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Biomedical subjects

O Korhonen

Publications and source records attributed to O Korhonen.

At least 55 records · Page 3Linked to original sources
PubMed1985

Effects of an SCBA on breathing pattern, gas exchange, and heart rate during exercise.

The effects of a pressure demand-type self-contained breathing apparatus (SCBA) (total weight, 15.5 kg) on breathing pattern, gas exchange, and heart rate were studied in 13 firemen. The subjects performed sequential progressive exercise tests on a treadmill both without and with an SCBA. The use of an SCBA consistently limited tidal volume. During submaximal exercise oxygen consumption and heart rate increased remarkably more with the SCBA than without it. Four subjects reached their maximal heart rate with the SCBA. Their mean ventilation rate was 68% and oxygen consumption was 83% of the maximal values attained without the SCBA. The shoulder harness of the heavy SCBA prevented free motion of the thorax, affecting the regulation of breathing, and thus seriously disturbed ventilation and gas exchange, particularly at heavier exercise levels.

Adult↗
PubMed1984

Cardiorespiratory and thermal effects of wearing gas protective clothing.

Six healthy men aged 25 to 37 walked on a treadmill at work levels of 21 and 41% of their VO2max for 25 to 30 min wearing gas protective clothing (GPC) consisting of an impermeable suit with a self-contained breathing apparatus (total weight 25 kg) or shorts (control tests, CT) in a temperate environment (ta 24.3 degrees C +/- 1.0 degrees C, rh 30-50%). When the GPC was worn at 21 and 41% VO2max, the most prominent increases, compared with the CT, were noted in the heart rate (means +/- SE, 120 +/- 5 vs 76 +/- 3 beats min-1 and 171 +/- 5 vs 103 +/- 3 beats min-1), mean skin temperature (36.1 +/- 0.2 vs 31.3 degrees C +/- 0.1 degree C and 36.9 +/- 0.3 vs 30.9 degrees C +/- 0.4 degrees C) and sweat rate (473 +/- 51 vs 70 +/- 23 g m-2 h-1 and 766 +/- 81 vs 135 +/- 18 g m-2 h-1) indicating a high cardiovascular and thermoregulatory strain, which was not decreased by ventilating the suit with an air flow of 281 min-1 at 41% VO2max. The ventilation, oxygen consumption and production of carbon dioxide increased in relation to the extra weight of the GPC, partly dependent on the dynamic work level. It was concluded that the increase in the physiological load caused by the GPC was so high that the work-rest regimens, workers' level of physical fitness, cardiovascular health and heat tolerance should be considered whenever gas protective clothing is used.

Adult↗
PubMed1984

Reduction of isometric muscle endurance after wearing impermeable gas protective clothing.

The isometric endurance of forearm muscles at 40% maximum voluntary contraction was measured in six healthy male subjects, after they had walked for 25-30 min on a treadmill while wearing an impermeable gas protective suit and a self-contained breathing apparatus at a light (21% VO2 max), and a moderate 41% VO2 max) work level. The mean endurance times were 12% (NS) and 24% (P less than 0.01) shorter than the average control value after exercise for the light and moderate work levels, respectively. These changes were accompanied by an increased heart rate, and rectal and skin temperatures. Ventilating the suit with an air flow of 181 . min-1 at the moderate work level did not significantly affect isometric endurance (decreased 27%), heart rate or body temperatures. It was concluded, that muscular performance capacity is reduced after wearing gas-protective clothing in a temperate environment, presumably due to the increased muscle temperature, and this should be considered in scheduling work times and rest periods.

Adult↗
PubMed1984

Cardiorespiratory effects of respiratory protective devices during exercise in well-trained men.

The effects of a filtering device, an air-line breathing apparatus and a self-contained breathing apparatus ( SCBA ) on pulmonary ventilation, oxygen consumption and heart rate were studied in 12 well-trained firemen aged 21-35 years. Their average maximal oxygen consumption (VO2 max) was 64.9 ml X min-1 X kg-1. Sequential tests without and with the respirator were performed on a treadmill. The continuous test contained five components, each of which lasted 5 min: sitting at rest, walking at 20%, 40%, and 60% of the individual VO2 max, and recovery sitting. During the higher submaximal work levels and recovery, ventilation, heart rate, and oxygen consumption in particular increased more with respirators than without them. At the highest work level the increments in oxygen consumption caused by the respirators were 13%, (8.7 ml X min-1 X kg-1), 7% (4.4 ml X min-1 X kg-1), and 20% (12.7 ml X min-1 X kg-1) of VO2 max. All three respirators hampered respiration, resulting in hypoventilation. The additional effort of breathing and the weight of the apparatus (15 kg with the SCBA ) increased the subjects' cardiorespiratory strain so clearly that the need for rest periods and the individual's work capacity when the respirators are worn must be carefully considered, particularly with the SCBA .

Adult↗
PubMed1984

Extrinsic allergic alveolitis in the tobacco industry.

A total of 57 subjects who had been exposed to mould dust in the tobacco industry were studied. Their working environment showed exposure to spores of different moulds, and 29 subjects (51%) showed antibodies against one or more of the microbes. Fifteen (26%) had work related respiratory symptoms. Eight (14%) showed slight radiographic pulmonary fibrosis. Spirometry showed a tendency toward restriction and obstruction, especially in small airways. Diffusion capacity was decreased in 18% of the workers. Three clinical cases of typical allergic alveolitis were also found. All this suggests that exposure of spores of different moulds (especially Aspergillus fumigatus) in the manufacture of tobacco products may induce symptoms and signs relating to extrinsic allergic alveolitis.

Adult↗
PubMed1984

Asbestosis, the nervous system and cancer.

Asbestosis patients have a high cumulative risk of cancer: four of ten asbestosis patients develop cancer. Paraneoplastic involvement of the nervous system, peripheral neuropathy in particular, is often encountered in cancer patients, even at very early stages of the disease. In order to estimate the occurrence of paraneoplastic neuropathy among asbestosis patients, we formed a small cohort (115 asbestosis patients, mean age 56 years, mean duration of exposure to asbestos 21 years) in 1979. Neurological examination revealed slight peripheral neuropathy in 44 (39%) of the patients, 24 (22%) of whom also had central nervous system signs (disturbances in gait and posture, memory and fine movements). The prevalence of peripheral neuropathy among asbestosis patients was higher than among various referent patients (fibrosing alveolitis, diagnosed solvent poisoning and gynaecological carcinoma). No significant differences were found between the patients with and without peripheral neuropathy regarding the following parameters: pulmonary function tests, tumour markers (CEA, ferritin, beta-2-microglobulin), antinuclear antibodies, C3, C4 and circulating immune complexes. Nevertheless, at group level, the asbestosis patients had increased levels of the three tumour markers. Estimates based on the data accumulated so far (10 cancer patients) show that within three years we shall probably have a sufficient number of cancer cases to draw some conclusions about the value of neuropathy in the early diagnosis of occupational cancer.

Adult↗
PubMed1983

Lung function and nervous system involvement in asbestosis.

A group of 115 patients with asbestosis of the lungs was tested in detail for neurological functions and lung functions in order that any possible impaired pulmonary function and neurological signs (especially peripheral neuropathy) could be discovered. Attention was also paid to finding out whether peripheral neuropathy, which is frequently encountered among asbestosis patients, had any role in decreased pulmonary function. A slight trend towards lowered spirometrical values (vital capacity, forced expiratory volume in one second, maximal mid-expiratory flow and maximal expiratory flow at 25% of vital capacity) was found for the group of patients with peripheral neuropathy. No differences in diffusing capacity were found between the groups of patients either with or without peripheral neuropathy. We concluded that the spirometrical findings are more indicative of a parallel phenomenon than a causal factor. Nor was the involvement of the central nervous system associated with decreased pulmonary function. In short, the pulmonary dysfunction of our asbestosis patients did not appreciably contribute to the occurrence of nervous system involvement, whether central or peripheral.

Adult↗
PubMed1983

Wollastonite exposure and lung fibrosis.

Wollastonite is a naturally occurring acicular or fibrous metasilicate used in ceramics and as a substitute for asbestos in some applications. Wollastonite fibers are rather similar in form, length, and diameter to amphibole asbestos fibers but mineralogically they are different. Dust measurements in both the Finnish limestone--wollastonite quarry and in the flotation plant yielded high concentrations of both total dust and respirable fibers in some operational stages. The clinical study comprised a total of 46 men who had been exposed to wollastonite at the quarry for at least 10 years. Three of the fifteen nonsmokers showed chronic bronchitis. Radiographs revealed slight lung fibrosis among fourteen men, and slight bilateral pleural thickening among thirteen men. Their sputum specimens were normal. Spirometry and nitrogen single breath tests indicated the possibility of small airways disease.

Adult↗
PubMed1983

Vibration syndrome and vibration in pedestal grinding.

At one Finnish foundry all the workers had typical symptoms of vibration induced white finger (VWF) after they began using a new type of pedestal grinding machine. The objectives of this study were to establish the severity of the symptoms and the difference in vibration exposure between the new and the old machines. Vibration detection thresholds and grip forces were measured, as well as the vibration in the casting and in the wrist simultaneously. The mean latency for VWF among the grinders was 10.3 months after the change of pedestal grinding machines. All the grinders had numbness in their hands. The vibration detection threshold was significantly higher for the grinders than for their referents. At the same circle speed, the new wheels caused vibration levels up to 12 dB more than the old wheels. The circle speed had a slight influence on the vibration. The vibration levels of light (0.5 kg) casting were up to 25 dB higher than the heavy (5 kg) casting. The use of a pneumatic pressing device decreased the vibration levels in the wrist by 5-10 dB. The increase in vibration, which occurred when the new wheels were taken into use, was too small to explain such a dramatic outbreak of VWF. This led to the conclusion that some other feature such as the impulse character of the vibration also contributed to the effects of vibration.

Adult↗
PubMed1983

Blood pressure, flow, and peripheral resistance of digital arteries in vibration syndrome.

The peripheral circulation was studied in 19 lumberjacks and in 12 control subjects. Twelve of the lumberjacks were free from vascular symptoms and seven had vibration induced white finger (VWF). Using the strain-gauge plethysmographic technique, the digital circulation was examined at rest, during cooling of the upper body, and during heating of the upper body. At rest and during vasodilatation no significant differences were found between the lumberjacks and the controls. During reflexive vasoconstriction, digital blood flow in the upper body was more reduced in lumberjacks with VWF than in control subjects. Furthermore, digital blood pressure of the lumberjacks with VWF fell more than in the control group. The peripheral resistance also increased more, but this difference was not statistically significant. There was no evidence that the exaggerated vasoconstriction of VWF resulted from a narrowing of the lumen of arterioles due to hypertrophy of the vessel wall. The present findings suggest that VWF is produced by the highly sensitive responsiveness of the affected vessel to normal vasoconstrictor stimuli.

Adult↗
PubMed1983

Long-term effects of exposure to sulfur dioxide. Lung function four years after a pyrite dust explosion.

The lung function of 7 men accidentally exposed to sulfur dioxide (SO2) in a pyrite dust explosion was followed for 4 yr. The greatest decrease in forced vital capacity, forced expiratory volume in one second, and maximal midexpiratory flow was observed 1 wk after the accident. After about 3 months no further decrement occurred. The pattern of spirometric findings was obstructive in 6 and restrictive in 1 of the patients. Four years after the accident a reversible obstruction of the bronchi was still observable in 3. Four patients reacted positively to the histamine challenge test. Two patients either did not respond to bronchodilator or did not react to histamine. The results suggest that bronchial hyperreactivity is a frequent sequela after exposure to high concentrations of SO2. The hyperreactivity may persist for several years.

Accidents, Occupational↗
PubMed1983

Surgical treatment of chronic laryngeal stenosis secondary to vocal cord paralysis: pre and postoperative evaluation of ventilatory function.

Thirteen patients with chronic laryngeal stenosis were operated upon with total excision of stenotic scar tissue, enlargement of the lumen by sectioning the back and front wall of the larynx, and application of an indwelling Teflon prosthesis for 4 months. The stenosis was in many cases caused by long-standing recurrent paralysis complicated by attempted surgical correction of the stenosis. Following operation, the specific airway conductance increased in all patients (mean +/- SD pre and postoperative values 0.51 +/- 0.30 and 1.12 +/- 0.51 kPa-1.s-1, respectively). The FIV1/FVC ratio was determined in 9 patients and an increase was postoperatively noted in all of them (mean +/- SD pre and postoperative values 43 +/- 17 and 76 +/- 13%, respectively). The physiological findings confirmed the excellent clinical results of the treatment.

Adult↗
PubMed1982

Respiratory status of stainless steel and mild steel welders.

Eighty-three full-time stainless steel and 29 mild steel welders from one shipyard were examined clinically, and their lung function was measured. The stainless steel welders had used both tungsten inert-gas (low-fume concentration) and manual metal-arc (MMA) (high-fume concentration) welding methods. The individual exposure of the welders was estimated based on the time spent doing MMA welding, the amount of retained contaminants in the lungs (magnetopulmography), and urinary chromium excretion. The results suggest that there is a greater prevalence of small airway disease among shipyard mild steel MMA welders than among stainless steel welders. Among the stainless steel welders the impairment of lung function parameters was associated with the MMA welding method. The type of welding, then, is important when the health hazards of welders are studied, and welders cannot be regarded as a single, homogeneous group.

Adult↗
PubMed1981

Firefighters' reaction to alarm, an ECG and heart rate study.

Firemen's reaction to alarm was investigated with a pulse rate and ECG analysis. The frame of reference was the psychophysiological alarm reaction and its relation to psychosomatic diseases. ECG and pulse rate measurements were recorded continuously from 22 first-string firemen. According to an exercise stress test, the subjects were healthy, but not more fit than a sedentary population. High pulse rates occurred during the alarm due to vigorous movement to the trucks. No anticipatory pulse rate rise occurred as the firemen approached the fire. Non-pathological ECG deviations were found 13 subjects although no abnormalities were found in the same subjects during exercise test. Different firefighting practices, environment, selection, and training might explain the differences between the findings of the present investigation and those of other recent studies.

Adult↗
PubMed1981

Hand-arm vibration in the aetiology of hearing loss in lumberjacks.

A longitudinal study of hearing loss was conducted among a group of lumberjacks in the years 1972 and 1974--8. The number of subjects increased from 72 in 1972 to 203 in 1978. They were classified according to (1) a history of vibration-induced white finger (VWF), (2) age, (3) duration of exposure, an (4) duration of ear muff usage. The hearing level at 4000 Hz was used to indicate the noise-induced permanent threshold shift (NIPTS). The lumberjacks were exposed, at their present pace of work, to noise, Leq values 96-103 dB(A), and to the vibration of a chain saw (linear acceleration 30-70 ms-2). The chain saws of the early 1960s were more hazardous, with the average noise level of 111 dB(A) and a variation acceleration of 60-180 ms-2. When classified on the basis of age, the lumberjacks with VWF had about a 10 dB greater NIPTS than subjects without VWF. NIPTS increased with the duration of exposure to chain saw noise, but with equal noise exposure the NIPTS was about 10 dB greater in lumberjacks with VWF than without VWF. With the same duration of ear protection the lumberjacks with VWF consistently had about a 10 dB greater NIPTS than those without VWF. The differences in NIPTS were statistically significant. The possible reason for more advanced NIPTS in subjects with VWF is that vibration might operate in both of these disorders through a common mechanism--that is, producing a vasoconstriction in both cochlear and digital blood vessels as a result of sympathetic nervous system activity.

Adult↗
PubMed1980

Vibration-induced decrease in the muscle force in lumberjacks.

Isometric maximal hand grip force was measured with a strain gauge dynamometer in 91 lumberjacks and 31 controls during a 2-min compression-relaxation task. Measurements were carried out on both hands with and without simultaneous vibration exposure. The muscle forces of older subjects were smaller than those of younger men, independent of occupational vibration exposure. The fatigue curves of lumberjacks and control subjects had the same shape. During vibration exposure in the test, the forces diminished in the left hand significantly in the lumberjacks but not in the control subjects. The force level of fatigue curves of the lumberjacks with a history of diminished grip force was lower and decreased more during vibration exposure than in the lumberjacks with a history of normal grip force. The reduction in the hand grip force during vibration exposure in the lumberjacks seemed to be linked to lesions in the peripheral nerves and to activation of a tonic vibration reflex, but probably not to circulation disturbances. The fatigue mechanism seemed to be the same in lumberjacks and control subjects.

Adult↗
PubMed1980

Circadian variation of physiological functions related to physical work capacity.

The circadian variation of selected physiological functions related to physical work capacity was studied in four trained young male subjects. The twofold objective was to describe, in parametric terms, the variation of these functions and estimate the times and values of their maximum and minimum responses. Statistically significant periodic regression effects were found for the following functions: oral temperature; systolic blood pressure; heart rate at rest, during work (245 and 270 W) and after a 5-min recovery; ratings of perceived exertion; strength of hand grip; and neuromuscular coordination measured with a seesaw board balance test. The Fourier curve (sine curve) accounted for 63 % of the variation in oral temperature and from 13 to 38 % of the variation in the other significant harmonic intensities. In phase with the rhythm of oral temperature, but with larger amplitude, were systolic blood pressure, heart rate at rest and heart rate during work; roughly in phase were strength of hand grip and neuromuscular coordination. Ratings of perceived exertion and heart rate after a 5-min recovery showed a rhythm which was out of phase with the oral temperature. The number of disturbances in neuromuscular coordination was greatest at 2400 and smallest at 1200, the difference being as large as 44 %. The results suggest that the measured capacities of muscle strength and neuromuscular coordination are the lowest, that physical work is perceived as the heaviest, and recovery after work is the slowest at night. These findings appear to support the notion that performance capacity is reduced during the night.

Adult↗