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Biomedical subjects

J F Potter

Publications and source records attributed to J F Potter.

At least 109 records · Page 6Linked to original sources
PubMed1991

Possible impairment of the sympathetic nervous system response to postprandial hypotension in elderly hypertensive patients.

In a randomised, single-blind, cross-over study, the effects of a high carbohydrate meal or 'no meal' on BP, pulse rate, blood glucose, plasma insulin and catecholamine levels were assessed in eight fit, untreated, elderly hypertensive subjects. A significantly greater fall in supine (P = 0.006) and erect (P = 0.03) systolic blood pressure (SBP) occurred post-meal compared with the no meal phase. The maximum postprandial fall in supine SBP (-24 mmHg, 95% CI -16 to -32 mmHg) occurred at 60 minutes and was associated with a significant rise in supine pulse rate. No overall difference in diastolic BP was seen between the two phases and orthostatic control of BP was maintained. Blood glucose and plasma insulin levels rose after the meal but plasma noradrenaline levels were unchanged during both phases. Thus in these elderly hypertensive subjects the postprandial fall in SBP was not associated with an overall increase in sympathetic nervous system (SNS) activity (as gauged by plasma noradrenaline levels), unlike the findings previously reported in normotensive elderly and young subjects. These changes in BP and the possible impairment of the SNS response to postprandial hypotension should be considered when assessing the BP control, particularly after therapeutic intervention, in elderly hypertensive patients.

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PubMed1990

Blood pressure, heart rate and neuroendocrine responses to a high carbohydrate and a high fat meal in healthy young subjects.

1. The responses of blood pressure, heart rate, autonomic function and plasma insulin to a high carbohydrate and a high fat meal of equivalent energy value were studied in nine young volunteers. 2. Neither meal produced a significant change in supine or erect blood pressure. The high carbohydrate meal, however, resulted in an overall rise in both supine (6 beats/min) and erect (6 beats/min; P less than 0.05) heart rate, no such changes being seen after the high fat meal. 3. Plasma noradrenaline levels increased by a maximum of 126% at 90 min (0.98 to 2.22 nmol/l) after the high carbohydrate meal but were virtually unchanged after the high fat meal (P less than 0.01). Parasympathetic function showed no between-meal differences. Plasma insulin and glucose levels were significantly higher after the high carbohydrate meal than after the high fat meal. No postprandial difference in packed cell volume was found between meal types. 4. We conclude that, in young subjects, the postprandial blood pressure after a high carbohydrate meal is maintained by an increase in heart rate associated with increased sympathetic nervous system activity. These changes are at variance with the blood pressure and heart rate responses seen in the elderly after a high carbohydrate meal. A high fat meal has no significant cardiovascular or neuroendocrine effects in the young or old. The nutrient composition of meals has to be taken into account when studying the postprandial cardiovascular and neuroendocrine responses in the young.

Adult↗
PubMed1990

Potassium supplementation in the treatment of idiopathic postural hypotension.

We studied the effects of potassium supplementation (60 mmol/day) and matching placebo on the postural blood-pressure fall in ten elderly patients with symptomatic idiopathic postural hypotension in a double-blind, randomized cross-over trial. There was a significant decrease in the orthostatic fall in systolic blood pressure (SBP 33 +/- 5 mmHg to 16 +/- 9 mmHg, p less than 0.01) and in supine SBP (162 +/- 7 to 150 +/- 7 mmHg, p less than 0.01) between placebo and potassium phases. Supine diastolic and erect blood pressures were unchanged, though pulse rate showed a greater orthostatic increase (7 +/- 3 beats/min to 14 +/- 2 beats/min, p less than 0.05) following potassium therapy. No significant changes were seen in intracellular electrolytes, plasma renin activity, aldosterone levels or body weight. Seven patients reported symptomatic improvement with potassium, but none during the placebo phase. Potassium therapy was well tolerated and may be a successful and safe method of treating idiopathic postural hypotension.

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PubMed1990

Benefits of anti-hypertensive therapy in the elderly.

Hypertension is common in the elderly, up to half of the population over the age of 65 years can be so classified. Raised systolic and diastolic blood pressure levels increase the risk of cardiovascular morbidity and mortality in those aged up to 80 years. Recent intervention studies have shown that antihypertensive treatment reduces death from stroke and myocardial infarction, without producing intolerable side-effects. The benefits of treating isolated systolic hypertension and hypertension following stroke are, as yet, unproven. The therapeutic goals for treating hypertension in the elderly should be to lower blood pressure while keeping adverse reactions to a minimum and thereby not impairing the patient's quality of life. Non-pharmacological methods should be tried initially before resorting to drug therapy. Both thiazide diuretics and beta-adrenoceptor antagonists are of proven value as first line hypotensive agents in the elderly. Drug therapy should be tailored to the individual patient and increased slowly to reduce the incidence of side-effects.

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PubMed1990

The effect of age on the relative potency of midazolam and diazepam for sedation in upper gastrointestinal endoscopy.

Diazepam and midazolam are considered safe and effective sedative agents for diagnostic procedures. However, there have been recent reports of deaths in older patients receiving midazolam for sedation. We examined the relative potency of diazepam compared with midazolam as a function of age in two large groups of patients receiving intravenous benzodiazepines for upper gastrointestinal endoscopy. While midazolam and diazepam are approximately equivalent before age 60, after age 60 the relative potency of midazolam compared with diazepam increases markedly. The rapid decline in dose necessary to sedate older patients with midazolam may explain deaths occurring in older patients who have received this drug. Until this problem receives definitive study, we advise that diazepam be preferred over midazolam for intravenous sedation in patients over 60.

Adult↗
PubMed1990

Does the Williams Manual Test predict service use among subjects undergoing geriatric assessment?

This study examines the utility of the Williams Manual Test (WMT) in predicting those older patients who will eventually require formal services. One hundred seventeen older subjects underwent comprehensive geriatric assessment that included administration of the WMT and questionnaires assessing current service use. Study participants returned at 6 and 12 months for repeat measurement of study variables. The WMT was found to be a significant predictor of additional service use at 12 months (chi 2 = 6.4, P less than .01). The test had high specificity (83%) but relatively low sensitivity (40%). The lack of sensitivity in this study group was likely due to high levels of stress among caregivers whose relative was otherwise not predicted to need services. When the WMT was repeated after 6 and 12 months, the results were highly reproducible. The WMT appears to be a useful predictor of increasing formal service use. However, in certain study groups, its predictive ability may be affected by high levels of caregiver stress.

Activities of Daily Living↗
PubMed1990

Caregiver burden should be evaluated during geriatric assessment.

This study examines the relationship between caregiver burden and use of long-term care services following geriatric assessment. One hundred nine older subjects underwent comprehensive assessment, which included a questionnaire completed by the primary caregiver to assess the sense of burden in providing care. Logistic regression was used to identify independent predictors of service use at 12 months. Among measures of the older person's cognitive and physical abilities, only activities of daily living predicted increased use of services. When the measure of caregiver burden was added, it also entered as an independent predictor, which significantly improved the prediction of service use (chi 2 = 5.9, P less than .02). In a separate analysis, caregiver burden predicted both the use of home services and nursing-home placement. During longitudinal follow-up, the measure of burden decreased over 12 months for the sample, with the greatest reduction in burden occurring for caregivers whose relative was placed in a nursing home. The fact that caregiver burden was the most important factor in determining who would use formal services suggests that burden should be evaluated as part of geriatric assessment.

Activities of Daily Living↗
PubMed1989

Effects of meal composition on the postprandial blood pressure, catecholamine and insulin changes in elderly subjects.

1. The effects of four meals of similar energy, but different nutritional, composition on postprandial blood pressure, heart rate, autonomic function, catecholamines, insulin and packed cell volume levels were studied in seven fit elderly subjects. 2. The high carbohydrate and high protein meals led to a significant overall fall in supine systolic and diastolic blood pressure compared either with no change or a rise after the normal (i.e. mixed) and high fat meals. Similar between-meal differences were seen with erect diastolic but not erect systolic blood pressure. No significant postural blood pressure fall occurred after any of the meals. Supine heart rate was unaffected by meal type or by time, and although erect heart rate showed a small increase during the study there was no between-meal difference. 3. Parasympathetic function was unaffected by meal type. Plasma noradrenaline rose after the high carbohydrate and mixed meals only, remaining elevated for 120 min after meal consumption. This increase was not related to the changes in blood pressure or plasma insulin levels. 4. Plasma insulin and glucose rose after the high carbohydrate and mixed meals, but were unchanged after the high protein and high fat meals. Packed cell volume showed a small decrease towards the end of the study, although there was no between-meal variation. 5. The differences in the cardiovascular changes after the different meals could not be ascribed to alterations in autonomic function, insulin release or fall in plasma volume. We propose that the postprandial changes in blood pressure are due to the nutrient composition of the meal rather than the actual energy load.

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PubMed1989

Delivery of services in rural settings to the elderly mentally retarded-mentally ill.

A number of controversial arguments exist regarding the ability of sparsely populated areas to adequately provide for their elderly mentally retarded; the elements of distance, education, and capital are said to effectively obstruct access to psychiatric and social support. Yet several facts speak soundly for the necessity to overcome these obstacles: a five-fold increase in the life spans of the mentally retarded in recent decades, and the amply demonstrated reality that individuals with mental retardation are nearly twice as likely as the general population to develop severe behavioral disorders. This article examines both the methods and the reasons for ensuring that rural populations of elderly mentally retarded citizens receive modern psychiatric assistance and community support.

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PubMed1988

In-hospital mortality as a function of body mass index: an age-dependent variable.

In a retrospective review of 8428 hospital admissions, the relationship between age, sex, disease category, body mass index, and mortality during hospitalization was examined. Records were analyzed for adult admissions whose principal diagnosis fell into one of three categories: malignant disease, heart and cerebrovascular disease, and other diseases. In this study, age, disease category, and body mass index were predictors of survival; sex and race were not. Predicted mortality calculated by logistic regression was greatest at the extremes of body weight in all age groups and in each disease category describing a U-shaped relationship. Obesity was associated with higher mortality only when subjects were 100% or more overweight, whereas being at or below ideal weight was usually associated with increased mortality. Lowest mortality occurred at moderate overweight. The deleterious effects of extremes of body weight take on increasing importance the older the age of the patient. Underweight seems to be a more important predictor of mortality than overweight in older hospitalized subjects. The higher mortality in thin patients could not be explained by weight loss between hospitalizations.

Adult↗
PubMed1988

Hearing impairment as a predictor of cognitive decline in dementia.

Thirty-eight patients with dementia of various etiologies were studied longitudinally to determine the change in cognition over time in subjects with and without hearing impairment. Hearing impaired subjects were older (P less than .0001), but subject groups were otherwise comparable with respect to living arrangements, medical illness, number of drugs taken, mood, years of education, and cognitive functioning at the beginning of the study period. Decline in cognitive functioning at follow-up was greater in hearing impaired subjects and this difference persisted after adjustment for the greater age of hearing impaired subjects (P less than .009). Further division of subject by diagnosis showed that only in the Alzheimer's group did hearing impairment predict more rapid cognitive decline at follow-up.

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PubMed1988

High erythrocyte water content causes discrepancy between values of automated and micro-centrifuged haematocrit.

Erythrocyte water content, micro-haematocrit (micro-Hct) and haematocrit (Hct) as derived by Coulter Counter were determined on 41 subjects. Significant discrepancies were observed between manual and automated Hct which could not be explained by abnormal red cell morphology and abnormal plasma osmolality, but appeared to be related to high erythrocyte water content (r = 0.54, p less than 0.001). As human ageing is associated with increased erythrocyte water content, these results question the reliability of Hct readings in the elderly. Further studies need to be performed to evaluate which estimation of Hct should be applied for subjects with high erythrocyte cell water.

Adult↗
PubMed1988

Age-related changes in human memory: normal and abnormal.

The evaluation of memory complaints in the elderly is one of the major challenges in geriatric medicine. Determining this deficit as either age-related change or dementia is a frequent problem in primary care practice. A careful history, an interview of a collateral source, and neuropsychological tests will shed light on the seriousness of the memory complaint. Several factors affect memory function of the elderly: anxiety, depression, and failure to use specific learning strategies commonly used by younger age groups. Memory training programs using mnemonics, lists, categorization, visual aids, rehearsal, and imagery may improve memory function.

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