A cross-sectional study of exposures, lung function and respiratory symptoms among aluminium cast-house workers.

UNLABELLED: OBJECTIVES To investigate exposures, respiratory symptoms, lung function and exposure-response relationships among aluminium cast-house workers. METHODS: A cross-sectional study was conducted among 182 workers. Exposure data were used to model exposure to irritants. Lung function and questionnaire data on respiratory symptoms were compared to a general population sample and an internal reference group. Blood samples were taken from 156 workers to examine total IgE, eosinophils and sensitisation to common allergens. RESULTS: Average daily mean exposure to inhalable dust, metals, hydrogen fluoride, fluoride salts and sulphur dioxide was relatively low compared to reference values. Airflow patterns in the hall were disturbed regularly and resulted in pot emissions with high concentrations of fluorides. Peak exposures to chlorine gas occurred intermittently due to production process disturbances. Workers reported significantly more respiratory symptoms (continuous trouble with breathing (prevalence ratio (PR) 2.5; 95% CI 1.2 to 5.3), repeated trouble with breathing (PR 1.8; 95% CI 1.1 to 3.0), wheezing (PR 1.4; 95% CI 1.1 to 1.8), asthma attack (ever) (PR 2.8; 95% CI 1.7 to 4.6) and doctor diagnosed asthma (PR 2.6; 95% CI 1.5 to 4.4). Regression analysis showed significantly lower FEV(1) values (-195 ml) and FVC values (-142 ml) compared to a general population sample. Lung function did not differ between groups. CONCLUSION: This epidemiological study suggests cast-house workers in the aluminium industry are exposed to respiratory hazards. Exposure-response relationships could not be demonstrated but this study supports preventive measures in the work environment with a focus on (peak) exposures to irritants.

A cross-sectional study among detergent workers exposed to liquid detergent enzymes.

OBJECTIVES: To investigate sensitisation and respiratory health among workers who produce liquid detergent products and handle liquid detergent enzymes. METHODS: We performed a cross-sectional study among 109 eligible workers of a detergent products plant. 108 were interviewed for respiratory and allergic symptoms and 106 blood samples were taken from them to examine sensitisation to enzymes. Those sensitised to > or = 1 enzymes were referred for clinical evaluation. Workers and representatives were interviewed to characterise exposure qualitatively and estimate exposure semi-quantitatively. Workers were classified into three exposure groups with varying exposure profiles to enzymes, based on frequency, duration, and level of exposure. RESULTS: Workers were exposed to proteases, alpha-amylase, lipase and cellulase. The highest exposures occurred in the mixing area. Liquid spills with concentrated enzyme preparations and leakage of enzymes during weighing, transportation and filling were causing workplace contaminations and subsequently leading to both dermal and inhalation exposure for workers. Workers with the highest exposures reported significantly more work-related symptoms of itching nose (prevalence ratio (PR) = 4.2, 95% CI 1.5 to 12.0) and sneezing (PR = 4.0, 95% CI 1.5 to 10.8) and marginally significant more symptoms of wheezing (PR = 2.9, 95% CI 0.9 to 8.7) compared with the least exposed group. Fifteen workers (14.2%) were sensitised to > or = 1 enzymes. A marginally statistically significant gradient in sensitisation across the exposure categories was found (p = 0.09). There was a clinical case of occupational asthma and two others with probable occupational rhinitis. CONCLUSIONS: Workers exposed to liquid detergent enzymes are at risk of developing sensitisation (14%) and respiratory allergy.

A cross-sectional study of lung function and respiratory symptoms among chemical workers producing diacetyl for food flavourings.

OBJECTIVES: Four diacetyl workers were found to have bronchiolitis obliterans syndrome. Exposures, respiratory symptoms, lung function and exposure-response relationships were investigated. METHODS: 175 workers from a plant producing diacetyl between 1960 and 2003 were investigated. Exposure data were used to model diacetyl exposure. Lung function and questionnaire data on respiratory symptoms were compared to a general population sample and respiratory symptoms to an internal reference group. RESULTS: Workers were potentially exposed to acetoin, diacetyl, acetaldehyde and acetic acid. Historic diacetyl exposure ranged from 1.8 to 351 mg/m(3), and from 3 to 396 mg/m(3) for specific tasks. Diacetyl workers reported significantly more respiratory symptoms compared to the general population sample (continuous trouble with breathing (prevalence ratio (PR) = 2.6; 95% CI 1.3 to 5.1), daily cough (PR = 1.5; 95% CI 1.1 to 2.1), asthma attack (ever) (PR = 2.0; 95% CI 1.2 to 3.4), doctor diagnosed asthma (PR = 2.2; 95% CI 1.3 to 3.8) and asthma attack in the last year (PR = 4.7; 95% CI 1.9 to 11.4)) and to a minimally exposed internal reference group (ever trouble with breathing (PR = 2.8; 95% CI 1.1 to 7.0) and work-related shortness of breath in the last year (PR = 7.5; 95% CI 1.1 to 52.9)). Lung function did not differ between groups. A positive relationship between exposure and FEV(1) was found. CONCLUSION: The excess of respiratory symptoms in this retrospective cohort suggests that diacetyl production poses an occupational hazard. Limited historical exposure data did not support a quantitative individual diacetyl exposure-response relationship, but our findings suggest that preventive measures are prudent.

Exposure to trichloramine and respiratory symptoms in indoor swimming pool workers.

The association between swimming pool characteristics and activities of employees and respiratory symptoms in employees was studied. Trichloramine levels were measured to evaluate relationships with pool characteristics and to estimate long-term exposure levels. Questionnaires were available from 624 pool workers and 38 swimming facilities. Chloramine levels were measured by area sampling over 2-h periods and analysed using ion chromatography. Work-related and general respiratory symptoms, and symptoms indicative of atopy and bronchial hyperresponsiveness were considered. Respiratory symptom prevalence among pool workers was compared with symptoms in a Dutch population sample. Chloramine levels were modelled with regression analysis. This model was used to estimate long-term average chloramine levels for each pool studied. Employees with higher exposure reported upper respiratory symptoms with greater frequency. Upper respiratory symptoms were statistically significantly associated with cumulative chloramine levels (odds ratio (OR) >1.4 for hoarseness, lost voice, sinusitis). General respiratory symptoms were significantly elevated compared with a Dutch population sample (OR ranged 1.4-7.2). An excess risk for respiratory symptoms indicative of asthma was observed in swimming pool employees. Aggravation of existing respiratory disease or interactions between irritants and allergen exposures are the most likely explanations for the observed associations.

[The Netherlands Expertise Center for Occupational and Respiratory Disorders]. / Nederlands Kenniscentrum Arbeid en Longaandoeningen.

In 2000 the Netherlands Expertise Centre for Occupational Respiratory Disorders (NECORD) was started as a centre of expertise in occupational health. The centre received a grant from the ministry of Health Welfare and Sport for a period of 5 years. Their mission was to collect, develop and implement knowledge in the fields of diagnosis, treatment, reintegration and prevention of work-related health- and occupational disorders. In cooperation with two other institutes for health, NECORD has become a multidisciplinary clinical occupational respiratory health service. Occupational hygienists, occupational health physicians and chest physicians are working on three programmes: research projects on the prevalence and monitoring of respiratory health effects resulting from exposure to substances in the work place; patient care (out-patient clinic); and support of professionals (website, helpdesk, development and implementation of guidelines, education and postgraduate training).

Eccentric exercise training in patients with chronic obstructive pulmonary disease.

The oxygen cost of eccentric exercise is lower than that of concentric exercise at similar work-loads. In this study, the response to eccentric cycle exercise training (EET) in addition to general exercise training (GET) on exercise performance and quality of life was investigated in 24 patients with severe chronic obstructive pulmonary disease (COPD). All patients had a normal resting PaO2 and an arterial oxygen saturation (SaO2) below 90% at Wmax, achieved during a maximal incremental concentric cycle exercise test. The patients participated in a comprehensive inpatient pulmonary rehabilitation programme of 10 weeks. They were randomly assigned either to GET (GET group: mean FEV 38% predicted) or to GET and additional EET (GET/EET group: FEV1 45% predicted). During EET, the patients were able to cycle eccentrically for 15 min continuously at a mean of 160 (69%) of Wmax whereas the Borg dyspnoea score did not exceed 3.0 and SaO2 did not fall below 90%. Parameters of cardiocirculatory fitness and gas exchange improved in the GET/EET group but no further improvement in exercise capacity occurred compared to GET. It is concluded that eccentric cycle exercise is a safe and attractive training modality for patients with severe COPD and can be performed at a high intensity without the patient becoming out of breath or needing supplemental oxygen.

[CBO guideline 'Oxygen therapy at home']. / CBO-richtlijn 'Zuurstofbehandeling thuis'.

In the Netherlands, domiciliary oxygen therapy is regularly prescribed incorrectly and thus inefficiently, and the policies surrounding this therapy are inconsistent. This applies particularly to patients with chronic hypoxaemia due to chronic obstructive pulmonary disease (COPD). In order to establish a scientific basis for a uniform prescription policy, guidelines have been developed under the auspices of the Dutch Thoracic Society with the support of the Dutch Institute for Health Care Improvement. Based on scientific research, recommendations have been formulated for the indications and aims of domiciliary oxygen therapy and long-term oxygen therapy (LTOT). The most important recommendations (summarised on the back of an oxygen application form) are: domiciliary oxygen therapy is only indicated for severe hypoxaemia by day at rest; if domiciliary oxygen therapy was prescribed following recovery from an acute exacerbation or hospitalisation, the arterial oxygen tension should be rechecked within three months of starting oxygen therapy; prescription of LTOT is only justified in case of an optimal (non-)medical regimen, clinical stability, and chronic hypoxaemia, and providing a number of preconditions, such as smoking cessation (partly due to the fire hazard), have been met; LTOT is a lifelong therapy that should be prescribed for at least 15, and preferably 24, hours per day, and the oxygen flow rate settings for rest, exertion and sleep should be adjusted to meet the patient's needs; for ambulatory patients, the prescribing physician should consider the portability of the oxygen equipment; as patient education and supervision are essential to secure the success of LTOT, the prescribing physician should cooperate with the general practitioner, the district nurse and the oxygen supplier in this respect.

Risk of overtreatment with current peak flow criteria in self-management plans. Dutch CNSLD Study Group. Chronic Non-Specific Lung Disease.

Home peak expiratory flow (PEF) measurements have become the cornerstone of asthma self-management plans. However, the cut-off values for changing treatment have not been formally tested. This study focusses on the possible overtreatment brought about by the different cut-off values and denominators currently employed. Data from 133 clinically stable asthmatic patients from a 2.5 yr follow-up study were analysed. The results showed that strict adherence to current criteria would lead to severe overtreatment, with up to 30% of clinically stable patients crossing into the lowest (red) zone at least once a year when personal best is the denominator and when it has not been limited to a defined time of day or to defined prior bronchodilator use. As expected, the passage of clinically stable patients into the lower zones became less frequent when cut-off values were sharpened and when time- and treatment-specific PEFs were used as the denominators. Strict adherence to commonly used peak expiratory flow cut-off values would lead to considerable overtreatment. In order to avoid overtreatment, the morning peak expiratory flow before any (bronchodilator) treatment should be related to the personal best peak expiratory flow measured under the same conditions. The choice of the right cut-off value will also depend on studies being performed to test the amount of undertreatment with a given value.

Cardio-respiratory load of exercise training in patients with severe COPD.

The effect of physical training depends on the intensity at which exercise is performed. Patients with chronic obstructive pulmonary disease (COPD) may not tolerate high exercise intensities during training due to breathlessness. The purpose of the present study was to investigate the cardiorespiratory load of exercise training, during pulmonary rehabilitation, in patients with severe COPD. We also studied the effects of pulmonary rehabilitation on maximum exercise performance. Thirteen patients with stable COPD (FEV1 (S.D.) 1.0 (0.3) L) performed an incremental cycle exercise test at baseline and after a 10 week in-patient pulmonary rehabilitation programme. Exercise training consisted of dynamic and isometric strength training exercises, and training of specific daily life activities. Training sessions were held 5 days per week for 10 weeks. Heart rate (HR) and dyspnoea ratings (Borg scale) were measured during one session in the second or third week of training, and were compared with values obtained during incremental cycle exercise at baseline. The ventilatory load during the training was estimated by using the relationship between HR and minute ventilation (VE) during incremental cycle exercise at baseline. The duration of a training session was 80 (7) min, including periods of rest. The HR during various exercises of the training programme varied between 94 (17) and 103 (14)% of peak HR during incremental cycle exercise. Borg scores during the training varied between 2.0 and 5.7, and were lower than the Borg score at peak exercise (6.5 (2.0)). HR was more than 90% of peak HR during 36 (33) min of the whole training session, which corresponded with a VE of 81 (11)% of peak VE during incremental cycle exercise. Training significantly increased maximum work load (Wmax) from 62 (25) to 73 (21) W (P < 0.05), without any change in peak HR, VE and VO2. In patients with severe COPD, the training intensity in terms of cardio-respiratory load was high in relation to individual maximum values. Pulmonary rehabilitation, including exercise training, improved maximum exercise performance.

Potassium and ventilation during positive and negative work in patients with chronic obstructive pulmonary disease.

In patients with chronic obstructive pulmonary disease (COPD), reduced ventilatory reserves limit exercise tolerance. In these patients, the ventilatory requirements of eccentric exercise (negative work, Wneg) are lower than those of concentric exercise (positive work, Wpos) at similar workloads. In this study, we investigated the relationship between plasma potassium levels and ventilation during Wpos and Wneg in these patients. Twelve patients with stable COPD [mean (SD) FEV1 46% (16) of predicted] performed Wpos and Wneg on a cycle ergometer (6 min of exercise; interval > or = 1 h) in a randomized order at a constant workload of 50% of the individual maximum (positive) work capacity. Minute ventilation (VE) and arterial plasma potassium concentration ([K+]a) were measured at rest, and at 1-min intervals during exercise and during 3 min of recovery. VE increased less during Wneg than during Wpos [6 (range 3-26) vs. 18 (range 8-28) 1 min-1; P < 0.01]. VE during Wneg was reduced in proportion to VCO2. The increase in [K+]a during Wpos and Wneg [0.45 (range 0.26-0.75) and 0.34 (range 0.1-0.97) mM] did not differ significantly. VE was closely correlated with VCO2 during both types of exercise. VE was also closely correlated with [K+]a, but the slope of the relationship between [K+]a and VE was steeper during Wpos than during Wneg [39.1 (range 15.2-88.6) vs. 18.3 (range 7.2-37.3) 1 min-1 mM-1; P = 0.012]. In contrast, the slope of the relationship between VCO2 and VE was similar during both types of exercise [27.8 (range 19.2-37.1) vs. 32.1 (range 19.8-48.4)]. Thus, for a given increase in [K+]a, the increase in VE was significantly less during Wneg. In patients with COPD, potassium did not explain the difference in exercise ventilation between Wneg and Wpos, and may not play a significant role in the control of breathing during low-intensity exercise.

Training with supplemental oxygen in patients with COPD and hypoxaemia at peak exercise.

Supplemental oxygen has acute beneficial effects on exercise performance in patients with chronic obstructive pulmonary disease (COPD). The purpose of this study was to investigate whether oxygen-supplemented training enhances the effects of training while breathing room air in patients with severe COPD. A randomized controlled trial was performed in 24 patients with severe COPD who developed hypoxaemia during incremental cycle exercise (arterial oxygen saturation (Sa,O2) <90% at peak exercise). All patients participated in an in-patient pulmonary rehabilitation programme of 10 weeks duration. They were assigned either to general exercise training while breathing room air (GET/RA group: forced expiratory volume in one second (FEV1) 38% of predicted; arterial oxygen tension (Pa,O2) 10.5 kPa at rest; Pa,O2 7.3 kPa at peak exercise), or to GET while breathing supplemental oxygen (GET/O2 group: FEV1 29% pred; Pa,O2 10.2 kPa at rest; Pa,O2 7.2 kPa at peak exercise). Sa,O2 was not allowed to fall below 90% during the training. The effects on exercise performance while breathing air and oxygen, and on quality of life were compared. Maximum workload (Wmax) significantly increased in the GET/RA group (mean (SD) 17 (15) W, p<0.01), but not in the GET/O2 group (7 (25) W). Six minute walking distance (6MWD), stair-climbing, weight-lifting exercise (all while breathing room air) and quality of life significantly increased in both groups. Acute administration of oxygen improved exercise performance before and after training. Training significantly increased Wmax, peak carbon dioxide production (V'CO2) and 6MWD while breathing oxygen in both groups. Differences between groups were not significant. Pulmonary rehabilitation improved exercise performance and quality of life in both groups. Supplementation of oxygen during the training did not add to the effects of training on room air.

Ventilatory response to positive and negative work in patients with chronic obstructive pulmonary disease.

In healthy subjects, oxygen consumption and cardiorespiratory responses are lower during eccentric exercise (negative work, Wneg) than during concentric exercise (positive work, Wpos) at the same work load. The aim of the present study was to investigate the ventilatory response to Wneg in patients with chronic obstructive pulmonary disease (COPD). The study population consisted of 12 subjects with COPD [forced expiratory volume in 1 s (FEV1) mean (SD): 1.5 (0.4) 1, 46 (16)% of predicted]. Concentric and eccentric exercise tests (6 min exercise; interval > or = 1 h) were performed in random order at constant work loads of 25 and 50% of the individual maximal (positive) work capacity. Expired ventilation per minute (VE), oxygen consumption (VO2) and carbon dioxide production (VCO2) were 30% lower during Wneg than during Wpos for both work intensities. The breathing reserve during 25% Wneg was 11 (8)% and during 50% Wneg was 18 (14)% higher than during Wpos at corresponding work loads (P < 0.01). VE/VO2 and VE/VCO2 were similar during Wpos and Wneg. Arterial carbon dioxide tension (PaCO2) increased by 0.1 (0.4) kPa during 50% Wneg and by 0.7 (0.5) kPa during 50% Wpos (P < 0.01). During 50% Wneg' perceived leg effort (modified Borg scale) tended to be higher than perceived breathlessness (2.4 (1.2) vs. 2.0 (1.1). It was concluded that in subjects with COPD, the ventilatory requirements of Wneg were considerably lower than those of Wpos at similar work loads up to 50% of maximal work capacity. During Wneg, the ventilatory reserve was higher and gas exchange was less disturbed as a result of a lower VO2 and VCO2.

[Subnormal vitamin B6 levels in theophylline users]. / Subnormale vitamine-B6-spiegels bij theofyllinegebruik.

OBJECTIVE: To study the effect of theophylline use on the vitamin B-6 status. DESIGN: Descriptive. SETTING: Department of Geriatric Medicine of Nijmegen Academic Hospital and Department of Pulmonary Diseases, University of Nijmegen, the Netherlands. PATIENTS AND METHODS: Vitamin B-6 status was determined by measuring pyridoxal-5'-phosphate (PLP) in whole blood (using a high performance liquid chromatography method, reference values: 35-107 mumol/l) in 141 patients from the Geriatric department (84 non-chronic obstructive pulmonary disease (COPD), 40 COPD patients without theophylline and 17 COPD patients with theophylline) and in 25 non-geriatric COPD patients on theophylline. RESULTS: Of the 84 geriatric non-COPD patients (mean age: 82 years; SD: 6) 56% had a subnormal vitamin B-6 status, of the 40 geriatric COPD patients without theophylline (82 years; SD: 6) 70%, of the 17 geriatric COPD patients on theophylline (80 years; SD: 5) 94% and of the 25 non-geriatric COPD patients on theophylline (62 years; SD: 11) 96%. CONCLUSION: In patients who used theophylline a higher prevalence of subnormal vitamin B-6 status was found than in patients who did not.

[Examination of the mediastinum in staging of primary bronchial carcinoma]. / Onderzoek van het mediastinum bij de stadiëring van het primaire bronchuscarcinoom.

Mediastinoscopy and CT are used to evaluate the mediastinum in patients with non small cell lung cancer to determine operability. Generally, the sensitivity and negative predictive value of CT are high, in a personal study in 150 patients 86% and 92%, respectively. When CT does not reveal enlarged lymph nodes, we recommend thoracotomy without mediastinoscopy. However, micrometastases in non-enlarged lymph nodes will be missed. All positive CT scans necessitate mediastinoscopy, because enlarged lymph nodes frequently are not invaded with tumour (in our study in 33%). CT used in this way will increase the percentage of positive results of mediastinoscopy. In patients with a peripheral tumour lymphogenic spread to the mediastinum is not uncommon (in our study in 22%) and mediastinal evaluation should not be omitted. In these patients mediastinoscopy is also of diagnostic value.