Simultaneous assessment of posture and limb movements (e.g., periodic leg movements) with calibrated multiple accelerometry.

This study describes new applications for the method of calibrated multiple accelerometry, which detects posture and distinct motion patterns, and limb movements continuously. The aim of our study was to evaluate this assessment technique in terms of its suitability for exploring the relationships between pathological limb movement activity (e.g., periodic leg movements) and posture. The new method proved to be appropriate for the simultaneous assessment of pathological leg jerks and posture and provided a means to revealing possible relations. Generally, our study demonstrates the application of this (ambulatory) assessment technique in the field of sleep and neurological disorders.

Aversive tension in patients with borderline personality disorder: a computer-based controlled field study.

OBJECTIVE: This study was designed to examine the subjective appraisal of aversive tension under conditions of daily life in patients with borderline personality disorder (BPD). METHOD: A sample of 63 female subjects with BPD and 40 mentally healthy controls were each given a hand-held computer. For two consecutive days, participants were prompted at hourly intervals to record their current state of aversive tension and prompting events. RESULTS: Compared with controls, states of aversive tension occurred significantly more frequently in BPD patients. The average levels of aversive tension were significantly higher, and the rate of increase in tension was markedly more rapid. Furthermore, states of aversive tension persisted for a longer period. Among BPD subjects three events (rejection, being alone, and failure) account for 39% of all events preceding states of tension. CONCLUSION: The study provides support for the theory that patients with BPD experience more frequent, stronger, and longer-lasting states of aversive tension.

Tremor in Parkinson's disease: 24-hr monitoring with calibrated accelerometry.

Monitoring systems enable the long-term registration of tremor in patients with Parkinson's disease This method is useful in the objective measurement of tremor during the course of treatments. Indeed, the symptoms of tremor as well as the aggravating and attenuating influences can be observed under real-life conditions. The methodology of data recording and analysis, described in previous investigations, was extended to automatically detect body position and certain movement patterns with calibrated 4-channel accelerometry. The main purpose of the present investigation was to apply this refined and extended methodology to patients in a clinical rehabilitation program, and to examine its practability with respect to the results of the treatment and the patients' compliance. The methodology was tested on 30 patients (17 male, 13 female) with Parkinson's disease. The mean age was 64.8 years (s = 8.9). The Hoehn-Yahr index ranged from 1 to 3 (m = 2.3, s = 0.7) and the overall UPDRS scale between 10 and 74 (m = 42.9, s = 18.1). The data recording included: (1) the registration of tremor under standardised conditions of rest and postural tremor test with and without distraction; (2) a standard protocol to obtain reference values for body position and movement; and (3) the 24-hr monitoring. 21 patients could be recorded a second time, on average 18 days after the first recording. Between the two registrations, patients received individually tailored drug treatment supplemented with specific activating physiotherapy, ergotherapy measures, and individual psychotherapeutic counseling. Changes between first and second recording were evident for the three tremor variables, but significant only for the 24-hr ambulatory monitoring. The between and within-subjects correlations of the tremor variables were rather low except the correlations between occurrence and amplitude (between-subjects. 87; within-subjects. 67). Conditions of rest and postural tremor test showed a correlation with corresponding segments of the ambulatory monitoring of about. 50 for the tremor occurrence. The best prediction of the day-time monitoring was made by the tremor tests with distraction, whereas the night segment was best predicted by the standard protocol.

Motion pattern and posture: correctly assessed by calibrated accelerometers.

Basic motion patterns and posture can be distinguished by multichannel accelerometry, as recently shown. A refinement of this method appeared to be desirable to further increase its effectiveness, especially to distinguish walking and climbing stairs, and body rotation during sleep. Recordings were made of 31 subjects, according to a standard protocol comprising 13 motions and postures. This recording was repeated three times with appropriate permutation. Five uni-axial sensors and three sites of placement (sternum with three axes, right and left thigh) were selected. A hierarchical classification strategy used a standard protocol (i.e., individual reference patterns) to distinguish subtypes of moving behaviors and posture. The analysis method of the actometer signals reliably detected 13 different postural and activity conditions (only 3.2% misclassifications). A minimum set of sensors can be found for a given application; for example, a two-sensor configuration would clearly suffice to differentiate between four basic classes (sitting, standing, lying, moving) in ambulatory monitoring.

Symptomatic myocardial ischemia and everyday life: implications for clinical use of interactive monitoring.

In coronary heart disease (CHD), pathological myocardial ischemic changes do not always occur with the symptom of heart pain. Methodological problems make it difficult to examine the factors that influence silent and symptomatic myocardial ischemia in everyday life. This study uses a computer-assisted monitoring system with an interactive Holter ECG, an actometer, and an electronic diary. Self-report measurements indicate that symptomatic patients tend toward increased neuroticism, whereas asymptomatic patients engage in beneficial and active coping skills more frequently. The results of the monitoring study demonstrate the same degree of ischemia in silent and symptomatic episodes. However, these episodes show differences in certain psychological context variables. Symptomatic episodes are linked to high subjective strain and severe tension. Because angina pectoris is not a reliable warning signal of myocardial ischemia, the use of the interactive monitoring system is recommended for educating CHD patients on how to cope with excessive strain in everyday life.

Assessment of posture and motion by multichannel piezoresistive accelerometer recordings.

Modern assessment of posture and motion involves the use of wide bandwidth piezoresistive accelerometers. The direct current (DC) component allows for assessment of slow motion and change in position referring to the gravitational axis: the alternating current (AC) component, calibrated in g. represents acceleration along the sensitive axis of the device. A method study was designed to evaluate the division in DC and AC components, reliabilities, discrimination between conditions, and detection of types of physical activities. Recordings were made in 26 student participants for eight conditions: sitting, standing, lying supine, sitting and typing on a PC keyboard, walking, climbing stairs, walking downstairs, and cycling. This procedure was repeated in reversed order. A classification of physical activities according to the eight conditions (first trial) and based on four parameters, that is DC components trunk, thigh, and lower leg and AC component trunk, was correct in almost 100% of patterns, when applied to the second trial.

Non-invasive estimations of ventricular ejection time and stroke volume: comparison of impedance cardiography and the Portapres 2.

Stroke volume estimates and left ventricular ejection time (1) derived from calibrated finger pulse pressure recordings (Portapres 2, TNO-BMI, Amsterdam) based on the Model Flow method and (2) derived from impedance cardiography were compared in 20 student subjects. The recordings were made for seven conditions: supine rest, standing, mental arithmetic, ergometer exercise 50 W, motor performance test, reading aloud, and walking. Findings indicated that caution is required in assuming concurrent validity for both methods in tracking haemodynamic changes. Within-subject correlations were low or even negligible. Basic discrepancies were evident regarding the estimation of left ventricular ejection time but obviously more sources of measurement error exist which necessitate further research.

Somatic complaints in the German population.

The Freiburg Complaint List (Freiburger Beschwerdenliste FBL-R) is a self-report questionnaire which consists of 80 somatic complaints. A survey was conducted in 1993 and a sample of N = 2070, representative for the German adult population of 16 years and above, was obtained. Factor analysis, cluster analysis and item analysis were employed to develop nine scales: General Condition, Tiredness, Cardiovascular, Gastrointestinal, Head-Throat, Tenseness, Emotional Reactivity, Pain, Sensory and Total Score. Regression analyses revealed substantial effects of gender, age group, and, to a lesser extent, social class on FBL-R scores. Furthermore, highly significant correlations were found between FBL-R scores and indicators of illness, health concern, and utilization of health services. The standardization provides normative data (stanine norms) that account for gender and age groups. This representative survey provides essential data, i.e. base rates of somatic complaints in the general population and subsamples. These base rates are relevant to the future development of criteria for diagnosis of somatization disorder.

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.

Is elevated blood pressure level associated with higher cardiovascular responsiveness in laboratory tasks and with response specificity?

Cardiovascular responsiveness and response specificity were investigated in male students, 48 with moderately elevated blood pressure (systolic blood pressure [SBP] > 140 mmHg and/or diastolic blood pressure [DBP] > 90 mmHg), 31 with mildly elevated blood pressure, and 57 with normal blood pressure. The behavioral tests and physically demanding tasks in the laboratory included mental arithmetic, free speech condition, cold pressor test, upright tilt, and ergometer exercise. Subjects with elevated blood pressure differed in baseline, task, and recovery levels of SBP, DBP, and heart rate. There were no significant effects in task-baseline differences or in residualized change scores. However, a positive initial-value dependency (LIV) in blood pressure responses was found: elevated blood pressure is associated with a larger increase under task conditions. Response scaling that employed reliability estimates and true difference scores indicated higher responsiveness in subjects with moderately elevated blood pressure and, thus, are in accordance with the positive LIV as compared with response measures based on task-baseline differences or residualized change scores. Findings from the specificity analysis indicated a higher incidence of SBP responders, that is, subjects with maximum response in SBP, among subjects with elevated blood pressure. Some of the inconsistencies in the literature with respect to blood pressure responsiveness and heart rate level in individuals with borderline hypertension may be attributed to the specific method of response scaling and to insufficient habituation to the setting and measurement.

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.

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.

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.

Covariation and consistency of activation parameters.

Individual differences in activation processes, as well as the consistency and predictability of these differences, constitute a classical issue eliciting much theoretical discussion in this field and as such poses an essential question for any practical application of psychophysiological methods. A typical activation experiment assessing 125 male students on four self-report and 21 physiological measures under five conditions (rest, mental arithmetic, interview, anticipation and blood taking) was performed supplying an empirical basis for a multivariate analysis. A partition of covariance, factor analyses, item analyses and scale construction procedures as well as models engaging an increasing number of components were used to study the covariation and consistency of these activation parameters. Several biometric problems that are generally thought to complicate the evaluation of such data (i.e. non-linear relations, the problem of initial values, differing sensibility curves of physiological response systems, individual response specificities) are considered and tested empirically. Findings suggest that the use of a single variable or a composite measure as an 'indicator' of individual differences in state or reaction aspects of activation is inadequate, due to empirical inconsistency and the lack of predictability between functional subsystems. A multicomponent model or a set of marker variables, having empirically derived discriminative efficiency as well as reliability estimates, seem to be preferable.

[Psychophysiological time series study of 54 patients with cardiovascular diseases during rehabilitation. Evaluation, group differences, and periodicities (author's transl)]. / Eine psychophysiologische Zeitreihenstudie an 54 Herz-Kreislauf-Patienten im stationären Heilverfahren. Erfolgsbeurteilung, Gruppenunterschiede und Periodizitäten.

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.