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Biomedical subjects

P Harber

Publications and source records attributed to P Harber.

At least 55 records · Page 3Linked to original sources
PubMed1991

Work coding: beyond SIC and SOC, BOC and DOT.

Traditional coding schemes for occupational health related factors (eg, SIC, SOC, CAS) are structured similarly as hierarchical, exclusive, and exhaustive systems. Each is limited to information of one particular type (eg, industry) and, therefore, the relationships implicit in the coding scheme are limited. This study empirically determined that "natural" coding schemes used by occupational health professionals do not share these characteristics but are more akin to semantic network data bases. There is therefore a need to re-evaluate how occupational data are to be coded.

Databases, Factual↗
PubMed1991

Asbestosis: diagnostic dilution.

The term "asbestosis" usually has been applied to a disease characterized by diffuse pulmonary interstitial fibrosis. It was often associated with a significant adverse impact on the individual. A review of case definitions employed in published research studies show stability of the criteria for asbestosis case definitions over the past decade. Nevertheless, additional modalities have been suggested for the early diagnosis of asbestosis. It is probable that the significance of such abnormalities may be different from that of usual asbestosis, and there is therefore a need to carefully define the manner in which the terms are used. Additional anomalies may be seen in asbestos-exposed individuals including small airway physiologic abnormality, pathologic evidence of inflammation near the airways, positive gallium scan, abnormal lung compliance, exercise test abnormalities, CAT scan findings, and high-resolution CAT scan findings.

Asbestosis↗
PubMed1990

Effect of exercise level on ventilatory adaptation to respirator use.

The effect of exercise on the adaptation to an air-purifying respirator type load (dead space + inspiratory resistance) was studied in a group of 13 volunteers with a rapidly incremental exercise protocol. The difference between loaded and unloaded breathing at each exercise level was determined for each subject for a series of parameters describing the ventilatory work to overcome the respirator load pattern of breathing and metabolic work. Linear regression and t tests determined the average effect of the respirator load and the extent to which this effect was affected by the level of exercise. The inspiratory time and duty cycle were increased by the load, and exercise did not significantly affect the magnitude of this adaptation. High exercise did, however, increase the magnitude of the effect of the respiratory load on ventilatory work. These findings suggest that constraints to respiratory pattern adjustment, which may decrease respirator tolerance, occur at high exercise levels.

Adaptation, Physiological↗
PubMed1989

Effects of respirator dead space, inspiratory resistance, and expiratory resistance ventilatory loads.

The effects of respiratorlike inspiratory resistance (IR), expiratory resistance (ER), and dead space (DS) were assessed in a group of 11 normal volunteers during moderate steady-state (SS) and rapidly incremented (RI) exercise. The physiologic effects of IR were predominant, increasing inspiratory time, duty cycle, and several measures of ventilatory work. Effects of DS appear related to increased minute ventilation and include increasing flow rates and duty cycle and requiring greater ventilatory work; during RI exercise, the DS effect became relatively smaller at higher exercise levels. ER compressed expiratory time. These results characterize the response to IR, ER, and DS loads and suggest that DS may be relatively less physiologically significant than IR.

Airway Resistance↗
PubMed1989

Noninvasive measurement of respirator effect at rest and during exercise.

Ventilation and respiratory timing during rest and exercise were measured in normal volunteers by pneumotachograph and by respiratory inductive plethysmography (RIP) to determine if RIP is accurate and to determine if the usual methods of ventilation measurement during respirator research lead to artifacts. Data were collected with a mouthpiece, a sham mouthpiece, and no mouthpiece. A dead space and inspiratory resistance load similar to respirators were employed also. The study showed that no significant artifact is produced, particularly during exercise, by measurements using a mouthpiece. RIP is sufficiently accurate and precise for use in unobtrusively measuring ventilation during respirator studies when traditional methods cannot be used.

Humans↗
PubMed1989

Relationship of subjective tolerance of respirator loads to physiologic effects and psychophysical load sensitivity.

The degree to which subjective tolerance of respirator loads is related to physiologic effects and to psychophysical load sensitivity was investigated in this study. Fifty-two normal volunteers walked on a treadmill while breathing through a variety of respirator-type resistance and dead-space loads. Visual analog scales measuring perceived time limit of exercise and discomfort were both related to the ventilatory work imposed by the loads. Respiratory timing was related to discomfort but not to time limit. Psychophysical sensitivity to added resistive loads (LSS) was measured by the magnitude estimation method. Persons with higher objectively measured LSS had greater subjective intolerance induced by respirator use than persons of lower LSS. These findings suggest that subjective respirator tolerance is related to a person's psychophysical characteristics and to the actual physiologic effects. Furthermore, discomfort may be dissociated from actual exercise limitation.

Efficiency↗
PubMed1989

Predicate calculus, artificial intelligence, and workers' compensation.

Application of principles of predicate calculus (PC) and artificial intelligence (AI) search methods to occupational medicine can meet several goals. First, they can improve understanding of the diagnostic process and recognition of the sources of uncertainty in knowledge and in case specific information. Second, PC provides a rational means of resolving differences in conclusion based upon the same premises. Third, understanding of these principles allows separation of knowledge (facts) from the process by which they are used and therefore facilitates development of AI-based expert systems. Application of PC to recognizing causation of pulmonary fibrosis is demonstrated in this paper, providing a method that can be generalized to other problems in occupational medicine. Application of PC and understanding of AI search routines may be particularly applicable to workers' compensation where explicit statement of rational and inferential process is necessary. This approach is useful in the diagnosis of occupational lung disease and may be particularly valuable in workers' compensation considerations, wherein explicit statement of rationale is needed.

Artificial Intelligence↗
PubMed1988

Determinants of pattern of breathing during respirator use.

The relationship between the pattern of breathing in response to respirator-type loads and an individual's psychophysiologic sensitivity to loads (load scaling sensitivity, LSS) was investigated in the study of 11 normal volunteers. LSS was measured by having the subjects numerically rate a series of resistors; Steven's Psychophysical Law was used to evaluate sensitivity as the slope relating log (sensation) to log (stimulus). Peak pressure and actual added resistance were the stimuli. Inspiratory time, peak pressure, duty cycle, and tidal volume were inversely related to independently measured LSS during exercise and with a respiratory-type dead space and inspiratory resistance load. Because the need for changes in respiratory timing is a major adaptation in respirator use, it suggests that workers who are very sensitive to loads may have limited ability to adapt to respirator use.

Adult↗
PubMed1988

Occupational back pain of nurses: Special problems and prevention.

An observational study was performed to asses the nature and relative frequency of special circumstances of nursing which might contribute to occupational back pain and of preventive methods unique to nursing practice. The activities of 63 nurses were observed and coded in a behavioral scoring system. The group included registered nurses, licensed vocational nurses, aides and orderlies, and they worked in several different nursing units including intensive care units, medical/surgical units, post-anesthesia room and delivery room. Physical obstruction to easy contact with patients and fragile, extended attachments to patients were the most frequently observed problems. Mechanical assist devices, although available, were rarely employed. Assistance by a second staff member was the most commonly used preventive method. Such information is valuable for worker training programme design, job design and guiding priorities for future research.

Journal Article↗
PubMed1988

Subjective tolerance of respirator loads and its relationship to physiological effects.

Subjective and physiological responses to a variety of respiratory loads were measured in a group of 52 normal volunteers during steady, moderate treadmill exercise. Subjective response (SR) was determined with two visual analogue scales developed for this study: EXERT (perceived limitation of exercise duration) and DISC (perceived discomfort). There was a linear relationship between inspiratory resistance and SR. Expiratory and inspiratory resistance loading produced similar subjective effects. Dead space loading, however, produced very little subjective effect on either scale. The study suggests that subjective response can be measured quantitatively and should be considered in respirator design.

Adult↗
PubMed1988

Nurses' beliefs about cause and prevention of occupational back pain.

Nurses' beliefs and attitudes about causes and prevention of occupational back pain of nurses (OBPN) were studied by interviewing 68 nurses using a semi-structured format. Direct patient contact activities, particularly patient transfers, were most frequently mentioned as causes of OBPN. Attitudes and beliefs about preventive methods focused upon personal work practices and personal behavior such as choice of clothing and personal exercise. The findings of this study suggest that the causes of and preventive methods for OBPN identified by nurses differ from the actual work tasks performed and possibly associated with OBPN as determined by other studies. The authors postulate that nurse training and attitudes lead to a narrow focus; avoiding preconceived concepts is necessary for preventing OBPN.

Adult↗
PubMed1988

Symptoms, ventilatory function, and environmental exposures in Portland cement workers.

Data on respiratory symptoms and pulmonary function were obtained for 2736 Portland cement plant workers and 755 controls. Personal dust samples contained a geometric mean concentration of 0.57 mg/m3 for respirable dust and 2.90 mg/m3 for total dust. Cement workers and controls had similar prevalences of symptoms, except that 5.4% of the cement workers had dyspnoea compared with 2.7% of the controls. The mean pulmonary function indices were similar for the two groups. Among cement plant workers, the prevalence of chronic phlegm increased with tenure whereas the prevalence of wheezing increased with both tenure and current dust level. Other symptoms and pulmonary function indices were not significantly related to exposure.

Adult↗
PubMed1988

Veracity of disability claimants' self-reports of current smoking status. Comparison of carboxyhemoglobin levels from disability claimant and reference population.

Carboxyhemoglobin level (%COHB) obtained during pulmonary function testing was used as a measure of recent tobacco smoking among persons claiming to be nonsmokers and ex-smokers. Asbestos disability applicants and reference routine clinical patients had similar mean %COHB (2.09 +/- 1.34 and 1.99 +/- 0.88, respectively) and proportions with abnormally elevated %COHB (35 and 46 percent, respectively, had %COHB greater than 2 percent). However, comparisons of persons claiming to be ex-smokers and nonsmokers showed that the ex-smokers had higher mean %COHB (p less than 0.001 by analysis of variance) and proportions with elevated %COHB. This study suggests that disability applicants and routine clinical patients do not differ in veracity of self-stated smoking information, but many persons claiming to be ex-smokers are actually not.

Asbestosis↗
PubMed1988

Effects of industrial respirators on respiratory timing and psychophysiologic load sensitivity.

Loads imposed by industrial respirators include inspiratory flow resistance and dead space. Eleven normal subjects were studied at five levels of treadmill exercise (from resting to peak) with and without a respirator surrogate load (single air-purifying cartridge plus 300 ml dead space). Analysis of variance with linear contrasts was used to separate interpersonal from respirator effects. The respiratory pattern was significantly affected, prolonging inspiration, decreasing peak inspiratory flow rates, and increasing tidal volume. Sensitivity to respiratory loads was measured by the magnitude estimation method; the respirator load, but not exercise, decreased load sensitivity. Interpersonal differences in load sensitivity were relatively large. This study suggests that tolerance to respiratory loads similar to those of respirators may be significantly affected by respiratory timing and load sensitivity adaptation. Poor tolerance by some workers might be related to abnormal psychophysiologic load sensitivity.

Adaptation, Physiological↗
PubMed1987

Factor analysis of clinical data from asbestos workers: implications for diagnosis and screening.

Clinical data from 624 asbestos exposed workers were analysed by factor analysis. Fifteen clinical variables were found to reflect several underlying factors: "obstruction," "interstitial disorder," "x ray change," "air tapping," and "age/exposure." Scoring individual subjects along these axes can facilitate identifying early cases and avoiding false diagnosis. The analysis suggests that screening should be multimodal and that radiographic abnormality need not imply physiological impairment.

Asbestosis↗
PubMed1987

Physiologic categorization of asbestos-exposed workers.

Categorization of the pattern of physiologic abnormalities in patients with asbestos-associated disease may be important for clinical, compensation, and epidemiologic reasons. A population of 658 asbestos-exposed workers was divided into six groups (restrictive, mixed restrictive-obstructive, obstructive, abnormal diffusing capacity, small airway disease, and normal) based upon pulmonary function test results. Use of two commonly employed prediction equations for diffusing capacity produced divergent results. Adjustment of the forced vital capacity for airtrapping based upon measurement of residual volume or of total lung capacity can improve the accuracy of categorization, particularly in smokers. Hence, the process of interpretation of pulmonary function testing should be chosen carefully.

Adult↗
PubMed1987

Importance of non-patient transfer activities in nursing-related back pain: I. Questionnaire survey.

Work and personal factors associated with occupational back pain were investigated based upon responses to questionnaires administered to hospital nurses. Factor analysis of outcome measures developed two indices of occupational back pain: "pain factor" and "impact factor." Factor analysis also separated reported work activities into five groups. By logistic regression, frequency of "carrying and pushing" and "patient care activity" were associated with occupational back pain. These findings suggest that research and training should not focus on patient transfers only, but must emphasize nonpatient contact activities performed by nurses.

Back Pain↗