Measuring postural changes in blood pressure in the healthy elderly.

BACKGROUND: Background The reproducibility of postural changes in blood pressure of a healthy elderly population determined using standard clinical measurements is not known. OBJECTIVE: To assess the differences in reproducibility of postural changes in blood pressure in healthy elderly subjects 1 and 3 min after standing within a day and between visits spaced 6 weeks apart. METHODS: Casual readings of blood pressures of supine and standing subjects were measured twice during the day by the same observer on two occasions 6 weeks apart using a semi-automatic syphgmomanometer. Twenty-two subjects with no known risk factors for orthostatic hypotension (13 men) aged 69+/-3 years (mean+/-SD) with a mean initial screening supine blood pressure of 153+/-19/88+/-11 mmHg were recruited. RESULTS: There were significant differences(P<0.001) between the postural changes both for systolic and for diastolic blood pressure between 1 and 3 min of standing, the largest falls occurring after 1 min of standing, though we found no variation between morning and afternoon measurements and between visits. The coefficients of reproducibility between visits for the postural changes in blood pressure after 1 and 3 min of standing were large both for systolic and for diastolic blood pressure, ranging from 9.8 to 29.3 mmHg. CONCLUSIONS: There was a consistent and significant difference between the postural changes in blood pressure after 1 and 3 min of standing for this healthy elderly population, but there was no significant difference between the postural changes in morning and afternoon measurements and between visits. This marked variability in the postural change in blood pressure with duration of standing must be taken into account when assessing the prevalence of orthostatic hypotension and the effects of treatment in patients with orthostatic falls in blood pressure.

Responses to the prolonged head-up tilt followed by sublingual nitrate provocation in asymptomatic older adults.

BACKGROUND: prolonged head-up tilt testing and sublingual nitrate provocation are increasingly used in the diagnosis of neurocardiogenic syncope. However there are few data regarding the results of these tests in asymptomatic older subjects. OBJECTIVE: to assess the responses to the prolonged head-up tilt test followed by sublingual glyceryl trinitrate provocation in asymptomatic subjects over the age of 60 years. DESIGN: observational study. METHODS: we recruited 64 asymptomatic subjects over the age of 60 (39 men, 25 women) from two general practice lists in Nottingham and Leicester. Exclusion criteria were: history of syncope, ischaemic heart disease, cerebrovascular disease, marked aortic stenosis, carotid artery disease and being unable to stand for the duration of the test. All subjects underwent a full clinical examination, a 12-lead electrocardiogram and a 30-40-min head-up tilt test, during which we monitored the heart rate and blood pressure continuously. We ended the test prematurely if the subjects developed syncope or symptoms of presyncope associated with hypotension with or without bradycardia. If they remained asymptomatic at the end of this period, they received 400 microg of sublingual glyceryl trinitrate and monitoring continued for another 15 min. SETTINGS: two teaching hospitals in Nottingham and Leicester. RESULTS: six (9%) of the subjects had a positive response (syncope or presyncope) to the prolonged head-up tilt test prior to glyceryl trinitrate provocation. After provocation, 30 (52%) of the remaining 58 subjects had a positive response. CONCLUSION: the role of sublingual glyceryl trinitrate provocation following prolonged head-up tilt testing in the diagnosis of neurocardiogenic (vasovagal) syncope in older people is questionable, as many asymptomatic older subjects demonstrate syncopal or presyncopal symptoms.

Comparison of diurnal systolic blood pressure change as defined by wrist actigraphy, fixed time periods and cusum.

AIMS: To assess whether differences exist in nocturnal blood pressure (BP) levels and the diurnal BP change when using fixed time and wrist actigraphy methods to define the night-time period. METHODS: Untreated hypertensive (n = 48) and normotensive (n = 33) subjects (mean age 67 years: range 29-90) underwent simultaneous 24-h ambulatory BP monitoring and wrist actigraph monitoring. The diurnal BP change and nocturnal BP levels were assessed using two fixed night-time definitions-a reference period of 22.00-06.59 and also 00.00-05.59, as well as unedited and edited actigraph values and cumulative sums (cusums) analysis. RESULTS: The reference definition of night-time 22.00-06.59 resulted in the highest values for night-time BP compared to other definitions (p < 0.05), although actigraph defined night-time BP values were not significantly different from the more restrictive definition of night-time (00.00-05.59). Restrictive night-time, edited and unedited actigraph and cusums values for the day-night difference were all significantly greater than the value calculated using the reference night-time period. Dipping status changed significantly depending on which definition of night-time was used. CONCLUSIONS: Significant differences exist in nocturnal BP levels and circadian change between the various methods for defining night-time. The routine use of wrist actigraphy does not however appear to alter the value of night-time BP levels when compared to a more restrictive fixed-time definition of night-time.

The reproducibility of cardiac baroreceptor activity assessed non-invasively by spectral sequence techniques.

Baroreceptor sensitivity (BRS) is increasingly used as a prognostic indicator in cardiovascular disease. Traditionally it has been measured using invasive techniques with pharmacological manipulation of blood pressure (BP). With the advent of newer methods to measure pulse interval and beat-to-beat changes in BP it is now possible, using sophisticated mathematical modelling techniques, to calculate cardiac BRS non-invasively. However, there are virtually no data on the reproducibility of these newer techniques and what factors may affect the repeatability of these measurements. We studied 39 subjects, aged 22-82 years, with a supine systolic BP range 97-160 mmHg and a diastolic BP range 57-94 mmHg on two occasions between 1 week and 6 months apart. Cardiac BRS was measured by power spectral analysis using Fast Fourier Transformation (FFT), sequence analysis (using up, down and combined sequences) and from phase IV of the Valsalva manoeuvre. There was no significant difference between visits for any of the methods for measuring cardiac BRS. Mean BRS values were similar for FFT (16.7 +/- 11.2 ms/mmHg) and sequence analysis (15.8 +/- 11.4 ms/mmHg); however, results using phase IV of the Valsalva manoeuvre were significantly lower (8.1 +/- 2.9 ms/mmHg, p < 0.0001). The coefficient of variation for the five measures of cardiac BRS varied from 16.8% for Valsalva-derived values to 26.1% for 'down' sequence analysis. However, in ten subjects BRS could not be calculated from the Valsalva manoeuvre. None of the independent variables tested (including age, BP levels and time between testing) significantly influenced the degree of repeatability. In summary, there appears to be little difference between these non-invasive methods in their degree of reproducibility. These techniques would seem suitable for longitudinal studies of changes in cardiac BRS and overcome many of the problems associated with the invasive pharmacological methods.

Older subjects show no age-related decrease in cardiac baroreceptor sensitivity.

OBJECTIVE: To examine the relationship between age, blood pressure and cardiac baroreceptor sensitivity derived from spectral analysis, the Valsalva manoeuvre and impulse response function. METHODS: We studied 70 healthy normotensive volunteers who were free from disease and not taking medication with cardiovascular or autonomic effects. We measured beat-to-beat arterial blood pressure and used standard surface electrocardiography to record pulse interval under standardized conditions with subjects resting supine as well as during three Valsalva manoeuvres. We performed single, multiple and stepwise regression of patient characteristics against cardiac baroreceptor sensitivity results. RESULTS: There is a non-linear decline in cardiac baroreceptor sensitivity with advancing age, increasing systolic blood pressure and heart rate values (except for the Valsalva-derived result), but little further decline after the fourth decade. Only age significantly influenced values derived using the Valsalva manoeuvre and impulse response analysis. Using spectral analysis, age, systolic and diastolic blood pressure and heart rate influenced cardiac baroreceptor sensitivity, age contributing to 50% of the variability. Age also influenced the relationship between pulse interval and blood pressure, possibly indicating more non-baroreceptor-mediated changes with advancing age. CONCLUSIONS: Although age is the dominant factor influencing cardiac baroreceptor sensitivity in this normotensive population, there is little change in mean values after 40 years of age. The differences in the relationship between pulse interval and blood pressure with advancing age have implications for the calculation of cardiac baroreceptor sensitivity using spectral analysis.