Cerebrovascular hemodynamics, gait, and falls in an elderly population: MOBILIZE Boston Study

OBJECTIVE

To determine whether alterations in cerebral blood flow regulation are associated with slow gait speed and falls in community-dwelling elderly individuals.

METHODS

The study sample consisted of 419 individuals from the MOBILIZE Boston Study (MBS) who had transcranial Doppler ultrasound measures of cerebral blood flow velocity. The MBS is a prospective cohort study of a unique set of risk factors for falls in seniors in the Boston area. We measured beat-to-beat blood flow velocity in the middle cerebral artery in response to 1) changes in end-tidal CO(2) (cerebral vasoreactivity) and 2) blood pressure changes during a sit-to-stand protocol (cerebral autoregulation). Gait speed was measured during a 4-meter walk. Falls were tracked by monthly calendars, and demographic and clinical characteristics were assessed at baseline.

RESULTS

A multivariate linear regression analysis showed that cerebral vasoreactivity was cross-sectionally related to gait speed (p = 0.039). Individuals in the lowest quintile of vasoreactivity had lower gait speeds as compared to those in the highest quintile (p = 0.047). In a negative binomial regression analysis adjusted for relevant covariates, the relationship between cerebral vasoreactivity and fall rate did not reach significance. However, when comparing individuals in the lowest to highest quintile of cerebral vasoreactivity, those in the lowest quintile had a higher fall rate (p = 0.029).

CONCLUSIONS

Impaired cerebral blood flow regulation, as measured by cerebral vasoreactivity to CO(2), is associated with slow gait speed and may lead to the development of falls in elderly people.

The yield of head CT in syncope: a pilot study

Although head CT is often routinely performed in emergency department (ED) patients with syncope, few studies have assessed its value.

OBJECTIVES

To determine the yield of routine head CT in ED patients with syncope and analyse the factors associated with a positive CT.

METHODS

Prospective, observational, cohort study of consecutive patients presenting with syncope to an urban tertiary-care ED (48,000 annual visits).

INCLUSION CRITERIA

age >or=18 and loss of consciousness (LOC). Exclusion criteria included persistent altered mental status, drug-related or post-trauma LOC, seizure or hypoglycaemia. Primary outcome was abnormal head CT including subarachnoid, subdural or parenchymal haemorrhage, infarction, signs of acute stroke and newly diagnosed brain mass.

RESULTS

Of 293 eligible patients, 113 (39%) underwent head CT and comprise the study cohort. Ninety-five patients (84%) were admitted to the hospital. Five patients, 5% (95% CI=0.8%-8%), had an abnormal head CT: 2 subarachnoid haemorrhage, 2 cerebral haemorrhage and 1 stroke. Post hoc examination of patients with an abnormal head CT revealed focal neurologic findings in 2 and a new headache in 1. The remaining 2 patients had no new neurologic findings but physical findings of trauma (head lacerations with periorbital ecchymoses suggestive of orbital fractures). All patients with positive findings on CT were >65 years of age. Of the 108 remaining patients who had head CT, 45 (32%-51%) had signs or symptoms of neurologic disease including headache, trauma above the clavicles or took coumadin. Limiting head CT to this population would potentially reduce scans by 56% (47%-65%). If age >60 were an additional criteria, scans would be reduced by 24% (16%-32%). Of the patients who did not have head CT, none were found to have new neurologic disease during hospitalisation or 30-day follow-up.

CONCLUSIONS

Our data suggest that the derivation of a prospectively derived decision rule has the potential to decrease the routine use of head CT in patients presenting to the ED with syncope.

Noise and poise: Enhancement of postural complexity in the elderly with a stochastic-resonance-based therapy

Pathologic states are associated with a loss of dynamical complexity. Therefore, therapeutic interventions that increase physiologic complexity may enhance health status. Using multiscale entropy analysis, we show that the postural sway dynamics of healthy young and healthy elderly subjects are more complex than that of elderly subjects with a history of falls. Application of subsensory noise to the feet has been demonstrated to improve postural stability in the elderly. We next show that this therapy significantly increases the multiscale complexity of sway fluctuations in healthy elderly subjects. Quantification of changes in dynamical complexity of biologic variability may be the basis of a new approach to assessing risk and to predicting the efficacy of clinical interventions, including noise-based therapies.

Predicting cerebral blood flow response to orthostatic stress from resting dynamics: effects of healthy aging

The transfer function relating arterial pressure (AP) to cerebral blood flow velocity (CBFV) during resting conditions has been used to predict the CBFV response to hypotension. We hypothesized that this approach could predict the CBFV response to posture change in elderly individuals if impaired autoregulation allowed changes in AP to be passively transferred to CBFV. AP (Finapres) and CBFV (middle cerebral artery transcranial Doppler) were measured in 10 healthy young (age 24 +/- 1 yr) and 10 healthy elderly (age 72 +/- 3 yr) subjects during 5 min of quiet sitting and 1 min of active standing while breathing was paced at 0.25 Hz. Transfer functions between AP and CBFV changes during sitting were estimated from each full waveform in both low-frequency (LF; 0.05-0.2 Hz) and heartbeat-frequency (HBF; 0.7-1.4 Hz) ranges. The impulse-response function was used to compute changes in CBFV during posture change. The LF transfer function did not predict orthostatic changes in CBFV in either group, suggesting normal cerebral autoregulation. In the HBF range, the prediction was high in elderly (R = 0.65 +/- 0.23) but not young subjects (R = 0.19 +/- 0.35; P < 0.003, young vs. elderly). Thus rapidly acting regulatory mechanisms that reduce the transmission of beat-to-beat changes in AP to CBFV may be engaged during posture change in young but not elderly subjects.

Estrogen replacement therapy improves baroreflex regulation of vascular sympathetic outflow in postmenopausal women

BACKGROUND

Menopausal estrogen loss has been associated with increased cardiovascular disease in postmenopausal women. However, the link between estrogen and cardiovascular disease remains unclear. Some data suggest estrogen mediates its effect through changes in arterial pressure and its regulation. However, the data available in older women are equivocal regarding estrogen's ability to reduce resting arterial pressure or to improve its regulation.

METHODS AND RESULTS

We studied 11 healthy, postmenopausal women before and after 6 months of estrogen administration. Arterial pressure was measured by brachial auscultation and finger photoplethysmography. Vascular sympathetic nerve activity was measured in the peroneal nerve by microneurography, and the slope of the relations between changes in heart period, sympathetic activity, and arterial pressure caused by bolus infusions of nitroprusside and phenylephrine were used as an index of baroreflex gain. Estrogen therapy did not change systolic pressure (128+/-2 versus 123+/-2 mm Hg) or cardiac-vagal baroreflex gain (6.6+/-0.9 versus 6.7+/-0.7 ms/mm Hg). However, vascular sympathetic baroreflex gain was increased (-4.6+/-0.6 versus -7.4+/-1.0 arbitrary integrated units/mm Hg; P=0.02).

CONCLUSION

These findings suggest long-term estrogen replacement therapy has effects on cardiovascular regulation that may not be reflected in resting arterial pressures.

Intra-individual postural blood pressure variability and stroke in elderly nursing home residents

Orthostatic hypotension (OH) is a potential risk factor for adverse cardiovascular events, but OH is highly variable and may not be detected on a single occasion. To assess the relation between intra-individual variability of systolic orthostatic blood pressure change (DeltaSBP) and cardiovascular outcomes, an algorithm was developed to identify DeltaSBP instability using repeated supine and standing BP measurements. A cohort of 673 nursing home residents underwent baseline postural BP measurements (supine to 1 minute of standing, four times in a single day) and were followed for up to 2 years. Two groups (stable vs. unstable) were identified based on an analysis of DeltaSBP variance components. Differences in outcomes were compared via Cox survival analysis. At baseline 12.6% were unstable, defined as a one standard deviation difference of at least 20.2 mmHg between DeltaSBP readings. Unstable subjects were more likely to have OH on at least one measurement (systolic BP drop of 20 mmHg or more; 85% vs. 36%, respectively) and to be on psychotropic medication at baseline (47% vs 35%) (P-values <0.001). Other characteristics (including previous stroke) did not differ. During a mean follow-up of 10.3 months, stroke incidence was higher in unstable subjects (13.1% vs. 4.9%; P = 0.012), but ischemic heart disease and mortality rates were not significantly different (respectively, 13.5% vs. 7.4%, P = 0.115; 14.8% vs. 10.7%, P = 0.178). Survival analyses (adjusted for age, sex, psychotropic medications, body mass index, ischemic heart disease, and supine systolic pressure) confirmed a higher risk of stroke in unstable subjects (relative risk = 3.7, 95% CI: 1.6-8.4). Highly variable orthostatic BP measures may reflect impaired BP regulatory mechanisms in elders with occult cerebrovascular disease, or may directly affect cerebral blood flow. Orthostatic BP variability may be a better indicator of future stroke than a single supine or orthostatic change measure.

Reduced hip extension during walking: healthy elderly and fallers versus young adults

OBJECTIVES

To test the hypothesis that reduced hip extension range during walking, representing a limiting impairment of hip tightness, is a consistent dynamic finding that (1) occurs with increased age and (2) is exaggerated in elderly people who fall.

DESIGN

Using a 3-dimensional optoelectronic motion analysis system, we compared full sagittal plane kinematic (lower extremity joint motion, pelvic motion) data during walking between elderly and young adults and between elderly fallers and nonfallers. Comparisons were also performed between comfortable and fast walking speeds within each elderly group.

SETTING

A gait laboratory.

PARTICIPANTS

Twenty-three healthy elderly subjects, 16 elderly fallers (otherwise healthy elderly subjects with a history of recurrent falls), and 30 healthy young adult subjects.

MAIN OUTCOME MEASURES

All major peak joint angle and pelvic position values.

RESULTS

Peak hip extension was the only leg joint parameter measured during walking that was both significantly lower in elderly nonfallers and fallers than in young adult subjects and was even lower in elderly fallers compared with nonfallers (all p <.05). Peak hip extension +/- standard deviation during comfortable walking speed averaged 20.4 degrees +/- 4.0 degrees for young adults, 14.3 degrees +/- 4.4 degrees for elderly nonfallers, and 11.1 degrees +/- 4.8 degrees for elderly fallers. Peak hip extension did not significantly improve when elderly subjects walked fast.

CONCLUSION

An isolated and consistent reduction in hip extension during walking in the elderly, which is exaggerated in fallers, implies the presence of functionally significant hip tightness, which may limit walking performance. Overcoming hip tightness with specific stretching exercises is worthy of investigation as a simple intervention to improve walking performance and to prevent falls in the elderly.

Autonomic and neurohumoral control of postprandial blood pressure in healthy aging

BACKGROUND

Postprandial hypotension (PPH) is a common and morbid problem in elderly people that is associated with an impaired vascular response to meal digestion. Healthy aging in the absence of blood pressure elevation is associated with autonomic and neurohumoral changes that may influence the vascular response to meal ingestion. However, it is not known whether these age-related changes are associated with the development of PPH.

METHODS

We measured hemodynamic (blood pressure, heart rate, and forearm vascular resistance), autonomic (power spectral analysis of heart rate and blood pressure variability), and neurohumoral (plasma norepinephrine, renin, aldosterone, and endothelin) responses to a mixed 425 kilocalorie (kcal) meal in 89 rigorously screened healthy subjects aged 20-39, 40-59, and 60-83 years.

RESULTS

After the meal, supine mean arterial blood pressure fell significantly only in the middle-aged group by 5.4 +/- 7.9 mm Hg at 30 minutes (p = .02). Forearm vascular resistance fell after the meal in all age groups ( p = .0001). Older groups had higher plasma norepinephrine (p = .02), lower heart rate (p = .03), lower cardiovagal activity (p = .0001), and lower sympathetic vasomotor (p = .000) activity, but there was no difference in the response of these variables to a meal.

CONCLUSION

Healthy aging, in the absence of blood pressure elevation, alters the level of autonomic activity without further impairing the ability to maintain blood pressure during meal digestion. Hemodynamic, autonomic, and neurohumoral responses to meal ingestion remain unchanged in very healthy, normotensive elderly adults.

Dynamic regulation of middle cerebral artery blood flow velocity in aging and hypertension

BACKGROUND AND PURPOSE

Although aging and hypertension may predispose hypertensive elderly subjects to cerebral hypoperfusion during orthostatic stress, their effects on the acute cerebral autoregulatory response to hypotension are not known.

METHODS

Continuous middle cerebral artery blood flow velocity (BFV) (transcranial Doppler ultrasound) and mean arterial pressure (MAP, Finapres) were measured in response to (1) acute hypotension during standing, (2) steady-state sitting and standing, and (3) hypercarbia during CO(2) rebreathing in 10 healthy young subjects (age 24+/-1 years), 10 healthy elderly subjects (age 72+/-3 years), and 10 previously treated hypertensive elderly (age 72+/-2 years) subjects. CO(2) reactivity was computed as the slope of cerebrovascular conductance (CVC=BFV/MAP) versus end-expiratory CO(2). Coherence, transfer magnitudes, and phases between low-frequency MAP and BFV signals were computed from their autospectra during 5 minutes of sitting and standing.

RESULTS

MAP fell to a similar extent in all groups by an average of 21 to 26 mm Hg (22% to 26%) within 30 seconds of standing. Mean BFV also fell in all subjects but significantly less in the older subjects (-4.7+/-0. 7 cm/s in hypertensives and -5.3+/-1.2 cm/s in normotensives, P=NS) compared with younger subjects (-10.1+/-1.1 cm/s, P<0.05). CO(2) reactivity was greater in the young subjects (0.19+/-0.01) compared with normotensive (0.14+/-0.01, P<0.05) and hypertensive elderly subjects (0.11+/-0.02, P<0.05) (P=NS between elderly groups). Fewer hypertensive subjects had coherence between MAP and BFV signals; for subjects with coherence, there were no significant group differences in phase or transfer magnitudes in either sitting or standing positions.

CONCLUSIONS

Despite reduced CO(2) reactivity, elderly normotensive and previously treated hypertensive subjects retain cerebral autoregulatory capacity in response to acute orthostatic hypotension.

Large neutral amino acid changes and delirium in febrile elderly medical patients

A hypothesized but unexplored mechanism for delirium in older persons is that changes in plasma large neutral amino acid (LNAA) concentrations alter brain serotonin levels, result in neurotoxicity, or both. Therefore we performed a prospective study of 21 acutely febrile long-term-care residents to study the relationship between LNAA changes and delirium. Plasma LNAA concentrations were evaluated during illness and 1 month later. Delirium was diagnosed by using the Confusion Assessment Method. Other data included age, body mass index, cognitive impairment, comorbidity, gender, maximum temperature, and medication use. Seven subjects (33%) were delirious during febrile illness. Although the phenylalanine (PHE)/LNAA ratio was higher during illness in both delirious and nondelirious groups, a two-sample t test demonstrated that delirium was associated with a higher illness PHE/LNAA ratio (p = .03). The amount of change in PHE/LNAA from illness to recovery was not different between the delirious and nondelirious groups. Tryptophan/LNAA was not associated with delirium during illness or at recovery. These findings identify another potentially fruitful area of investigation for the prevention and treatment of delirium in older persons.

A cross-national survey of tube-feeding decisions in cognitively impaired older persons

OBJECTIVES

Many factors affect the decision to institute long-term tube-feeding in older persons. The objectives of this cross-national survey are to examine the tube-feeding decision-making process for cognitively impaired older persons from the perspective of the substitute decision-makers (SDM) and to contrast this process in US and Canadian healthcare settings.

DESIGN

Survey.

SETTING

Chronic care facilities in Ottawa and nursing homes in Boston.

PARTICIPANTS

Patients more than age 65 who were tube-fed for at least 2 months and who were unable to make their own healthcare decisions at the time of tube placement were identified at both sites. The SDMs of 46 patients in Ottawa and 48 patients in Boston were surveyed.

MEASUREMENTS

The survey asked questions relating to the following categories: health status of the patient, advance directives, communication with the healthcare team, perceived goals of tube-feeding, decision satisfaction, and sociodemographic data.

RESULTS

Tube-fed patients in Boston were more likely to have a diagnosis of dementia than those in Ottawa (60.4% vs 10.9%, P < .001) and were less likely to have had an acute neurological event (35.4% vs 71.7%, P < .001). There was a greater likelihood in Boston than in Ottawa (68.7% vs 6.5%, P < .001) for tube-feeding decisions to be made in a nursing home (vs an acute hospital). In the combined cohort, 19.1% of patients had a living will, and only 47.9% of SDMs felt confident that the patients would want to have a feeding tube. The majority of SDMs at both sites felt they understood the benefits (83.0%), but not the risks (48.9%), of tube-feeding. The most commonly perceived reasons for tube-feeding were to "prolong life" (84.0%) and to "prevent aspiration" (67.0%). Approximately half of all SDMs felt they had received adequate support from the healthcare team. A minority of SDMs (38.3%) at both sites stated that they would want a feeding tube for themselves, and only 40% of SDMs felt the feeding tube had improved the patients' quality of life.

CONCLUSIONS

A greater proportion of patients have feedings tubes inserted because of a degenerative dementia in Boston compared with an acute neurological event in Ottawa. Despite the difference in diagnostic indication for tube-feeding, the substitute decision-making process was seriously limited at both sites by poor implementation of the principle of substituted judgement, a need for broader advance directives, and improved transfer of knowledge between clinicians and decision-makers.

The association between orthostatic hypotension and recurrent falls in nursing home residents

PURPOSE

Orthostatic hypotension is common among the elderly, but its relation to falls is not certain. We determined whether orthostatic hypotension, including its timing and frequency, was associated with falls in elderly nursing home residents.

SUBJECTS AND METHODS

We conducted a prospective study of 844 elderly (60 years of age and older), long-stay residents at 40 facilities that were part of a multistate nursing home chain. All subjects were able to maintain weight-bearing for at least 1 minute. Orthostatic hypotension was defined as a 20 mm Hg or greater decrease in systolic blood pressure from supine to standing, as measured after 1 or 3 minutes of standing on four occasions (before or after breakfast, or before or after lunch). The outcome was any subsequent fall during a mean of 1.2 years of follow-up.

RESULTS

Orthostatic hypotension was present (at least on one measurement) in 50% of the subjects but was not associated with subsequent falls. However, among subjects with a history of previous falls in the past 6 months, those with orthostatic hypotension had an increased risk of recurrent falls [adjusted relative risk (RR) = 2.1; 95% confidence interval (CI), 1.4 to 3.1 ]. The risk of subsequent falls was greatest in previous fallers who had orthostatic hypotension at two or more measurements (RR = 2.6; 95% CI, 1.7 to 4.6). The association between orthostatic hypotension and recurrent falls was independent of measured demographic or clinical risk factors for falls. The timing of orthostatic hypotension (before or after meals) did not affect the risk of falls.

CONCLUSIONS

Orthostatic hypotension is an independent risk factor for recurrent falls among elderly nursing home residents. Although the benefit of treating orthostatic hypotension will require further study, it may be prudent to identify high-risk residents and institute precautionary measures.

Effects of angiotensin-converting enzyme inhibitors and digoxin on health outcomes of very old patients with heart failure. SAGE Study Group. Systematic Assessment of Geriatric drug use via Epidemiology

BACKGROUND

Randomized trials have shown that angiotensin-converting enzyme (ACE) inhibitors reduce mortality and morbidity, and improve symptoms and exercise tolerance in selected patients with congestive heart failure (CHF). There is, however, no evidence on the effectiveness of ACE inhibitors in the typical, very old and frail patients with CHF.

OBJECTIVE

To compare the effects of ACE inhibitors and digoxin on 1-year mortality, morbidity, and physical function among patients aged 85 years.

METHODS

We conducted a retrospective cohort study using the SAGE database, a long-term care database linking patient information with drug utilization data. Among 64637 patients with CHF admitted to all nursing homes in 5 states between 1992 and 1995, we identified 19492 patients taking either an ACE inhibitor (n = 4911) or digoxin (n = 14890). Record of date of death was derived from Medicare enrollment files, and we used the part A Medicare files to identify hospital admissions and discharge diagnoses. As a measure of physical function, we used a scale for activities of daily living performance. The effect of ACE inhibitors was estimated using Cox proportional hazards models with digoxin users as the reference group.

RESULTS

The overall mortality rate among ACE inhibitor recipients was more than 10% less than that of digoxin users (relative rate, 0.89; 95% confidence interval, 0.83-0.95). Mortality was equally reduced regardless of concomitant cardiovascular conditions and baseline physical function. Treatment with ACE inhibitors was associated with a tendency toward reduced hospital admissions that was more evident among patients with greater functional impairment. The adjusted relative rate for hospitalization for any reason was 0.96 (95% confidence interval, 0.91-1.01). The rate of functional decline was greatly reduced among ACE inhibitor recipients (relative rate, 0.74; 95% confidence interval, 0.69-0.80), and this effect was consistent and independent of background comorbidity and baseline physical function.

CONCLUSIONS

These data suggest that survival and functional benefits of ACE inhibitor therapy extend to patients with CHF 85 years and older, and mostly women, both systematically underrepresented in randomized trials. Alternatively, digoxin has a detrimental effect in this population.

Management of heart failure among very old persons living in long-term care: has the voice of trials spread? The SAGE Study Group

BACKGROUND

Increasing prevalence, use of health services, and number of deaths have made congestive heart failure (CHF) a new epidemic in the United States. Yet there are no adequate data to guide treatment of the more typical and complex cases of patients who are very old and frail.

METHODS

Using the SAGE database, we studied the cases of 86,094 patients with CHF admitted to any of the 1492 long-term care facilities of 5 states from 1992 through 1996. We described their clinical and functional characteristics and their pharmacologic treatment to verify agreement with widely approved guidelines. We evaluated age- and sex-related differences, and we determined predictors of receiving an angiotensin-converting enzyme (ACE) inhibitor by developing a multiple logistic regression model.

RESULTS

The mean age of the population was 84.9 +/- 8 years. Eighty percent of the patients 85 years of age or older were women. More than two thirds of patients underwent frequent hospitalizations related to CHF in the year preceding admission to a long-term care facility. Coronary heart disease and hypertension were the most common causes. Half of the patients received digoxin and 45% a diuretic, regardless of background cardiovascular comorbidities. Only 25% of patients had a prescription for ACE inhibitors. The presence of cardiovascular comorbidity, already being a recipient of a large number of medications, a previous hospitalization for CHF, and admission to the facility in recent years were associated with an increased likelihood of receiving an ACE inhibitor. The presence of severe physical limitation was inversely related to use of ACE inhibitors, as were a series of organizational factors related to the facilities.

CONCLUSIONS

Patients in long-term care who have CHF little resemble to those enrolled in randomized trials. This circumstance may explain, at least in part, the divergence from pharmacologic management consensus guidelines. Yet the prescription of ACE inhibitors varies significantly across facilities and depends on organizational characteristics.

Effects of postprandial walking exercise on meal-related hypotension in frail elderly patients

The purpose of this study was to assess the hemodynamic effects of a postmeal walk in frail elderly patients with postprandial hypotension. We demonstrated that frail elderly patients with postprandial hypotension are able to increase their blood pressure and heart rate in response to a postmeal walking exercise, but this effect is limited to the exercise period only and is not sustained during subsequent rest.

Correlates and management of nonmalignant pain in the nursing home. SAGE Study Group. Systematic Assessment of Geriatric drug use via Epidemiology

OBJECTIVE

Nonmalignant pain is a common problem among older people. The prevalence of pain in the nursing home is not well studied. We looked at the association between nonmalignant pain, psychological and functional health, and the practice patterns for pain management in the nursing home.

DESIGN

A cross-sectional study.

SETTING

Nursing Home in four US states.

PARTICIPANTS

A total of 49,971 nursing home residents from 1992 to 1995.

MEASUREMENTS

We used the SAGE database (Systematic Assessment of Geriatric drug use via Epidemiology), which linked information from the Minimum Data Set and nursing home drug utilization data. The MDS items measured included pain, activities of daily living (ADL) function, mood, and time involved in activities. The use of analgesics, anxiolytics, and antidepressants was also documented.

RESULTS

Daily pain was reported in 26% of nursing home residents. The prevalence was lower among men, persons more than age 85, and racial minorities. Persons suffering pain daily were more likely to have severe ADL impairment, odds ratio (OR) (2.47 (95% CI, 2.34-2.60)), more depressive signs and symptoms (OR 1.66 (95% CI, 1.57-1.75)), and less frequent involvement in activities (OR 1.35 (95% CI, 1.29-1.40)). Approximately 25% of persons with daily pain received no analgesics. Residents who were more than 85 years old (OR 1.15 (95% CI 1.02-1.28)), cognitively impaired, (OR 1.44 (95% CI, 1.29-1.61)), of male gender (OR 1.17 (95% CI, 1.06-1.29)), or a racial minority (OR 1.69 (95% CI, 1.40-2.05) and OR 1.56 (95% CI, 0.70-1.04) for blacks and Hispanics, respectively) were at greater risk of not receiving analgesics. Approximately 50% of those in pain used physical and occupational therapies, which was more than two times higher (OR 2.44 (95% CI, 2.34-2.54)), than use for those not in pain.

CONCLUSIONS

Daily nonmalignant pain is prevalent among nursing home residents and is often associated with impairments in ADL, mood, and decreased activity involvement. Even when pain was recognized, men, racial minorities, and cognitively impaired residents were at increased risk for undertreatment. More education and research is necessary to improve the recognition and management of pain in the nursing home, remembering that attention should be paid to populations at increased risk for underrecognition and undertreatment.

Neural mechanisms of delirium: current hypotheses and evolving concepts

The purpose of this article is to review current knowledge regarding potential neural mechanisms of delirium. A MEDLINE search for relevant English language articles was undertaken using various combinations of delirium (including cognitive disorders, encephalopathy, and confusion) with pathogenesis and pathophysiology. These articles were scanned for content related to hypotheses concerning the neurobiology of delirium. Additional references were obtained from a manual search of the bibliography of these articles. A secondary MEDLINE search of delirium with the mechanism in question (i.e., serotonin, acetylcholine, etc.) was then undertaken. Literature review was last updated as of April 1998. Despite being a common problem among elderly patients, the mechanisms of delirium are poorly understood. Delirium is a syndrome that may occur as the result of multiple complex interacting neurotransmitter systems and pathologic processes. The neurotransmitters acetylcholine and serotonin may play particularly important roles in common medical and surgical delirium. Other neurotransmitters such as dopamine and gamma-aminobutyric acid each may be involved in the development of delirium under special conditions. Other neurobiologic factors such as cytokines, cortisol abnormalities, and oxygen free radicals will require further study to define their role in delirium. Distinct neuropathologic processes leading to delirium are beginning to be defined. Such mechanisms may differ in various clinical settings. There is probably no final common pathway to delirium, but rather, delirium is the final common symptom of multiple neurotransmitter abnormalities. Further situation-specific studies of delirium pathophysiology should lead to more effective prevention and treatment strategies.

Assessing muscle stiffness from quiet stance in Parkinson's disease

In previous studies, we developed a postural stiffness measure that is extracted from foot center-of-pressure (COP) trajectories from quietly standing individuals and is based on an analytical mechanical model of posture control. Here we apply this measure to patients with Parkinson's disease (PD). We correlated the postural stiffness measure with different clinical rating scales, obtained from patients. Kendall's rank correlation was highly significant between the stiffness measure and rigidity, bradykinesia, posture impairment, gait, and leg agility, respectively, as rated by the Unified Parkinson's Disease Rating Scale. These results provide further evidence that a higher intrinsic muscle stiffness may contribute to the aforementioned clinically defined symptoms. From a clinical standpoint, this work indicates that the proposed postural stiffness measure may be useful as an assessment tool for the evaluation of PD patients subsequent to pharmacological and surgical treatment.

Effects of age and gender on autonomic control of blood pressure dynamics

Both age and gender influence cardiovascular autonomic control, which in turn may influence the ability to withstand adverse cardiac events and respond to orthostatic stress. The purpose of this study was (1) to quantify age- and gender- related alterations in autonomic control of blood pressure (BP) and (2) to examine the impact of these autonomic alterations on BP response to orthostatic stress. We measured continuous BP and R-R intervals and vasoactive peptide levels in the supine and 60 degrees head-up tilt positions during paced respiration (0.25 Hz) in 89 carefully screened healthy subjects (41 men, 48 women, aged 20 to 83 years). Data were analyzed by gender (age adjusted) and by age group (gender adjusted). During tilt, women had greater decreases in systolic BP than men (-10.2+/-2 versus -1.2+/-3 mm Hg; P=0.02) and smaller increases in low-frequency (sympathetically mediated) BP power (P=0.02). Upright plasma norepinephrine was lower in women (P=0.02). Women had greater supine high-frequency R-R interval power than men (P=0.0001). In elderly subjects, the tilt-induced increase in low-frequency BP power was also diminished (P=0.01), despite higher supine (P=0.02) and similar upright norepinephrine levels compared with younger subjects. Thus, healthy women have less sympathetic influence on BP and greater parasympathetic influence on R-R interval than men. Elderly subjects also have reduced sympathetic influence on BP, but this appears to be more consistent with a reduction in vasomotor sympathetic responsiveness.

Blood pressure behavior in the nursing home: implications for diagnosis and treatment of hypertension

OBJECTIVES

To determine patterns of elevated blood pressure (BP) behavior, their clinical correlates, and the relationship to diagnosis and management of hypertension.

DESIGN

A cross-sectional, prevalence survey.

SETTING

Forty-five nursing homes owned or managed by a large national chain.

PARTICIPANTS

A total of 857 older residents (mean age = 84 years).

MEASUREMENTS

Supine and standing (1 and 3 minutes) BP and heart rate, taken four times in one day (before and after breakfast, and before and after lunch) by trained nurses using a random zero sphygmomanometer; medication profile; active medical diagnoses; functional status; sociodemographics.

RESULTS

The prevalence of a single, elevated, supine systolic pressure (> or = 160 mm Hg) was 14.3%, and of two to four elevated measures was 14.9%. The pre-breakfast reading was consistently the highest, and mean systolic pressures decreased after breakfast. Compared with those not treated, older residents taking antihypertensive medications had higher systolic pressures at all times and showed the same pattern of decline after breakfast. Isolated diastolic hypertension was uncommon (0.9%). Cardiovascular disease, orthostatic hypotension, diabetes, and use of angiotensin converting enzyme inhibitors or calcium channel blockers were more prevalent among older residents who had elevated pressures on multiple occasions (P < .03). Successful antihypertensive treatment was associated with a lower prevalence of orthostatic hypotension. Diuretic use was more likely to be associated with blood pressure control.

CONCLUSION

The diagnosis of hypertension in frail older people would benefit from multiple, within-day measures, including postural BP, taken before and after meals. Diuretic use alone, or in conjunction with ACE inhibitors or calcium channel blockers, was more likely to be associated with normalized blood pressures.

Serum anticholinergic activity changes with acute illness in elderly medical patients

BACKGROUND

Elevated serum anticholinergic activity levels have been associated with delirium in cross-sectional studies of ill older persons. This study used serial measures of serum anticholinergic activity levels to determine whether these levels change following illness resolution, and if such changes are specific to those with delirium.

METHODS

Twenty-two nursing home residents with a febrile illness had serum specimens drawn and were evaluated for the presence of delirium during the acute illness and at 1-month follow-up. Delirium was diagnosed using the Confusion Assessment Method. Serum anticholinergic activity was determined using a previously described radionuclide competitive-binding assay.

RESULTS

Delirium was present during illness in 8 of 22 subjects (36%), and had resolved by 1-month follow-up in all but one resident. Serum anticholinergic activity levels were significantly higher during illness than at 1-month follow-up in both the delirious (0.69 +/- 0.85 nM atropine equivalents/200 microL sample versus 0.10 +/- 0.16; p = .06) and non-delirious (0.65 +/- 0.51 nM atropine equivalents/200 microL sample versus 0.08 +/- 0.12; p < .001) groups. Medication changes did not seem to be related to changes in serum anticholinergic activity.

CONCLUSIONS

In older nursing home residents with a fever, serum anticholinergic activity appears to be elevated during illness, and declines following recovery from illness. This effect does not seem to be specific to those residents with delirium, nor does it seem related to medication changes.

Nursing home characteristics and the development of pressure sores and disruptive behaviour

OBJECTIVE

To determine how nursing home characteristics affect pressure sores and disruptive behaviour.

METHOD

Residents (n = 5518, aged > or =60 years) were selected from 70 nursing homes in the National Health Care chain. Homes were classified as high- or low-risk based on incidence tertiles of pressure sores or disruptive behaviour (1989-90). Point-prevalence and cumulative incidence of pressure sores and disruptive behaviour were examined along with other functional and service variables.

RESULTS

The overall incidence of pressure sores was 11.4% and the relative risk was 4.3 times greater in high- than low-risk homes; for disruptive behaviour, the incidence was 27% and the relative risk was 7.1 times greater in the high-risk group. At baseline, fewer subjects in homes with a high risk of pressure sores were white or in restraints, but more had received physician visits monthly and had had problems with transfers and eating. High-risk homes also had fewer beds and used less non-licensed nursing staff time. At follow-up (1987-90), 52% of homes in the low-risk group and 35% of those in the high-risk group had maintained their risk status; low-risk homes were more likely to have rehabilitation and maintenance activities. Having multiple clinical risk factors was associated with more pressure sores in high- (but not low-) risk homes, suggesting a care-burden threshold. By logistic regression, the best predictor of pressure sores was a home's prior (1987-88) incidence status. Interestingly, 67% of homes with a high risk of pressure sores were also high-risk for disruptive behaviour, while only 27% of homes with a low risk of pressure sores were high-risk for disruptive behaviour. A threshold effect was also observed between multiple risk factors and behaviour. More homes with a high risk of disruptive behaviour (68%) remained at risk over 4 years, and the best predictor of outcome was a home's previous morbidity level.

CONCLUSION

Nursing-home characteristics may have a greater impact than clinical factors on pressure sores and disruptive behaviour in long-stay, institutionalized elders.

Age-related changes in the initiation of gait: degradation of central mechanisms for momentum generation

OBJECTIVE

To investigate cross-sectionally age-related changes in the expression and biomechanical efficiency of the gait-initiation motor program.

DESIGN

Case-control study.

PARTICIPANTS AND SETTING

Twenty healthy young research subjects and 20 healthy elderly subjects who volunteered from the community participated in this study at a university research laboratory.

MAIN OUTCOME MEASURES

Participants performed gait-initiation trials at three speeds from a starting position on a force platform while ground reaction force data, 3-D motion analysis data, and electromyographic data were collected. Measures included: latency of tibialis anterior (TA) activation and soleus (SOL) and gastrocnemius (GA) inhibition, magnitude of center of pressure (COP) displacement, magnitude of momentum generated, and final walking velocity.

RESULTS

The expression of the central motor program governing gait initiation, as evidenced by the invariant timing between TA activation and SOL/GA inhibition, was seen in both the young and elderly populations, but the frequency was diminished in the latter group. The momentum-generating capacity of the COP shift mechanism was present but significantly diminished in the elderly population.

CONCLUSIONS

These findings suggest that the central nervous system uses stable, efficient mechanisms for dealing with the inherent instability of upright bipedalism and that the integrity of these mechanisms degrades with aging.