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At least 1,243 records · Page 69Linked to original sources
PubMed1998

Symptoms of hand-arm vibration syndrome in gas distribution operatives.

OBJECTIVES: To survey the prevalence and severity of hand-arm vibration syndrome symptoms (HAVS), and to estimate past and current exposure to hand held vibrating tools in a sample of gas distribution operatives breaking and re-instating road surfaces. METHODS: 153 gas distribution operatives (participation rate 81%) from three company districts were assessed by an administered questionnaire, a clinical examination, and a simple cold challenge test to the hands. Exposure histories were taken aided by a picture album of past and current tools. Information was obtained from several sources on the likely vibratory characteristics of those tools. Estimates were thus obtained of the frequency of blanching and neurological complaints in operatives, and of their lifetime hours of exposure and lifetime dose of vibration. RESULTS: On average, the sample had spent 16 years in employment involving use of vibratory tools. 24% had symptoms or signs of blanching after use of tools in the industry; 46% had troublesome persistent complaints of paraesthesiae or numbness, and these symptoms extended into the hands or arms in 18% of workers. In 5.9% the distribution of symptoms was suggestive of carpal tunnel syndrome; and of ulnar nerve entrapment in a further 3.9%. The risks of blanching and neurological complaints rose significantly with lifetime hours of use of vibrating tools and lifetime dose of vibration. Symptoms were generally mild and apparent only after a prolonged interval, but there were exceptions, and cases had occurred after lower recent exposures. CONCLUSIONS: It has been suggested that aspects of the gas distribution operative's work mitigate against the risk normally anticipated from use of pneumatic road breaking tools. By contrast our data suggest that symptoms of HAVS do occur, given sufficient exposure, a finding relevant not only to gas supply workers, but also to workers from other industries who break and repair road surfaces.

Adult↗
PubMed1995

Proprioceptive sensory codes mediating movement trajectory perception: human hand vibration-induced drawing illusions.

To study the organization of the proprioceptive sensory codes subserving movement trajectory perception, complex hand drawing illusions were elicited using various vibration patterns applied to the wrist muscles of nine human subjects. It was established that it is possible to elicit kinesthetic illusions involving spatially oriented lines and geometrical shapes such as rectilinear or curvilinear figures by activating four groups of muscle tendons at the wrist level. The vibration sequences specifically evoking each shape were determined by varying the vibration frequency, the duration of each stimulus applied, and the vibrator onsets, and by applying the vibrations either successively or simultaneously. The proprioceptive coding of a trajectory can be modelled in terms of a series of vectors, the direction of which depends on the anatomical sites of the muscles that are stretched and shortened during the movement. The vector giving the spatial path of a movement is the sum vector of the vectors determined on the basis of the proprioceptive inputs originating from each muscle, and the modulus of the resulting vector is the instantaneous velocity of the movement. In line with previous cortical data, our results suggest that the perception of the spatial paths of limb segment movements is coded in joint space kinematic coordinates on the basis of the relevant ongoing proprioceptive information. It therefore emerges from the results of this study that muscle proprioception is able to generate spatiotemporal afferent patterns that may mediate complex cognitive operations such as those involved in the memorizing and recognition of motor forms.

Female↗
PubMed1996

Mechanoenergetics of negative inotropism of ventricular wall vibration in dog heart.

Mechanical vibration depresses cardiac contractility. We studied the mechanoenergetic effects of this negative inotropism in the left ventricle (LV) of an isolated, cross-circulated dog heart preparation. We took full advantage of the mechanoenergetic relationship among the LV end-systolic elastance (Emax, contractility index), systolic pressure-volume area (PVA), and myocardial oxygen consumption (VO2). PVA is a measure of the total mechanical energy that cardiac contraction generates. PVA correlates closely with VO2. The VO2 intercept of the VO2-PVA relation reflects the VO2 component for excitation-contraction (E-C) coupling plus basal metabolism (PVA-independent VO2). VO2 above the PVA-independent VO2 reflects the VO2 component for mechanical contraction (PVA-dependent VO2). When we applied 70-Hz vibration of 2-mm amplitude to a LV wall region, it instantly decreased Emax and PVA by 20%, followed by a 10% decrease in VO2 at a fixed volume. However, the vibration neither lowered the VO2-PVA relation obtained at different LV volumes, unlike ordinary negative inotropism, nor changed its slope (1.88 +/- 0.23 vs. 1.86 +/- 0.23 x 10(-5) ml O2.mmHg-1.ml-1). The virtually zero delta PVA-independent VO2/delta Emax with vibration indicates a much smaller O2 cost of Emax than that seen with calcium and propranolol inotropism. These mechanoenergetics support the hypothesis that mechanical vibration primarily suppresses cardiac contractility without suppressing E-C coupling.

Animals↗
PubMed1981

Ventilatory responses to muscular vibrations in healthy humans.

In healthy humans, we studied the effect of high-frequency mechanical vibrations applied unilaterally to the tendon of the biceps or triceps brachialis on ventilation and the breathing pattern. This stimulus preferentially activates the muscle spindle afferents. Increase of respiratory frequency and changes in the ventilatory timing started at the first or second inspiration during tendon stimulation, and no adaptation occurred as long as the vibrations continued. The tidal volume and mean inspiratory flow rate were only enhanced in individuals having high-frequency breathing during eupnea. The changes in ventilatory variables were observed when the motor response to vibrations was tested under isometric or isotonic conditions. Various experimental procedures enabled us to induce a tonic reflex contraction in either the vibrated muscle or the antagonist of no reflex contraction in either group of muscles. In all cases the increase in minute ventilation was identical. These changes in breathing pattern was not associated with a significant decrease in alveolar CO2 pressure and did not seem to be responsible for important variations in respiratory gas exchanges. The response to high-frequency vibrations was also studied after ventilation was increased with added dead space. The magnitude of hyperventilation an the pattern of ventilatory response produced by tendon stimulation did not change with increased ventilation. In conclusion, the stimulation of muscle spindles in human induces changes in ventilation and pattern of breathing , and the occurrence of a reflex muscular contraction does not seem necessary in order to obtain such effects.

Adult↗
PubMed1988

Respiratory pattern changes produced by intercostal muscle/rib vibration.

Large-amplitude vibration of the intercostal muscles/ribs has an inhibitory effect on inspiratory motor output. This effect has been attributed, in part, to the stimulation of intercostal muscle tendon organs. Intercostal muscle/rib vibration can also produce a decrease or increase in respiratory frequency. Studies were conducted 1) to determine whether, in addition to intercostal tendon organs, costovertebral joint mechanoreceptors (CVJR's) contribute to the inspiratory inhibitory effect of intercostal muscle/rib vibration (IMV) and 2) to explain the different respiratory frequency responses to IMV previously reported. Phrenic (C5) activity was monitored in paralyzed thoracotomized, artificially ventilated cats. Vibration (125 Hz) at amplitudes greater than 1,200 micron of one T6 intercostal space in decerebrated vagotomized rats reduced phrenic activity. This response was still present but weaker in some animals after denervation of the T6 intercostal muscles. Subsequent denervation of the T6 CVJR's by dorsal root sections eliminated this effect. Respiratory frequency decreased during simultaneous vibration (greater than 1,200 micron) of the T5 and T7 intercostal spaces in vagotomized cats. Respiratory frequency increased during IMV of two intercostal spaces (greater than 1,300 micron) in vagal intact cats. The use of different anesthetics (pentobarbital, allobarbital) did not alter these results. We conclude that CVJR's may contribute to the inhibitory effect of IMV on medullary inspiratory activity. The presence or absence of pulmonary vagal afferents can account for the different respiratory frequency responses to IMV, and different anesthetics did not influence these results.

Animals↗
PubMed2003

Hemodynamic and ventilatory effects of manual respiratory physiotherapy techniques of chest clapping, vibration, and shaking in an animal model.

Chest clapping, vibration, and shaking were studied in 10 physiotherapists who applied these techniques on an anesthetized animal model. Hemodynamic variables (such as heart rate, blood pressure, pulmonary artery pressure, and right atrial pressure) were measured during the application of these techniques to verify claims of adverse events. In addition, expired tidal volume and peak expiratory flow rate were measured to ascertain effects of these techniques. Physiotherapists in this study applied chest clapping at a rate of 6.2 +/- 0.9 Hz, vibration at 10.5 +/- 2.3 Hz, and shaking at 6.2 +/- 2.3 Hz. With the use of these rates, esophageal pressure swings of 8.8 +/- 5.0, 0.7 +/- 0.3, and 1.4 +/- 0.7 mmHg resulted from clapping, vibration, and shaking respectively. Variability in rates and "forces" generated by these techniques was <20% in average coefficients of variation. In addition, clinical experience accounted for 76% of the variance in vibration rate (P = 0.001). Cardiopulmonary physiotherapy experience and layers of towel used explained approximately 79% of the variance in clapping force (P = 0.004), whereas age and clinical experience explained >80% of variance in shaking force (P = 0.003). Application of these techniques by physiotherapists was found to have no significant effects on hemodynamic and most ventilatory variables in this study. From this study, we conclude that chest clapping, vibration, and shaking 1). can be consistently performed by physiotherapists; 2). are significantly related to physiotherapists' characteristics, particularly clinical experience; and 3). caused no significant hemodynamic effects.

Adult↗
PubMed2003

Vibration-induced changes in EMG during human locomotion.

The present study was set up to examine the contribution of Ia afferent input in the generation of electromyographic (EMG) activity. Subjects walked blindfolded along a walkway while tendon vibration was applied continuously to a leg muscle. The effects of vibration were measured on mean EMG activity in stance and swing phase. The results show that vibration of the quadriceps femoris (Q) at the knee and of biceps femoris (BF) at the knee enhanced the EMG activity of these muscles and this occurred mainly in the stance phase of walking. These results suggest involvement of Ia afferent input of Q and BF in EMG activation during stance. In contrast, vibration of muscles at the ankle and hip had no significant effect on burst amplitude. Additionally, the onset time of tibialis anterior was measured to look at timing of phase transitions. Only vibration of quadriceps femoris resulted in an earlier onset of tibialis anterior within the gait cycle, suggesting involvement of these Ia afferents in the triggering of phase transitions. In conclusion, the results of the present study suggest involvement of Ia afferent input in the control of muscle activity during locomotion in humans. A limited role in timing of phase transitions is proposed as well.

Adult↗
PubMed2005

Texture signals in whisker vibrations.

Rodents excel in making texture judgments by sweeping their whiskers across a surface. Here we aimed to identify the signals present in whisker vibrations that give rise to such fine sensory discriminations. First, we used sensors to capture vibration signals in metal whiskers during active whisking of an artificial system and in natural whiskers during whisking of rats in vivo. Then we developed a classification algorithm that successfully matched the vibration frequency spectra of single trials to the texture that induced it. For artificial whiskers, the algorithm correctly identified one texture of eight alternatives on 40% of trials; for in vivo natural whiskers, the algorithm correctly identified one texture of five alternatives on 80% of trials. Finally, we asked which were the key discriminative features of the vibration spectra. Under both artificial and natural conditions, the combination of two features accounted for most of the information: The modulation power-the power of the part of the whisker movement representing the modulation due to the texture surface-increased with the coarseness of the texture; the modulation centroid-a measure related to the center of gravity within the power spectrum-decreased with the coarseness of the texture. Indeed, restricting the signal to these two parameters led to performance three-fourths as high as the full spectra. Because earlier work showed that modulation power and centroid are directly related to neuronal responses in the whisker pathway, we conclude that the biological system optimally extracts vibration features to permit texture classification.

Action Potentials↗
PubMedDate not supplied

Vibration and its effects on the body.

OBJECTIVES: To assess the effects of machine-induced vibration on workers and to determine effective precautions for vibration-induced trauma. SUBJECTS AND METHODS: The study group consisted of 114 workers who were randomly selected: 50 rock drill workers and 64 truck heavy vehicle operators. Fifty-four office workers were designed as controls. The study and control groups were age-matched. All subjects were interviewed to determine subjective symptoms using a 38-item questionnaire designed by the Medical Committee of Vibration Disease, Japanese Association of Industrial Health. RESULTS: The complaints of pain in the fingers, sensitivity to cold, numbness and pain of fingers at night, weakness of static position, wrist-elbow pain, difficulty in bending and stretching elbow, pain in shoulder when holding up arms, lower back pain, sleeping disturbance and hearing difficulty were significantly higher in rock drillers than heavy vehicle operators and office workers (p < 0.05-0.01). CONCLUSION: Permanent vibration exposures cause negative physical effects that may lead to occupational diseases. In order to be protected against whole-body and hand-arm vibrations, technical and medical measures must be taken into account.

Adult↗
PubMedDate not supplied

Comparison of the protective efficacy of neurotrophins and antioxidants for vibration-induced trauma.

BACKGROUND: Patients undergoing temporal bone surgery or subjects working with vibrating tools may develop vibration-induced hearing loss (VHL). The aim of this study was to characterize the effects of pretreatment with N-acetylcysteine (NAC) or the neurotrophic factors, brain-derived neurotrophic factor (BDNF) and ciliary neurotrophic factor (CNTF), on VHL in an animal model. METHODS: Trauma to the cochlea was created with a vibrating probe placed on the bone of the external ear canal. BDNF and CNTF(Ax1) were delivered into the cochlea with mini-osmotic pumps. NAC was delivered into the cochlea by round window membrane (RWM) injection, by RWM permeation, or by oral administration. Hearing was evaluated with electrocochleography (ECoG). RESULTS: For control animals, vibration resulted in an average immediate threshold shift of 42 +/- 26 dB. NAC provided no protective benefit in animals subjected to VHL, regardless of the delivery method, with average threshold shifts varying from 38 to 56 dB across groups. NAC injection through the round window membrane was toxic, causing a ECoG threshold shift of >25 dB. In BDNF+CNTF(Ax1)-treated animals, immediate hearing loss was similar to that in control animals. There was a trend of threshold recovery by 1 day after vibration; however, the improvement was not statistically significant, nor was there a significant difference in 1-day thresholds across groups. CONCLUSIONS: Local infusion of BDNF and CNTF(Ax1) may enhance the rate of recovery from VHL, compared to control animals. In contrast, NAC had no effect on VHL, and when delivered by RWM injection, was actually toxic to the inner ear.

Animals↗
PubMed1975

Vibration-induced inhibition of vascular smooth muscle contraction.

Vascular smooth muscle is known to be exposed to an oscillating strain under physiological and patho-physiological conditions as well as in different occupational and environmental situations. The effect of vibrations of smooth muscle seems to be largly unknown. In the present experiments on isolated preparations of the rat portal vein and the rabbit thoracic aorta, imposed sinusoidal changes in length were found to cause prompt reduction in active force, the extent of which was dependent on amplitude (1-10% of tissue length, peak to peak, i.e. approximately plus or minus 50-500 mum) and frequency of vibration (1-400 Hz) as well as on the prevailing level of active and passive forces. Vibration caused only small and inconsistant reductions of passive force of vascular smooth muscle. The results are in accordance with the hypothesis that vibrations exert a direct action on the contractile process by causing an increased rate of detachment of actin-myosin cross-links. It is suggested that, in vivo, vibrations may affect the diameter of conduit arteries locally in the case of turbulent blood flow as seen in post-stenotic dilation and arterio-venous anastomosis. Possibly, even the normal pulse pressure oscillations may sometimes tend to inhibit the smooth muscle activity in such arteries and thereby influence their diameters.

Animals↗
PubMed1992

Diastolic vibration improves systolic function in cases of incomplete relaxation.

BACKGROUND: Incomplete relaxation of the left ventricle (LV) affects LV filling, but the subsequent effect on LV systolic function remains unclear. We attempted to improve relaxation by applying oscillatory mechanical perturbation during diastole (diastolic vibration) and examined the extent to which systolic function improved. METHODS AND RESULTS: Using 10 open-chest canine preparations, pacing tachycardia and administration of propranolol were imposed to induce various levels of incomplete relaxation. Myocardial length perturbation was induced with an oscillator attached to the LV surface (50 Hz, 1-mm amplitude) and was restricted to the period from the beginning of isovolumic relaxation to end diastole. At resting heart rates, diastolic vibration caused an immediate decrease in the time constant (T) of LV pressure fall without any influence on heart rate, LV peak systolic pressure (peak LVP), stroke volume (SV), LV peak positive dP/dt, and total systemic vascular resistance. With pacing tachycardia, diastolic vibration increased both peak LVP and SV at 160 beats per minute (before) and 120 beats per minute (after propranolol), simultaneously decreasing both T and LV diastolic pressures and increasing end-diastolic segment length. The increase in peak LVP and SV caused by diastolic vibration correlated with the T/diastolic interval (r = 0.82), the assumed index of severity of incomplete relaxation. CONCLUSIONS: These results suggest that diastolic vibration accelerates the LV relaxation rate and that this increased relaxation improves systolic function through the Frank-Starling mechanism.

Animals↗
PubMed2000

Circulating adhesion molecules in patients with vibration-induced white finger.

We investigated whether a relationship existed between soluble adhesion molecules and vascular damage from vibration-induced white finger. Thirty-five men exposed to vibration and 40 healthy control subjects were examined. Concentrations of soluble E-selectin intercellular adhesion molecules, and vascular cell adhesion molecules in serum were measured with sandwich enzyme-linked adhesion immunosorbent assay. Neither E-selectin nor intercellular adhesion molecule levels are elevated in men exposed to vibration with white finger compared to levels in men exposed to vibration without white finger and control subjects. The serum level of soluble vascular cell adhesion molecules is significantly increased in patients with vibration-induced white finger.

Aged↗
PubMed2001

Effects of length and depth of vibration of the vocal folds on the relationship between transglottal pressure and fundamental frequency of phonation in canine larynges.

The relationship between fundamental frequency of phonation (F0) and the change in F0 per unit change of transglottal pressure (dF/dP) was investigated in 3 excised canine larynges. The effects of the length and depth of vocal fold vibration on the relationship between dF/dP and F0 were evaluated. A positive correlation between dF/dP and F0 was observed when an increase in F0 was accompanied by a decrease in the depth of vibration while the length of vibration reached a plateau. Although a negative correlation between dF/dP and F0 was observed in only 1 case, this relationship seemed relevant to the length of vibration. These results help to clarify the adjustments of length and depth of vibration involved in regulating F0.

Animals↗
PubMed1983

Effects of vibration, noise and restraint on heart rate, blood pressure and renal blood flow in the pig.

Pigs and other farm animals are usually transported at least once during their lives; for example, all meat animals are finally taken to the abattoir for slaughter. The vibration, noise and handling associated with such transportation is usually novel to the animals, and therefore constitutes a potential 'stressor'. Such adverse stimuli may trigger physiological and psychological changes which rapidly produce profound changes in blood flow to peripheral organs, particularly the kidney, whose blood vessels are richly supplied with sympathetic nerve fibres. In the present study, ultrasonic techniques have been used with chronically implanted flow sensors for measuring heart rate (HR) and changes in renal blood flow (RBF) in conscious, freestanding and unanaesthetized pigs to monitor their cardiovascular responses to vibration, noise and various handling procedures. In addition, arterial blood pressure (BP) was measured via a catheter placed in the carotid artery. To ensure that vibration and noise could be accurately reproduced, a transport simulator (TS) was constructed in the laboratory. A small decrease of approximately 5% was observed in RBF during the first few minutes of exposure to vibration and noise, but this returned to the control levels monitored in undisturbed animals within a few minutes. Thereafter, RBF became significantly elevated for the remaining period of exposure to vibration and noise. In contrast, HR remained significantly increased throughout. BP was not significantly changed as a result of the experimental manipulation. Restraint and handling of the animals appeared to cause maximal disturbance. HR and BP were more than doubled compared with the resting value, but there was a concomitant marked decrease in RBF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Detection of wall vibrations by means of cepstrum analysis.

Preliminary studies on the usefulness of the cepstrum analysis of Doppler signals for detecting vibrations of periodically vibrating structures, such as aortic valves in children with innocent heart murmurs, were carried out in two stages. First, by cepstrum analysis of computer simulated frequency modulated signals, and second, by the analysis of real Doppler signals generated by a vibrating reflector. Simulation and experimental studies were performed for modulating frequencies from 10 Hz to 60 Hz while changing the amplitude of vibrations from 0.2 mm to 1 mm. The striking similarity between computed cepstra for simulated and for real Doppler signals encouraged further studies in patients. Cepstra computed from two Doppler recordings in children with weak innocent vibratory heart murmurs showed characteristic cepstral lines for modulating frequencies at 21 Hz and 30 Hz in the first and second child, respectively, which were interpreted as the vibration frequencies of the aortic valve leaflets.

Aortic Valve↗
PubMed2000

Vibrational angioplasty and hydrophilic guidewires in the treatment of chronic total coronary occlusions.

PURPOSE: To study the efficacy and safety of vibrational angioplasty versus hydrophilic guidewires for recanalizing chronic total occlusions (CTOs) of the coronary arteries. METHODS: In a retrospective study, 99 patients with old (>3 months) CTOs resistant to conventional techniques were treated either with vibrational angioplasty (group A, n = 72) or 0.014-inch hydrophilic guidewires (group B, n = 27). The selection of the technique (vibrational angioplasty or hydrophylic guidewires) was dependent only upon device availability. A variety of guidewires were employed in conjunction with vibrational angioplasty. RESULTS: The crossing success rates in groups A and B were 86.1% (62/72) and 55.5% (15/27) (p < 0.05), with final procedural success rates of 75% (54/72) and 44.4% (12/27) (p < 0.01), respectively. The main reasons for failure were inability to cross the lesion with a guidewire (10/18 in group A and 12/15 in group B) and large dissections resulting in vessel closure (2/18 in group A and 2/15 in group B). Three major complications were seen, 2 in group A and 1 in group B. Three vessel perforations were reported in group A. Both techniques needed prolonged fluoroscopy times. CONCLUSIONS: Vibrational angioplasty was more successful in treating CTOs compared to hydrophilic guidewires and had similar complication rates (most without clinical sequelae).

Adult↗
PubMed2006

Inaudible temporomandibular joint vibrations.

The aim was to test the hypothesis that inaudible vibrations with significant amounts of energy increasing during jaw movements can be recorded in the temporomandibular joint (TMJ) area. Twenty one subjects, who could perform wide opening movements without feeling discomfort, 12 with and 9 without TMJ sounds audible at conventional auscultation with a stethoscope, were included. Recordings were made during opening-closing, 2/s without tooth contact, and during mandibular rest, using accelerometers with a flat frequency response between the filter cutoff frequencies 0.1 Hz and 1000 Hz. The signals were digitized using a 24 bits card and sampled with the rate 96000 Hz. Power spectral analyses, and independent and paired samples t-tests were used in the analysis of the vibration power observed in frequency bands corresponding to audible and inaudible frequencies. An alpha-level of 5% was chosen for accepting a difference as being significant. In the group with audible sounds, about 47% of the total vibration energy was in the inaudible area below 20 Hz during opening-closing and about 76% during mandibular rest. In the group without audible sounds, the corresponding proportions were significantly different, 85% vs. 69%. The energy content of the vibrations, both those below and those above 20 Hz, increased significantly during jaw movement in both groups. Furthermore, percentage of signal energy above 20 Hz showed a noticeable increase in the group of subjects with audible sounds. This can physically be explained by decreased damping properties of damaged tissues surrounding the TMJ. Vibrations in the TMJ area can be observed with significant portions in the inaudible area below 20 Hz both during mandibular rest and during jaw movements whether or not the subjects have audible joint sounds. Further studies are needed to identify sources and evaluate possible diagnostic value.

Adult↗