Age-related changes in open-loop and closed-loop postural control mechanisms

In an earlier posturographic investigation (Collins and De Luca 1993) it was proposed that open-loop and closed-loop control mechanisms are involved in the regulation of undisturbed, upright stance. In this study, stabilogram-diffusion analysis was used to examine how the natural aging process affects the operational characteristics of these control mechanisms. Stabilogram-diffusion analysis leads to the extraction of repeatable center-of-pressure (COP) parameters that can be directly related to the steady-state behavior and functional interaction of the neuromuscular mechanisms underlying the maintenance of erect posture. Twenty-five healthy young males (aged 19-30 years) and twenty-five elderly males (aged 71-80 years) who were free of major gait and postural disorders were included in the study. An instrumented force platform was used to measure the time-varying displacements of the COP under each subject's feet during quiet standing. The COP trajectories were analyzed as one-dimensional and two-dimensional random walks, according to stabilogram-diffusion analysis. Using this technique, it was demonstrated cross-sectionally that healthy aging is associated with significant changes in the 'quasi-static' dynamics of the postural control system. (It was also shown that more traditional posturographic analyses, i.e., summary statistics, were not sensitive enough to detect these age-related differences.) It was found that the steady-state behavior of the open-loop postural control mechanisms in the elderly is more positively correlated and therefore perhaps more unstable, i.e., the output of the overall system has a greater tendency to move or drift away from a relative equilibrium point over the short term. In contrast with this result, it was also found that the steady-state behavior of the closed-loop postural control mechanisms in the elderly is more negatively correlated and therefore perhaps more stable, i.e., over the longer term, there is an increased probability that movements away from a relative equilibrium point will be offset by corrective adjustments back towards the equilibrium position. In addition, it was demonstrated that the elderly utilize open-loop control schemes for longer time intervals and correspondingly larger COP displacements during periods of undisturbed stance. This result suggests that in the elderly there is a greater delay, on average, before closed-loop feedback mechanisms are called into play. Finally, it was shown that there is an increased heterogeneity of postural control abilities in healthy older adults.

Older community-dwelling adults' attitudes toward and practices of health promotion and advance planning activities

OBJECTIVE

To describe the attitudes toward and practice of health prevention and advance planning measures by a group of community-dwelling older adults and to examine the effect of age on these practices.

DESIGN

A descriptive study performed by mail survey.

PARTICIPANTS

Members of a research registry who were 65 years of age or older.

MEASUREMENTS

By means of a written questionnaire, we asked about knowledge of various health prevention and advance planning topics, including exercise, cholesterol screening, rectal examination, influenza vaccination, sigmoidoscopy, mammography, prostate cancer screening, organ donation, autopsy, health care proxy, and advance directives. Of those who knew about the topic, we asked if the respondent had discussed it with a physician, who initiated the conversation, and if the respondent participated in the activity. We also asked how important the topic was to the respondent.

RESULTS

We received 598 completed surveys, a response rate of 83%. Respondents had a mean age of 74 years, were predominately white (96%), and were well educated, with 44% having completed college. The respondents were all knowledgeable about the topics, and, with the exception of sigmoidoscopy, organ donation, and autopsy, more than 70% thought these topics were important. In the case of health screening and prevention activities, a large percentage of respondents reported having discussed the topic with a physician, and a slightly smaller percentage reported regular participation. In the case of health care proxies and advance directives, however, only about one-half of those who had made these arrangements said they had discussed them with a physician. When discussion did occur, it was much more likely to have been initiated by the respondent. Controlling for level of education, age was inversely associated with the likelihood of a woman reporting she had undergone mammography (P < .05). Age, however, was not associated with decreased frequency of undergoing other screening tests.

CONCLUSIONS

Among a group of well educated older adults, reported interest in and compliance with health screening, health promotion, and advance planning activities were high. However, sigmoidoscopy, a relatively more invasive procedure that is generally recommended as a screening tool, is reported less likely to be practiced than prostate cancer screening, a less invasive procedure without such recommendation. Older adults state they are pursuing health care proxies and advance directives, often without the involvement of their physicians. Of the screening tests about which we asked, age was associated only with less frequent practice of mammography.

Epidemiologic and diagnostic aspects of bacteriuria: a longitudinal study in older women

OBJECTIVE

To examine month-by-month variability of bacteriuria in a cohort of older women and to evaluate the performance of rapid diagnostic tests commonly used to indicate the presence of significant bacteriuria.

DESIGN

Prospective, observational study.

SETTING

Community housing sites and a long-term care institution.

PARTICIPANTS

Sixty-one women, mean age 77.6, took part in the study.

MEASUREMENTS

Midstream clean-catch urine samples and medical information on subjects were collected at baseline, and then monthly for 6 months.

RESULTS

Bacteriuria alone (> or = 10(5) organisms per mL) occurred in 17% of all urine samples (28% of patients), bacteriuria with pyuria in 15% (26% of patients), and bacteriuria with symptoms in 3% (10% of patients). Spontaneous clearance of bacteriuria with pyuria was common (P = .30), as were new occurrences (P = .12) over 6 months of follow-up. For the outcome of bacteriuria with symptoms, sensitivity of urinary diagnostic tests such as bacteria and pyuria on microscopic analysis, and leukocyte esterase on dipstick testing, ranged from 79 to 93%. Negative predictive values of these tests approached 100%.

CONCLUSIONS

Bacteriuria was a very common event, occurring in almost one-fifth of all urine samples and one-third of all subjects during 6 months of follow-up. Month-by-month follow-up indicates that the natural history of bacteriuria is marked by frequent spontaneous alternation between positive and negative events. The high negative predictive value of many simple diagnostic tests commonly used for urinary tract disease suggests that they can quickly and cost-effectively rule out bacteriuria in the older female patient.

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.

The effects of exercise on falls in elderly patients. A preplanned meta-analysis of the FICSIT Trials. Frailty and Injuries: Cooperative Studies of Intervention Techniques

OBJECTIVE

To determine if short-term exercise reduces falls and fall-related injuries in the elderly.

DESIGN

A preplanned meta-analysis of the seven Frailty and Injuries: Cooperative Studies of Intervention Techniques (FICSIT)--independent, randomized, controlled clinical trials that assessed intervention efficacy in reducing falls and frailty in elderly patients. All included an exercise component for 10 to 36 weeks. Fall and injury follow-up was obtained for up to 2 to 4 years.

SETTING

Two nursing home and five community-dwelling (three health maintenance organizations) sites. Six were group and center based; one was conducted at home.

PARTICIPANTS

Numbers of participants ranged from 100 to 1323 per study. Subjects were mostly ambulatory and cognitively intact, with minimum ages of 60 to 75 years, although some studies required additional deficits, such as functionally dependent in two or more activities of daily living, balance deficits or lower extremity weakness, or high risk of falling.

INTERVENTIONS

Exercise components varied across studies in character, duration, frequency, and intensity. Training was performed in one area or more of endurance, flexibility, balance platform, Tai Chi (dynamic balance), and resistance. Several treatment arms included additional nonexercise components, such as behavioral components, medication changes, education, functional activity, or nutritional supplements.

MAIN OUTCOME MEASURES

Time to each fall (fall-related injury) by self-report and/or medical records.

RESULTS

Using the Andersen-Gill extension of the Cox model that allows multiple fall outcomes per patient, the adjusted fall incidence ratio for treatment arms including general exercise was 0.90 (95% confidence limits [CL], 0.81, 0.99) and for those including balance was 0.83 (95% CL, 0.70, 0.98). No exercise component was significant for injurious falls, but power was low to detect this outcome.

CONCLUSIONS

Treatments including exercise for elderly adults reduce the risk of falls.

Whether to transfer? Factors associated with hospitalization and outcome of elderly long-term care patients with pneumonia

OBJECTIVE

To determine factors associated with the decision to treat elderly long-term care patients with pneumonia in the hospital vs in the long-term care facility (LTCF) and factors associated with patient outcomes.

DESIGN

Retrospective cohort study.

SETTING

Hebrew Rehabilitation Center for Aged.

PATIENTS

Nursing home residents who had an episode of pneumonia, defined as a new respiratory sign or symptom and a new infiltrate.

MEASUREMENTS AND MAIN RESULTS

The majority of the 316 pneumonia episodes (78%) were managed in the LTCF, most (77%) with oral antibiotics. Both patient-related factors, such as elevated respiratory rate, and non-patient-related factors, such as evening evaluation, were associated with hospitalization. No patient who had a do-not-hospitalize (DNH) order was hospitalized. Equal proportions of patients given LTCF therapy (87%) and hospital therapy (88%) survived. Elevated respiratory rate was associated with dying from pneumonia in the LTCF but not in the hospital. Dependent functional status was associated with dying from pneumonia in both sites.

CONCLUSIONS

Many episodes of pneumonia can be managed in the LTCF with oral antibiotics. Because, in the absence of DNH orders, both patient-related and non-patient-related factors are associated with hospital transfer, discussion regarding preferences for hospitalization should occur prior to the development of an acute illness. A high respiratory rate may be a good marker for those LTCF patients requiring hospitalization. Dependent functional status may be a good marker for those LTCF patients unlikely to benefit from hospital transfer.

Postprandial hypotension: epidemiology, pathophysiology, and clinical management

OBJECTIVE

To show the clinical relevance of postprandial hypotension and to review its pathophysiology and management.

DATA SOURCES

Articles on postprandial hypotension were identified through MEDLINE and bibliographies of relevant articles.

STUDY SELECTION

All articles and case reports describing meal-related hypotension in the elderly and in patients with autonomic failure.

DATA SYNTHESIS

Postprandial hypotension, defined as a decrease in systolic blood pressure of 20 mm Hg or more, may result in syncope, falls, dizziness, weakness, angina pectoris, and stroke. Postprandial hypotension is distinct from and probably more common than orthostatic hypotension. Because meal-related hypotension is particularly common in older hypertensive patients, it has important implications for the evaluation and management of hypertension. The mechanism of postprandial hypotension is not fully understood. Possible contributors include inadequate sympathetic nervous system compensation for meal-induced splanchnic blood pooling; impairments in baroreflex function; inadequate postprandial increases in cardiac output; and impaired peripheral vasoconstriction, insulin-induced vasodilation, and release of vasodilatory gastrointestinal peptides. Although caffeine is often recommended as treatment for postprandial hypotension, available data do not support its use. Octreotide, a somatostatin analog, has been shown to be effective, but it is expensive and must be given parenterally.

CONCLUSION

All physicians caring for elderly patients should be aware of the hypotensive effects of food intake and should consider postprandial hypotension in the evaluation of syncope, falls, dizziness, and other cerebral ischemic symptoms.

Gender- and age-related differences in heart rate dynamics: are women more complex than men?

OBJECTIVES

This study aimed to quantify the complex dynamics of beat-to-beat sinus rhythm heart rate fluctuations and to determine their differences as a function of gender and age.

BACKGROUND

Recently, measures of heart rate variability and the nonlinear "complexity" of heart rate dynamics have been used as indicators of cardiovascular health. Because women have lower cardiovascular risk and greater longevity than men, we postulated that there are important gender-related differences in beat-to-beat heart rate dynamics.

METHODS

We analyzed heart rate dynamics during 8-min segments of continuous electrocardiographic recording in healthy young (20 to 39 years old), middle-aged (40 to 64 years old) and elderly (65 to 90 years old) men (n = 40) and women (n = 27) while they performed spontaneous and metronomic (15 breaths/min) breathing. Relatively high (0.15 to 0.40 Hz) and low (0.01 to 0.15 Hz) frequency components of heart rate variability were computed using spectral analysis. The overall "complexity" of each heart rate time series was quantified by its approximate entropy, a measure of regularity derived from nonlinear dynamics ("chaos" theory).

RESULTS

Mean heart rate did not differ between the age groups or genders. High frequency heart rate power and the high/low frequency power ratio decreased with age in both men and women (p < 0.05). The high/low frequency power ratio during spontaneous and metronomic breathing was greater in women than men (p < 0.05). Heart rate approximate entropy decreased with age and was higher in women than men (p < 0.05).

CONCLUSIONS

High frequency heart rate spectral power (associated with parasympathetic activity) and the overall complexity of heart rate dynamics are higher in women than men. These complementary findings indicate the need to account for gender-as well as age-related differences in heart rate dynamics. Whether these gender differences are related to lower cardiovascular disease risk and greater longevity in women requires further study.

Muscle strength and fall rates among residents of Japanese and American nursing homes: an International Cross-Cultural Study

OBJECTIVE

In Western society, aging if often associated with adoption of a sedentary lifestyle and associated disuse muscle atrophy and weakness. Recent studies suggest a relationship between quadriceps muscle weakness and falls in elderly residents of US nursing homes (NHs). We hypothesized that fall rates would be lower in Japanese NHs, where lifestyle differences such as squatting to toilet or sleeping on the floor may maintain quadriceps strength and result in fewer falls. Therefore, we examined the relationships between falls, muscle strength, lifestyle, and other clinical characteristics in residents of a Japanese and an American NH.

DESIGN

Cross-culture, prospective, cohort study.

MEASUREMENTS

We evaluated disease histories and current medications, quadriceps strength, and mobility of ambulatory American (n = 76) and Japanese (n = 89) NH residents, then followed these residents prospectively for the development of falls. Project staff from both sites trained together to assure uniform data ascertainment.

MAIN RESULTS

During a 6-month follow-up period, fall rates were nearly 4-fold higher in the American than in the Japanese residents (49% vs 13%, respectively; P < 0.0001). In the American sample, fall rates declined with increasing muscle strength, while in Japan there was no relationship between fall rates and quadriceps strength. Residents also differed in number of medical diagnoses and use of medications, which were greater among American residents. The Japanese had slower gait speeds. Very few Japanese residents practiced squatting behaviors while living in the NH.

CONCLUSIONS

The relationship between muscle weakness and falls is probably modified by multiple characteristics of the individual, their culture, and their environment. Information from cross-cultural studies may provide new insights into effective fall prevention strategies for nursing home residents.

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.

Reduced apolipoprotein epsilon 4 allele frequency in the oldest old Alzheimer's patients and cognitively normal individuals

Recent genetic studies show that the apolipoprotein E epsilon 4 allele (ApoE-epsilon 4) is a risk factor for Alzheimer's disease (AD). If ApoE-epsilon 4 individuals develop AD as they get older, we would expect a decrease in ApoE-epsilon 4 allele frequency with increasing age. We found a marked decline in ApoE-epsilon 4 allele frequency with advancing age in both AD and cognitively normal controls (p < 0.003), although in all age groups the ApoE-epsilon 4 allele was overrepresented (p < 0.0001). Nonetheless, a few cognitively normal nonagenarians were ApoE-epsilon 4 positive. Thus, our data support two new conclusions: (1) the ApoE-epsilon 4 associated risk for AD is age-dependent, probably due to censoring by the earlier development of AD in ApoE-epsilon 4 individuals, and (2) despite the ApoE-epsilon 4 associated risk for AD, it is possible to reach extreme old age with normal cognition.

MDS Cognitive Performance Scale

BACKGROUND

Chronic cognitive impairment is a major problem in U.S. nursing homes, yet traditional assessment systems in most facilities included only limited information on cognitive status. Following the Congressional mandate in the Omnibus Reconciliation Act of 1987 (OBRA '87), U.S. nursing homes now complete the Minimum Data Set (MDS), a standardized, comprehensive assessment of each resident's functional, medical, psychosocial, and cognitive status. We designed a Cognitive Performance Scale (CPS) that uses MDS data to assign residents into easily understood cognitive performance categories.

METHODS

Information was drawn from three data sets, including two multistate data sets constructed for the Health Care Financing Administration. The prevalence and reliability of the MDS cognitive performance variables were established when assessed by trained nursing personnel. Five selected MDS items were combined to create the single, functionally meaningful seven-category hierarchical Cognitive Performance Scale.

RESULTS

The CPS scale corresponded closely with scores generated by the Mini-Mental State Examination and the Test for Severe Impairment, nursing judgments of disorientation, and neurological diagnoses of Alzheimer's disease and other dementias.

CONCLUSIONS

The new CPS provides a functional view of cognitive performance, using readily available MDS data. It should prove useful to clinicians and investigators using the MDS to determine a resident's cognitive assets.

Exercise training and nutritional supplementation for physical frailty in very elderly people

BACKGROUND

Although disuse of skeletal muscle and undernutrition are often cited as potentially reversible causes of frailty in elderly people, the efficacy of interventions targeted specifically at these deficits has not been carefully studied.

METHODS

We conducted a randomized, placebo-controlled trial comparing progressive resistance exercise training, multinutrient supplementation, both interventions, and neither in 100 frail nursing home residents over a 10-week period.

RESULTS

The mean (+/- SE) age of the 63 women and 37 men enrolled in the study was 87.1 +/- 0.6 years (range, 72 to 98); 94 percent of the subjects completed the study. Muscle strength increased by 113 +/- 8 percent in the subjects who underwent exercise training, as compared with 3 +/- 9 percent in the nonexercising subjects (P < 0.001). Gait velocity increased by 11.8 +/- 3.8 percent in the exercisers but declined by 1.0 +/- 3.8 percent in the nonexercisers (P = 0.02). Stair-climbing power also improved in the exercisers as compared with the nonexercisers (by 28.4 +/- 6.6 percent vs. 3.6 +/- 6.7 percent, P = 0.01), as did the level of spontaneous physical activity. Cross-sectional thigh-muscle area increased by 2.7 +/- 1.8 percent in the exercisers but declined by 1.8 +/- 2.0 percent in the nonexercisers (P = 0.11). The nutritional supplement had no effect on any primary outcome measure. Total energy intake was significantly increased only in the exercising subjects who also received nutritional supplementation.

CONCLUSIONS

High-intensity resistance exercise training is a feasible and effective means of counteracting muscle weakness and physical frailty in very elderly people. In contrast, multi-nutrient supplementation without concomitant exercise does not reduce muscle weakness or physical frailty.

A longitudinal study of risk factors associated with the formation of pressure ulcers in nursing homes

OBJECTIVE

To determine risk factors associated with the formation of stage II-IV pressure ulcers in nursing homes.

DESIGN

Since the incidence rate for pressure ulcer formation varies among nursing homes, the homes were divided into tertiles based on these rates. Pooled logistic regression was used to model which factors are associated with the formation of pressure ulcers in both high and low incidence homes.

SETTING

78 National HealthCorp nursing homes.

SUBJECTS

We studied 4232 nursing home residents free of pressure ulcers on admission to a nursing facility and at 3-months follow-up. All remained in the home for at least 3 additional months to a maximum of 21 months.

MEASUREMENTS

The effects of age, gender, race, antipsychotic drug use, urinary incontinence, fecal incontinence, body mass index, diabetes mellitus, disorientation, ambulation, physical restraints, activities of daily living of bathing, feeding, or transferring, and nursing home bed size on the formation of a stage II-IV pressure ulcer while the subject was a resident in the nursing home were studied.

MAIN RESULTS

Significant factors associated with the formation of pressure ulcers in high incidence homes (21-month incidence = 19.3%) were ambulation difficulty (OR = 3.3; CI = 2.0, 5.3), fecal incontinence (OR = 2.5; CI = 1.6, 4.0), diabetes mellitus (OR = 1.7; CI = 1.2, 2.5), and difficulty feeding oneself (OR = 2.2; CI = 1.5, 3.3). In the low incidence homes (21-month incidence = 6.5%), significant factors associated with pressure ulcer incidence were ambulation difficulty (OR = 3.6; CI = 1.7, 7.4), difficulty feeding oneself (OR = 3.5; CI = 2.0, 6.3), and male gender (OR = 1.9; CI = 1.2, 3.6).

CONCLUSIONS

Although low and high incidence homes share similar risk factors, such as ambulation and feeding activities of daily living, the main difference was that diabetes and fecal incontinence played a major role only in high risk homes, while male gender was an important discriminator only in low incidence homes. Yet, it is unclear if these factors explain the three-fold difference in the incidence rates for pressure ulcers in these facilities. Baseline or resident clinical characteristic differences of any one factor between the high and low incidence homes varied by no more than 5%. While we identified certain conditions which are associated with pressure ulcer formation, there may be unknown or unmeasured facility effects in addition to the characteristics of a given resident in a particular home.

Reduction of bacteriuria and pyuria after ingestion of cranberry juice

OBJECTIVE

To determine the effect of regular intake of cranberry juice beverage on bacteriuria and pyuria in elderly women.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SUBJECTS

Volunteer sample of 153 elderly women (mean age, 78.5 years).

INTERVENTION

Subjects were randomly assigned to consume 300 mL per day of a commercially available standard cranberry beverage or a specially prepared synthetic placebo drink that was indistinguishable in taste, appearance, and vitamin C content but lacked cranberry content.

OUTCOME MEASURES

A baseline urine sample and six clean-voided study urine samples were collected at approximately 1-month intervals and tested quantitatively for bacteriuria and the presence of white blood cells.

RESULTS

Subjects randomized to the cranberry beverage had odds of bacteriuria (defined as organisms numbering > or = 10(5)/mL) with pyuria that were only 42% of the odds in the control group (P = .004). Their odds of remaining bacteriuric-pyuric, given that they were bacteriuric-pyuric in the previous month, were only 27% of the odds in the control group (P = .006).

CONCLUSIONS

These findings suggest that use of a cranberry beverage reduces the frequency of bacteriuria with pyuria in older women. Prevalent beliefs about the effects of cranberry juice on the urinary tract may have microbiologic justification.

The relationship between age, gender and cognitive performance in the very old: the effect of selective survival

OBJECTIVE

To determine the prevalence of cognitive disability as a function of advanced age and gender in elderly nursing home and community-dwelling populations. Since cognitive dysfunction is associated with increased mortality, we hypothesized that selective survival results in a decreased prevalence of cognitive disability in the oldest old.

DESIGN

Cohort study. An analysis of 6-month longitudinal data obtained from a national probability sample of older persons in 260 nursing homes (n = 1951) and 2-year-longitudinal data obtained from a sample of community-dwelling older persons (n = 2947).

MEASURES

In the nursing home sample, the primary outcome measure was cognitive performance score. In the community sample, cognitive performance was determined using the results of three orientation questions and assessment of decision-making ability. Cognitive performance and subsequent survival, controlling for various disease states and demographic factors, were examined in three age cohorts of men and women (ages 65-79, 80-89, 90-99).

RESULTS

In the nursing home sample, the cognitive performance of very old men (> or = 90 years) was better than that of younger men (aged 80-89 years, P < 0.05) and very old women (age > or = 90 years, P = 0.001). Among 80-89-year-olds with poor cognitive performance, the 6-month mortality rate was higher in men than in women (38% vs 19%, P = 0.001). However, the mortality rates of men and women with good cognitive performance were not statistically different in any age group. Proportional-hazards regression analysis demonstrated that poor cognitive performance remained a powerful predictor of death among men aged 80-89 years with a relative risk of 2.7 (95% Cl, 1.19-3.17; P = 0.0006) after controlling for covariates. Results from the community sample lent support to our findings: within each age group, mortality rates for men and women with intact cognitive performance were not statistically different. However, in the two older age groups, the mortality rates of subjects with impaired cognitive performance were significantly greater for men than for women (P < 0.01 for both age groups).

CONCLUSIONS

Decreased cognitive performance is significantly associated with mortality among elderly men. Survival by men who have relatively intact cognitive function results in a population of oldest men, those aged 90-99 years, with cognitive performance scores better than younger men or similarly-aged women. The same selective survival phenomenon was not observed among women. Thus, there may be less cognitive disability among very old men than previously expected.

Acute delirium and functional decline in the hospitalized elderly patient

BACKGROUND

Delirium is often considered a transient cognitive syndrome. Its effect on long-term physical function, however, has not been well defined.

METHODS

In a prospective study of 325 hospitalized community and nursing home elderly, we analyzed the effect of in-hospital delirium on subsequent physical function. ADL performance was assessed prior to admission, and at 3 and 6 months after hospital discharge.

RESULTS

There was a strong univariate (unadjusted) association between incident delirium and functional decline (p < .02). Delirious subjects lost a mean of almost one ADL, as measured 3 months after hospital discharge. Using multivariate linear regression analysis, with adjusted change in function as the dependent variable, delirium persisted as the sole predictor of loss of function (p = .009) at 3 months after discharge. The functional decline persisted at 6 months after hospital discharge.

CONCLUSION

This finding of a nontransient, perhaps permanent consequence of delirium invites reexamination of the definition of delirium from that of an acute, reversible syndrome to one of acute onset with long-term sequelae.

Antidepressants and falls among elderly people in long-term care

All eligible residents of a long-term care facility (488 women and 147 men with a 6-month minimum stay) were prospectively followed for 1 month for the development of falls. Use of psychotropic medications (excluding as needed prescriptions), functional status, and a history of falls were assessed at the start of the study month. Results of analyses using logistic modeling procedures suggest that institutionalized women on antidepressants may have an increased risk of falling, regardless of fall history, functional status, or age. A relationship between antidepressants and falls was not found for men. These results may help target high-risk individuals for future preventive efforts.

The Boston FICSIT study: the effects of resistance training and nutritional supplementation on physical frailty in the oldest old

Research indicates that lower extremity muscle weakness in the elderly is consistently related to impaired mobility and fall risk. Reversible components of the muscle weakness of aging include underuse syndromes and undernutrition, both of which are prevalent in nursing home populations. The Boston FICSIT study is a nursing home-based intervention to improve muscle strength through progressive resistance training of the lower extremities and/or multi-nutrient supplementation in chronically institutionalized subjects aged 70-100. Baseline measurements of falls, medical status, psychological variables, functional status, nutritional intake and status, body composition, muscle mass and morphology, muscle function, and gait and balance are taken. The nursing home residents are then randomly assigned to one of four treatment groups for 10 weeks: (1) high intensity progressive resistance training of the hip and knee extensors 3 days per week; (2) multi-nutrient supplementation with a 360-kcal high carbohydrate, low fat liquid supplement every day; (3) a combination of groups (1) and (2); and (4) a control group. Both non-supplemented groups receive a liquid placebo every day, and both non-exercising groups attend three sessions of "leisure activities" every week in order to control for the attentional aspects of the exercise and nutritional interventions. At the end of the 10-week period, all baseline measurements are re-assessed.

Impact near the hip dominates fracture risk in elderly nursing home residents who fall

Hip fractures among the elderly are a significant and rapidly growing public health problem. The prevailing view is that most hip fractures are the consequence of age-related bone loss or osteoporosis. However, because over 90% of hip fractures are the result of falls, we have undertaken a falls surveillance study to determine if factors related to the mechanics of falling are associated with increased risk of hip fracture. Case subjects with hip fracture and control subjects without hip fracture were sampled from falls recorded at the Hebrew Rehabilitation Center for Aged, a chronic care facility. Fall information was obtained by interview of the subject and witnesses if the fall was witnessed. Data were analyzed by multiple logistic regression. Increased risk of hip fracture from a fall was associated with impacting on the hip or side of the leg and potential energy associated with the fall. Quetelet, or body mass index, was inversely related to fracture risk. The adjusted odds ratio of hip fracture for a fall involving impact on the hip region was 21.7 (95% confidence interval, 8.2-58). The potential energy associated with these falls was an order of magnitude greater than the average energy required to fracture elderly, cadaveric, proximal femurs in earlier in vitro experiments. We conclude, therefore, that a fall from standing height should no longer be considered minimal trauma but rather trauma of sufficient magnitude to pose a high risk of hip fracture if impact occurs on the hip and if energy-absorbing processes are inadequate.(ABSTRACT TRUNCATED AT 250 WORDS)

Hemodynamic and autonomic nervous system responses to mixed meal ingestion in healthy young and old subjects and dysautonomic patients with postprandial hypotension

BACKGROUND

Although postprandial hypotension is a common cause of falls and syncope in elderly persons and in patients with autonomic insufficiency, the pathophysiology of this disorder remains unknown.

METHODS AND RESULTS

We examined the hemodynamic, splanchnic blood pool, plasma norepinephrine (NE), and heart rate (HR) power spectra responses to a standardized 400-kcal mixed meal in 11 healthy young (age, 26 +/- 5 years) and nine healthy elderly (age, 80 +/- 5 years) subjects and 10 dysautonomic patients with symptomatic postprandial hypotension (age, 65 +/- 16 years). Cardiac and splanchnic blood pools were determined noninvasively by radionuclide scans, and forearm vascular resistance was determined using venous occlusion plethysmography. In healthy young and old subjects, splanchnic blood volume increased, but supine blood pressure remained unchanged after the meal. In both groups, HR increased and systemic vascular resistance remained stable. Forearm vascular resistance and cardiac index increased after the meal in elderly subjects, whereas these responses were highly variable and of smaller magnitude in the young. Young subjects demonstrated postprandial increases in low-frequency HR spectral power, representing cardiac sympatho-excitation, but plasma NE remained unchanged. In elderly subjects, plasma NE increased after the meal but without changes in the HR power spectrum. Patients with dysautonomia had a large postprandial decline in blood pressure associated with no change in forearm vascular resistance, a fall in systemic vascular resistance, and reduction in left ventricular end diastolic volume index. HR increased in these patients but without changes in plasma NE or the HR power spectrum.

CONCLUSIONS

1) In healthy elderly subjects, the maintenance of blood pressure homeostasis after food ingestion is associated with an increase in HR, forearm vascular resistance, cardiac index, and plasma NE. In both young and old, systemic vascular resistance is maintained. 2) Dysautonomic patients with postprandial hypotension fail to maintain systemic vascular resistance after a meal. This impairment in vascular response to meal ingestion may underlie the development of postprandial hypotension. 3) The measurement of mean HR or plasma NE does not adequately characterize autonomic cardiac control. Power spectral analysis suggests an impairment in the postprandial autonomic modulation of HR in healthy elderly and dysautonomic subjects, possibly predisposing to hypotension when vascular compensation is inadequate.

Transcranial Doppler assessment of the cerebral circulation during postprandial hypotension in the elderly

OBJECTIVE

The aim of the present study was to evaluate whether alterations in postprandial hemodynamics in the elderly were associated with changes in cerebral perfusion assessed by transcranial Doppler ultrasonography.

DESIGN

Time series, ie, post-intervention compared to pre-intervention with no-intervention controls.

PARTICIPANTS

Ten elderly institutionalized subjects (4 women, 6 men, mean age 84.9 years). Three subjects had a history of syncope.

SETTING

A 725-bed academic long-term care facility.

INTERVENTION

A 400-kcal mixed meal.

MEASUREMENTS

Heart rate, blood pressure, and blood flow velocity in the middle cerebral artery by transcranial Doppler recording, before the test meal and at 5-minute intervals for 60 minutes afterwards.

RESULTS

Systolic, diastolic, and mean arterial blood pressure declined significantly from baseline between 30 and 55 minutes after the meal (P < 0.05, ANOVA); however, maximum and mean blood flow velocity did not change. The pulsatility index (end diastolic to peak systolic amplitude divided by mean velocity) increased significantly (P < 0.05, ANOVA) between 30 and 55 minutes after the meal, suggesting increased arteriolar resistance. There were no significant changes in blood pressure, blood flow velocity, and pulsatility index during a control study conducted with four subjects under identical conditions but without a meal.

CONCLUSIONS

The results of this study suggest a small, unexpected increase in resistance of the intracranial circulation following a meal in elderly people with postprandial hypotension. Although the clinical significance of this finding is not known, the occurrence of postprandial arteriolar vasoconstriction may lead to cerebral ischemia during periods of marked blood pressure decline.

Loss of 'complexity' and aging. Potential applications of fractals and chaos theory to senescence

The concept of "complexity," derived from the field of nonlinear dynamics, can be adapted to measure the output of physiologic processes that generate highly variable fluctuations resembling "chaos." We review data suggesting that physiologic aging is associated with a generalized loss of such complexity in the dynamics of healthy organ system function and hypothesize that such loss of complexity leads to an impaired ability to adapt to physiologic stress. This hypothesis is supported by observations showing an age-related loss of complex variability in multiple physiologic processes including cardiovascular control, pulsatile hormone release, and electroencephalographic potentials. If further research supports this hypothesis, measures of complexity based on chaos theory and the related geometric concept of fractals may provide new ways to monitor senescence and test the efficacy of specific interventions to modify the age-related decline in adaptive capacity.

Leg extensor power and functional performance in very old men and women

1. Residents of a chronic care hospital (13 men of mean age 88.5 +/- 6 SD years and 13 women of mean age 86.5 +/- 6 SD years) who had multiple pathologies were assessed for leg extensor capability in several ways. 2. A custom-built rig was used to assess leg extensor power, that is, maximal power output over less than 1 s in a single extension of one leg. Performance measures were obtained by timing chair rises (from a standard chair 0.43 m high), stair climbing (four risers, total height 0.635 m) and a walk (6.1 m). For each measurement the best of several trials were recorded as definitive. 3. Leg extensor power was significantly correlated with all performance measures, but the performance measures were not related to each other except for chair rising and walking speed. 4. Women had significantly less extensor power than men, but their power explained more of the variance in performance, e.g. power accounted for 86% of the variance in walking speed. 5. There was no relation within the group between age and any of the variables measured. 6. Measurement of leg extensor power in frail elderly people may prove useful in focusing effective rehabilitation programmes.

Risk factors for delirium in hospitalized elderly

OBJECTIVE

To determine risk factors for delirium in elderly hospitalized patients.

DESIGN

Cohort analytic study. Using a reliable and valid instrument for detection of delirium, we prospectively followed up a cohort of elderly patients admitted to an acute care hospital. Using standardized criteria, we collected risk factor data from patient medical records.

SETTING

General medical and surgical wards of a tertiary-care hospital.

PATIENTS

Patients (n = 325) were 65 years of age or older, from either a geographically defined community or a long-term-care institution. We studied those patients (n = 291) not delirious on first evaluation. Fifty-seven patients or their families refused participation.

MAIN OUTCOME MEASURES

Incidence of delirium and risk factors calculated as adjusted odds ratios (ORs).

MAIN RESULTS

Delirium developed in 91 patients. By stepwise logistic regression, the independent risk factors for in-hospital delirium included prior cognitive impairment (OR, 8.97; 95% confidence interval [CI], 3.99 to 20.14), age over 80 years (OR, 5.22; 95% CI, 2.60 to 10.46), fracture on admission (OR, 6.57; 95% CI, 2.23 to 19.33), symptomatic infection (OR, 2.96; 95% CI, 1.42 to 6.15), and male sex (OR, 2.40; 95% CI, 1.19 to 4.84). Among medication groups, only neuroleptic use (OR, 4.48; 95% CI, 1.82 to 10.45) and narcotic use (OR, 2.54; 95% CI, 1.24 to 5.18) were independently associated with delirium. Anticholinergic use was not associated with delirium.

CONCLUSIONS

Delirium in hospitalized patients is most closely associated with factors already present on admission such as prior cognitive impairment, advanced age, and fracture. In the hospital, use of neuroleptics and narcotics and the presence of infection are less strongly associated with this syndrome.

Delirium. The occurrence and persistence of symptoms among elderly hospitalized patients

We evaluated the occurrence and persistence of delirium in 325 elderly patients admitted to a teaching hospital from either a defined community or a long-term care facility. Of the study participants, 34 (10.5%) had Diagnostic and Statistical Manual of Mental Disorders, Third Edition--defined delirium at initial evaluation; of the remaining patients, 91 (31.3%) developed new-onset delirium. An additional 110 patients also experienced individual symptoms of delirium without meeting full criteria. Preexisting cognitive impairment and advanced age were associated with increased risk of incident delirium in the community sample but not the institutional one. Delirium was not associated with an increased risk of mortality, but it was associated with a prolonged hospital stay and an increased risk of institutional placement among community-dwelling elderly. Only five patients (4%) experienced resolution of all new symptoms of delirium before hospital discharge, and only 20.8% and 17.7%, respectively, had resolution of all new symptoms by 3 and 6 months after hospital discharge. These data suggest that delirium is a common disorder that may be substantially less transient than currently believed and that incomplete manifestations of the syndrome may be frequent.

Spectral analysis of heart rate dynamics in elderly persons with postprandial hypotension

Prior studies suggest that postprandial hypotension in elderly persons may be due to defective sympathetic nervous system activation. We examined autonomic control of heart rate (HR) after a meal using spectral analysis of HR data in 13 old (89 +/- 6 years) and 7 young (24 +/- 4 years) subjects. Total spectral power, an index of overall HR variability, was calculated for the frequency band between 0.01 and 0.40 Hz. Relatively low-frequency power, associated with sympathetic nervous system and baroreflex activation, was calculated for the 0.01 to 0.15 Hz band. High-frequency power, representing parasympathetic influences on HR, was calculated for the 0.15 to 0.40 Hz band. Mean arterial blood pressure declined 27 +/- 8 mm Hg by 60 minutes after the meal in elderly subjects, compared with 9 +/- 8 mm Hg in young subjects (p less than or equal to 0.0001, young vs old). The mean change in low-frequency HR power from 30 to 50 minutes after the meal was +19.4 +/- 25.3 U in young subjects versus -0.1 +/- 1.5 U in old subjects (p less than or equal to 0.02). Mean change in total power was also greater in young (19.0 +/- 26.6 U) subjects compared with old subjects (0.0 +/- 1.6 U, p greater than or equal to 0.02). Mean ratio of low:high-frequency power increased 3.1 +/- 3.3 U in young subjects vs 0.5 +/- 2.7 U in old subjects (p less than or equal to 0.01). The increase in low-frequency HR power and in the low:high frequency band ratio in young subjects is consistent with sympathetic activation in the postprandial period.(ABSTRACT TRUNCATED AT 250 WORDS)

Postural change in blood pressure associated with age and systolic blood pressure. The National Health and Nutrition Examination Survey II

The prevalence of postural change in blood pressure and its association with age and systolic blood pressure were examined in data from 8,574 White nondiabetic persons aged 25-74 who participated in the second National Health and Nutrition Examination Survey (1976-1980). Postural change in blood pressure was defined as a drop of 20 mm Hg or more on change from supine to seated position. In subjects on no antihypertensive medications (n = 7,316), the prevalence of postural change in blood pressure increased with older age and with higher blood pressure levels, regardless of age. However, systolic blood pressure levels also increased with age. In logistic regression models, level of supine systolic blood pressure was strongly related to postural change in blood pressure (Relative odds (RO) = 1.59, 95% confidence interval (CI) = 1.49, 1.70 for a 10 mm Hg increase in systolic blood pressure) whereas age was not related to postural change in blood pressure (RO for age = 1.07, Cl = .89, 1.19 for a 10-year increase in age). Results were similar for those medicated for hypertension. All results were unchanged by addition of health status indicators, including reports of hospitalization and number of medical conditions, to the model. These data suggest that the age-related increase in the prevalence of postural hypotension previously reported may be partially explained by age-associated increases in systolic blood pressure.

Causes and correlates of recurrent falls in ambulatory frail elderly

To determine causes and clinical correlates of recurrent falls in ambulatory frail elderly people, we evaluated 70 recurrent fallers and 56 nonfallers (mean age = 87 years) from two long-term care facilities. Evaluations included a detailed history, physical examination, performance-oriented mobility assessment, and laboratory studies. Primary causes including stroke, parkinsonism, blindness, drug-related hypotension, and arthritis were established for the most recent fall in 51 (73%) fallers. Eighteen fallers (26%) had multiple conditions that could not be prioritized for their contribution to the fall. Fallers were more often women, were functionally more impaired, and were taking more medications than nonfallers. Specific diseases did not distinguish fallers from nonfallers. Fallers of both sexes took more steps to turn 360 degrees, could not stand up from a chair without pushing off, had a higher prevalence of antidepressant use, and had impaired position sensation. These easily obtained clinical variables characterized nearly three-quarters of ambulatory elderly nursing home residents with a history of recurrent falls.

Aging and the complexity of cardiovascular dynamics

Biomedical signals often vary in a complex and irregular manner. Analysis of variability in such signals generally does not address directly their complexity, and so may miss potentially useful information. We analyze the complexity of heart rate and beat-to-beat blood pressure using two methods motivated by nonlinear dynamics (chaos theory). A comparison of a group of healthy elderly subjects with healthy young adults indicates that the complexity of cardiovascular dynamics is reduced with aging. This suggests that complexity of variability may be a useful physiological marker.

Forearm blood flow response to posture change in the very old: non-invasive measurement by venous occlusion plethysmography

Little is known about the peripheral vascular response to posture change in very elderly people who are vulnerable to the development of orthostatic hypotension. This is due, in part, to the risks of currently utilized invasive vascular monitoring techniques in the elderly population. We studied the forearm vascular response to active standing in 18 healthy young, 10 healthy old, and 19 impaired elderly subjects, using the non-invasive technique of venous occlusion plethysmography. In six subjects this technique was compared to duplex doppler ultrasonography for the measurement of postural changes in forearm blood flow. Forearm blood flow changes determined by venous occlusion plethysmography were 11% larger than doppler measurements, but the two methods strongly correlated (r = 0.90, P less than .001). Mean forearm vascular resistance increased to a significantly greater extent at 1 minute of standing in young subjects than in both groups of old, although the response was quite variable in all groups. Two healthy elderly (20%) and eight impaired elderly (40%) subjects had unexpected forearm vasodilatation at 1 minute of standing. By 3 minutes, forearm vascular resistance had increased by similar amounts in all three groups of subjects. Five impaired elderly and no healthy young or healthy old subjects had orthostatic hypotension, defined as greater than or equal to 10 mm Hg decline in mean arterial blood pressure at 1 or 3 minutes of standing. Forearm vascular resistance changes did not correlate with blood pressure response to standing. Thus, forearm vascular response to 1 minute of active standing is attenuated in many elderly subjects. This abnormality may impair adaptation to orthostatic stress in advanced age.

The epidemiology and natural history of pressure ulcers in elderly nursing home residents

We analyzed prospective data from 19,889 elderly residents of 51 nursing homes from 1984 to 1985 to determine the prevalence, incidence, and natural history of pressure ulcers. Among all residents admitted to nursing homes, 11.3% possessed a stage II through stage IV pressure ulcer. For those residents admitted to the nursing home without pressure ulcers during the study period, the 1-year incidence was 13.2%. This increased to 21.6% by 2 years of nursing home stay. People already residing in a nursing home at the start of the study had a 1-year incidence of 9.5%, which increased to 20.4% by 2 years. Pressure ulcers were associated with an increased rate of mortality, but not hospitalization. Longitudinal follow-up of residents with pressure ulcers demonstrated that a majority of their lesions were healed by 1 year. Most of the improvement occurred early in a person's nursing home stay. Although nursing home residents with pressure ulcers have a higher mortality, with good medical care pressure ulcers can be expected to heal.

Nonsteroidal anti-inflammatory drug-associated azotemia in the very old

We conducted a prospective study in 114 elderly patients to determine the renal effects of short-term therapy with nonsteroidal anti-inflammatory drugs (NSAIDs) in the very old. Study subjects were patients in a long-term care facility (mean age, 87 years) newly begun on a regimen of NSAID therapy. For the study group as a whole, the serum urea nitrogen level rose 1.7 mmol/L 5 to 7 days after initiation of therapy, with no significant changes in serum creatinine or potassium levels. In a comparison group of 45 patients not receiving NSAID therapy, no significant change in the serum urea nitrogen level was noted during a similar period. A subgroup of 15 patients (13%) experienced a greater than 50% increase in the serum urea nitrogen level during NSAID therapy, with a mean increase of 89% (8.6 mmol/L). A return to the baseline level occurred within 14 days after discontinuation of NSAID therapy. Two factors were significantly predictors of a greater than 50% increase in the serum urea nitrogen level: concurrent loop diuretic therapy (odds ratio, 2.2) and high NSAID dose (odds ratio, 2.0). These findings suggest that reversible azotemia develops in a sizable proportion of the very old who are treated with short-term NSAID therapy.

Hypotensive responses to common daily activities in institutionalized elderly. A potential risk for recurrent falls

Transient hypotension may be one of many factors contributing to the high prevalence of falls among elderly people. To determine the frequency and magnitude of hypotensive responses to common daily activities, and their potential relationship to falls in the elderly, we examined blood pressure (BP) and heart rate during a standardized series of activities in 38 institutionalized recurrent fallers (age, 87 +/- 6 years), 20 institutionalized nonfallers (age, 85 +/- 5 years), and 10 healthy young control subjects (age, 24 +/- 3 years). The coefficient of variation for systolic BP during all activities was higher in elderly subjects (fallers, 14% +/- 5%; nonfallers, 12% +/- 3%) than in young control subjects (8% +/- 1%). In contrast, the coefficient of variation for heart rate during all activities was higher in young subjects than in the elderly subjects. Elderly subjects had marked BP reduction following meals and nitroglycerin, which was significantly greater in fallers than in nonfallers, independent of the cause of the fall. Thus, institutionalized elderly have marked BP variability and hypotensive responses to meals and nitroglycerin. A decline in BP during common preload-reducing stresses may predispose some elderly people to falls.

Spectral characteristics of heart rate variability before and during postural tilt. Relations to aging and risk of syncope

Fourier analysis of heart rate (HR) may be used to characterize overall HR variability as well as low- and high-frequency components attributable to sympathetic and vagal influences, respectively. We analyzed HR spectral characteristics of 12 healthy young (18-35 years) and 10 healthy old (71-94 years) subjects before and during 60 degrees head-up tilt. Total spectral power in the 0.01-0.40-Hz frequency range and low-frequency (0.06-0.10 Hz) and high-frequency (0.15-0.40 Hz) components of the HR power spectrum were significantly lower in old than in young subjects in supine and upright positions. To characterize and compare overall HR variability in young and old subjects, we computed the regression lines relating the log amplitude to the log frequency of the supine HR spectra (l/fx plots). The regression lines for old subjects were lower and steeper (mean slope, -0.78 [5%, 95% confidence limits (CL), -0.73, -0.83]) than in young (mean slope, -0.67 [CL, -0.62, -0.72]), indicating not only reduced overall spectral amplitude but also relatively greater attenuation of high-frequency HR components in the old subjects. This finding illustrates a novel way to quantify the loss of autonomic influences on HR regulation as a function of age. During postural tilt, HR variability was unchanged in the old subjects. For the entire group of young subjects, total HR variability increased during tilt. Six young subjects developed vasovagal syncope during tilt, enabling us to examine differences in the HR spectra of these subjects while they were asymptomatic before syncope.(ABSTRACT TRUNCATED AT 250 WORDS)

Reduced supine cardiac volumes and diastolic filling rates in elderly patients with chronic medical conditions. Implications for postural blood pressure homeostasis

Very elderly individuals with multiple chronic illnesses are at high risk of orthostatic hypotension, falls, and associated morbidity and mortality. Alterations in cardiac volumes and filling characteristics may contribute in part to an increased prevalence of orthostatic hypotension and falls in these people. In this study cardiac function was evaluated with gated radionuclide ventriculography in eight healthy young subjects (19-38 years) and 25 elderly persons with stable chronic illnesses (73-96 years), 14 of whom had a history of recurrent falls. Blood pressure was measured supine during the radionuclide ventriculography, then after one minute of standing. Supine stroke volume index, end diastolic volume index, cardiac index, and peak filling rates were significantly lower in elderly subjects compared to young, and ejection fraction and end systolic volume index (measures of systolic function) were the same in young and old. Compared to the young, elderly subjects had a reduction in ventricular filling during the first third of diastole, but an augmentation in the last third, during atrial contraction. Within the group of elderly subjects, the directional change in systolic blood pressure during orthostasis was significantly correlated with basal supine systolic blood pressure (R = 0.81, P less than .0001) and supine cardiac index (R = 0.66, P = .002). Thus, very old people representative of those seen in clinical practice have reduced cardiac volumes and impaired early diastolic filling, a result possibly related to elevations in systolic blood pressure. These changes in cardiac structure and function may contribute, in part, to orthostatic hypotension in advanced age.

Reduced susceptibility to syncope during postural tilt in old age. Is beta-blockade protective?

Clinical studies of syncope suggest a decreased prevalence of vasovagal syncope in old age. To examine this possibility and its pathophysiologic implications, we report the results of two studies. The first evaluated responses to head-up tilt in young and old subjects. Presyncopal vasovagal symptoms occurred in 4 of 9 young subjects and only 1 of 22 old subjects. The second study asked whether decreased beta-adrenergic responsiveness protected the old during tilt via unopposed alpha-adrenergic-mediated vasoconstriction. Blood pressure, heart rate, and forearm vascular resistance responses to tilt in 11 healthy young subjects randomized to receive intravenous propranolol hydrochloride or saline were compared with those of 10 healthy elderly. Propranolol attenuated heart rate and forearm vascular resistance responses. Vasovagal symptoms occurred in 4 young and no old subjects; 2 were symptomatic during propranolol administration. Thus, presyncopal vasovagal symptoms are less common during tilt in old age. Propranolol did not prevent the vasovagal reaction or enhance forearm vasoconstriction. Propranolol's attenuation of vasoconstriction may be due to decreased activation of cardiopulmonary baroreceptors during beta-blockade.

Altered blood pressure homeostasis in advanced age: clinical and research implications

Aging and associated increases in systolic blood pressure may cumulatively produce alterations in many blood pressure regulatory mechanisms that impair an older person's ability to adapt to hypotensive stress. Both age and hypertension impair baroreflex sensitivity and decrease compliance of the heart and vasculature. These changes increase the risk of hypotensive responses to activities that reduce cardiac preload and to conditions that produce tachycardia or eliminate atrial contraction. Common clinical examples include orthostatic and postprandial hypotension, nitrate intolerance, and atrial fibrillation. The increased intra- and interindividual variability in blood pressure, resulting from impaired homeostatic capacity, challenges established diagnostic criteria for hyper- and hypotensive syndromes and necessitates new multivariate approaches to research data analysis. Gerontologic investigations utilizing blood pressure measurements should examine individual as well as group responses, and stratify subjects by level of basal blood pressure to isolate the effect of aging from the effects of blood pressure elevation.

Impaired heart rate responses to cough and deep breathing in elderly patients with unexplained syncope

To test the hypothesis that elderly patients with unexplained syncope have impaired autonomic control of heart rate, chronotropic responses to deep breathing and cough were studied in 12 elderly patients (85 +/- 4 years), 14 elderly control subjects (82 +/- 7 years) and 10 young subjects (26 +/- 5 years). There was no difference in resting RR interval between elderly patients with syncope and control subjects. However, the ratio of the maximum RR/minimum RR (an index of heart rate variability) during deep breathing was significantly lower in patients than in control subjects (p less than 0.005). In the minute following cough, there was no difference in initial reflex tachycardia, but subsequent rebound bradycardia was blunted in the elderly patients with syncope. The predominant impairment in elderly patients with unexplained syncope was the bradycardia component of the responses to deep breathing and cough, suggesting that these patients may have impaired parasympathetic modulation of heart rate. Although not likely to be the cause of syncope in these patients, these findings may reflect an underlying autonomic defect.

Biomedical research in the nursing home: methodological issues and subject recruitment results

Although nursing homes are potentially important sites for geriatric research, previous reports have identified impediments to subject recruitment in this setting. We are conducting five simultaneous clinical studies in a 725-bed nursing home. Utilizing a systematic subject recruitment methodology designed to minimize patient and staff burden, we have recruited over 100 subjects. The average recruitment rate over two years from nursing home residents meeting study entry criteria was 43%. The rate was highest (81%) for a study of urinary incontinence offering direct benefit to participants, and lowest (28% and 14% respectively) for physiologic studies of vasopressin regulation and dermal vitamin D production, offering no direct benefit. Studies of syncope and dementia which benefitted groups affected by these problems but not controls, had intermediate recruitment rates (46 and 44%, respectively, P less than .002 compared to incontinence). Thus, clinically relevant projects, sensitive to the needs of the patient and institution, can recruit subjects from the nursing home.

The prevalence and prognosis of minimally elevated creatine kinase-myocardial band activity in elderly patients with syncope

Syncope in elderly patients is often the initial manifestation of myocardial infarction (MI). Small elevations in creatine kinase-myocardial band (CK-MB) activity following syncope may represent MI, transient myocardial hypoperfusion, or insignificant background activity. To determine the prevalence and prognostic significance of minimal CK-MB elevations in elderly patients with syncope, serial serum CK-MB activities and subsequent survival experiences were determined for elderly syncope patients with and without MI, and for age-matched nonsyncopal controls. While all syncope patients with MI by specific clinical criteria had one or more abnormal CK-MB levels (greater than 5 U/L) and died within 31 months, 10% of syncope patients without MI and 10% of controls had abnormal CK-MB with no impact on mortality. Using standard clinical laboratory techniques, minimal elevation in CK-MB was found in 10% of elderly subjects with and without syncope and probably had no prognostic significance.