Search PubMed⌕ Search

Biomedical subjects

T K Hodous

Publications and source records attributed to T K Hodous.

14 recordsLinked to original sources
PubMed1992

A comparison of radiographic interpretation of silica exposed workers using the 1963 and the 1986 Chinese roentgenodiagnostic criteria of pneumoconioses.

As part of a larger study relating to silica exposure, silicosis, and lung cancer mortality in Chinese mine and factory workers, 1936 old posterior-anterior chest X-rays were re-interpreted according to the 1986 Chinese Roentgenodiagnostic Criteria of pneumoconioses. Each film was independently read by three individuals from a panel of eleven radiologists, and this reading was compared to the original one. Subsequent to the independent readings, a groups of three readers interpreted the films together, called the consensus readings. Comparisons were made by Chinese stage of pneumoconiosis. For the entire cohort, there was a crude agreement of 57.4% between the old and the new interpretations. Agreement within one step of full agreement was 92.5%. The interpretations done by median reading and by consensus were very similar. In general, there was a tendency for the old readings to be slightly higher compared to the new interpretations. This tendency was most marked in the tin mines, followed in decreasing order by the iron/copper mines, the potteries, and the tungsten mines. The agreement between the old and new interpretations is felt to be satisfactory.

Humans↗
PubMed1992

Pulmonary function of U.S. coal miners related to dust exposure estimates.

This study of 7,139 U.S. coal miners used linear regression analysis to relate estimates of cumulative dust exposure to several pulmonary function variables measured during medical examinations undertaken between 1969 and 1971. The exposure data included newly derived cumulative dust exposure estimates for the period up to time of examination based on large data bases of underground airborne dust sampling measurements. Negative associations were found between measures of cumulative exposure and FEV1, FVC, and the FEV1/FVC ratio (p less than 0.001). In general, the relationships were similar to those reported for British coal miners. Overall, the results demonstrate an adverse effect of coal mine dust exposure on pulmonary function that occurs even in the absence of radiographically detected pneumoconiosis.

Adult↗
PubMed1991

A comparison of pneumoconiosis interpretation between Chinese and American readers and classifications.

As a preliminary step in joint Sino-American pneumoconiosis research efforts, a formal chest X-ray pneumoconiosis reading trial was conducted among Chinese and American radiologists. Twelve Chinese readers from different institutions located in south central China used the 1986 Chinese Roentgenodiagnostic Criteria of Pneumoconioses. Three American radiologists, centified as NIOSH "B" readers, used the International Labour Office Classification of Pneumoconioses. The chest X-ray study set consisted of 150 posterior-anterior films. One-half were Chinese X-rays of silica-exposed workers, and the other half were American films of variously exposed workers but primarily coal miners. All readings were done independently. The results showed that the inter-reader variability among the Chinese was similar to that of the American readers, both being in an acceptable range. In addition, there was general agreement between the Chinese and American interpretations. For small opacity profusion, the Chinese readers tended to read slightly more diseases than their American counterparts, although there was exact agreement as to the major category in two-thirds of the films. Agreement for film quality, and pleural disease was less, but was not different from reported variation among American "B" readers. Overall, the results suggest that despite the use of two different classification systems, a valid correspondence exists between the Chinese and American Interpretations, which is suitable for use in epidemiologic research.

Anthracosilicosis↗
PubMed1991

Effects of thermal environment and chemical protective clothing on work tolerance, physiological responses, and subjective ratings.

This study examined the physiological and subjective responses of nine healthy men who performed work while wearing two types of protective ensembles in each of three thermal environments. The subjects, all experienced with the use of protective ensembles, each performed low intensity treadmill exercise (23% of VO2 max while not wearing a Self-Contained Breathing Apparatus [SCBA] or protective clothing) under six experimental conditions: two ensembles (SCBA--light work clothing and SCBA; and CHEM--a two-piece chemical protective ensemble with SCBA) during exposure to 'cool' (10.6 degrees C/water vapour pressure [Pw] 0.76 kPa), 'neutral' (22.6 degrees C/Pw 1.52 kPa), and 'hot' (34 degrees C/Pw 2.90 kPa) environments. Each test was intended to continue for 120 min; however the duration and number of work/rest periods within the testing session varied according to the specific responses of each individual. At the completion of each test seven subjective responses were recorded. Physiological data, collected every minute during each test, included heart rate, and skin and rectal temperature. The total worktime was significantly shorter in the hot environment while wearing the CHEM ensemble (53.4 min) compared to all the other conditions (103-105 min). The mean maximum physiological values also indicated significant differences due to thermal environment and/or ensemble. Work performance did not appear to be limited in a cold environment with either ensemble tested. The physiological responses to working in the CHEM/neutral condition were very similar to those occurring in a hot environment wearing the SCBA ensemble. The subjective responses also indicated significant differences due to thermal environment and ensemble, with subjects perceiving the CHEM ensemble as less favourable than the SCBA ensemble. The results suggested that, even at a low work intensity, individuals wearing chemical protective clothing in the heat will require progressively shorter work periods, and more frequent and longer rest periods.

Adult↗
PubMed1989

Work tolerance and subjective responses to wearing protective clothing and respirators during physical work.

This study examined work tolerance and subjective responses while performing two levels of work and wearing four types of protective ensembles. Nine males (mean age = 24.8 years, weight = 75.3 kg, VO2 max = 44.6 ml/kg min) each performed a series of eight experimental tests in random order, each lasting up to 180 min in duration. Work was performed on a motor-driven treadmill at a set walking speed and elevation which produced work intensities of either 30% or 60% of each subject's maximum aerobic capacity. Work/rest intervals were established based on anticipated SCBA refill requirements. Environmental temperature averaged 22.6 degrees C and average relative humidity was 55%. The four protective ensembles were: a control ensemble consisting of light work clothing (CONTROL); light work clothing with an open circuit self-contained breathing apparatus (SCBA); firefighter's turnout gear with SCBA (FF); and chemical protective clothing with SCBA (CHEM). Test duration (tolerance time) was determined by physiological responses reaching a predetermined indicator of high stress or by a 180-min limit. Physiological and subjective measurements obtained every 2.5 min included: heart rate, skin temperature, rectal temperature, and subjective ratings of perceived exertion, thermal sensation, and perspiration. The mean tolerance times were 155, 130, 26, and 73 min, respectively, for the CONTROL, SCBA, FF, and CHEM conditions during low intensity work; and 91, 23, 4, and 13 min, respectively, during high intensity work. Differences between ensemble and work intensity were significant. FF and CHEM heart rate responses did not reach a steady state, and rose rapidly compared to CONTROL and SCBA values. SCBA heart rates remained approximately 15 beats higher than the CONTROL ensemble during the tests. At the low work intensity, mean skin temperatures at the end of the test were 32.7, 33.1, 36.7, and 36.3 degrees C, while mean core temperatures were 37.6, 37.9, 37.9, and 38.5 degrees C, respectively. The subjective data indicated that, in general, subjects were able to perceive relative degrees of physiologic strain under laboratory conditions. Wearing protective clothing and respirators results in significant and potentially dangerous thermoregulatory and cardiovascular stress to the wearer even at low work intensities in a neutral environment. Physiologically and subjectively, firefighter's turnout gear (the heaviest ensemble) produced the most stress, followed by the CHEM, SCBA, and CONTROL protective ensembles.

Body Temperature↗
PubMed1989

Physiological and subjective responses to working in disposable protective coveralls and respirators commonly used by the asbestos abatement industry.

The physiological and subjective effects of working with different respirators while wearing lightweight disposable (Tyvek 1412 polyolefin) coveralls commonly used by the asbestos abatement industry were studied. Nine healthy men (mean age = 27.3 yr, weight = 76.9 kg) each performed a series of four exercise tests with four different respirator ensembles in counterbalanced order. Treadmill work was performed at a set walking speed of 4 kph (2.5 mph), 0 percent elevation (220 kcal/hr), a controlled environmental temperature of 33.9 degrees C, and 50% relative humidity. Each test continued up to 120 min, with repeated work/rest intervals of 26 min of work and 4 min of rest. Tyvek disposable coveralls and hoods were worn with each of these four different respirator ensembles: (1) control--a lightweight, low resistance mask; (2) HEPA--an air purifying, full facepiece respirator with dual high efficiency filters; (3) SAR--a supplied-air, pressure-demand respirator with escape filter; (4) SCBA--an open circuit, pressure-demand, self-contained breathing apparatus. Physiological measurements obtained every minute during each test included heart rate and skin and rectal temperatures. Subjective evaluations of clothing, respirator, and facepiece comfort, ease of breathing, temperature and perspiration in the mask and clothing, and respirator load also were measured at the end of the test. Data were analyzed using an analysis of variance. Results indicated that heart rate at the end of the test differed by less than 8 BPM between the control condition and the SCBA (heaviest) condition.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Workplace measurement of respirator effects using respiratory inductive plethysmography.

A useful system to study the cardiopulmonary effects of respirators in the workplace would be reliable, portable, and lightweight and would not encumber the nose or mouth or require modification to the respirator. Twenty men using such a system (which measured ventilatory parameters by respiratory inductive plethysmography [RIP]) were studied. The subjects all performed their usual jobs which involved some work with and some without a respirator. Twelve subjects used airline respirators and eight used air-purifying respirators. The RIP equipment measurements included respiratory frequency, tidal volume (VT), minute ventilation (V), and heart rate (HR). The RIP data from 20 other subjects was lost because of equipment malfunction, primarily lead separation in those whose jobs involved climbing around large workpieces. In general, the workers' cardiopulmonary parameters increased during respirator wear, probably because of a combination of factors, including the increased exercise of most respirator-requiring tasks and the weight and heat stress associated with the respirator and protective clothing. When the ventilatory parameters with and without a respirator were compared at the same heart rates, no significant differences were noted in VT for the entire group. Respiratory frequency, however, and V increased with respirator wear. The effects of respirators alone were found to be commonly confounded in the workplace by changes in protective clothing, exercise requirements, and ambient heat stress. Further improvements in the portable RIP system are needed before it can be accepted as a reliable ventilatory measurement device in the workplace.

Adult↗
PubMed1988

The use of inductive plethysmography in the study of the ventilatory effects of respirator wear.

The authors recently developed an ambulatory system, in which a self-contained respiratory inductive plethysmograph (RIP) was used, to measure noninvasively the volume and time components of breathing. Since it does not use nasal or oral devices, such a system is particularly suitable for use in studying the effects of respiratory protective masks on respiratory parameters. In order to validate this portable system, 22 healthy subjects were exercised on a treadmill; RIP and pneumotachographic minute ventilation measurements were compared. A short, graded submaximal exercise protocol was run 3 times by each subject under each of the following conditions: no oral mouthpiece; oral mouthpiece with pneumotachograph; and wearing an industrial protective mask (half facepiece, twin cartridge). Chest and abdominal RIP signals, a time signal and either a pneumotachograph or heart-rate signal were recorded on a small cassette recorder worn at the belt. The data tapes were later edited and analyzed by computer. Data from 5 subjects were excluded because of equipment malfunction. The average error in RIP-measured ventilation compared to values simultaneously measured by a pneumotachograph in the 17 remaining subjects over all exercise levels was -3.16%. Marked variability (SD = 11.26%), however, was found in individuals at different exercise levels and especially between subjects. Use of a respirator was associated with a decreased respiratory frequency, an increased tidal volume and minute ventilation, and an unchanged heart rate. At present, the portable RIP system has substantial variability that limits its ability to measure ventilation accurately.

Humans↗
PubMed1988

Physiological responses to the wearing of fire fighter's turnout gear with neoprene and GORE-TEX barrier liners.

This study examined the physiological effects of performing moderate and high intensity work while wearing fire fighter's turnout gear with either a neoprene or GORE-TEX barrier liner. Eight healthy men, experienced with the use of respirators and protective clothing, each performed moderate and high intensity treadmill exercise (44% and 71% of maximum work capacity) in a double-blind study at 27.6 degrees C (50% RH) while wearing complete fire fighter's turnout gear (weighing 23 kg) with either a neoprene or GORE-TEX barrier liner. Physiological measurements obtained included minute ventilation, heart rate, skin temperature, rectal temperature and sweat rate. Subjective evaluations of perceived exertion, comfort, clothing breathability, temperature and perspiration also were obtained. Tests were terminated (tolerance time) when objective or subjective signs of near maximal stress were observed (i.e., 90% of the maximum heart rate, rectal temperature of 39 degrees C, dizziness, etc.). Mean tolerance times for the moderate intensity exercise were 27.4 (+/- 7.3 S.D.) and 30.9 (+/- 7.9) min, respectively, for the neoprene and GORE-TEX barrier liners and at the high intensity were 7.2 (+/- 2.1) and 7.5 (+/- 2.3) min, respectively. Analysis of variance indicated that significant differences caused by liner were observed in skin temperature (0.6 degrees C higher with the neoprene ensemble). No significant differences caused by liner were seen in tolerance time, heart rate, sweat rate or subjective ratings.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Lung volume reference values for blue collar workers not exposed to occupational respiratory hazards.

Epidemiologic research into occupationally related lung disease often requires the comparison of a study group with an external nonexposed comparison group. In order to develop such an external comparison group, blue collar workers, who had no obvious adverse occupational pulmonary exposure, performed simple spirometry, were administered a standard questionnaire, and had standard posterior-anterior and lateral chest radiographs taken. Prediction equations were established for three indices of lung volume, namely total lung capacity, residual volume, and their ratio, for various combinations of race, sex, and smoking groups. Asymptomatic non-smokers with normal radiograph results were then extracted from the overall group, and separate prediction equations were established. The relationship between age and total lung capacity is discussed.

Adult↗
PubMed1987

Reduced work tolerance associated with wearing protective clothing and respirators.

This study examined worker tolerance and physiological responses to two levels of work while subjects wore various types of protective clothing and respirators. Nine healthy men (mean age = 24.8 years, weight = 75.3 kg, max VO2 = 44.6 mL/kg/min), experienced with the use of respirators, each performed a randomized series of eight experimental tests, each test scheduled to last 180 min. Work was performed on a motor-driven treadmill at a set walking speed and elevation indicative of either 30% (low work intensity) or 60% (high work intensity) of maximum work capacity for each individual. Four protective clothing ensembles were examined: light work clothing (LIGHT), light work clothing with SCBA (SCBA), firefighter's turnout gear with SCBA (FF) and chemical protective clothing with SCBA (CHEM). Physiological measurements included heart rate, skin and rectal temperature, and minute ventilation. Measurements were obtained every 2.5 min until test termination (tolerance time). If less than 180 min, tolerance time was defined by subjective or objective signs of near maximal stress. Mean tolerance times at the low work intensity were 167, 130, 26 and 73 min, respectively, for the LIGHT, SCBA, FF and CHEM ensembles. At the high intensity, mean tolerance times were 91, 23, 4 and 13 min, respectively. At the low work intensity, heart rate with SCBA rose very slowly during the tests and remained approximately 15 beats/min higher than the heart rate for subjects wearing the LIGHT ensemble. In contrast, heart rate with the FF and CHEM ensembles rose sharply and did not approach steady-state values.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

The use of helium-oxygen spirometry in occupational lung disease.

One of the major problems in the study and management of occupational lung disease is to detect early impairment so that corrective measures can be taken before irreversible or more severe damage occurs. Unfortunately standard spirometric tests are not sensitive to functional impairment in small airways where the earliest abnormalities in many pulmonary diseases are thought to occur. A a result, several new tests have been devised in the last decade to study this so-called silent zone. Helium-oxygen spirometry, one such test, is safe, convenient, and can eaily be added to conventional air spirometry apparatus. Two studies using helium-oxygen and air spirometry done by the Appalachian Laboratory are presented. In the first, non-exposed controls were compared to flax workers with either low or high dust exposure. Both air and helium-oxygen flow volume curves showed decreased flow rates after a work-shift in the high exposure group but no change in controls. In the low-dust exposure group, only helium-oxygen spirometry detected decreased post-shift flow rates suggesting small airways disease. Coal miners were compared to controls in the second study. Subgroups of younger subjects, smokers, non-smokers, bronchitics, and non-bronchitics were also analyzed. In no case did helium-oxygen spirometry detect differences which were not present on routine air spirometry. It is concluded that further studies in this area are needed. At present, random screening with helium-oxygen spirometry for early occupational disease is not warranted, and this test remains an investigative tool.

Epidemiologic Methods↗