Sequelae of moderate finger frostbite as assessed by subjective sensations, clinical signs, and thermophysiological responses.

The aim of the study was to investigate prevalence and qualities of sequelae following moderate finger frostbite. The study material comprised 30 subjects, who had suffered second-degree frostbite (73% contact frostbite) 4-11 years before this study. In clinical tests 66% of the subjects had an elevated tendency for vasospasm, yet only 20% suffered from white fingers. However, no marked traces of frostbite-related alterations were observed in systemic cardiovascular reflex tests or in X-ray examinations of the frostbite area. Subjective assessments revealed a high prevalence of sequelae (63%), although the primary frostbite was moderate and local. The sequelae in the frostbite area included hypersensitivity to cold (53%), numbness of fingers (40%), and declined sensitivity of touch (33%). Also working ability was lowered due to frostbite sequelae (13%). In cold air provocation tests, the skin temperature of the frostbitten areas decreased more quickly and reached lower values than in healthy control subjects. In conclusion the suffered frostbite was associated with an increased tendency for vasospasm. Subjective sensations of the frostbitten area were associated with thermophysiological changes. The sequelae were reported to worsen in the cold environment thus emphasizing the probable occupational limitations of even moderate cold injury.

Blood pressure responses to whole-body cold exposure: effect of carvedilol.

OBJECTIVE: The aim of this study was to test the effects of carvedilol on blood pressure (BP) and heart rate (HR) during whole-body cold exposure in hypertensive and normotensive subjects. METHODS: Ten hypertensive and twelve normotensive subjects were exposed to cold (-15 degrees C, wind 3.5 m/s) three times for 15 min with a 1-week interval between the exposures. The study design was made according to a randomised double-blind, crossover method. Before the cold exposures the subjects ingested carvedilol or placebo once a day (carvedilol 12.5 mg/day for 2 days and then 25 mg/day for 5 days) for 1 week. The systolic (SBP) and diastolic (DBP) blood pressure and HR were measured every 3 min during the test procedures using an indirect ambulatory blood pressure monitor device (ABPM-02, Meditech Co.). RESULTS: In the hypertensive group, the cold exposure increased SBP/DBP from 119/75 mmHg to 143/96 mmHg during carvedilol treatment (P<0.001) and from 132/85 mmHg to 159/106 mmHg during placebo (P<0.001). In the normotensive group the cold exposure increased SBP/DBP from 112/72 mmHg to 142/93 mmHg during carvedilol treatment (P<0.001) and from 121/75 mmHg to 147/98 mmHg during placebo (P<0.001). In the hypertensive group, the levels of SBP, DBP and MAP (mean arterial pressure) were significantly lower with carvedilol than with placebo during the cold exposure although carvedilol did not affect the cold-induced rise of the BP. The BPs were lower also with carvedilol in the normotensive group than the placebo during the cold exposure, but the differences were smaller than in the hypertensive group. Carvedilol decreased the BP more the higher the initial mean SBP/DBP was with placebo during the cold exposure. CONCLUSION: Carvedilol reduced the BP during the cold exposure, especially in the hypertensive subjects but also in normotensive ones, without effect on the cold-induced rise of the BP.

Long-term musculoskeletal disorders and work career in 55-year-old workers.

The purpose of the present study was to describe the associations between long-term disorders of musculoskeletal system and work career in elderly workers. The data were obtained by a postal questionnaire and clinical examinations. The study group consisted of 778 elderly urban persons, who were 55 years old and who lived in the city of Oulu in northern Finland. Long-term musculoskeletal disorders were reported by 62% of the women and 57% of the men. The high prevalence of musculoskeletal disorders was significantly associated with heavy physical work. However, job mobility and declining work career were correlated with the occurrence of long-term musculoskeletal disorders in women whereas advanced work career was connected with a low prevalence of long-term musculoskeletal disorders.

Effect of amlodipine on blood pressure responses in local and whole-body cooling in normotensive men.

The objective of this study was to determine the ability of amlodipine (CAS 88150-42-9, Norvasc) to affect the cold-induced rise of blood pressure and heart rate in normotensive men. Fourteen normotensive men underwent a one-hand cold pressor test (+10 degrees C, 5 min) and a whole-body cold air exposure test (+5 degrees C, 45 min) in a crossover study with and without amlodipine at a seven-day interval. Amlodipine decreased the levels of initial systolic and diastolic blood pressure before both tests, but it had no influence on heart rate. During the cold pressor test, amlodipine lowered the peak diastolic pressure from 96 +/- 10 mmHg (mean +/- SD) to 92 +/- 10 mmHg (p = 0.024). The rise of diastolic blood pressure was 13 +/- 7 mmHg with amlodipine and 16 +/- 8 mmHg without amlodipine (p = 0.138). During the whole-body cold air exposure test, amlodipine decreased the systolic pressure from 135 +/- 2 mmHg to 133 +/- 3 mmHg (p = 0.008) and the diastolic pressure from 88 +/- 2 mmHg to 86 +/- 1 mmHg (p = 0.005). However, the cold-induced rise of blood pressure in whole-body cooling was not affected by amlodipine, because it also decreased the initial values. Amlodipine did not affect the initial or cold-induced changes of heart rate in these tests. In conclusion, in normotensive men amlodipine lowers the peak of diastolic blood pressure in a cold pressor test. In whole-body cold air exposure, amlodipine slightly decreases the levels of both systolic and diastolic pressures, but has no effect on the cold-induced rise of blood pressure. Amlodipine does not prevent the cold-induced physiological responses of blood pressure or heart rate.

Progress of work career, retirement-orientation and health in middle-aged workers.

A lifelong work career has been stated to have an influence on a worker's health and ability to work. Nevertheless, the significance of the work career has been neglected in most retirement-studies. The aim of the present study was to describe the associations between progress of the work career, the retirement-orientation, health and ability to work among aged workers. The data was obtained by a postal questionnaire and clinical examinations. The study group consisted of 706 (70%) middle-aged urban persons (383 women and 323 men), who were 55 years old and who lived in northern Finland. The state of health and ability to work were significantly better among the work-oriented than among the retirement-oriented workers and the health of the retired was the worst. Correspondingly, the state of health and ability to work were estimated to be better among the participants who advanced during their work career than among the other participants.

Safety and indoor mobility in the elderly.

The aim of this study was to find the basis for developing and adapting the environment to support the easy and safe moving of the elderly. In the field study, the daily activities and previous falls were inquired, the performance of the elderly was examined and the safety of the residential environment was surveyed among 70-80 years old subjects (N15). The second part was performed in the laboratory. 70-80 years old subjects (N55) walked on the test track. The risk level of most houses studied was moderate. In the residential surveying, all subjects had problems to stretch to high levels and most had problems to stretch to low levels. In the laboratory, errors happened often during line walking and zigzag walking in the stick track. Unsteadiness in gait was caused by extra pieces on the track and box carrying in one third of the subjects. The old subjects estimated that stairs somewhat lower than normally recommended were easier to climb. The results indicated, that new criteria and regulations are needed for the residential environment for the elderly and that it is possible to improve the safety of indoor mobility among the elderly in many ways.

Concern about the environment among medical students.

The aim of this study was to survey concern about the environment among medical students in Oulu in northern Finland. A questionnaire was filled in by 181 (74%) students. Most of the students were very concerned about the environment. Over half of the students were very concerned about water pollution and destruction of the rain forests. Female gender, membership in any environmental organisations and a good knowledge about the health effects of environmental factors were found to be significant independent factors to increase the concern.

Thermal responses to light, moderate and heavy daily outdoor work in cold weather.

Working in the cold is part of the normal routine in outdoor occupations in winter in the subarctic regions, but there are few data available on occupational exposure to cold during outdoor work. In the present study, thermal responses were measured in winter in Finland during 23 working days among young, healthy men working in heavy, moderate and light daily outdoor jobs. During the measurements ambient temperature ranged from +3 to -27 degrees C, air velocity from 0.2 to 4.3 m.s-1, and the subjects wore normal winter clothing. The skin temperatures measured often indicated disturbed performance, discomfort and a risk of adverse health effects, especially during the very cold days (ambient temperature less than -15 degrees C) in the light work. The most common problems were cooling of the extremities and the face and cool or cold sensations. The temperatures on the distal parts of the upper extremities correlated significantly with the heaviness of the work (r = 0.51, P = 0.014). The core temperature remained at the safety level in each case. Apart from clothing, an appropriate work load proved to be an effective way of keeping up the temperature of the extremities in cold work, and that should be taken into account when outdoor work is being planned.

Dose-response relation between exposure to two types of hand-arm vibration and sensorineural perception of vibration.

OBJECTIVES: 31 railway workers and 32 lumberjacks were examined to compare the dose-response relation between the exposure to two types of hand-arm vibration and the sensory disturbances in peripheral nerves as evaluated by the vibration perception thresholds (VPTs). METHODS: Clinical examinations were carried out that included measurements of the VPTs, and electroneuromyography (ENMG), and an inquiry to confirm the use of vibrating tools. Diseases of the central nervous system and neuropathies were checked by inquiry and a clinical examination, diabetes was excluded by a blood sample analysis, and the subjects with carpal tunnel syndrome confirmed with ENMG were excluded from the study. RESULTS: Lifetime use of hand held tamping machines (railway workers) and chain saws (lumberjacks) had a significant correlation with the VPTs at frequencies from 32 to 500 Hz. The increase of the VPTs (250 Hz) in relation to use of vibrating tools was 1.8-fold higher on average in the whole group and 2.3-fold higher in the young (< 45) railway workers who had used hand held tamping machines, than in the corresponding groups of lumberjacks, who had used chain saws, whereas the frequency weighted acceleration of vibration in tamping machines was fourfold. CONCLUSION: There was a significant dose-response relation between the exposure to hand-arm vibration and the VPTs. The VPTs as a function of the frequency weighted acceleration of vibration and the exposure to vibration gave promising results for assessment of the risk of damage to sensory nerves induced by vibration.

Temperature and vibration perception thresholds in workers exposed to hand-arm vibration.

Exposure to hand-arm vibration causes damage in the peripheral nerves of the upper extremities, and a method for early detection of neuropathy induced by vibration is needed. The thin nerve fibres seem to be the most sensitive to vibration and may be damaged first. In the present study, vibration and thermal thresholds in workers exposed to hand-arm vibration were compared in a case-control study. Previously, both vibration perception and temperature sense have been impaired in workers exposed to hand-arm vibration. The study population consisted of 15 workers exposed to hand-arm vibration (mean age 37.1 yrs) and 15 controls matched for age (mean age 36.1 yrs). The vibration perception thresholds (VPT) were measured with modified Bruel & Kjaer's equipment with the limits technique method. Thermal sense was measured by the Marstock method with a thermostimulator, in which the Peltier element controls the temperature of a thin metal plate (surface 35 x 40 mm) in contact with the skin. The lumberjacks had lower cold thresholds and wider neutral zones of temperature sensation in the hands and slightly higher VPTs at the high frequencies (125-500 Hz) than the controls. The results for the matched pairs showed 80-87% of the lumberjacks to have wider neutral zones, but only 53-66% of them had higher VPTs than the controls. In an intraindividual comparison of the lumberjacks (the newly scaled results with the mean and standard deviation of the controls), the temperature sense was often (66-73%) deteriorated more than the VPTs at 125-500 Hz. In addition, the newly scaled results showed the width of the neutral zone to be significantly more deteriorated than the VPTs at 125 and 250 Hz in the fingers. This indicates that measurement of the temperature sense is useful in the prevention of nerve damage caused by vibration and might be more sensitive to vibration than vibration perception.

Vibration syndrome in railway track maintenance workers.

An inquiry was sent to all railway maintenance workers in three railway districts in Finland and hand-arm vibration was measured on the handlebars of tools used by maintenance workers. The study group included 252 (82%) subjects, whose mean age was 41 years and who had worked in track maintenance for 14 years (SD 9). In Finland there are over 600 railway maintenance workers who use vibrating tools. The frequency-weighted acceleration of hand-arm vibration was calculated according to the ISO 5349 standard. Hand-held tamping machines had caused most of the vibration exposure, and aw4h was 10.6 m/s2 measured on the handlebar of tamping machine, but many workers also used other vibrating tools. The annual vibration level was 2.5 m/s2 when the use of all vibrating tools and the exposure time was taken into account. In the questionnaire the prevalence of vibration-induced white finger (VWF) was 14% in the entire material, and the prevalence of VWF increased significantly with the total duration of the maintenance work. In addition, 39% of the subjects had suffered numbness of the hands, and the prevalence of hand numbness also increased significantly with the total duration of maintenance work. According to the measurements of vibration and the prevalence of hand symptoms the present investigation indicates vibration syndrome as being related to railway track maintenance work. In the exposure group, where tamping machines mainly were used and exposure to other vibration was small, the prevalence of VWF was also significantly higher, but the prevalence of hand numbness insignificant compared with the control group. In this study vascular and nerve hand symptoms were considered to cause serious trouble in work by 4-11% of the maintenance workers.

Hand-arm vibration and terrain vehicles.

Hand-arm vibration was measured on the handlebars of terrain vehicles (N = 36) and a postal inquiry was made among N = 2705 reindeer herders (snowmobile drivers). Since many subjects had also used other vibrating tools the snowmobile group proper (N = 334) was established. In the whole group 19% of the subjects reported having experienced white finger attacks and 48% numbness of the hands. The frequency-weighted acceleration of snowmobile vibration was 3.5 m/s2, and risk evaluation using the ISO 5349 standard predicted the prevalence of white finger well in the snowmobile group proper. The vibration levels were 1.6-7.9 m/s2 on snowmobiles, 5.5-11.8 m/s2 on all-terrain vehicles and 6.9-12.7 m/s2 on terrain motorcycles. The most critical points for damping the vibration were the motor mounting and resonance in the steering yoke. There is need for health care, technical improvements, and other protection means to reduce the symptoms of vibration in driving terrain vehicles.

Responses of workers exposed to vibration in autonomic nervous function tests.

Heart rate variation in quiet breathing and deep breathing tests and the response of blood pressure in a cold pressor test were measured in 34 railway workers and 13 lumberjacks. The age-adjusted results showed a significant relationship between exposure to hand-arm vibration and the coefficient of beat-to-beat variation in the quiet breathing test (CVS) in the railway workers. The vibration-induced white finger (VWF) and non-VWF subjects showed non-significant differences in respect of all the indices used. This investigation, in common with previous results, suggests that vibration might cause changes in cardiovascular reflexes, but the indices used here seem to be of low sensitivity, at least partially due to wide physiological variation; other more suitable indicators and studies of the pathophysiological background of the suspected effect are needed to confirm the results.

Dose-response relationship between smoking and impairment of hearing acuity in workers exposed to noise.

The study included an inquiry and clinical examination of 443 reindeer herders (mean age 43 years) who frequently used noisy tools and vehicles, in particular snowmobiles and chain-saws. Age-adjusted hearing thresholds at 3 and 4 kHz deteriorated significantly with increased exposure to noise. There was the dose-response relationship between the amount of smoking and the impairment of hearing acuity when exposure time to noise was used as covariance. The amount of smoking was not significant until very heavy smoking (more than 144,000 cigarettes, i.e. 20 cigarettes/day for more than 20 years), and no smoking effect could be seen using the classification of current smoking habits. The results support the practice that screening of hearing acuity should be repeated more often in smokers than in non-smokers in noisy work so that hearing damage can be found in an incipient stage and noise-induced hearing loss effectively prevented.

Hand-arm vibration in snowmobile drivers.

Hand-arm vibration was measured on the handlebars of snowmobiles (N = 29) and a postal inquiry was made among reindeer herders, N = 2,705. Since many subjects had used also other vibrating tools a snowmobile group proper (N = 334) was established, and in this group 18% of the subjects reported that they had experienced white finger attacks and 48% numbness of the hands. The age-adjusted prevalence of the white finger syndrome was more than three times higher in the snowmobile group than in the controls. The frequency-weighted acceleration of snowmobile vibration was 3.5 m/s2, and risk evaluation based on the annex of the ISO 5349 standard predicted the prevalence of the white finger syndrome well in the snowmobile group. The most critical points for damping the vibration were the motor mounting and resonance in the steering yoke. There is a need for health care, technical improvements, changes in working habits and other protection means to reduce the symptoms of vibration associated with driving terrain vehicles.

Thermal responses in the body during snowmobile driving.

Thermal responses were examined in 12 healthy men during snowmobile driving (tests for 1 1/2-2 1/2 hours) in mild winter conditions. Ambient temperature ranged from -1 to -13 degrees C and average wind chill index from 1,050 to 1,520 kcal*m2/h. The subjects (23-49 years old) wore their ordinary winter clothing (insulation 1.7 - 2.4 clo). Work rate during the driving was 280-350 W. Rectal temperature increased slightly during driving, and mean skin temperature decreased quickly and fluctuated afterwards at a level 2-3 degrees C lower. Mean body temperature decreased by 1.2 degrees C in the most extreme case. Local cooling on the face and on the peripheral area of the extremities was considered the most serious problem: those temperatures were often below the limit of performance degradation and indicated occasionally the risk of frostbite. The winter conditions were mild in the present study, and on colder days cooling problems will be more severe, as the high incidence of frost injuries reported earlier indicates.

Noise and hearing loss in reindeer herders.

Air conduction hearing thresholds were examined in 512 reindeer herders (aged 18-65 years, clinically normal ears) to evaluate the prevalence of noise-induced hearing loss. The hearing thresholds at 6 kHz showed significant noise-type impairment of hearing compared with those in the ISO 7029 standard or a Finnish reference population. The subjects were exposed to noise mainly in the use of snowmobiles and chain saws: daily noise exposure ranged from 93 to 104 dB(A). The age adjusted hearing thresholds deteriorated with the total noise exposure time, especially at 3 and 4 kHz. The prevalence of significant (class IV) hearing loss was 15% and impairment of hearing was frequently found even in the younger age groups. Although the use of ear protectors seems to be increased among reindeer herders, it still appears to be insufficient, and efforts to promote their use are needed.

Combined effects of cold, vibration and smoking, particularly in snowmobile users.

In a living and working environment more than one factor is usually important for physiological and psychological responses in the body. In this report the effects and combined effects of hand-arm vibration and cold, in particular their effect on frostbite, has been reviewed. As a second example is given the combined effect of vibration and smoking on vibration-induced white finger. In both cases our previous work among reindeer herders frequently using snowmobiles has been utilised as an example. Descriptive terms for combined effects have varied in previous multi-exposure studies. Here, the terminology recommended in the Saariselkä agreement has been applied, and according to that the combined effect between cold and vibration on frostbite was called synergism and between vibration and smoking on white finger Bliss synergism.