Ventilatory Capacity Research Articles

Effects of maximal interval training on arterial oxygen desaturation and ventilation during heavy exercise.

The purpose of the present study was to clarify longitudinally the effects of exercise training on arterial O(2) saturation (Sa(O(2))) and ventilation during heavy exercise. A group of six subjects (training group) volunteered to train four times a week for 12 weeks. Each training session consisted of five 3-min periods of exercise on a cycle ergometer at a power output of 100% maximal O(2) uptake (V(.)(O(2 max))), interspersed with 2-min recovery period cycling at 50% V(.)(O(2 max)). During the training, V(.)(O(2 max)), Sa(O(2)), the ventilatory equivalent for oxygen (V(.)E/V(.)(O(2))), and the end-tidal partial pressure of O(2) (PET(O(2))) during heavy exercise were measured periodically. The same parameters were measured simultaneously in another group of five subjects (control group) who led normal lives. Maximal interval training increases V(.)(O(2 max)), with little change in V(.)E(max) and pulmonary functions at rest. The training decreased PET(O(2)), V(.)E/V(.)(O(2)), and Sa(O(2)) during heavy exercise. Sa(O(2)) is significantly related to V(.)E/V(. )(O(2)) (r(2) = 0.49). These results suggest that less hyperventilatory response to exercise occurs with progress in physical training because the adaptability of ventilatory capacity is less than that of aerobic work capacity, which half induces arterial O(2) desaturation during heavy exercise. PET(O(2)) as well as V(.)E/V(.)(O(2)) and V(.)(O(2 max)) did not change anymore after the 6th week, nevertheless Sa(O(2)) kept decreasing up to the last 2 weeks. In addition, when the Sa(O(2))-V(.)E/V(.)(O(2)) plot was compared between the two groups, the regression line of the training group was steeper than that of the control groups; i.e., compared at a lower level of V(.)E/V(.)(O(2)) ( approximately 30 ml.ml(-1)), the Sa(O(2)) of the trained subjects exercising at a higher V(.)(O(2)) level was lower than that of the control subjects. Predominance of less hyperventilation and another factor, increased A-aDO(2), in the genesis of arterial hypoxemia and O(2) desaturation may be dependent upon V(.)(O(2)) levels in heavy exercise and the state of training.

RETROSPECTIVE Physiological variation and adaptability in human populations

This review traces some of the developments in population physiology based on contributions to the Annals over the last 25 years. Two broad themes are evident, physiological systems variation and adaptation, and by way of introduction an historical perspective of their relationship within human ecology is explored. Studies of physical fitness and work capacity, and the efforts to create standardized field procedures make up a number of the early papers. Longitudinal studies have provided reliable reference standards for Westernized populations, but are virtually non-existent for primitive groups. The relative importance of phenotypic and genotypic variations in working capacity have yet to be clearly defined. The level of habitual activity during childhood contributes to the development of ventilatory capacity though constitutional influences are of major importance. Variability in strength and motor performance of skeletal muscles are shown to have a direct bearing on aspects of growth, development and biological maturation. Physicaland psychologicalstress in communities have been investigated. These and other studies contribute valuable data on the issue of stress, hypertension and cardiovascular morbidity and mortality. On the theme of human adaptability, high altitude populations, variations in thermal tolerance and adaptations in ageing populations have all received recent investigation. Highland people of all ages have considerably larger lung volumes than coastaldwellers. Haematological, biochemical and pulmonary function show adaptive phenomena that vary in different highland groups. In the tropical biome, more recent work includes the functional consequences of malnutrition, ethnic and cultural differences in work capacity, and the effects of endemic disease on physical performance. Annals of Human Biology papers have more recently contributed to investigations on morphological and physiological changes with human ageing. Though there is a decline in the ability to adapt to environmental stresses with age this may be met by changes in adaptational strategy in physiological systems.

Mechanical ventilatory constraints in aging, lung disease, and obesity: perspectives and brief review.

Mechanical ventilatory constraints in aging, lung disease, and obesity; perspectives and brief review. Med. Sci. Sports Exerc., Vol. 31, No. 1 (Suppl.), pp. S12-S22, 1999. One of the most difficult tasks of cardiopulmonary exercise testing is to determine the influence of ventilatory limitations on the ventilatory response to exercise. Currently there is no generally accepted method in which to quantify the magnitude of mechanical ventilatory constraints during exercise. Nor is there agreement on how to quantify maximal ventilatory capacity. To address these issues, this article focuses on the evaluation of mechanical ventilatory constraints during exercise and provides an overview of the mechanical ventilatory constraints that are encountered with aging, lung disease, and obesity.

Ventilatory Mechanics and Gas Exchange during Exercise before and after Lung Volume Reduction Surgery

Many patients with emphysema are able to meet ventilatory demands during resting conditions, but they show severe limitations during exercise. To examine the effect of lung volume reduction (LVR) surgery on exercise performance and the mechanism of possible improvement, we measured ventilatory mechanics (pulmonary resistance [RL], work of breathing [WOB], dynamic intrinsic positive end-expiratory pressure [PEEPi,dyn], peak expiratory flow rate [PEFR]), breathing pattern, oxygen uptake (V O2), and carbon dioxide removal (V CO2) at rest and during cycle ergometry in eight patients before and 3 mo after LVR surgery. Ventilatory mechanics were evaluated assessing esophageal pressure and air flow. Three months after LVR surgery, the tolerated workload was doubled when compared with the preoperative value (p < 0.0005), associated with a reduction of RL (p < 0.05), PEEPi,dyn (p < 0.005), and WOB (p < 0. 005) at comparable workloads. Maximal ventilatory capacity and maximal tidal volume (VT) increased significantly (p < 0.01). Maximal V O2 increased from 474 +/- 23 to 601 +/- 16 ml/min (p < 0. 005) and maximal V CO2 from 401 +/- 13 to 558 +/- 21 ml/min (p < 0. 005), though no significant difference at comparable workloads could be observed. In conclusion, emphysema surgery leads to an improvement of ventilatory mechanics at rest and during exercise. Higher maximal VT and minute ventilation were observed, resulting in improvement of maximal V O2 and V CO2 and exercise capacity.

New Techniques to Evaluate Functional Impact of Bovine Respiratory Disease

Despite prophylactic measures, mainly including vaccination programs and management measures, respiratory disease remains the major cause of economic losses in bovine species. Therapeutic strategies include three targets: the etiologic agents, the inflammatory reaction and the mechanical disorders. Choice of treatment is currently main based on the clinician's personal experience.&#x0D; A theoretical method has been proposed earlier to classify this syndrome_into four grades of severity: Grade 1, subclinical disease (no treatment); Grade 2, compensated clinical disease (antibiotics only); Grade 3, noncompensated clinical disease (antibiotics + antiinflammatory drugs and Grade 4, irreversible clinical disease (no treatment). However, objective methods to evaluate immediate, in an easy and cheap way, the functional impact of respiratory pathologies and to determine the level of severity are not available.&#x0D; Three techniques, each one evaluating the oxygen transport chain at a different level, have been studied and validated, i.e. pulse oximetry, lactate dosage and the lobeline test.&#x0D; Measurement of arterial hemoglobin oxygen saturation is an important means to evaluate effectiveness of the oxygen transport chain. Assessment is usually performed based on an arterial blood sample analyzed by a blood gas analyzer. This technique presents several disadvantages: it's invasive, discontinuous and expensive. Pulse oximetry is a non-invasive, immediate and cheap method of measuring percentage oxygen saturation of arterial hemoglobin, based on differential absorption of red and infrared light. It showed to be useful and accurate in bovines when the probe was fitted to the animal's tail, even with low values of hemoglobin saturation.&#x0D; Blood lactate levels are elevated in case of severe bovine respiratory disease because of diminished tissue oxygenation and because of elevated respiratory muscle effort. Assessment used to be done by a complex laboratory test. Recently a handportable apparatus, named "Accusport" and measuring blood lactate concentration immediately, has been introduced in equine medicine. It proved also to be reliable and useful in the evaluation of severity of bovine respiratory disease.&#x0D; Finally, assessment of ventilatory reserve capacity by administration oflobeline, a respiratory analeptic, revealed to be very sensitive and especially valuable in animals with minor respiratory problems.&#x0D; The theoretical classification into four grades of severity of bovine respiratory disease is worthless without practical means to evaluate functional impact in the field. The three presented tests could help us to realize this objective and finally economize therapeutic strategies in bovine respiratory disease.

TRAINING AND NEUROMUSCULAR DISEASE

127 The purpose of this study was to determine if 32 weeks of cardiovascular and strenght training coud improve the aerobic and ventilatory capacities and muscle strength of 6 male patients (age range 15 to 34 yrs) with neuromuscular disease (limb-girdle dystrofy, n=1; type III progressive spinal muscle atrophy, n=3; Steinert myotonic systrophy, n=1; and facioscapulohumeral muscular dystrophy, n=1) Cardiovascular training consisted of cycle ergometry at 70% VO2peak for 20 min., 3 times/week. Weight training involving the arms and shoulder muscles were performed at 70% maximal streight, 3 times/week with 3 sets of 8 repetition per exercise. Significante increases were seen in cardiovascular and respiratory capacities following training (see table above). Significant impovements were also seen for maximal voluntary ventilation(116.9±8.1 vs 125.7±8.8 L.min-1), maximal inspiratory pressure (33.3±8.0 vs 73.8±11.1 cm H2O) and maximal expiratory pressure (36.7±7.9 vs 70.8±11.5 cm H2O). Increases immuscle strenght were seen in the biceps (13%) and triceps (80%) brachii, trapezious (21%) and latissimus dorsi-pectoralis major (32%) muscles. This training regimen did not accelerate the progress of the disease. Indeed, the training saw improvements in cardiovascular, ventilatory and muscular capacities.Table

Fixed maximal stroke index in patients after pneumonectomy.

Patients who have undergone pneumonectomy (PNX) show limited exercise capacity, partly attributable to an impaired stroke index (SI). To determine whether this limitation is due to deconditioning, we assessed exercise performance and cardiopulmonary function in seven patients after PNX (age: 59 +/- 2 yr, mean +/- SEM) and eight normal, healthy nonsmokers (52 +/- 3 yr) before and after an ergometer exercise training program for 30 min per day, 5 d per week, for 8 wk at 65% of measured maximal O2 uptake. Lung volume, diffusing capacity of carbon dioxide (DL(CO)) and cardiac index (CI) were determined during steady-state exercise by a rebreathing method. Exercise endurance was measured at 80% of maximal power. As compared with normal subjects, patients who had had PNX showed diminished maximal oxygen uptake (VO2max), as well as diminished lung volumes, ventilatory capacities, and maximal cardiac and stroke indexes. After training, VO2max, endurance, and peripheral O2 extraction improved in both groups. However, maximal cardiac and stroke indexes increased only in normal subjects and not in patients. We conclude that an irreversibly fixed maximal SI is a major source of exercise limitation after PNX, probably because of pulmonary arterial hypertension and/or mechanical distortion of the cardiac fossa. Ventilatory impairment after PNX did not prevent a training-induced increase in VO2max. Exercise training confers significant functional benefit on postpneumonectomy patients by enhancing peripheral O2 extraction.

An epidemiology study of lung function changes of toluene diisocyanate foam workers in the United Kingdom

To determine whether longitudinal declines in ventilatory capacity and the occurrence of respiratory symptoms in workers manufacturing polyurethane foam were related to toluene diisocyanate (TDI) exposure. A population of 780 workers in 12 United Kingdom factories was followed for 5 years. Modified United Kingdom Medical Research Council (MRC) respiratory questionnaires and three or more lung function measurements were completed for each subject. Mean TDI exposures for all jobs in which subjects were employed were assessed by personal monitoring (2294 measurements) and related to their occupational histories. The United Kingdom 8-h and 15-min maximum exposure limits for TDI were exceeded in 4.7% and 19.0% of the samples taken, respectively. There was some increase in reported respiratory symptoms amongst exposed workers, but the annual declines of 1-s forced expiratory volume (FEV1) and forced vital capacity (FVC) were not related to TDI exposure and were typical of those observed in other longitudinal populations. FEV1 declines were smoking-related. Evidence was found suggesting that a small excess decline in FEV1 and FVC occurred in the first few years of employment for workers not previously exposed to TDI. This study does not provide evidence that there is a TDI-related decline in FEV1 and FVC in workers exposed to less than the United Kingdom 8-h occupational exposure limit of 5.8 ppb.

Lung Function During Hoist Rescue Operations

A case is presented in which a 43-year-old man suffering from a severe asthma attack, had ventilatory arrest during a hoisting procedure. Based on this experience, the influence of three hoisting techniques on lung function was tested. The ventilatory capacity of 12 healthy volunteers was tested during three commonly used hoisting techniques: 1) single sling; 2) double sling; or 3) strapped to a stretcher. The vital capacity (VC) and the one-second, forced expiratory volume (FEV1) were reduced significantly during all hoisting techniques compared to the standing position. The reduction was significantly more pronounced on a stretcher than in either sling position. There were no differences in the FEV1 to VC ratio between the positions. The small reduction in ventilatory capacity during hoisting procedures is tolerated easily by healthy individuals, but should be taken into account when planning such procedures on patients with severe pulmonary disease.

Glycogen depletion and lactate accumulation in human intercostal muscles after administration of succinylcholine

I.m. glycogen content, lactate concentration and staining intensity for glycogen in slow- (ST) and fast-twitch (FTa and FTb) fibres were determined in the external and internal intercostal muscles after thoracotomy. Thirteen patients received a precurarizing dose of a non-depolarizing neuromuscular blocking agent followed by the depolarizing agent, succinylcholine, to facilitate intubation of the trachea (succinylcholine group). Nine patients received pancuronium or gallamine (control group). There were no significant differences in ventilatory functional capacity between the two groups. In the external intercostal muscles, lower i.m. glycogen content was observed in the succinylcholine compared with the control group (P < 0.05). I.m. glycogen was depleted from the FT fibres and in particular from FTb fibres, while little depletion was noted in ST fibres. In both the external and internal intercostal muscles, a higher lactate concentration was observed in the succinylcholine than in the control group (P < 0.05). The results indicate that the use of succinylcholine for tracheal intubation stimulated breakdown of i.m. glycogen, particularly in fast-twitch muscle fibres, and caused accumulation of lactate in intercostal muscles.

Prediction equations for forced spirometry from European origin populations

The objective of this study was the analysis of five sets of reference equations for forced spirometry (Crapo et al., ECSC, Knudson et al., Paoletti et al. and Roca et al.) using measurements of FVC and FEV 1 obtained in the European Community Respiratory Health Survey (ECRHS) in Spain. Standardized forced spirometry was measured in 998 non-asthmatic subjects (20–44 years), randomly selected from the general population, participating in the ECRHS in four different Spanish cities. Observed minus predicted values for both FVC and FEV 1 were examined for each set of predicted equations. Observed FVC (4448 ± 980 ml) and FEV 1 (3715 ± 813 ml) showed a good agreement with values predicted by Roca et al. (99% and 101%, respectively). The mean observed minus predicted difference (residual) for FVC and FEV 1 were − 34 ± 527 ml and 30 ± 455 ml, respectively. The regression line between observed and predicted values was not different from the identity line for both FVC and FEV 1. These results indicate that reference values obtained by Roca et al. are useful for the assessment of the ventilatory capacity in the general population of Spain. In addition, the study indicates that discrepancies among the reference equations from different authors compared in the present study are unlikely to be due to ethnic differences within European origin populations.

Respiratory function and immunological status in workers employed in a latex glove manufacturing plant.

A study was performed in 17 female workers employed in a latex glove manufacturing plant. The mean age of these workers was 42 years and the mean duration of their employment was 19 years. The employees were primarily nonsmokers or light smokers. The presence of chronic respiratory symptoms and acute work-related symptoms was recorded for these workers. Ventilatory capacity was measured during the morning work shift by recording maximum expiratory flow-volume curves from which forced vital capacity (FVC), 1-second forced expiratory volume (FEV1) and maximum expiratory flow at 50%, and the last 25% of the vital capacity (FEF50, FEF75) were measured. A control group of 17 nonexposed women workers was also studied. The prevalence of chronic respiratory symptoms was greater among latex workers than among control confectionary packer workers, varying from 5.9% (vs. 0% in controls) for occupational asthma to 58.8% (vs. 0% in controls) for dyspnea grades 3 or 4. There was also a high prevalence of acute work-related symptoms in this industry, in particular, eye irritation (76.5%), dryness of the nose (70.6%), throat burning (70.6%), dryness of the throat (64.7%), and cough (58.8%). Among exposed workers, measured ventilatory capacity data were significantly lower than among controls, particularly FEF75 (75.1% +/- 10.5%). One of the 17 studied workers (5.9%) had a positive skin reaction to latex and had symptoms compatible with occupational asthma. Our data suggest that in addition to occupational asthma, the manufacture of latex gloves is associated with frequent, nonspecific respiratory findings.

Lung Transplantation at the University of Lund 1990-1995: Analysis of the First 39 Consecutive Patients

Between 1990 and 1995 39 patients were lung transplanted at the University Hospital in Lund. This is a retrospective review of survival and lung function in these patients. There were 17 single-lung transplants (SLT), 21 double-lung transplants (DLT) and 1 heart-lung transplant (HLT). Seven patients died during the period, giving an overall survival of 82%. One-year survival according to Kaplan-Meier survival analysis was 87%, and 2-year survival was 83%. Vital capacity and forced expiratory volume in 1 s (FEV) 1 year after transplantation were 91% and 100% of predicted, respectively, in the DLT group and 60% and 50% in the SLT group. Bronchiolitis obliterans syndrome (BOS) developed in 11 of the 35 patients (31%) surviving more than 6 months, 2/21 in the DLT group and 8/13 in the SLT group and in the patient with HLT. The median time until detection of BOS was 11 months after the operation (range 6-18 months). Working capacity 1 year after transplantation was 60% of predicted in the DLT group and 47% of predicted in the SLT group. Ventilatory capacity was no longer function limiting. Lung transplantation today is a therapeutic option with a good medium-term survival and good functional results in selected patients with severe lung disease.

Respiratory function and immunological status in cocoa and flour processing workers.

Respiratory function and immunological status were studied in 40 cocoa and 53 flour processing workers employed as packers in a confectionery industry and in 65 unexposed control workers in the same industry. A high prevalence of chronic respiratory symptoms was recorded in exposed workers, varying from 5.0% to 30.0% in cocoa workers and from 5.7% to 28.3% in flour workers. Occupational asthma was diagnosed in 2 (5%) of the cocoa workers and in 3 (5.7%) of the flour workers. None of the control workers suffered from occupational asthma. The prevalence of almost all chronic respiratory symptoms was significantly greater in cocoa and flour workers than in control workers. There was also a high prevalence of acute symptoms that developed during the work shift, being highest for cough (cocoa: 57.5%; flour: 50.9%) and eye irritation (cocoa: 50.0%; flour: 54.7%). Significant across-shift reductions of ventilatory capacity were recorded in exposed workers, being largest for flow rates at 50% and the last 25% of the vital capacity on maximum expiratory flow-volume (MEFV) curves (FEF50, FEF75). The prevalence of positive skin tests for cocoa (60.2%) was significantly higher than the prevalence of positive skin tests for flour (25.8%) among the 93 exposed workers (p < 0.05). Control workers had significantly lower prevalences of positive skin tests to cocoa (4.6%) and flour (12.3%) than exposed workers (p < 0.01). Increased total serum IgE levels were found in 17.5% of cocoa and in 18.7% of flour workers; none of the control workers had increased IgE levels. Bronchoprovocation testing demonstrated significant decreases in lung function following inhalation of cocoa dust extract and flour dust in workers with respiratory symptoms and large across-shift reductions in lung function. Dust concentrations in the working environment were higher than those recommended by Croatian standards. These data suggest that workers employed in the processing of cocoa and flour may be at a high risk for the development of allergic sensitization and respiratory impairment.

Methyl Isocyanate Exposure

The Authors Reply: Drs Cullinan and Acquilla are correct in that a comparison of the findings of our study with those carried out on the Bhopal survivors would be inappropriate. The populations concerned are not comparable in that our subjects were exposed to much lower levels that would not lead to death or immediate serious impairment. Your correspondents ask us whether our population included only those who were still working. Our study subjects comprised a group of currently employed workers and also a group of retired workers who had undergone several examinations over the period of observation. Thus our study included both cross-sectional and longitudinal data. The cross-sectional data include only active workers, whilst the latter included both active and retired subjects; however, it was not possible to examine all of the retired workers. In our description of the subjects studied, we referred to a group of employees of a former owner of the facility who were retired or deceased. The retirees were a group of workers whose exposure was indirectly assessed by their former long-term supervisors. It will be noted that we were somewhat concerned about the accuracy of the assessments; nevertheless, the data available to us indicated that the vast majority of this group retired because of age rather than illness. For this reason, we doubt any serious survivor bias was present. Turning to the second question, namely, what they term "highly subjective exposure measurements," and ask whether they reflect short-term intensity exposures to MIC. Our paper described a significant number of workers who were seen at the clinic with acute symptoms, mainly eye and nasal irritations, which resulted from exposure to MIC. Some of these workers were seen during the time serial measurements of exposure were being made. The ventilatory capacity of these workers immediately after exposure was normal or virtually so, and when the examination was repeated later, there was no evidence of any airways obstruction. This information is contained in the last paragraph of the Results section, and we are somewhat surprised that it eluded your correspondents. In regard to Drs Cullinan and Acquilla's point relating to small airways disease, we are quite willing to accept that those exposed in the Bhopal disaster developed severe bronchiolitis. Nonetheless, we would point out that the detection of small airways diseases in the general population, many of whom smoke cigarettes (or Bidis in India), some of whom have asthma or are overweight, and who may also be exposed to many other irritant agents that affect the small airways, is fraught with difficulty. Thus it is necessary to exclude large airways disease first, ie, those subjects in whom small airways disease is sought must have a normal forced expiratory volume in one second(FEV1) and a normal forced vital capacity (FVC). In addition, they must have a normal compliance curve.1 Provided that both of these impairments are absent, one can try to persuade an asymptomatic subject to undergo one or another of a series of tests, some of which are unpleasant, most of which are time-consuming, and all of which are imprecise and lack the ability to predict the development of irreversible airways obstruction or respiratory disability.2 In this connection, we are referring to tests such as frequency dependence of dynamic compliance, closing volume, the performance of flow volume curves with helium and oxygen, the measurement of upstream airways resistance, lung elastic recoil, etc. We used these extensively some 25 or more years ago in a variety of occupationally exposed populations3-5 and found it difficult to decide the significance, if any, of our findings. Perhaps Drs Cullinan and Acquilla could advise us in this regard. This is not to deny that small airways disease can cause disability; it is a statement indicating how frustrating and futile it is to try to detect small airways disease in a working population by using tests that are imprecise and impractical. We would add that we enjoyed carrying out these studies, but we now realize that they were really a form of play therapy for potential respiratory physiologists. W. K. C. Morgan, MD Robert B. Reger, PhD Chest Diseases Unit; London Health Sciences Centre; London, Ontario, Canada

Health effects of diesel emissions

We have reviewed the literature relating to the health effects of diesel emissions with particular reference to acute and chronic morbidity and to carcinogenicity. It is apparent that exposure to diesel fumes in sufficient concentrations may lead to eye and nasal irritation but there is no evidence of any permanent effect. A transient decline of ventilatory capacity has been noted following such exposures. There is also some evidence that the chronic inhalation of diesel fumes leads to the development of cough and sputum, that is chronic bronchitis, however, it is usually impossible to show a cause and effect relationship because of the concomitant and confounding exposures to mine dust and cigarette smoke.Although there have been a number of papers suggesting that diesel fumes may act as an carcinogen, the weight of the evidence is against this hypothesis. Finally, the role of small particles, less than 10 μm, which are frequently present in diesel emissions requires further study since there is some limited evidence that they may be partly responsible for some of the exacerbations of asthma.

A follow-up study of respiratory function in workers exposed to acid aerosols in a food-processing industry.

A follow-up investigation was performed on 49 female workers studied 2 years earlier in a vegetable-pickling plant. Acute and chronic respiratory symptoms and ventilatory capacity measurements were recorded during the original and the follow-up studies. Maximal expiratory flow-volume (MEFV) curves were recorded during the Monday morning work shift. The forced vital capacity (FVC), 1-s forced expiratory volume (FEV1), and flow rates at 50% and the last 25% of the FVC (FEF50, FEF25) were measured. There were small increases in the prevalence of chronic symptoms between the two studies for both smokers and nonsmokers, but these did not reach statistical significance. Five workers at the time of the initial study had a diagnosis of occupational asthma; only one of these was still working at the time of follow-up. Workers lost to the follow-up had lower lung function than those seen at follow-up. In workers who were followed, larger than expected mean annual declines were noted for all ventilatory capacity parameters in both smokers (FVC 0.070 1, FEV1 0.070 1; FEF50 0.3551/s, FEF25 0.270 1/s) and nonsmokers (FVC 0.045 1, FEV1 0.045 1, FEF50 0.285 1/s; FEF25 0.130 1/s). The decrease was particularly pronounced for FEF50 and FEF25. The accelerated decline in ventilatory capacity tests noted in the female nonsmokers suggests an independent effect on lung function of work exposure in this environment. Our data confirm that work in the pickling industry, particularly in small, poorly regulated plants, has deleterious effects on respiratory function.

The Effect of Exercise on Lymphocyte Redistribution and Leucocyte Function in Asymptomatic HIV-Infected Subjects

This study was undertaken to examine the responsiveness of circulating leucocyte and lymphocyte populations to the physiological demands of exercise in asymptomatic HIV-infected subjects with CD4+ counts greater than 500/μl. Thirteen subjects infected with HIV and 14 control subjects underwent 20 min of defined moderate exercise at estimated 65% of their maximal ventilatory capacity on a bicycle ergometer. Blood samples were obtained for serum cortisol, norepinephrine, lymphocyte subsets (CD4, CD8, CD19, CD16–CD56), and phagocytic function at rest immediately after exercise and 20 min following the cessation of the exercise. The HIV-infected subjects had increased circulating concentrations of CD8 cells (p= .007) and CD16–CD56+ NK cells (p= .02) in response to the exercise, whereas the control group did not. There was a greater increase in monocyte respiratory burst activity following recovery from exercise in the control subjects (p= .016) but not in the HIV-infected subjects. The control subjects experienced an increase in serum cortisol in response to the exercise (p= .006), but the HIV-infected subjects did not. Our results show that the changes in the distribution and function of circulating leucocytes and adrenal neuroendocrine responses to moderate exercise differ in asymptomatic HIV-infected and control subjects.

Lung function testing: methods and reference values for forced expiratory volume (FEV1) and transfer factor (TL).

Accepted 20 November 1996 Background WHICH TESTS? Almost 50 years ago Gilson et al embarked on the first large scale investigation into impaired lung function and breathlessness on exertion resulting...

Respiratory function of textile workers employed in dyeing cotton and wool fibers.

A group of 135 textile dyeing workers (97 male and 38 female) was studied for the prevalence of acute and chronic respiratory symptoms and lung function changes. Respiratory symptoms were elicited by a standardized questionnaire, and lung function testing was performed before and after the morning shift by recording maximum expiratory flow-volume (MEFV) curves. In addition, 103 nonexposed control workers were studied. The prevalence of all chronic respiratory symptoms was significantly higher in the exposed than in the control workers; in particular, the prevalence of occupational asthma was 6%. The exposed nonsmoking workers had more complaints than the controls who were nonsmokers. As expected, most of the symptoms were more prevalent in smokers than in nonsmokers. Nonsmokers with both long- and short-term work exposure had higher prevalences of dyspnea and rhinitis than control workers. Smokers exposed for 10 years or less had significantly higher prevalences of chronic phlegm than nonsmokers with the same duration of exposure (p < 0.05). In workers exposed for > 10 years, there were significantly higher prevalences of chronic cough, chronic phlegm, and chronic bronchitis in smokers than in nonsmokers (p < 0.01). A high prevalence of shift-related symptoms was found in exposed workers. Significant across-shift reductions of ventilatory capacity tests were documented in this cohort and varied from an average of 4.0% for FVC to 14.2% for FEF25. Preshift values of ventilatory capacity were significantly lower in this exposed population compared to predicted values suggesting a chromic effect. Our data suggest that textile dyeing workers develop acute and chronic respiratory impairment as a result of their exposures. These findings are exacerbated by cigarette smoking.