The diagnosis and management of occupational asthma

INTRODUCTION: Occupational asthma (OA), with a latency period induced by multiple exposures, is characterized by immunological sensitization to the responsible agent, based on both an IgE mediated mechanisms and non specific bronchial hyper responsiveness. DIAGNOSTIC METHODS: In the diagnosis of OA, the medical history is obviously the starting-point. Onset of respiratory symptoms at work and resolution on vacation are indications of the diagnosis. After analysis of several publications, this element appears to have the best level of proof (grade 2+) according to the criteria of evidence-based medicine. A visit of the workplace, with the cooperation of the industrial physician, is essential to characterize the nature of the exposure. Positive immunological tests (skin tests and/or specific IgE) associated with objective criteria of symptoms related to work (modification of PEFR, lung function and/or nonspecific bronchial hyper responsiveness) will confirm the aetiological diagnosis of OA. Specific bronchial provocation tests performed in the laboratory allow the identification of new agents involved in OA and are necessary when other investigations are discordant or unavailable. OA needs a stepwise approach including induced sputum eosinophilic counts and measurements of exhaled nitric oxide. MANAGEMENT OF OA: OA requires removal from the workplace because persistence of exposure to respiratory sensitisers may lead to an increase and prolongation of asthma symptoms. However, removal from the workplace can have tremendous professional, financial and social consequences, and sometimes a compromise must be found with reduction of exposure by various methods combined with adequate treatment. The pharmacological treatment of patients with OA should be the same as for patients with non OA, the use of bronchodilators and corticoids depending on the severity of asthma. Concerning the medico-legal aspects, OA can be recognised as an occupational disease. In France OA is included in several tables of work-related diseases.     

Integrated approach to diagnosis of associated occupational asthma and rhinitis

Patients with coexisting work-related rhinitis and asthma would benefit from an adequate and simultaneous recognition of both diseases. The present case illustrates the advantages and importance of using an integrated approach to confirm a diagnosis of occupational rhinitis (OR) and occupational asthma (OA).A 38-year-old woman, who worked as an animal laboratory technician since 2004, first noticed the appearance of rhinitis and conjunctivitis symptoms in 2007 when she was exposed to rats. A skin-prick test with rat extract was strongly positive. A specific inhalation challenge with parallel assessment of nasal and bronchial responses was conducted. After 10 min of exposure, she developed rhinitis and conjunctivitis symptoms, her forced expiratory volume in 1 s dropped by 27.5% and her nasal volume, measured by acoustic rhinometry, decreased by 80% from baseline values. After allergen exposure, induced sputum and nasal lavage examination demonstrated an increase in eosinophils (11% and 20%, respectively). A diagnosis of associated allergic OA and OR was confirmed and she was advised to stop working with rats.A systematic and parallel diagnostic approach enables confirmation of a diagnosis of OA and OR in patients complaining of work-related rhinitis and asthma symptoms.     

Hyperlipidaemia—management and views amongst physicians in general practice,in occupational health care and in internal medicine

Abstract. Objectives. To study aspects of management and views about hyperlipidaemia and its treatment amongst different categories of physicians. Design. A postal questionnaire was sent to selected physicians. Reminders were used. Setting. The study included physicians in primary health care (PHCPs), occupational health care (OHCPs), and in departments of internal medicine in hospitals (IMPHs). Subjects. All 146 PHCPs in the south-western region of Stockholm, 147 OHCPs, randomly selected from the directory of occupational health care offices, and all 157 IMPHs in six hospitals, in the greater Stockholm area, were offered the questionnaire. Main outcome measures. Differences in views, attitudes and treatment policy amongst different categories of physicians. Results. Response rate was 70% (61–81%). Intervention was initiated by the OHCPs at lower levels of cholesterol than by the other two groups, with diet (P < 0.001) and with drug intervention as primary (P < 0.01) and secondary prevention (P < 0.005). When other cardiovascular risk factors were present, intervention was started earlier by the OHCPs only in comparison with the PHCPs (P < 0.01). Knowledge of one's own cholesterol level was more common amongst the OHCPs than in the other two groups (P < 0.001). Patient follow-up was the same in all groups. Conclusions. Disagreement amongst physicians about hyperlipidaemia leads to conflicting information being given to patients. It is important to be aware of these differences when trying to reach a consensus on this topic. Corresponding knowledge and attitudes amongst members of the public should also be studied.     

职业性哮喘病因与诊断

本文对职业性哮喘(OA)的病因、临床表现、诊断进行综述.能引发OA的物质达300多种,分为高分予和低分子物质两类.OA以病因诊断为基础,根据确切的职业史、哮喘史、结合异常肺功能和实验室资料确立职业接触和哮喘发病之间的因果关系,排除其他原因喘息或呼吸道疾患方可诊断.特异变应原吸入支气管激发试验是最接近金标准的诊断方法.     

A systematic review of the diagnosis of occupational asthma

Background:This study systematically reviews literature regarding the diagnosis of occupational asthma (OA) and compares specific inhalation challenge (SIC) testing with alternative tests.Methods:Electronic databases and trials registries were searched; additional references were identified from bibliographic searches of included studies, hand searches of conferences, and author contacts. Various study designs (clinical trials, cohorts, cross-sectional, or case series) were included involving workers with suspected OA. All diagnostic tests were compared to a “reference standard,” and two researchers independently extracted 2 × 2 data. Pooled sensitivities and specificities (95% confidence intervals [CIs]) were derived.Results:Seventy-seven studies were included. For high molecular weight (HMW) agents, the nonspecific bronchial provocation (NSBP) test, skin-prick test (SPT), and serum-specific IgE had sensitivities > 73% when compared to SIC. Specificity was highest for specific IgE vs SIC (79.0%; 95% CI, 50.5 to 93.3%). The highest sensitivity among low molecular weight asthmagens occurred between combined NSBP and SPT vs SIC (100%; 95% CI, 74.1 to 100%). When compared to SIC, specific IgE and SPT had similar specificities (88.9%; 95% CI, 84.7 to 92.1%; and 86.2%; 95% CI, 77.4 to 91.9%, respectively). For HMW agents, high specificity was demonstrated for positive NSBP tests and SPTs alone (82.5%; 95% CI, 54.0 to 95.0%) or when combined with specific IgE (74.3%; 95% CI, 45.0 to 91.0%) vs SIC. Sensitivity was somewhat lower (60.6% and 65.2%, respectively).Conclusions:In appropriate clinical situations when SIC is not available, the combination of a NSBP test with a specific SPT or specific IgE may be an appropriate alternative to SIC in diagnosing OA. While positive results of single NSBP test, specific SPT, or serum-specific IgE testing would increase the likelihood of OA, a negative result could not exclude OA.     

Validation of an exposure system to particles for the diagnosis of occupational asthma.

STUDY OBJECTIVE: We previously described a closed-circuit system for exposure to particles in humans. This system has three components: a particle generator, an exposure chamber connected to an orofacial mask, and monitors. We describe results of challenges in 56 subjects who underwent challenges with the apparatus using occupational sensitizers in particles. SUBJECTS: Fifty-six consecutive subjects referred for the investigation of occupational asthma to occupational sensitizers in particles were included. The agents were the following: flour and grains (n = 19), cedar (n = 10), psyllium (n = 9), guar gum (n = 9), drugs (n = 3), persulfate (n = 2), and miscellaneous (n = 4). INTERVENTION: The duration of exposure was progressive and varied from one breath to a maximum of 180 min depending on the reaction. When no significant fall in FEV1 occurred after exposure with the aerosolization device, the standard approach of tipping particles from one tray to another was used. RESULTS: Twenty-nine subjects (52 percent) had a significant (greater than or equal to 20 percent) fall in FEV1 after exposure. This includes 18 subjects with isolated immediate reactions, four with dual asthmatic reactions, and two with atypical reactions. In 20/24 instances (83 percent), the percentage of fall in FEV1 did not exceed 30 percent, thus showing that dose-response curves can generally be obtained in a safe way. In all instances except one (26/27 cases), subsequent exposures using the traditional method did not result in significant falls in FEV1. CONCLUSION: This new procedure results in safe tests in terms of the percentage of changes in FEV1 during the immediate reactions and very rare false-negative challenges.     

The diagnosis and reporting of occupational diseases: the performance of physicians in Thailand

The diagnosis and reporting of occupational diseases are important components of any occupational disease surveillance system. These two factors were assessed in 222 Thai physicians by using a self-administered questionnaire. Study results show that a proper diagnosis of occupational disease is hampered by the following: lack of knowledge about occupational medicine; a shortage of environmental data; a lack of consultation services and laboratory facilities. Concern about possible legal implications also prevents physicians from making a diagnosis of occupational disease. Evidence shows that financial incentive seems to play a crucial role in physicians' compliance with the reporting system. A number of remedial approaches are proposed, including the improvement of professional training, the development of standard practice guidelines, and novel financial measures for healthcare providers. Improvement calls for the collaborative effort of all responsible agencies and warrants further research that will guide policy and practice.     

Effect of respiratory protective devices on development of antibody and occupational asthma to an acid anhydride

STUDY OBJECTIVES: To determine whether the use of respiratory protective equipment would reduce the incidence of occupational asthma due to exposure to hexahydrophthalic anhydride (HHPA). DESIGN: Prospective cohort study. SETTING: A facility that makes an epoxy resin product requiring HHPA for its manufacture. PARTICIPANTS: Sixty-six individuals newly hired at a facility that makes an epoxy resin product requiring HHPA for its manufacture. INTERVENTION: Employees who wished to use respiratory protective equipment could choose from three types of masks: dust mask, half-face organic vapor respirator, or full-face organic vapor respirator. MEASUREMENTS: Workers were evaluated annually for development of positive antibody to HHPA and occupational, immunologic respiratory disease, including occupational asthma. RESULTS: With use of respiratory protective equipment, the rate of developing an occupational immunologic respiratory disease was reduced from approximately 10 to 2% per year. Occupational asthma developed in only three individuals, and they were all in the higher exposure category. Statistically, one respirator was not superior to the others. CONCLUSION: Respiratory protective equipment can reduce the incidence of occupational immunologic respiratory disease, including occupational asthma, in employees exposed to HHPA.     

When to suspect occupational asthma

Occupational asthma (OA) is a difficult diagnosis to make. The present review describes the work environments in which workers are at risk for developing OA, the characteristics of the individuals in whom OA should be suspected and the investigation that can be performed to diagnose the condition. Accurately diagnosing OA is crucial because of the major social and economic consequences of this diagnosis on the patient.     

Value of realistic exposure tests in the diagnosis of occupational asthma due to exotic woods

Respiratory pathology related to the increased use of exotic woods has become much more extensive in recent years. The recognition of occupational asthma due to these woods is easy when the history is sufficiently striking. By contrast, the diagnosis may be much more difficult because of frequent inadequacy in classical allergological and immunological tests. This leads to the need for more extensive special investigations. Realistic tests are the most valuable. In the present report, the authors describe the results of such tests in 10 cases of occupational asthma due to exotic woods. They compared history (past, clinical manifestations), results of pulmonary function tests, allergological studies (skin tests and laboratory) and realistic exposure tests. They describe the principles, value, results, limitations and disadvantages.     

Awareness of issues related to sleep disordered breathing amongst practicing physicians

BACKGROUND: Most of the sleep related breathing disorders currently in India are both under diagnosed and under treated. The exact prevalence of sleep disordered breathing (SDB) in our country is not clearly known and this is partly due to lack of awareness amongst physicians and lack of formal epidemiological data from Indian subcontinent. Several international agencies have emphasised the urgent need for medical training at all levels in sleep medicine, so as to include an exposure to the broader aspects of sleep medicine. OBJECTIVE: To assess the knowledge of practicing chest physicians on the issues related to sleep disordered breathing in the local set-up. METHODS: A standardised questionnaire with strong face validity was utilised for this purpose to interview 65 physicians at their work place. RESULTS: The overall awareness about sleep disordered breathing amongst the practicing physicians in Hyderabad, Secunderabad and the neighbouring district of Warangal was poor. There was no association between professsional qualifications and level of awareness. Furthermore, the awareness was found to be similarly low both amongst young and middle aged physicians and this was statistically significant (p<0.001). CONCLUSION: The overall awareness about sleep disordered breathing amongst practicing physicians in and around Hyderabad is rather poor.     

合并呼吸道感染的支气管哮喘诊治

呼吸道感染与支气管哮喘有密切关系.呼吸道感染可使许多支气管哮喘患者诱发喘息,或使支气管哮喘的临床症状加重.支气管哮喘患者支气管的异常和部分平喘药物均易于引起呼吸道和肺部感染.呼吸道合胞病毒、鼻病毒等可引起喘息症状.该文讨论了呼吸道病毒感染诱发支气管哮喘的机制、临床特点和诊治方法.