation is evaluated by data from 27 subjects. It is illustrated that the correlation of PTT’s variation is up to 0.91 and the errors of SBP and DBP are 5.54±7.62 mmHg and 4.68±6.15 mmHg respectively. The developed system in this work suggested that single radar has the potential to continuously measure BP in daily life.

Self-monitoring of psychological stress-induced blood pressure in daily life using a wearable watch-type oscillometric device in working individuals with hypertension

This study investigated psychological stress-induced blood pressure (BP) elevation according to self-measured data obtained by a wearable watch-type oscillometric device for multiple days in 50 working hypertension patients (mean ± SD age: 60.5 ± 8.9 years; 92.0% men; 96% treated for hypertension). Participants were asked to self-measure their BPs at five predetermined times as well as at any additional time points at their own discretion under ambulatory conditions for a maximum of 7 days. At the time of each BP measurement, participants self-reported their location, emotion, and degree of stress. A total of 1220 BP readings with self-reported situational information were obtained from 50 participants over 5.5 ± 1.2 days. Systolic BP (SBP) and diastolic BP (DBP) measured during moments of self-reported negative emotions (i.e., anger, tension, anxiety, or sadness) were significantly higher (5.0 ± 1.3 and 2.0 ± 0.8 mmHg, both p < 0.05) than those during moments of self-reported positive emotions (i.e., happiness or calm). SBP/DBP were significantly increased under a moderate or high degree of stress by [4.5 ± 1.1]/[2.5 ± 0.7] and [10.2 ± 3.0]/[4.7 ± 1.8] mmHg, respectively. As a result, it was estimated that SBP/DBP increased 15.2/8.5 mmHg in the presence of highly stressful negative emotions. In conclusion, self-measurement of BP monitoring with a wearable device for multiple days is a feasible method to detect daily stress-induced BP elevation in working adults.

A large-scale study of stress, emotions, and blood pressure in daily life using a digital platform

Stress is often associated with pathophysiologic responses, like blood pressure (BP) reactivity, which when experienced repeatedly may be one pathway through which stress leads to poor physical health. Previous laboratory and field studies linking stress to physiological measures are limited by small samples, narrow demographics, and artificial stress manipulations, whereas large-scale studies often do not capture measures like BP reactivity in daily life. We examined perceived stress, emotions, heart rate, and BP during daily life using a 3-wk app-based study. We confirmed the validity of a smartphone-based optic sensor to measure BP and then analyzed data from more than 330,000 daily responses from over 20,000 people. Stress was conceptualized as the ratio of situational demands relative to individual resources to cope. We found that greater demands were associated with higher BP reactivity, but critically, the ratio of demands relative to resources improved prediction of BP changes. When demands were higher and resources were lower, there was higher BP reactivity. Additionally, older adults showed greater concordance between self-reported stress and physiologic responses than younger adults. We also observed that physiologic reactivity was associated with current emotional state, and both valence and arousal mattered. For example, BP increased with high-arousal negative emotions (e.g., anger) and decreased with low-arousal positive emotions (e.g., contentment). Taken together, this work underscores the potential for expanding stress science and public health data using handheld phones to reliably and validly measure physiologic responses linked to stress, emotion, and physical health.

Abstract P487: Network Stressors, Personal Stressors, And Sustained Hypertension In African American Women

Introduction: Stressful life events (SLE) have been associated with poor cardiovascular health but most studies have focused on stressors that directly impact the individuals under study, or personal stressors. Research suggests that women, particularly African-American women, may actually be more vulnerable to network stressors (e.g. SLE that impact important others, such as children, spouses and friends). However, few studies have examined this phenomenon. Hypothesis: We tested the hypothesis that greater exposure to network, versus personal stressors, would be associated with elevated clinic blood pressure (BP) as well as BP in daily life, assessed via 48-hour ambulatory monitoring. Methods: Participants were 395 African-American women aged 30-45 (Mean= 39.5 ±4.6 yrs) from a range of educational backgrounds recruited from a large southeastern metropolitan area. SLE were assessed using a 22-item Stressful Life Events checklist and further classified into personal (e.g. “major accident/assault/robbery happened to you”) or network (e.g. “serious physical illness, injury or drug/alcohol problem in someone family member/friend”) stressors and summed. Clinic and 48-hr ambulatory BP measurements were assessed and sustained hypertension (HTN) was defined as both clinic (≥130/80mmHg) and ambulatory HTN (≥130/80mmHg), using 2017 AHA/ACC guidelines. Logistic regression analyses were used to examine the associations between types of stressors and sustained HTN after adjusting for age, education, body mass index, and BP meds. Results: Approximately 51.2% (N=211) of women had clinic HTN and 29.9% (N=123) of women had sustained HTN (elevated in both clinic and in daily life). In unadjusted multivariable logistic regression analyses, each additional network stressor was associated with a greater likelihood of having elevated clinic (OR-1.21 [1.04-1.40]) and sustained HTN (OR- OR-1.22 [1.04-1.43]). Findings for clinic (OR-1.25, [1.06-1.48]) and sustained HTN (OR-1.23, [1.04-1.46]) remained significant after adjustment for covariates. There were no significant associations between reports of personal stressors and either clinic, or sustained HTN in unadjusted or adjusted analyses. Discussion: Network, but not personal stressors, were associated with elevated rates of HTN, both in clinic and daily life for African-American women. Future research is needed to determine whether interventions targeting stress management for network stressors specifically might impact BP in this high-risk population.

Relationship between mechanisms of blood pressure change and facial skin temperature distribution

Hypertension causes cerebrovascular and cardiovascular diseases. To help prevent this, early detection requires continuous monitoring of blood pressure in daily life, which must be measured without contact. We previously proposed a noncontact technique for measuring blood pressure in which we evaluated the relationship between the variation in blood pressure caused by the cardiac-dominant pattern and facial skin temperature distribution using independent component analysis and multiple regression analysis. The mechanism of blood pressure change is roughly classified into cardiac-dominant patterns and vascular-dominant patterns. An elucidation of the relationship between these patterns and facial skin temperature distribution is the objective of this study. Two tests resulting in cardiac-dominant and vascular-dominant patterns were conducted. These common and different features related to each mechanism of BP change in each subject were then evaluated. The results of the tests show that similar features were extracted from the nasal region and contrasting feature quantities were extracted from the other facial regions. Hence, individual models were constructed for estimating blood pressure using the common features related to both mechanisms. A high coefficient of determination was obtained from these models, suggesting that models for estimating blood pressure caused by both mechanisms can be constructed using the proposed approach.

FIVE CONSECUTIVE OFFICE BLOOD PRESSURE MEASUREMENTS VERSUS CURRENT PRACTICE. HOW AGE, GENDER, DIABETES AND HYPERTENSION AFFECT BLOOD PRESSURE

Objective: Recently, new data from trials conducted on hypertension have been surging, leading to changes in the management of patients with arterial hypertension, and subsequently giving rise to modifications of practice guidelines. Yet, there is no consensus on the number of readings that should be considered to measure the accurate BP. The study aimed to determine the impact of age, gender, diabetes mellitus and hypertension on the systolic (SBP) and diastolic blood pressure (DBP) variability patterns in cardiac patients. Moreover, we highlighted the variability that occurs in percentage of patients diagnosed with hypertension according to different current guidelines Vs using mean of 5 consecutive BP readings.Methods: 1389 cardiac patients (median age, 54 (18, 87 y)) presenting at Alhyatt Heart and Vascular Center were studied. Five consecutive blood pressure measurements were taken, with one-minute interval. High SBP and DBP were classified according to the mean of the 5 readings as SBP >140 and DBP >90 mmHg according to different guidelines and SBP>130 and DBP>80 as per to new AHA/ACC cutoffs. Young subjects were defined as those <50y of age. A decrease in BP over 5 readings were defined as a difference between BP-reading 5 (R5) and R1 of -1 mmHg or more, while an increase was defined as R5-R1 ≥ 1 mmHg. Result: Number of patients diagnosed with hypertension varied among different guidelines and protocols, we found that this number was significantly altered when comparing different guidelines to the mean of five BP readings as follows: 560 (40.3%) patient as per to ESC (P < 0.001), 518 (37.3%) patient as per to CHEP (p < 0.001), 862 (62%) patients according to new AHA/ACC (p < 0.001). SBP decreased from R1 to R5 in 66% of patients by a mean of 6 mmHg. The decrease was greater in younger subjects (8 mmHg) compared to older patients (4 mmHg, P < 0.001). Sex, age, DM and hypertension significantly affected the SBP pattern. DBP declined in 55% of the population (mean decrease = 3 mmHg). Only hypertension and gender, but not DM or age affected the DBP pattern. The second reading of the SBP was notably higher than the other readings in hypertensive patients, diabetic patients, and older individuals with an average of 3–5 mmHg. Conclusion: Subject characteristics such as age, gender, DM and HTN have an impact on blood pressure which might alter the diagnosis of hypertension. The study suggests that relying on the average of 5 BP measurements is more appropriate as the second reading often shows the greatest divergence based on subject characteristics and because 5 readings reflects an individual's daily life blood pressure variability more closely.

Feasibility study for the non-invasive blood pressure estimation based on ppg morphology: normotensive subject study

BackgroundBlood pressure is a critical bio-signal and its importance has been increased with the aged society and the growth of cardiovascular disease population. However, most of hypertensive patients have been suffered the inconvenience in monitoring blood pressure in daily life because the measurement of the blood pressure depends on the cuff-based technique. Nowadays there are many trials to measure blood pressure without cuff, especially, photoplethysmography (PPG) based research is carried out in various ways.MethodsOur research is designed to hypothesis the relationship between vessel wall movement and pressure-flow relationship of PPG and to validate its appropriateness by experimental methods. PPG waveform is simplified by approximate model, and then it is analyzed as the velocity and the acceleration of blood flow using the derivatives of PPG. Finally, we develop pressure index (PI) as an estimation factor of blood pressure by combining of statistically significant segments of photoplethysmographic waveform.ResultsTwenty-five subjects were participated in the experiment. As a result of simulation, correlation coefficients between developed PI and blood pressure were represented with R = 0.818, R = 0.827 and R = 0.615 in systolic blood pressure, pulse pressure and mean arterial pressure, respectively, and both of result showed the meaningful statistically significance (P < 0.05).ConclusionsCurrent study can estimate only the relative variation of blood pressure but could not find the absolute pressure value. Moreover, proposed index has the limitation of diastolic pressure tracing. However, the result shows that the proposed PI is statistically significantly correlated with blood pressures, and it suggests that the proposed PI as a promising additional parameter for the cuff less blood pressure monitoring.

Abstracts From the 36th Annual Scientific Meeting of the HBPRCA

### CONTRIBUTION OF THE AREA POSTREMA TO THE INCREASED CARDIAC SYMPATHETIC NERVE ACTIVITY IN OVINE HEART FAILURE Abukar Y, Ramchandra R, May CN The Florey Institute of Neuroscience and Mental Health, Melbourne, Victoria, Australia Background : Heart failure (HF) is associated with an increase in cardiac sympathetic nerve activity (CSNA), which is directly linked to mortality in HF patients. The mechanisms responsible for the elevated CSNA remain unclear. Previous studies indicate that the area postrema (AP), a circumventricular organ in the brainstem, plays a role in the control of sympathetic nerve activity. We hypothesized that the elevated CSNA in HF is mediated by the AP and lesioning this region would reduce the increased CSNA in sheep with HF. Aims : To determine the effect of sham lesion or lesion of the AP on CSNA and hemodynamics in conscious sheep with HF. Methods : Studies were conducted in 2 groups of sheep with pacing-induced HF: sham (n=6) and AP lesion (n=6) sheep. Mean arterial blood pressure (MAP), heart rate (HR) and CSNA were recorded simultaneously in conscious sheep at least 4 days after surgery. Results : Heart failure was associated with a significant decrease in ejection fraction (from 74±2 % to 38±1 %; P<0.001), which was similar in both groups. There was a significant reduction in CSNA burst incidence in the AP lesion group compared with the sham group (45±10 and 89±3 bursts/100 heartbeats, respectively; P<0.01). Conclusions : In sheep with HF, the group with lesion of the AP had a significantly lower CSNA compared with the sham group. These data suggest that the AP plays a role in setting the detrimental high levels of CSNA in HF. ### G PROTEIN-COUPLED ESTROGEN RECEPTOR SIGNALING IMPROVES STROKE OUTCOME IN FEMALE MICE Broughton BRS, Jansen GL, Sobey CG Department of Pharmacology, Monash University, Clayton, Victoria, Australia Background: Estrogen has been assumed to provide neuroprotection following stroke entirely via classical estrogen receptors. Interestingly, there is recent evidence that activation of a novel G …

On the importance of knowing your partner's views: attitude familiarity is associated with better interpersonal functioning and lower ambulatory blood pressure in daily life.

Relationships have been linked to significant physical health outcomes. However, little is known about the more specific processes that might be responsible for such links. The main aim of this study was to examine a previously unexplored and potentially important form of partner knowledge (i.e., attitude familiarity) on relationship processes and cardiovascular function. In this study, 47 married couples completed an attitude familiarity questionnaire and ambulatory assessments of daily spousal interactions and blood pressure. Attitude familiarity was associated with better interpersonal functioning between spouses in daily life (e.g., greater partner responsiveness). Importantly, attitude familiarity was also related to lower overall ambulatory systolic blood pressure and diastolic blood pressure. These data suggest that familiarity with a spouse's attitudes may be an important factor linking relationships to better interpersonal and physical health outcomes.

Continuous Blood Pressure Monitoring in Daily Life

Continuous monitoring of blood pressure in daily life could improve early detection of cardiovascular disorders, as well as promoting healthcare. Conventional ambulatory blood pressure monitoring (ABPM) equipment can measure blood pressure at regular intervals for 24 hours, but is limited by long measuring time, low sampling rate, and constrained measuring posture. In this paper, we demonstrate a new method for continuous real-time measurement of blood pressure during daily activities. Our method is based on blood pressure estimation from pulse wave velocity (PWV) calculation, which formula we improved to take into account changes in the inner diameter of blood vessels. Blood pressure estimation results using our new method showed a greater precision of measured data during exercise, and a better accuracy than the conventional PWV method.

The association between anger-related personality trait and cardiac autonomic response abnormalities in elderly subjects

Cardiac autonomic response abnormality associated with trait anger has been recognized to elevate blood pressure in daily life, leading to atherosclerotic progression and cardiovascular disease. To clarify the relationship between anger-related personality traits and cardiac autonomic response in healthy elderly subjects, 54 volunteers consisting of 30 male (mean age 62.2+/-5.4) and 24 female (mean age 58.4+/-4.6) subjects underwent testing of heart rate variability (HRV) with head-up tilt. For the evaluation of trait anger, we used a questionnaire corresponding to the trait anger score taken from the State and Trait Anger Expression Inventory. Furthermore, we measured carotid intima-medial thickness (IMT) to evaluate atherosclerotic progression in subjects with anger trait. In female subjects, higher trait anger was positively associated with elevated carotid IMT and the suppression of HRV vagal attenuation from the supine to head-up position, and negatively associated with the HRV sympathetic activity in the head-up position and also with the HRV sympathetic response from the supine to head-up position. In male subjects, trait anger was not significantly associated with carotid IMT or any HRV component with or without head-up tilt testing. We conclude that a simple noninvasive measure, short-term HRV with head-up tilt testing, could be a useful method to investigate the association between cardiac autonomic imbalance and increased risk of atherosclerosis associated with trait anger in healthy elderly subjects.

Effective Ambulatory Blood Pressure Control in Medical Practice

A large number of studies has addressed the question of how effective is blood pressure (BP) control in the hypertensive population,1–3 with a consistent and unequivocal answer. That is, BP control is disappointingly low, because only a small fraction of patients diagnosed as having a BP elevation show on-treatment BPs <140 mm Hg systolic and 90 mm Hg diastolic, which are the target values for treatment recommended by international guidelines.4,5 This is the case regardless of whether patients are followed by general practitioners or specialists6,7 and have a low or high cardiovascular risk profile,8–10 the latter condition making the need of BP control even more compelling given the imminent risk of a cardiovascular event. Reality is obviously even worse when the lower BP targets that have been shown to be additionally protective in high-risk hypertensive patients, that is, <130/80 mm Hg, are considered.4,5 In a recent study performed in Italy, for example, we have shown that in diabetic (and, thus, high risk) hypertensive patients followed by general practitioners, an on-treatment BP <130/80 mm Hg was achieved in only 3% of the sample,7 the conclusion being that …

Relationship of Office, Home, and Ambulatory Blood Pressure to Blood Glucose and Lipid Variables in the PAMELA Population

Alterations in blood glucose and cholesterol are more frequently detectable in hypertensive than in normotensive conditions. However, no information exists as to whether this phenomenon involves only office or also home and 24-hour ambulatory blood pressure (ie, when values are representative of daily life). In 2045 subjects enrolled in the Pressioni Arteriose Monitorate E Loro Associazioni (PAMELA) study, we measured home, 24-hour, and office blood pressure. Measurements also included fasting blood glucose and serum total and HDL cholesterol values. Prevalence of diabetes (> or =126 mg/dL or use of antidiabetic drugs), impaired fasting blood glucose (> or =110 to <126 mg/dL), and hypercholesterolemia (serum total cholesterol > or =240 mg/dL or 200 mg/dL) increased progressively from "optimal" to "normal," "high-normal," and "elevated" office systolic or diastolic blood pressure. Fasting blood glucose and total serum cholesterol also increased progressively from the first to the fourth group, with HDL cholesterol values showing a concomitant progressive decrease. This was also the case for quartiles of office, home, and 24-hour blood pressure. In the whole population, there was a positive correlation between serum cholesterol or blood glucose and all blood pressure values (P always <0.0001), with a much smaller and less consistent relationship with heart rate. In a multivariate analysis that included gender, body mass index, age, and antihypertensive treatment, all blood pressure values remained highly significantly related to values of either metabolic variables. Thus, in the PAMELA population, glucose and lipid values are independently related to blood pressure. This is also the case when daily life blood pressure values are considered.

Ring-Shaped Pulse Oximeter and Its Application: Measurement of SpO2 and Blood Pressure During Sleep and During Flight

Respiratory and cardiovascular functions show circadian and day-to-day changes. We have developed a wireless ring-shaped pulse oximeter in collaboration with MC Medical Inc. and Advanced Medical Inc. We investigated the accuracy of this pulse oximeter and its application in daily life. Percutaneous arterial oxygen saturation (SpO2) of 47 volunteers was measured simultaneously with the ring-shaped pulse oximeter and a standard pulse oximeter. A total of 103 volunteers underwent measurement of SpO2 for 24 hr, and 11 healthy volunteers underwent measurement of SpO2 and blood pressure (BP) during flight. SpO2 and heart rate (HR) were measured and recorded every 20 sec, cabin barometric pressure and cabin oxygen concentration equivalent to sea level were measured minute-to-minute, and BP was measured every 3 min with a portable BP recorder during each flight. The SpO2 values measured with the ring-shaped pulse oximeter were similar to those measured with the standard method. The mean SpO2 during sleep was significantly lower in the group with high-normal BP or mild hypertension than in the group with normal BP. During flight, the mean change in SpO2 was -2.4 +/- 1.7% during nose-up flight, and 2.1 +/- 2.6% during nose-down flight. There was a significant correlation between change in SpO2 and change in systolic BP during nose-up flight. The wireless ring-shaped pulse oximeter was useful for investigating changes in SpO2 and its effect on BP in daily life during sleep and during air travel.

Ring-Shaped Pulse Oximeter and Its Application: Measurement of SpO2 and Blood Pressure During Sleep and During Flight

Respiratory and cardiovascular functions show circadian and day-to-day changes. We have developed a wireless ring-shaped pulse oximeter in collaboration with MC Medical Inc. and Advanced Medical Inc. We investigated the accuracy of this pulse oximeter and its application in daily life. Percutaneous arterial oxygen saturation (SpO2) of 47 volunteers was measured simultaneously with the ring-shaped pulse oximeter and a standard pulse oximeter. A total of 103 volunteers underwent measurement of SpO2 for 24 hr, and 11 healthy volunteers underwent measurement of SpO2 and blood pressure (BP) during flight. SpO2 and heart rate (HR) were measured and recorded every 20 sec, cabin barometric pressure and cabin oxygen concentration equivalent to sea level were measured minute-to-minute, and BP was measured every 3 min with a portable BP recorder during each flight. The SpO2 values measured with the ring-shaped pulse oximeter were similar to those measured with the standard method. The mean SpO2 during sleep was significantly lower in the group with high-normal BP or mild hypertension than in the group with normal BP. During flight, the mean change in SpO2 was − 2.4 ± 1.7% during nose-up flight, and 2.1 ± 2.6% during nose-down flight. There was a significant correlation between change in SpO2 and change in systolic BP during nose-up flight. The wireless ring-shaped pulse oximeter was useful for investigating changes in SpO2 and its effect on BP in daily life during sleep and during air travel.

303 Context in ambulatory blood pressure readings: Explaining activity and posture variance in daily life blood pressure

303 Context in ambulatory blood pressure readings: Explaining activity and posture variance in daily life blood pressure

Effects of different stress settings on cardiovascular parameters and their relationship to daily life blood pressure in normotensives, borderline hypertensives and hypertensives

The aim of this study was to compare a traditional stress setting, consisting of two mental arithmetic tasks and two Stroop test modifications, and a stress setting of varying task demand and decision latitude according to Karasek's job strain model, with respect to their feasibility to elicit differences in cardiovascular reactivity and recovery in 20 normotensives, 20 borderline hypertensives, and 20 non-medicated hypertensives, carefully selected by means of World Health Organization criteria. In addition, the relationship between laboratory and everyday blood pressure was investigated. All subjects were tested under both stress settings in counterbalanced order. Blood pressure was recorded both intermittently from the brachial artery (Riva-Rocci) and continuously from the finger (Finapres). Heart rate and electrodermal activity were continuously measured as well. Furthermore, daily life blood pressure recorded by means of 24 h ambulatory monitoring during a normal working day served as criterion for the re-classification of the blood pressure groups by means of discriminant analysis using physiological recordings from baseline, test phases and rest phases. The groups did not show significant differences in their reactivity to the various mental stressors including the Karasek-model oriented ones but marked differences in their behaviour occurred during the 10 min of recovery following each stress setting. Both systolic and diastolic blood pressure in hypertensives failed to recover during this period. The results also showed the superiority of the Finapres method with respect to reflecting the dynamics of physiological recovery processes. None of the stress settings showed an advantage in predicting blood pressure in daily life. In general, the results question the validity of mental laboratory stressors for the prediction of cardiovascular changes in daily life but point to a possible role of recovery processes after stress in the development of essential hypertension.

Pressor Responses to Laboratory Stresses and Daytime Blood Pressure Variability

We studied 56 patients with essential hypertension to determine whether responses to standardized laboratory mental and physical challenges accurately reflect blood pressure variability during routine daily activities. Four activities were performed in the laboratory: mental arithmetic, a reaction time test, isometric exercise, and submaximal bicycle exercise. Blood pressure was measured directly from a brachial artery catheter. We then recorded intra-arterial ambulatory blood pressure away from hospital over 24 h. A frequency histogram was constructed from all cardiac cycles when subjects were awake. Variability of ambulatory blood pressure was defined as the standard deviation about the mean waking value. The increase in mean arterial pressure (MAP) during each of these four challenges correlated significantly with the variability of mean arterial pressure (highest correlation: reaction time test, r = 0.53, P less than 0.00001; lowest correlation: mental arithmetic, r = 0.26, P less than 0.03), and five subjects who were highly reactive to all four challenges also demonstrated increased blood pressure variability. We therefore conclude that these commonly used laboratory tests can give some information about the behaviour of blood pressure in daily life in some subjects, but overall the variance in blood pressure variability that can be accounted for by the pressor response to these standardized challenges is low.