Search PubMed⌕ Search

Biomedical subjects

O Korhonen

Publications and source records attributed to O Korhonen.

At least 37 records · Page 2Linked to original sources
PubMed1990

Vibration perception threshold of forest worker's finger during temporary obstructed blood circulation.

Vibration detection threshold (VPT) of 149 professional forest workers was measured during a compulsory annual health examination. The authors' earlier developed measuring method for VPT of finger was modified. The blood circulation of the hand was obstructed for 6 min and VPT was measured 4 min after releasing the obstruction. VPTs of all forest workers increased during obstruction. In forest workers suffering from decreased hand grip force (decreased HGF) the increase of VPT differed significantly from forest workers without symptoms, and VPT in the former group still increased after releasing the obstruction. VPT remained also at the raised level after releasing the obstruction with forest workers suffering from vibration-induced white finger (VWF). Nevertheless, on an individual basis even the modified measuring method failed to discriminate subjects without symptoms from those with symptoms of hand-arm vibration syndrome. The raised VPT and sensitivity for obstruction of blood circulation suggest that the reason for decreased HGF in forest workers may be a consequence of an injury in the peripheral nerves.

Adult↗
PubMed1990

Measuring method for vibration perception threshold of fingers and its application to vibration exposed workers.

A measuring method for the vibration perception threshold (VPT) of fingers has been developed. The VPTs of 118 and 149 professional forest workers were measured during a compulsory annual health examination in 1979 and 1983, respectively. Also the VPTs of eight pedestal grinders, who were suffering vibration-induced white finger (VWF), were measured in 1979 and 1983. The control group consisted of 20 research workers who had no vibration exposure in the past and no symptoms in their hands. The measuring system for VPT gave repeatable results. The frequency of the most sensitive VPT of vibration exposed workers alternated between 63 and 125 Hz instead of 125 Hz of subjects without vibration exposure. The VPT of the pedestal grinders and forest workers with decreased hand grip force and with vibration-induced white finger were significantly higher than those of the controls. The VPTs of the forest workers decreased slightly and that of the grinders increased from 1979 to 1983. In spite of long vibration exposure in the past and continuing lower level vibration exposure, the increased VPT of forest workers does not seem to be permanent.

Adult↗
PubMed1988

Forestry workers exposed to vibration: a neurological study.

Neurological findings were examined in 186 forestry workers with a mean exposure to chain saw vibration of 16.6 hours. The prevalence of active vibration induced white fingers was 5%, parethaesias of the hands 53%, and muscle weakness 13%. Clinical polyneuropathy was observed in 16 forestry workers in the hands (7.5%) which did not correlate with alcohol consumption. Seventy nine forestry workers of the total population were selected for electromyographic examination. Generalised EMG based polyneuropathy in the hands was observed in only two of the 79 forestry workers (2.5%). The carpal tunnel syndrome was found in 20 of the 79 forestry workers (26%). Headache and vertigo were not linked with exposure to vibration in forestry and a significant part of the numbness reported may be due to the carpal tunnel syndrome. Sensorimotor polyneuropathy is rare among forestry workers. The rise in the vibration detection thresholds was linked to the carpal tunnel syndrome.

Adult↗
PubMed1987

Skin blood flow during incremental exercise in a thermoneutral and a hot dry environment.

Eight physically fit men performed two incremental bicycle ergometer tests, one in an ambient temperature of 25 degrees C and the other at 40 degrees C. Oesophageal temperature (Tes) increased continuously throughout the tests up to 38.0 and 38.3 degrees C, respectively. In both environments, forearm blood flow (plethysmography) was linearly related to Tes above the Tes threshold for vasodilation, but at the heaviest work loads this relationship was clearly attenuated and therefore indicated skin vasoconstriction, which tended to be more pronounced at 25 degrees C. During recovery at 25 degrees C, in some subjects the forearm blood flow increased above the levels observed at the end of the graded exercise in spite of a decreasing Tes. Skin blood flow, measured by laser Doppler flow meter at the shoulder, was quantitatively different but, on average, seemed to reveal the same response pattern as the forearm blood flow. In spite of the higher level of skin blood flow in the heat, blood lactate accumulation did not differ between the two environments. The present results suggest that there is competition between skin vasoconstriction and vasodilation at heavy work rates, the former having precedence in a thermoneutral environment to increase muscle perfusion. During short-term graded exercise in a hot environment, skin vasoconstriction with other circulatory adjustments seems to be able to maintain adequate muscle perfusion at heavy work levels, but probably not during maximum exercise.

Adult↗
PubMed1987

Autonomic neuropathy and vibration exposure in forestry workers.

The variation in heart rate (HRV) at rest and during deep breathing (6 cycles a minute) of 88 professional lumber jacks was studied using a computer technique. The traditional indexes of HRV (CV, CVS, MEAN) were calculated and the spectral components of the HRV were also computed. There was a significant difference (p less than 0.001) between the HRV indexes during the deep breathing test in those with the shortest (CV = 10.1 +/- 1.1) and those with the longest (CV V 6.2 +/- 0.4) exposures to vibration. The values of the HRV indexes decreased with age, but multiple regression analysis showed that the total exposure time to vibration had an independent negative association with the HRV. There were significant differences in all the frequency bands (frequency related power, FRP) of the heart rate between those with the longest and those with the shortest exposures. The HRV during a deep breathing test is associated with the activity of the parasympathetic nervous system and is decreased in autonomic neuropathies. Our results suggest that prolonged exposure to the vibration caused by a chain saw has a negative effect on the parasympathetic activity and thus causes autonomic dysfunction.

Adult↗
PubMed1987

Circulatory and thermal responses of men with different training status to prolonged physical work in dry and humid heat.

Eight physically trained and eight untrained, unacclimated men walked on a treadmill at 30% of their maximum oxygen consumption up to 3.5 h in a thermoneutral [20 degrees C/40% relative humidity (RH)], a warm humid (30 degrees C/80% RH), and a hot dry (40 degrees C/20% RH) environment while wearing industrial work clothing. Their oxygen consumption, rectal and skin temperatures, sweating, cardiac output, heart rate, stroke volume, and peripheral blood pressure were measured during the tests. Thirteen of the 32 heat stress tests were prematurely stopped due to high rectal temperature, high heart rate, subjective fatigue, or heat syncope. The physiological strain, as indicated by the rectal temperature and heart rate, was not significantly different between the warm humid and hot dry environments (wet bulb globe temperature approximately 28 degrees C). The rectal temperature and heart rate responses of the physically trained and untrained subjects did not differ in any of the environments. In the heat, the heart rate was significantly higher than in the thermoneutral environment, but because of the markedly reduced stroke volume the average cardiac output was not different between the three environments. The impaired work performance in the heat seemed mainly to be related to the circulatory instability accompanying the increased cutaneous circulation.

Adult↗
PubMed1987

Effect of indoor feeding season for cattle on lung function of dairy farmers.

The effect of the indoor feeding season for cattle on pulmonary function was studied in 91 randomly selected healthy, non-smoking dairy farmers who did not use personal dust respirators. All the farmers lived in the rural municipality of Pielavesi in eastern Finland. The reference group consisted of 90 healthy, non-smoking urban dwellers who were teachers randomly selected from all the teachers employed by the city of Kuopio (situated in the same administrative district as Pielavesi). Studies of pulmonary function included flow-volume spirometry and measurement of pulmonary diffusing capacity. Among farmers, even a follow-up period of only 6 months was long enough to reveal restrictive impairment in lung function; among teachers restrictive impairment was not found. No evidence of impairment of pulmonary diffusing capacity was found in either of the study groups during the follow-up. Among teachers, changes in lung function did not differ from those previously reported as physiologically normal.

Adult↗
PubMed1987

Methodological aspects of lung function studies.

With several variables, such as patient or subject, disease, surroundings, machine and personnel, it is a wonder that successful epidemiological studies using lung function parameters can be done at all.

Calibration↗
PubMed1986

Hand-grip force in lumberjacks: two-year follow-up.

Hand-grip force was measured in 63 professional lumberjacks in 1978 and again in 1980. Lumberjacks with vibration-induced white fingers (VWF) had lost 21% of their muscle force during the two years. Lumberjacks with no hand-arm symptoms had lost 5% of their muscle force in the same time period. Lumberjacks with subjectively diminished hand muscle force had a slight increase in muscle force during the follow-up time. These results suggest that long-term exposure to vibration causes a decrease in muscle force.

Adult↗
PubMed1986

Effects of industrial respirators on breathing pattern at different work levels.

The effects of a filtering device and an air-line apparatus on breathing pattern were studied in healthy men with different physical characteristics and work capacity. The subjects comprised nine construction workers aged 35-44, and nine firemen aged 21-35. The construction workers' mean maximal oxygen consumption (VO2max) was 34.5 ml min-1 kg-1, the firemen's 66.9 ml min-1 kg-1. Breathing pattern was analyzed for its components, inspiratory time, expiratory time, breathing frequency, tidal volume, and pulmonary ventilation at rest, during two submaximal treadmill walks when the subjects' absolute work load was equal, and during recovery. Neither the filtering device nor the air-line apparatus had a significant effect on breathing pattern when compared with the control values measured twice with a low-resistance breathing valve. A significantly longer expiratory time, lower breathing frequency, and smaller pulmonary ventilation were found for the firemen with the breathing valve and the industrial respirators. The breathing pattern of the construction workers and the firemen differed, but the alterations were not induced by the use of the filtering device or the air-line apparatus when studied at aerobic work levels up to 60% VO2max.

Adult↗
PubMed1986

Aerobic and anaerobic responses to incremental exercise in a thermoneutral and a hot dry environment.

In an investigation of the effect of acute heat exposure on aerobic and anaerobic metabolism, eight unacclimated men performed two incremental bicycle ergometer tests in random order, once under thermoneutral conditions (25 degrees C) and once in a hot dry (40 degrees C) environment. Oxygen consumption (VO2) and pulmonary ventilation were measured every minute. Fingertip blood samples were taken at each work level for blood lactate (LA) determination. Compared to the results at 25 degrees C, the mean VO2 was significantly (P less than 0.01) lower during exercise at 40 degrees C. In the hot dry environment the blood lactate threshold was slightly reduced in four subjects, but neither the average peak nor the post-exercise blood LA values differed from the findings at 25 degrees C. During the exercise-heat stress, the ventilatory threshold did not change significantly. The results indicated that, during relatively short-term incremental exercise in a hot environment, almost adequate muscle metabolism can be maintained.

Adult↗
PubMed1986

Finger peripheral resistance during local cold provocation in vasospastic disease.

Finger systolic blood pressure (FSBP), finger arterial inflow (FAI), finger venous opening pressure (FVOP), and finger peripheral resistance (FPR) were evaluated in 56 workers exposed to chain-saw vibration. Twenty-one of the workers were free from vibration-induced white finger (VWF). In 17 subjects VWF had ceased; 12 of the subjects had active VWF; 6 subjects had Raynaud's disease. The subjects were examined in a supine position under thermoneutral conditions with strain-gauge plethysmography. Cold provocation of the finger caused a significant reduction in FSBP in the groups with Raynaud's disease and active VWF. The finger circulation of the subjects with active VWF and that of those with Raynaud's disease showed a significantly reduced FAI when compared with that of the symptom-free referents. Finger cooling produced a gradual reduction in the FVOP and a significantly increased FPR of the subjects with active VWF and in those with Raynaud's disease. FPR was already increased in the Raynaud's disease group at the beginning of the test, whereas it increased in the VWF group as the temperature fell. The results suggest that in Raynaud's disease the fault is in the level of activity of the sympathetic outflow and in VWF it is peripheral mechanisms controlling the vessel tone.

Cold Temperature↗
PubMed1986

Cold provocation tests in the evaluation of vibration-induced white finger.

Two types of cold provocation tests, a classical test with immersion of the hand in cold water and the evaluation of finger systolic blood pressure (FSBP) during local cooling, were administered to forest workers. Raynaud's phenomenon in the classical test correlated positively with the number of disabled phalanges, recovery time, and frequency of attacks. It did not correlate with the severity of paresthesia of the hands and arms. Repetition of the test enhanced the number of positive results. A significant reduction in the FSBP was observed in 22 and 25% of the subjects with inactive and active forms of vibration-induced white finger (VWF), respectively. In the same groups of subjects the classical cold provocation test yielded positive results in 7 and 25% of the subjects, respectively. A cold provocation test was found to produce a positive result even some years after the cessation of VWF attacks. The rather low severity of VWF among the examined subjects may explain the lack of positive test results. FSBP measurement was not superior to cold provocation by water immersion, but it is recommended because it is easier to standardize and more convenient for the test subject.

Adult↗
PubMed1986

Vibration syndrome among Finnish forest workers, a follow-up from 1972 to 1983.

A longitudinal survey on the prevalence of vibration syndrome among professional forest workers was conducted from 1972 (118 workers) to 1983 (206 workers). The prevalence of vibration-induced white finger (VWF) was 40% among the workers in 1972; it gradually declined to 5% in 1983. Three new workers developed VWF symptoms during the follow-up period. They had only used saws equipped with antivibration handles. The prevalence of VWF has decreased mainly due to the reduction of chain-saw vibration. The prevalence of paresthesias of the hands and arms declined from 78% in 1972 to 37% in 1976, and then increased to 51% in 1983. The recent increase was thought to be due to static muscle load and the ageing of the workers. No correlation was found between the severity of VWF and peripheral nerve symptoms. No significant changes in muscle fatigue occurred during the follow-up period; it was present in about 10-15% of the workers. The forest workers subjectively assessed musculoskeletal load and strain as being more harmful than the symptoms of vibration syndrome. The preventive measures aimed at reducing chain-saw vibration, implemented since 1970, have been beneficial and explain the decreased prevalence of VWF.

Cross-Sectional Studies↗
PubMed1985

Cardiorespiratory strain in jobs that require respiratory protection.

Twenty-one workers in the construction, foundry, shipyard, and metal industries, and nine firemen were studied in jobs that require the regular use of various industrial respirators. The subjects' heart rates (HR) were continuously recorded during 1 to 2 workshifts or during special tasks. Their oxygen consumption (VO2) and ventilation rates were measured during main work phases. The subjects' VO2max were determined by a submaximal bicycle-ergometer test. In construction and industrial jobs, when a filtering device or an air-line apparatus was worn, the subjects' mean HR-values ranged from 66 to 132 beats min-1, which is equivalent to a relative aerobic strain of 12 to 57% VO2max. In smog-diving and repair and rescue tasks with self-contained breathing apparatus and protective clothing, the corresponding mean values were 142 to 160 beats min-1 and 54-74% VO2, respectively. The field results were compared with those measured in the laboratory with the same type of respirator. The suitability of different respirators in practical work situations was then evaluated, as were the physical qualifications required of the wearer.

Adult↗
PubMed1985

Physiological strain in work with gas protective clothing at low ambient temperature.

Wearing an impermeable gas protective suit (Dräger 500 or 600) and a self-contained breathing apparatus (Dräger PA 80; total weight 27 kg (59.5 lb], seven experienced firemen and one mechanic performed simulated repair and rescue tasks in a chemical plant. The subjects' mean (+/- SD) age, height, weight and estimated maximal oxygen consumption were: 36 +/- 4 years; 181 +/- 6 cm; 83 +/- 8 kg; and 42 +/- 5 mL/min/kg, respectively. The operations took place outdoors (ambient temperature 2.0 degrees C (35.6 degrees F), wind velocity 0-4 m/s). The total work time averaged 37 minutes. During tasks of search, handling vents, and sawing and replacing bolts, the mean (+/- SE) heart rates measured by a Depex recording device were 146 +/- 2, 148 +/- 2, and 147 +/- 5 beats/min, respectively. The mean rectal temperature increased 0.8 degrees C during the whole work period. Weight loss due to sweat averaged 300 g. In conclusion, typical tasks with gas protective clothing caused marked physiological strain among subjects in average physical condition even though the thermal strain was relatively low because the weather was cool. The results emphasized the need to evaluate physical fitness during the periodic check-ups of workers who may have to use gas protective clothing.

Adult↗
PubMed1985

Vibration-induced neuropathy among forestry workers.

The neurological findings of 217 forestry workers were evaluated during a compulsory annual health examination. Vibration detection thresholds were determined for the left hand and foot. The handgrip forces were measured for both hands. A reduction in the vibration detection threshold or handgrip force was not associated with clinical neuropathy. Polyneuropathy was found in 4% of the lumberjacks whereas neuropathy restricted to the arms was found in 7.5% of the lumberjacks. The neuropathic findings were not linked with alcohol consumption but were associated with a history of numbness in the hands and diminished muscle force. The findings support the concept that local vibration can cause neuropathy in the arms, but the mechanism of vibration-induced neuropathy still remains uncertain.

Adult↗