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Biomedical subjects

J Fahrenberg

Publications and source records attributed to J Fahrenberg.

At least 19 recordsLinked to original sources
PubMed1995

Awareness of blood pressure: interoception or contextual judgement?

Most patients with mild to moderate hypertension are asymptomatic but some patients report symptoms and seem to be aware of their blood pressure. The research question is whether the estimation of blood pressure is primarily derived from interoception or is inferred by contextual judgement. A psychophysiological ambulatory assessment was conducted with 51 male hypertensive patients and 30 either normotensive or hypotensive student subjects employing (1) a multichannel recording system for blood pressure, heart rate and physical activity; and (2) a pocket computer for assessing estimated BP, setting variables and self-ratings of subjective state. Within-subject correlations revealed that there was no significant relationship between estimated BP and concurrently recorded systolic BP. Estimated BP is, however, related to self-ratings of feeling physically tense and self-ratings of physical activity. Blood pressure awareness appears to be a rather inconsistent and subjective phenomenon, based on contextual judgements and inferences instead of "perception", but it is a relevant methodological issue (and possible bias) in hypertension research.

Adult↗
PubMed1995

Cortisol, ACTH, and cardiovascular response to a cognitive challenge paradigm in aging and depression.

Aging and hypercortisolism may be associated with alterations of stress-induced hormone release. We therefore studied 20 normal controls of two different age groups (< 30 and > 60 yr of age) and 20 age-matched patients with major depression; baseline ACTH and cortisol secretion (between 1400 and 1700) as well as blood pressure and heart rate and their responses to a 45-min lasting signal detection task (1705-1750) were determined. No difference in basal hypothalamic-pituitary-adrenal (HPA) system activity between young and older healthy controls was noted. The cognitive challenge resulted in an increase in stress-induced hormonal secretion that was greater in the older controls than in their young counterparts. Basal hypercortisolemia and, at baseline, heart rates were higher in depressed patients, regardless of age. Blood pressure was elevated in older healthy controls as well as depressed patients. With the exception of the young depressed patients, all groups responded with an increase of the cardiovascular parameters during stress.

Adrenocorticotropic Hormone↗
PubMed1990

Methodological guidelines for impedance cardiography.

Impedance cardiography was introduced over 20 years ago as a noninvasive and unobtrusive technique for measuring systolic time intervals and cardiac output. Although our understanding of the physiological events reflected in the impedance cardiogram has become more refined, the technique's theoretical basis remains somewhat controversial and acceptance of its validity has relied heavily upon empirical validation. Largely as a consequence of this status, there have been inadequate grounds on which to develop sound methodological standardization. Currently, the methodological approaches that have been most frequently adopted may be viewed as representing the standard. The various aspects of impedance methodology are discussed, and alternative approaches described, with the objective of providing an informed basis for choosing among these methodological alternatives. It is recommended that studies utilizing impedance cardiography should be reported with clear and detailed methodological description. This should help clarify the extent to which methodological differences may underlie any discrepant research observations, as well as facilitate the emergence of improved methodological standards.

Cardiac Output↗
PubMed1987

Psychophysiological assessments in a repeated-measurement design extending over a one-year interval: trends and stability.

Intra-individual variability in psychophysiological parameters of activation processes can be attributed to functional fluctuation and/or error of measurement. A repeated measurement design at intervals of about three weeks, three months and one-year duration, in which a laboratory-field comparison was made with respect to predictability of individual differences, provided data on a broad spectrum of physiological and psychological variables measured under various conditions. We investigated the reproducibility of commonly used laboratory measures in a sample of male students of physical education (N = 58). Results indicate that a hypothetical general trend component accounts for less than 10 percent of the total variance in a two-factorial ANOVA (Subjects X Replications). Stability coefficients based on raw scores (rest and strain scores) are relatively higher than those based on change scores. Stability of heart rate, pulse wave velocity, respiration rate during rest, mental arithmetic and cold pressor test and cardiovascular and respiratory parameters during ergometer exercise and 1000m run exceed the stability of blood pressure, parameters from impedance cardiography, eye blink and electrodermal activity during the respective laboratory conditions. The implications of such descriptive studies for the planning and evaluation of longitudinal studies and for selection of parameters depicting habitual dispositions in differential psychophysiological research are indicated.

Adult↗
PubMed1979

[Psychophysiological time series study of 54 patients with cardiovascular diseases during rehabilitation. Evaluation, group differences, and periodicities (author's transl)].

In the course of a cardiac rehabilitation program 36 patients with myocardial infarction and 18 patients with functional cardiovascular disorders have been studied for 4 to 6 weeks. Data included daily self-report scales of condition, mood, bodily complaints, and daily routine. Physiological variables (blood pressure, heart rate, ventilation, respiratory gas exchange) were measured three times weekly under different conditions (breath holding, hyperventilation, reaction time, multiple reaction test). Analysis of variance indicated positive effects of the rehabilitation program for physiological as well as psychological variables. There were no obvious differences in state change between groups but there were some differences in the average level of variables. Time series analysis by means of autocorrelations revealed circaseptane periodicities which may be interpreted as a reflection of the exogene weekly rhythms.

Adult↗
PubMed1977

[A psychophysiologic time series study with 20 students over 8 weeks].

A longitudinal (time series) study was performed (N = 20 students; T = 16 points of observation during 8 weeks) on a considerable number of psychological and physiological variables to investigate the suitability of these parameters for general and individual state change description. Some problems of correlational analysis and the generality-individuality-dilemma of this kind of research are discussed.

Adult↗