Patterns of orthostatic blood pressure change and their clinical correlates in a frail, elderly population.

OBJECTIVES: To determine patterns of within-day orthostatic blood pressure (BP) changes and clinical factors correlated with them in frail, elderly nursing home residents. DESIGN: Prevalence study of orthostatic BP change. SETTING: Sample of 45 nursing homes. PARTICIPANTS: A total of 911 long-stay residents, aged 60 years or older, able to stand for at least 1 minute. MAIN OUTCOME MEASURES: Supine and 1-minute and 3-minute standing BP measurements and heart rates, taken by a random-zero sphygmomanometer before and after breakfast and before and after lunch, symptoms upon standing, medication use, and clinical and functional assessments. RESULTS: Four orthostatic hypotension (OH) groups were defined based on the frequency of a 20 mm Hg or greater orthostatic BP decline during any of 8 postural change measures: no OH group (48.5%); isolated OH group (only once, 18.3%); variable OH group (2-3 times, 19.9%); and persistent OH group (> or =4 times, 13.3%). Orthostatic hypotension was most prevalent before breakfast, especially 1 minute after standing (21.3%), and least prevalent after lunch after 3 minutes of standing (4.9%) (P=.001). A regression approach to repeated measures analysis (method of general estimating equations) showed the following to be significantly associated with OH (P< or =.05): elevated supine systolic BP before breakfast, dizziness/light-headedness on standing, male sex, medication for Parkinson disease, time of day (particularly before breakfast), greater independence in activities of daily living, and low body mass index. CONCLUSIONS: Orthostatic hypotension occurs in more than half of frail, elderly nursing home residents, but is highly variable over time. It is most prevalent in the morning when subjects first arise and when supine BP is highest. The relationship of OH with elevated BP, but not antihypertensive medication use, suggests that the treatment of hypertension may improve postural BP regulation.

Cardiovascular adaptation to orthostatic stress during vasodilator therapy.

BACKGROUND: Orthostatic hypotension is a dangerous problem in elderly patients, often exacerbated by vasodilator medications. Age- and disease-related impairments in cardioacceleration and diastolic ventricular function may make older patients particularly vulnerable to the hypotensive effects of these drugs. Therefore we aimed to determine mechanisms of postural blood pressure regulation in elderly patients with coronary artery disease and to compare the effects of isosorbide dinitrate and nicardipine hydrochloride on postural blood pressure homeostasis in these patients. METHODS: Twenty elderly subjects with stable coronary artery disease (age, 76 +/- 4 [SD] years) underwent a baseline evaluation followed by a double-blind, randomized crossover comparison of nicardipine (20 mg by mouth t.i.d.) versus isosorbide (20 mg by mouth t.i.d.). Doppler echocardiography and a 15-minute 60-degree head-up tilt test were conducted on no study medications and then after successive 3-week treatment periods with nicardipine or isosorbide. Blood pressure, heart rate, vascular resistance, cardiac output, and spectral characteristics of heart rate and blood pressure variability were measured before and during each tilt. RESULTS: Isosorbide treatment was associated with a higher prevalence of symptoms of cerebral hypoperfusion and a failure to increase systemic vascular resistance during tilt. While taking isosorbide subjects were able to preserve cardiac output and maintain upright blood pressure through enhanced cardioacceleration. During nicardipine treatment systemic vascular resistance and low-frequency blood pressure variability were reduced, but the ability to increase systemic vascular resistance during tilt was preserved. CONCLUSIONS: Although nicardipine may decrease vascular responsiveness to sympathetic activation, the baroreflex-mediated vasoconstrictor response to upright tilt remains intact. In contrast, isosorbide impairs the systemic vascular response to orthostatic stress in elderly patients with stable coronary artery disease.

Effects of chronic estrogen replacement therapy on beat-to-beat blood pressure dynamics in healthy postmenopausal women.

Recent data showing gender differences in autonomic control of heart rate and acute estrogen effects on vasodilatation suggest that estrogen may influence autonomic regulation of heart rate and blood pressure. We aimed to determine the effect of postmenopausal estrogen replacement therapy on autonomic control of beat-to-beat heart rate and blood pressure dynamics. Subjects included 20 healthy postmenopausal women aged 60 to 75 years with normal exercise tolerance tests, 10 of whom were taking oral estrogen for 13 +/- 3 (+/- SEM) years. Six healthy premenopausal women were also studied. Continuous electrocardiographic and noninvasive radial artery blood pressure measurements and intermittent forearm blood flow recordings (by venous-occlusion plethysmography) were obtained before and after a 20-minute, 60 degrees head-up tilt and a 420-kcal meal during periods of spontaneous and metronomic breathing (at 0.25 Hz). Low-frequency (0.01- to 0.15-Hz) and high-frequency (0.15- to 0.50-Hz) heart rate and blood pressure spectral powers were compared with a fast Fourier transform. Cardiovascular and heart rate spectral power responses to upright tilt and meal digestion were the same in postmenopausal estrogen users and nonusers. However, during spontaneous breathing the blood pressure spectral power responses to upright tilt and meal ingestion were significantly different between the two groups of women. The low-frequency systolic pressure power response to upright tilt was smaller in estrogen users than nonusers (P = .01). After meal ingestion nonusers had an early postprandial fall (20 to 30 minutes after the meal) and late rise (50 to 60 minutes) in low-frequency systolic and diastolic pressure powers, which were significantly attenuated in estrogen users (P < .02).(ABSTRACT TRUNCATED AT 250 WORDS)

Postprandial hypotension in elderly patients with unexplained syncope.

BACKGROUND: Syncope in older patients may be caused by a variety of disorders, including hypotension, but frequently remains unexplained. Postprandial hypotension is a common disorder of blood pressure regulation in the elderly. OBJECTIVE: To determine the pathogenic mechanisms and potential role of postprandial hypotension in elderly patients with otherwise unexplained syncope. METHODS: We studied 16 elderly patients with unexplained syncope and nine elderly controls. Blood pressure, heart rate, forearm vascular resistance, plasma norepinephrine level, and cardiac and splanchnic blood volumes were measured before and after a 1680-kJ meal. RESULTS: Eight elderly patients with syncope had postprandial hypotension, with a decline in supine mean arterial blood pressure of 17 +/- 2 mm Hg after a meal (P < .001). The blood pressure remained unchanged after the meal in the other patients with syncope and the controls. In patients with postprandial hypotension, systemic vascular resistance fell after the meal, while it remained unchanged in the other groups. Heart rate and plasma norepinephrine level increased to a similar extent in all three groups. Forearm vascular resistance increased only in the control subjects. Splanchnic blood volume increased by 26% (P < .01) in patients with syncope who had postprandial hypotension and by 22% (P < .01) in control subjects. Splanchnic blood volume remained unchanged in the patients with syncope without postprandial hypotension. CONCLUSIONS: Postprandial hypotension may be an important causative factor in elderly patients with unexplained syncope. The evaluation of syncope in elderly patients should therefore include blood pressure measurements surrounding a meal. Elderly patients with syncope who have postprandial hypotension fail to maintain systemic vascular resistance, probably because of splanchnic blood pooling without a compensatory increase in peripheral vascular resistance.

Haemodynamic and neurohumoral effects of caffeine in elderly patients with symptomatic postprandial hypotension: a double-blind, randomized, placebo-controlled study.

1. The aim of this study was to determine the effects of caffeine on haemodynamic and neurohumoral responses to meal ingestion in elderly patients with a history of symptomatic postprandial hypotension. 2. Postprandial hypotension is a common disorder of blood pressure regulation in the elderly, associated with falls and syncope. The pathophysiological mechanism is thought to be related to impaired vascular compensation for splanchnic blood pooling after a meal. Since caffeine inhibits vasodilatory adenosine receptors in the splanchnic circulation, we postulated that caffeine would reduce splanchnic blood pooling and prevent the development of postprandial hypotension. 3. We conducted a randomized, double-blind, placebo-controlled, cross-over study in nine elderly patients [age 76 +/- 9 (SD) years] with histories of symptomatic postprandial hypotension. Standardized 1674kJ liquid meals with 250 mg of caffeine or placebo were given on two occasions, at least 1 week apart. Blood pressure, heart rate, forearm vascular resistance (by venous occlusion plethysmography), and plasma caffeine and catecholamine levels were measured. Cardiac and splanchnic blood volume were determined by radionuclide scans. 4. By 30 min after both caffeine and placebo meal studies, supine mean arterial blood pressure fell significantly (P = 0.006) by 31 +/- 7 and 19 +/- 6 mmHg, respectively (mean +/- SEM, between group difference was not significant). Heart rate, cardiac output and splanchnic blood volume increased significantly, but to a similar extent, after caffeine and placebo. Forearm vascular resistance was unchanged after both meals. 5. Oral caffeine given with a meal does not reduce splanchnic blood pooling nor prevent postprandial hypotension in symptomatic elderly patients.