Biomedical subjects

Stein Knardahl

Publications and source records attributed to Stein Knardahl.

12 recordsLinked to original sources

PubMed2006

Work factors and psychological distress in nurses' aides: a prospective cohort study.

BACKGROUND: Nurses' aides (assistant nurses), the main providers of practical patient care in many countries, are doing both emotional and heavy physical work, and are exposed to frequent social encounters in their job. There is scarce knowledge, though, of how working conditions are related to psychological distress in this occupational group. The aim of this study was to identify work factors that predict the level of psychological distress in nurses' aides. METHODS: The sample of this prospective study comprised 5076 Norwegian nurses' aides, not on leave when they completed a mailed questionnaire in 1999. Of these, 4076 (80.3 %) completed a second questionnaire 15 months later. A wide spectrum of physical, psychological, social, and organisational work factors were measured at baseline. Psychological distress (anxiety and depression) was assessed at baseline and follow-up by the SCL-5, a short version of Hopkins Symptom Checklist-25. RESULTS: In a linear regression model of the level of psychological distress at follow-up, with baseline level of psychological distress, work factors, and background factors as independent variables, work factors explained 2 % and baseline psychological distress explained 34 % of the variance. Exposures to role conflicts, exposures to threats and violence, working in apartment units for the aged, and changes in the work situation between baseline and follow-up that were reported to result in less support and encouragement were positively associated with the level of psychological distress. Working in psychiatric departments, and changes in the work situation between baseline and follow-up that gave lower work pace were negatively associated with psychological distress. CONCLUSION: The study suggests that work factors explain only a modest part of the psychological distress in nurses' aides. Exposures to role conflicts and threats and violence at work may contribute to psychological distress in nurses' aides. It is important that protective measures against violent patients are implemented, and that occupational health officers offer victims of violence appropriate support or therapy. It is also important that health service organisations focus on reducing role conflicts, and that leaders listen to and consider the views of the staff.

Adult↗

PubMed2006

Placebo-induced changes in spinal cord pain processing.

Pain is an essential sensory modality, signaling injury or threat of injury. Pain perception depends on both biological and psychological factors. However, it is not known whether psychological factors modify spinal mechanisms or if its effect is limited to cortical processing. Here, we use a placebo analgesic model to show that psychological factors affect human spinal nociceptive processes. Mechanical hyperalgesia (hypersensitivity) after an injury is attributable to sensitized sensory neurons in the spinal cord. After a 5 min, 46 degrees C heating of the skin, subjects developed areas of mechanical hyperalgesia. This area was smaller in a placebo condition compared with a baseline condition. This result suggests that placebo analgesia affects the spinal cord as well as supra-spinal pain mechanisms in humans and provides strong supporting evidence that placebo analgesia is not simply altered reporting behavior. Central sensitization is thought to mediate the exaggerated pain after innocuous sensory stimulation in several clinical pain conditions that follow trauma and nervous-system injury. These new data indicate that expectation about pain and analgesia is an important component of the cognitive control of central sensitization.

Adult↗

PubMed2005

Effects of repeated electrocutaneous pain stimulation on facial blood flow.

The purpose of the study was to examine the effects of repeated electrocutaneous pain stimulation of the hand on facial blood flow responses in healthy human subjects (58 adult women). Finger blood flow, mean arterial blood pressure, and heart rate were also monitored. To investigate the influence of psychological factors, the subjects' affect states were assessed, and physiological responding was explored during cognitive distraction, i.e., when attention was turned away from the unpleasant stimulus. Consistently, electrocutaneous stimulation elicited vasodilatation in the cheek, together with finger vasoconstriction. This response pattern was evident even at non-painful stimulation intensities. The facial blood flow response showed habituation across stimulation trials and was largely unrelated to systemic cardiovascular changes, affect states, and attentional manipulation. These findings indicate (1) that the experimentally induced facial blood flow changes are part of a non-specific physiological response pattern elicited during noxious stimulation, and (2) that they are not dependent on regional (orofacial) stimulation for their occurrence.

Adult↗

PubMed2005

A prospective study of the relationship between musculoskeletal or psychological complaints and muscular responses to standardized cognitive and motor tasks in a working population.

The present study sought to determine the relationship between musculoskeletal or psychological complaints and muscular responses to standardized cognitive and motor tasks. The prospective study design examined (i) whether complaint severity predicts muscular responses during standardized tasks and (ii) whether the muscular responses predict changes in complaint severity over one year. Musculoskeletal and psychological complaints were recorded by monthly reports the four months preceding and 12 months succeeding a work session in the laboratory; complaint-severity indices were computed from complaint-severity scores (intensity scorexduration score). Surface electromyography (EMG) was recorded bilaterally from the upper trapezius, middle deltoid, and forearm extensor muscles in 45 post-office workers (30 women) during two identical task series. Between the series, exhausting submaximal muscle contractions (25% of peak torque) were performed. In adjusted regression models, no relations between musculoskeletal complaints the last four months and muscle activity during the task series were found. However, psychological complaints the last four months predicted higher muscle activity levels and a steeper rise in muscle activity in the muscles not engaged in motor task performance. Sleep disturbance was the strongest individual predictor of increased muscle responses. In contrast, psychological complaints the last four months predicted lower EMG levels in the task-engaged muscle during the complex-choice-reaction-time tasks. None of the muscle-activity responses to the standardized tasks predicted changes in severity of musculoskeletal or psychological complaints over the subsequent one-year period. In conclusion, psychological complaints predict different responses in task-engaged and non-involved muscles during cognitive and motor tasks. Musculoskeletal complaints did not predict responses to the tasks.

Adult↗

PubMed2005

Personality, affective response, and facial blood flow during brief cognitive tasks.

Blood pressure, heart rate, and changes in facial and finger blood flow were monitored in 58 women during three laboratory tasks, i.e., reading out a neutral text, a personally relevant speech (including a silent preparation phase), and a tracking task. Participants rated the tasks as mild to moderate with regard to affect intensity. Significant effects of personality on affect states were demonstrated, indicating higher levels of anxiety, depression, and anger in the high-neuroticism group, and more curiosity in the high-extraversion group. Arterial pressure, heart rate, and facial blood flow increased during task performance in all three conditions. No relationship between facial blood flow changes and muscle activity measured by m. masseter electromyography (EMG) were demonstrated. Digital vasoconstriction occurred in parallel with facial vasodilatation during tracking and in the preparation phase before the speech. There were no moderator effects of neuroticism or extraversion on blood flow or other cardiovascular responses.

Adult↗

PubMed2004

Kinin peptides in human trapezius muscle during sustained isometric contraction and their relation to pain.

To determine the muscular concentration of bradykinin and kallidin during static contraction, microdialysis probes were implanted bilaterally in the trapezius muscles of healthy women. Three hours after probe implantation, 200 microM of the angiotensin-converting enzyme (ACE) inhibitor enalaprilat were added to the perfusion solution in one of the sides for 30 min. Thirty minutes later, the subjects performed a sustained bilateral shoulder abduction at 10% of the maximal voluntary contraction until exhaustion. This protocol was repeated twice, with an interval of at least 17 days. High intersession repeatability was observed in the concentration of bradykinin but not of kallidin. Enalaprilat induced a significant increase in bradykinin levels in the dialysate, without affecting kallidin levels. The sustained contraction induced a significant increase in dialysate levels of both kinin peptides. The contraction also induced a significant increase in pain ratings, as measured by a visual analog scale. During contraction, positive correlations were found between pain ratings and levels of kinin peptides in dialysate, predominantly in the side previously perfused with enalaprilat. Subjects with the higher pain ratings also showed larger increases in kinin peptides in the side previously perfused with enalaprilat. The present results show that both plasma and tissue kinin-kallikrein are activated during muscle contraction, but that their metabolic pathways are differently regulated during rest and contraction, because they showed a different response to ACE inhibition. They also indicate that intramuscular kinin peptides levels, and ACE activity, may contribute to muscle pain.

Adult↗

PubMed2004

Cardiovascular responsiveness to brief cognitive challenges and pain sensitivity in women.

The primary purpose of the study was to determine the relationship between cardiovascular (CV) responsiveness to brief cognitive tasks and pain sensitivity in normotensive individuals. Fifty-eight healthy women without a history of chronic pain were exposed to three laboratory tasks (reading aloud, speech task, and tracking task) and repeated pain testing (electrocutaneous and pressure pain stimulation) while mean arterial pressure (MAP) and heart rate (HR) were continuously recorded. Generally, subjects with higher HR responsiveness to the cognitive tasks displayed a reduced pain sensitivity, particularly to electrocutaneous pain stimulation. Moreover, the two types of pain stimulation seemed to trigger somewhat different CV response patterns. Inclusion of pain-related CV changes as control variables affected the relationship between HR responsiveness and pain sensitivity, although differently for electrocutaneous and pressure pain. However, inclusion of psychological control variables had no significant effects. Although relatively large CV changes were observed during the experimental tasks, small and insignificant changes in simultaneous or subsequent electrocutaneous pain sensitivity occurred. However, significant increases in pressure pain threshold and tolerance occurred after the speech task, during which MAP level was at its highest. The present findings support the hypothesis that pain sensitivity and CV response share a common mechanism, which, however, is not necessarily linked to either elevated blood pressure levels or other risk factors for hypertension.

Adaptation, Psychological↗

PubMed2004

Variation in reporting of pain and other subjective health complaints in a working population and limitations of single sample measurements.

Measuring health complaints by administrating a single report is common. Our aim was to assess variation in pain and other subjective complaints over an extended period, whether a single-sample produces representative data, and determine associations between complaints. Health-complaint reports were collected from postal workers at monthly intervals over a period of 32-34 consecutive months (1997-2000). We computed six compound complaint-severity indices of 30 complaint-severity scores (intensity score x duration score, scale 0-9). In 67% of the scores, the complaints exhibited larger deviation from a reference (12 consecutive reports in the last 24 months of the study period) when using one report from the respective reference period compared with the mean of two consecutive reports. Four consecutive samples were needed to obtain agreement for 95% of the data when the criterion of accepted deviation from the reference was set to +/-1.0. Neither inspection of graphs nor statistical tests revealed any seasonal pattern or trend on either a group or individual level. The musculoskeletal and psychological complaint-severity indices correlated strongly (rs > 0.66). Correlations between the different somatic indices were generally weak or moderate (rs < 0.55). The initial report produced higher complaint ratings than subsequent reports did. Due to large intra-individual complaint variability and higher complaint-severity level exhibited on the initial report compared to those that followed, measuring subjective health with a single-sample approach does not produce data representativeness for average complaints over a period. More than two samples should be collected when the purpose is to reveal changes in health.

Adult↗

PubMed2004

Prospective study of the relationship between musculoskeletal and psychological complaints and electromyographic activity during isometric muscular contractions in a working population.

OBJECTIVES: This study focused on determining whether musculoskeletal and psychological complaints reported monthly over a 4-month period predicted muscular activity during and immediately after standardized worktasks and whether muscular activity during and immediately after these tasks predicted changes in complaint severity in the following 12 months. METHODS: Surface electromyography (EMG) was recorded bilaterally from the upper trapezius, middle deltoid, and forearm extensor muscles of 45 postal workers (30 women) during sustained submaximal (25% of peak force) isometric contractions (wrist extension and shoulder abduction). Self-reported health complaints were recorded monthly. Musculoskeletal and psychological complaint-severity indices (MSI and PI, respectively) were computed from complaint-severity scores (intensity score x duration score). The history of complaints over the previous 4 months was included in adjusted regression models to predict muscular activity during and immediately after submaximal contractions. Muscular activity was included in adjusted models to predict changes in the complaint severity over the subsequent 12-month period. RESULTS: A higher MSI predicted a lower EMG level in the trapezius muscle during submaximal contractions (P<0.014), whereas the PI did not predict the level of EMG in any of the muscles studied (P > 0.194). The EMG activity did not predict changes in the complaint severity over the subsequent 12 months. CONCLUSIONS: These findings may support the hypotheses of pain adaptation or the dysfunction of synergistic muscular control in relation to musculoskeletal complaints. However, the findings did not indicate that increased or decreased muscular activity is a risk factor for heightened levels of complaints in the subsequent 12 months.

Adult↗

PubMed2002

Contraction-related factors affect the concentration of a kallidin-like peptide in rat muscle tissue.

In order to study the effects of the manipulation of various factors related to muscular activity on the concentration of kinins in muscular tissue, a microdialysis probe was implanted in the adductor muscle of the hindlimb in anaesthetized rats. After collection of baseline samples, the perfusion fluid was changed to a Ringer solution containing sodium lactate (10 or 20 mM), adenosine (50 or 100 microM) or a lower pH (7.0 or 6.6). Whereas perfusion with lactate did not have any significant effect on the concentration of kinins in the dialysate, the perfusion with a lower pH or with adenosine dose-dependently increased the kinin content in the samples. In a second microdialysis experiment, by using specific radioimmunoassays (RIA) for bradykinin and kallidin, we observed that about 70 % of the total kinins dialysed from rat muscle are a kallidin-like peptide. Also, the simultaneous perfusion with 100 microM caffeine totally abolished the increase in kinin levels induced by the perfusion at pH 6.6. In a third experiment, soleus muscles from rat were stimulated in vitro during 30 min in the presence or absence of 77 microM caffeine. Electrically stimulated contraction, but not the addition of 10 mU ml(-1) insulin, induced an increase in the concentration of the kallidin-like peptide in the buffer. This effect was totally prevented by the addition of the adenosine antagonist caffeine. These results show that a kallidin-like peptide is released from rat muscle, and that its production is enhanced by muscle activity. Furthermore, the increase in kinin peptides during muscle contraction may be mediated by an increase in adenosine levels.

Adenosine↗

PubMed2002

Effects of localization and intensity of experimental muscle pain on ankle joint proprioception.

Accurate proprioceptive input is a prerequisite for balance control and coordination of movement. The present study investigated whether experimental muscle pain induced in healthy human subjects disturbed movement sense (detection of movement) or position sense (recognition of a reference position). Muscle pain was produced by infusion of 6% hypertonic saline simultaneously in m. tibialis anterior (TA) and m. soleus (experiment 1), by infusion of 6% hypertonic saline in TA (experiment 2) and by infusion of 9% hypertonic saline in TA (experiment 3). Control measurements were done with infusions of 0.9% isotonic saline. All infusions of 6% and 9% saline produced pain intensities significantly higher than the corresponding control infusions. Only infusion of 6% saline in two muscles (visual analogue scale=4-5) produced an elevation in movement detection thresholds which was significantly higher, compared with before infusion. No other significant changes in movement and position sense were found during the painful or control infusions. Pain of relatively high intensity in two antagonist muscles is necessary to disturb the movement detection threshold. The ability to recognize a reference position is not disturbed by experimentally induced muscle pain. Whether the disturbed movement sense is caused by sensitivity changes in muscle spindle afferents or altered processing of proprioceptive input cannot be answered. The present findings indicate that human ankle proprioception is rather robust to muscle pain.

Adult↗

PubMed1998

Sympathetic nerve activity after acupuncture in humans.

The aim of the present study was to determine if acupuncture stimulation inhibits sympathetic nerve activity in humans. Multiunit efferent postganglionic sympathetic activity was recorded with a tungsten microelectrode inserted in a muscle fascicle of the peroneal nerve. Mean arterial pressure, heart rate and skin blood flow were also monitored. Pain thresholds were measured by electrical tooth pain stimulation. After a 30 min rest, acupuncture needles were inserted bilaterally into the Li 11 and the Li 4 acupuncture points, and manipulated until 'chi' cramp-like sensation was reported. Electrical stimulation (2 Hz, 0.6-0.8 ms duration, maximal tolerated stimulation without discomfort) was delivered for 30 min and the physiological recordings were continued for 90 min after the end of acupuncture. In a placebo control experiment, the same procedure was followed, except that acupuncture needles were inserted subcutaneously and no manipulation or stimulation was given. The stimulator delivered pulses to an unconnected channel, hence, the same audiovisual stimuli were experienced as with acupuncture, and care was taken to ask the same questions about sensations in the placebo and the acupuncture groups. Electroacupuncture produced an increase in pain threshold which was paralleled by a transient increase in muscle sympathetic nerve activity. During acupuncture, there was a small increase in heart rate and mean arterial pressure, but there was no post-acupuncture hypotension. The placebo control procedure did not change pain threshold or sympathetic nerve traffic. The findings suggest that electroacupuncture produces moderate hypoalgesia in humans paralleled by a significant increase in muscle sympathetic nerve activity.

Acupuncture Therapy↗