Effect of timing and number of baseline blood pressure determinations on postural blood pressure response

Sensitivity to changes in rate of heartbeats as a measure of interoceptive ability

Individuals vary in their ability to perceive, as conscious sensations, signals like the beating of the heart. Tests of such interoceptive ability are, however, constrained in nature and reliability. Performance of the heartbeat tracking task, a widely used test of cardiac interoception, often corresponds well with individual differences in emotion and cognition, yet is susceptible to reporting bias and influenced by higher-order knowledge, e.g., of expected heart rate. The present study introduces a new way of assessing cardiac interoceptive ability, focusing on sensitivity to short-term, naturalistic changes in frequency of heartbeats. At rest, such heart rate variability typically reflects the dominant influence of respiration on vagus parasympathetic control of the sinoatrial pacemaker. We observed an overall tendency of healthy participants to report feeling fewer heartbeats during increases in heart rate, which we speculate reflects a reduction in heartbeat strength and salience during inspiratory periods when heart rate typically increases to maintain a stable cardiac output. Within-participant performance was more variable on this measure of cardiac interoceptive sensitivity relative to the "classic" heartbeat tracking task. Our findings indicate that cardiac interoceptive ability, rather than reflecting the veridical monitoring of subtle variations in physiology, appears to involve more interpolation wherein interoceptive decisions are informed by dynamic working estimates derived from the integration of afferent signaling and higher-order predictions.NEW & NOTEWORTHY This study presents a new method for evaluating cardiac interoceptive ability, measuring sensitivity to naturalistic changes in the number of heartbeats over time periods. Results show participants have an overall tendency toward sensing fewer heartbeats during higher heart rates. This likely reflects the influence of changing heartbeat strength on cardiac interoception at rest, which should be taken into account when evaluating cardiac interoceptive ability and its relationship to anxiety and psychosomatic conditions.

A practical guide to active stand testing and analysis using continuous beat-to-beat non-invasive blood pressure monitoring

PURPOSE

The average adult stands approximately 50-60 times per day. Cardiovascular responses evoked during the first 3 min of active standing provide a simple means to clinically assess short-term neural and cardiovascular function across the lifespan. Clinically, this response is used to identify the haemodynamic correlates of patient symptoms and attributable causes of (pre-)syncope, and to detect autonomic dysfunction, variants of orthostatic hypotension, postural orthostatic tachycardia syndrome and orthostatic hypertension.

METHODS

This paper provides a set of experience/expertise-based recommendations detailing current state-of-the-art measurement and analysis approaches for the active stand test, focusing on beat-to-beat BP technologies. This information is targeted at those interested in performing and interpreting the active stand test to current international standards.

RESULTS

This paper presents a practical step-by-step guide on (1) how to perform active stand measurements using beat-to-beat continuous blood pressure measurement technologies, (2) how to conduct an analysis of the active stand response and (3) how to identify the spectrum of abnormal blood pressure and heart rate responses which are of clinical interest.

CONCLUSION

Impairments in neurocardiovascular control are an attributable cause of falls and syncope across the lifespan. The simple active stand test provides the clinician with a powerful tool for assessing individuals at risk of such common disorders. However, its simplicity belies the complexity of its interpretation. Care must therefore be taken in administering and interpreting the test in order to maximise its clinical benefit and minimise its misinterpretation.

Diagnosing orthostatic hypotension: a narrative review of the evidence

BACKGROUND

Orthostatic hypotension (OH) is very common, particularly in older populations. Diagnostic criteria exist but appear to be arbitrary rather than evidence based. This review will visit the evidence for diagnostic strategies for OH.

DATA SOURCES

Medline (OvidSP), EMBASE (OvidSP), ISI Web of Science, the Health Technology Assessments Database and the Cochrane Library.

AREAS OF AGREEMENT

A 5-min rest is required before measuring baseline. An active stand with continuous blood pressure (BP) monitoring is preferable to a tilt test to identify initial OH in particular. At least 2 min in the upright position is required. A systolic drop of 20 or a diastolic drop of 10 is supported by the evidence. Reproducibility when testing for OH is poor.

AREAS OF CONTROVERSY

Is the active stand preferable to the tilt test to diagnose classical OH? Although continuous BP monitoring increases diagnostic rates, does it improve clinical outcomes? Should symptoms be used to inform diagnosis?

AREAS TIMELY FOR RESEARCH

Establishing the long-term clinical outcomes for transient drops in BP detected on continuous, non-invasive monitoring. Evaluating the different patterns of BP drop to aid diagnosis and direct treatment.

Prevalence of orthostatic hypotension in the unselected ambulatory population of persons aged 65 years old and above

BACKGROUND

The diagnostic recommendation for orthostatic hypotension (OH) is to measure blood pressure during the first 3 min after getting up from a lying position. There are no clear definitions as to the amount of time that the patient should lie down before this, and the number of measurements to be taken in lying and standing positions. The aim of this study was to identify the optimal time to measure blood pressure when lying and standing.

METHODS

This was a prospective study of 99 patients aged 65 years and above in an urban primary care clinic. Blood pressure was measured at 1 min intervals over 10 min in the lying position and 7 min standing.

RESULTS

OH was found in 37 patients (37.4%). Of these, 56.8% were identified in the 1st minute, 67.6% after 2 min and 83.8% after 3 min of standing. In all cases, participants with OH were asymptomatic. In the lying position, blood pressure stabilized after 7 min, but when the 7th minute was used as a reference for OH many cases were lost.

CONCLUSION

To optimize the identification of OH, blood pressure should be measured at 1 min intervals over the first 3 min after standing up. The amount of time that patients should lie down before blood pressure is measured standing up still has to be determined.

Orthostatic hypotension: a common, serious and underrecognized problem in hospitalized patients

Orthostatic hypotension (OH) is strongly age-dependent, with a prevalence ranging from 5% to 11% in middle age to 30% or higher in the elderly. It is also closely associated with other common chronic diseases, including hypertension, congestive heart failure, diabetes mellitus, and Parkinson's disease. Most studies of OH have been performed in population cohorts or elderly residents of extended care facilities, but in this review, we draw attention to a problem little studied to date: OH in hospitalized patients. The prevalence of OH in all hospitalized patients is not known because most studies have included only older individuals with multiple comorbid diseases, but in some settings as many as 60% of hospitalized adults have postural hypotension. Hospitalized patients are particularly vulnerable to the consequences of OH, particularly falls, because postural blood pressure (BP) regulation may be disturbed by many common acute illnesses as well as by bed rest and drug treatment. The temporal course of OH in hospitalized patients is uncertain, both because the reproducibility of OH is poor and because conditions affecting postural BP regulation may vary during hospitalization. Finally, OH during hospitalization often persists after discharge, where, in addition to creating an ongoing risk of falls and syncope, it is strongly associated with risk of incident cardiovascular complications, including myocardial infarction, heart failure, stroke, and all-cause mortality. Because OH is a common, easily diagnosable, remediable condition with important clinical implications, we encourage caregivers to monitor postural BP change in patients throughout hospitalization.

The inaccuracy of automatic devices taking postural measurements in the emergency department

Automatic devices are used to take postural blood pressures in the emergency department despite research proving their inaccuracy in taking single blood pressures. This study assessed the accuracy of an automatic device compared with a manual aneroid reference standard for determining orthostatic hypotension and postural drops at triage. Supine and standing blood pressures were taken with an automatic and a manual device in a sequential and random order, and postural drops were calculated. The manual device indicated 10/150 emergency department patients had orthostatic hypotension (7%) and the automatic device detected this with a sensitivity of 30% and a specificity of 91%. The automatic-manual differences were clinically significant in 13% of systolic drops and 37% of diastolic drops. Findings suggest that automatic devices cannot reliably detect or rule out orthostatic hypotension, indicating that triage nurses need to use manual devices to take accurate postural blood pressures for optimal patient care.

Orthostatic Hypotension in the Nursing Home Setting

Orthostatic hypotension is a common condition among nursing home (NH) residents. NH residents tend to have multiple disease processes and tend to be on multiple medications associated with orthostatic hypotension and are predisposed to a myriad of negative clinical consequences, most notably falls. This article discusses a commonsense approach to diagnosis, evaluation, and treatment of patients with this disorder, with an emphasis on nonpharmacological interventions, such as patient and staff education.

Orthostatic hypotension in the elderly: are the diagnostic criteria adequate?

Orthostatic hypotension (OH) is a common finding in the elderly. OH is defined as a fall of at least 20 mmHg in systolic blood pressure (BP) and/or 10 mmHg in diastolic BP upon assuming an upright posture. Some patients exhibit a fall in BP of less than the defined OH upon standing. The aim of this study was to estimate the prevalence of BP changes not defined as OH among elderly in-patients and to assess the relationship between these changes in the morning and the occurrence of OH during the day. Postural BP measurements were performed in 502 in-patients; in the morning, early afternoon, and in the evening. We defined intermediate postural drop (ID) in BP as a decrease of 10-19 mmHg in systolic BP and/or of 5-9 mmHg in diastolic BP. We observed that OH and ID occurred in 39.2 and 18.5% of the measurements in the morning, respectively. The prevalence of OH and ID was lower in the evening than in the morning (P<0.05) and afternoon (P<0.005). Postural BP changes in the morning correlated with those occurring later in the day. Patients who had ID in the morning had a 57% probability of having OH later during the day. In conclusions, ID is prevalent in elderly in-patients. ID in the morning predicts OH later in the day. Thus, postural BP drops below the OH range may be an important finding in the geriatric population.

Comparison of different methods of obtaining orthostatic vital signs

The purpose of this study was to compare two lying and standing procedures for measuring orthostatic vital signs. Thirty-five normotensive participants (mean age 21.6 years)participated in a randomized crossover study. Measures of blood pressure (BP), heart rate, and dizziness were collected at different lying and standing times. AU subjects participated in a standardized walk paced at 4 miles per hour prior to lying. Using analysis of variance (ANOVA) with post hoc contrasts, the mean systolic BP differed between 5 and 10 minutes of lying (F = 21.33, p < .001) and the mean diastolic BP tended to differ between those time points (F = 5.23, p < .03). The mean standing systolic BP and dizziness rating were different between 0- and 2-minute intervals (F = 8.36, p < .01 and F = 7.15, p < .10). In normotensive participants following standardized exercise, orthostatic vital signs stabilized after lying 10 minutes.

Achieving haemodynamic baseline values with Finapres in elderly subjects during supine rest

BACKGROUND

Clear guidelines for the resting time necessary to achieve stable blood pressure (BP) levels are scant in gerontology research. Therefore, we aimed to determine the minimum period required for obtaining haemodynamic baseline values in elderly subjects during supine rest. In addition, we evaluated the effect of cardiovascular morbidity, such as diastolic heart failure, and the effect of complex comorbidity of geriatric patients, on haemodynamic changes during supine rest.

METHODS

A total of 17 healthy subjects, 18 heart failure patients with normal systolic function and 24 geriatric patients, aged 70 years and more, participated. After an overnight fast, changes in systolic BP (SBP), diastolic BP (DBP), heart rate (HR), and stroke volume (SV) were determined by Finapres beat-to-beat non-invasive BP monitoring during a 20-min supine rest. The procedure was repeated in the healthy subjects and geriatric patients on a second day.

RESULTS

Complete BP stabilization was reached in each group within 5 min of supine rest, as SBP remained essentially unchanged and DBP did not change significantly anymore after the fourth minute. In the heart failure patients, HR decreased and SV increased until the twelfth minute of rest. The SBP, DBP, HR, and SV changes during supine rest showed good reproducibility.

CONCLUSIONS

A span of 5 min of supine rest ensured achievement of reliable and reproducible baseline BP values by Finapres in elderly subjects. However, we recommend at least 12 min of rest to obtain full haemodynamic stability in elderly patients with diminished cardiac compliance and diastolic function.

Orthostatic hypotension as a risk factor for stroke: the atherosclerosis risk in communities (ARIC) study, 1987-1996

BACKGROUND AND PURPOSE

The association between orthostatic hypotension (OH) and stroke has rarely been investigated in longitudinal studies. The purpose of the present study was to determine whether OH predicts ischemic stroke in a middle-aged, biethnic population after adjustment for known stroke risk factors. Diastolic, systolic, and consensus OH were evaluated for baseline associations and for the ability to predict stroke.

METHODS

In 11 707 persons from the Atherosclerosis Risk in Communities (ARIC) cohort who were free of stroke and overt heart disease at baseline, Cox proportional hazards analyses modeled the association between OH at baseline and incident ischemic stroke over 7.9 years of follow-up. OH was defined as a systolic blood pressure drop >/=20 mm Hg (systolic OH), a diastolic blood pressure drop >/=10 mm Hg (diastolic OH), or a drop in either (consensus OH) when a person changed from a supine to standing position.

RESULTS

OH was predictive of ischemic stroke, even after adjustment for numerous stroke risk factors (consensus OH: hazard ratio, 2.0; 95% CI, 1.2 to 3.2). While the baseline characteristics associated with OH varied depending on the type of OH, all types of OH had a similar risk of stroke.

CONCLUSIONS

OH is an easily obtained measurement that may help to identify middle-aged persons at risk for stroke.

Distribution and observed associations of orthostatic blood pressure changes in elderly general medicine outpatients

Factors associated with orthostatic blood pressure change in elderly outpatients were determined by surveying 398 medical clinical outpatients aged 65 years and older. Blood pressure was measured with random-zero sphygmomanometers after patients were 5 minutes in a supine and 5 minutes in a standing position. Orthostatic blood pressure changes were at normally distributed levels with systolic and diastolic pressures dropping an average of 4 mm Hg (standard deviation [SD]=15 mm Hg) and 2 mm Hg (SD=11 mm Hg), respectively. Orthostatic blood pressure changes were unassociated with age, race, sex, body mass, time since eating, symptoms, or other factors. According to multiple linear regression analysis, supine systolic pressure, chronic obstructive pulmonary disease (COPD), and diabetes mellitus were associated with a decrease in systolic pressure on standing. Hypertension, antiarthritic drugs, and abnormal heartbeat were associated with an increase in systolic pressure on standing. For orthostatic diastolic pressure changes, supine diastolic pressure and COPD were associated with a decrease in diastolic pressure on standing. Congestive heart failure was associated with an increase in standing diastolic pressure. Using logistic regression analysis, only supine systolic pressure was associated with a greater than 20-mm Hg drop in systolic pressure (n=53, prevalence=13%). Supine diastolic pressure and COPD were the only variables associated with a greater than 20-mm Hg drop in diastolic pressure (n=16, prevalence=4%). These factors may help physicians in identifying older persons at risk for having orthostatic hypotension.

Orthostatic blood pressure changes on prolonged standing in elderly hospital in-patients

To determine early and delayed orthostatic BP responses in elderly hospitalized patients on prolonged standing, 85 patients, including normotensive and hypertensive persons, both treated and untreated, aged between 60 and 90 years, were studied. Following 10 min rest a series of nine supine BP measurements were undertaken, first with a mercury sphygmomanometer, immediately followed by an automatic oscillometric BP monitor (SpaceLabs 90207), then again by the sphygmomanometer. Patients then stood and the series of BP measurements was repeated, giving a total of nine standing BP determinations at 1 min intervals. Orthostatic BP measurements recorded by both devices were assessed at 1-3 min (early phase), 4-6 min (mid-phase), and 7-9 min (late phase). The orthostatic fall in SBP was greater during the late than early phase when measured by both the sphygmomanometer (-7.5+/-14.9 vs -2.6+/-10.3 mmHg; difference 4.9+/-8.7 mmHg, p<0.001, 95% CI: 3.0, 6.7 mmHg) and the automatic monitor (-3.5+/-16.9 vs 0.5+/-14.5 mmHg, difference 4.0+/-11.6 mmHg; p=0.002, CI: 1.5, 6.5 mmHg). Orthostatic changes in DBP were similar during early and late phases. More patients had systolic orthostatic hypotension (SBP fall > or =20 mmHg on standing) measured by the sphygmomanometer during the late than early phase (19 [22%] vs 6 [7%]; respectively, p=0.009), but not when measured by the monitor (10 [12%] vs 9 [11%], respectively). Many hospitalized elderly patients may exhibit systolic orthostatic hypotension as measured by sphygmomanometry only after prolonged (> or =7 min) standing.

Head-up tilt table test: how far and how long?

There is great variation between laboratories in the angle and duration of tilt used in the head-up tilt table test. We compared the hemodynamic response to three sequential randomized 20-min tilts of 60 degrees, 80 degrees and 90 degrees in 20 normal subjects. We studied 66 patients to determine the duration of tilt needed to document three types of orthostatic intolerance. Blood pressure and heart rate were monitored non-invasively. Thirty-nine patients with orthostatic hypotension of diverse causes and 17 patients with orthostatic tachycardia plus were tilted to 90 degrees for 10 min. Ten patients with vasovagal syncope were tilted to 90 degrees for 30 min. A multivariate analysis of variance performed to assess the hemodynamic responses to 60 degrees, 80 degrees and 90 degrees tilts did not show a statistically significant difference (F = 0.459). Logistic regression analyses revealed that the duration of tilt required to document orthostatic hypotension was 5 min (73% cases correctly identified), orthostatic tachycardia plus 10 min (86.5% cases correctly identified) and neurally mediated syncope 10 min (86.5% cases correctly identified). Tilt duration is a more important variable than tilt angle and the duration of the tilt should depend on the suspected cause of orthostatic intolerance.

Is there a relationship between supine systemic blood pressure and orthostatic hypotension in the elderly?

The relationship between blood pressure and orthostatic hypotension was studied in 48 elderly patients with orthostatic hypotension and 29 healthy age-matched controls. Individuals were designated as hypertensive (systolic > 160 and or diastolic > 90 mmHg) or normotensive on the basis of supine blood pressure levels. Systolic, diastolic and mean blood pressures, heart rate, stroke volume, cardiac output, cardiac index and total peripheral resistance were measured every 5 min before, during and after 10 min head-up tilt to 70 degrees. Eighteen orthostatic hypotension subjects and six controls were hypertensive, while 30 orthostatic hypotension subjects and 23 controls were normotensive. There were no differences between hypertensive and normotensive patients in mean age, weight, height or body surface area. Mean systolic blood pressure in orthostatic hypotension subjects was higher than in controls (148.8 +/- 3.6 vs. 137.5 +/- 3.34 mmHg). Mean diastolic pressure was not different (79.1 +/- 2.0 vs. 79.0 +/- 2.0 mmHg). There were no differences between patients with or without hypertension in the haemodynamic changes produced by head-up tilt. Heart rates in orthostatic hypotension subjects with hypertension were significantly lower throughout the study when compared with normotensive orthostatic hypotension patients. Further, the increases in heart rate on tilting were significantly smaller (8.4 +/- 1.9 vs. 14.5 +/- 1.8 beats/min). Control hypertensive subjects had significantly higher mean cardiac output and cardiac index compared with non-hypertensives from before and during tilt. We conclude that hypertension is not related to the development or the degree of orthostatic hypotension in the elderly.(ABSTRACT TRUNCATED AT 250 WORDS)

Orthostatic hypotension in older adults. The Cardiovascular Health Study. CHS Collaborative Research Group

The purpose of the present study was to assess the prevalence of orthostatic hypotension and its associations with demographic characteristics, cardiovascular risk factors and symptomatology, prevalent cardiovascular disease, and selected clinical measurements in the Cardiovascular Health Study, a multicenter, observational, longitudinal study enrolling 5,201 men and women aged 65 years and older at initial examination. Blood pressure measurements were obtained with the subjects in a supine position and after they had been standing for 3 minutes. The prevalence of asymptomatic orthostatic hypotension, defined as 20 mm Hg or greater decrease in systolic or 10 mm Hg or greater decrease in diastolic blood pressure, was 16.2%. This prevalence increased to 18.2% when the definition also included those in whom the procedure was aborted due to dizziness upon standing. The prevalence was higher at successive ages. Orthostatic hypotension was associated significantly with difficulty walking (odds ratio, 1.23; 95% confidence interval, 1.02, 1.46), frequent falls (odds ratio, 1.52; confidence interval, 1.04, 2.22), and histories of myocardial infarction (odds ratio, 1.24; confidence interval, 1.02, 1.50) and transient ischemic attacks (odds ratio, 1.68; confidence interval, 1.12, 2.51). History of stroke, angina pectoris, and diabetes mellitus were not associated significantly with orthostatic hypotension. In addition, orthostatic hypotension was associated with isolated systolic hypertension (odds ratio, 1.35; confidence interval, 1.09, 1.68), major electrocardiographic abnormalities (odds ratio, 1.21; confidence interval, 1.03, 1.42), and the presence of carotid artery stenosis based on ultrasonography (odds ratio, 1.67; confidence interval, 1.23, 2.26). Orthostatic hypotension was negatively associated with weight. We conclude that orthostatic hypotension is common in the elderly and increases with advancing age. It is associated with cardiovascular disease, particularly those manifestations measured objectively, such as carotid stenosis. It is associated also with general neurological symptoms, but this link may not be causal. Differences in prevalence of and associations with orthostatic hypotension in the present study compared with others are largely attributed to differences in population characteristics and methodology.

Prevalence of postural hypotension at baseline in the Systolic Hypertension in the Elderly Program (SHEP) cohort

OBJECTIVE

The objective of this study was to examine the prevalence and correlates of postural hypotension (defined as a drop in systolic blood pressure of greater than or equal to 20 mm Hg) in a cohort of elderly persons with isolated systolic hypertension (ISH).

DESIGN

Baseline cross-sectional analysis of the 4,736 persons randomized in the Systolic Hypertension in the Elderly Program (SHEP).

SETTING

A randomized multi-center double-blind outpatient clinical trial of the impact of treating ISH.

PARTICIPANTS

Men and women age greater than or equal to 60 years with the systolic blood pressure (SBP) greater than or equal to 160 mm Hg and diastolic blood pressure (DBP) less than 90 mm Hg.

MEASURES

Medical histories were obtained using interviewer-administered, standardized clinical history forms. At entry into the study, seated and standing BP was measured by certified BP technicians using a random zero sphygmomanometer. Postural hypotension (PH) was assessed at 1 and 3 minutes after the participant arose from a seated position.

MAIN RESULTS

PH was found in 10.4% of participants at 1 minute and in 12.0% of participants at 3 minutes. 5.3% of participants demonstrated PH at both time intervals while 17.3% demonstrated PH at either or both of the time intervals. Factors significantly (P less than 0.05) associated with the presence of PH were higher mean SBP and a lower mean body mass index.

CONCLUSIONS

Somewhat different persons were defined as having PH based upon the 1 minute and 3 minute standing measures of BP, and prevalence estimates of PH can vary depending on whether one or more intervals of measurement are used. Cross-sectional data analysis indicated that PH, in healthy community-dwelling older persons with ISH, may not be associated with a history of disorders or problems usually thought to be related to PH. However, prospective data are needed to determine the prognostic significance of PH, and whether one or multiple measurements carry more significance.