Changes In Ventilatory Function Research Articles

Individual Changes in Respiratory Compliance Upon Immersion May Predict Susceptibility to Immersion Pulmonary Edema

BackgroundImmersion pulmonary edema (IPE) is a frequent diving accident, and it is the primary cause of hospitalization for young military divers during training. The objective of this study was to identify immersion-induced parameters predicting individual susceptibility to IPE.MethodsEighteen experienced male divers having completed at least 100 dives were recruited. Eight divers had previously been hospitalized for IPE (IPE), and the other ten had never developed IPE (non-IPE). The two groups were matched for age, BMI, and number of dives performed. Ventilatory function and overall compliance of the respiratory system (Crs) were measured on land and during head-out-of-water immersion. Subjects also performed 30 min of fin swimming in a channel at 33 m min−1. Following this exercise, the presence of extravascular lung water, revealed by ultrasound lung comets (ULC), was assessed.ResultsIn the whole group, the decrease in Crs upon immersion correlated with the immersion-induced alterations to expiratory reserve volume, ERV (r2 = 0.91; p < 0.001), inspiratory reserve volume, IRV (r2 = 0.94; p < 0.001), and tidal volume, Vt, changes (r2 = 0.43; p < 0.003). The number of ULC correlated strongly with immersion-induced changes in ventilatory function (r2 = 0.818; p < 0.001 for ERV, r2 = 0.849; p < 0.001 for IRV, r2 = 0.304; p = 0.0164 for Vt) and reduced Crs (r2 = 0.19; p < 0.001).The variations of ERV, IRV, and Crs at rest induced by head-out-of-water immersion and the number of ULC measured after swimming for 30 min were significantly greater in IPE subjects.ConclusionIn the face of similar immersion stresses, the extent of alterations to ventilatory function and the number of ULCs were very different between individuals but remained statistically correlated. These parameters were significantly greater in divers with a history of IPE. Alterations to pulmonary function and, in particular, to pulmonary compliance induced by head-out-of-water immersion, through their effects on work of breathing appear to allow the identification of divers with a greater susceptibility to developing IPE. Measurement of these parameters could therefore be proposed as a predictive test for the risk of developing IPE.

Breathing With Heart Failure

The syndrome of heart failure (HF) is often accompanied by numerous derangements in ventilatory function. These pathophysiological changes in ventilatory function are believed to augment the mechanical work required to breathe during exercise (Wb). However, the precise contributions of resistive and elastic work to this overall higher Wb in HF remain unclear. PURPOSE: To quantify the resistive and elastic components of Wb during exercise in HF patients and age-matched, healthy controls at standardized levels of minute ventilation ( ). METHODS: The elastic and resistive Wb were assessed in 9 male HF patients (NYHA class I-III) and 9 age-matched, healthy male controls at minute ventilations of 20, 40, 60 and 80 L[BULLET OPERATOR]min-1 during graded exercise. The components of Wb were quantified using oesophageal manometry and modified Campbell diagrams. RESULTS: Dynamic lung compliance was lower across all minute ventilations in HF patients (P<0.05). Moreover, the inspiratory and expiratory resistive Wb was higher in HF patients compared with controls at any given (P<0.05). The inspiratory elastic Wb was higher at minute ventilations of 40-60 L[BULLET OPERATOR]min-1 during exercise in HF patients. (P<0.05). CONCLUSIONS: The findings of this study indicate that the overall higher Wb in HF patients may be more so related to greater amounts of resistive than elastic Wb during exercise.

Respiratory symptoms and ventilatory function among health-care workers exposed to cleaning and disinfectant chemicals, a 2-year follow-up study.

Previous cross-sectional studies have shown that exposure to cleaning chemicals among health-care workers (HCWs) is associated with respiratory disorders and ventilatory function changes. This study aimed to further explore this association using a longitudinal approach. A prospective 2-year follow-up study was carried out at a tertiary care hospital in Saudi Arabia from June 2012 to June 2014 among 56 nurses who were responsible for disinfection and sterilization of medical instruments and equipment. The workplaces of the participants were assessed for engineering, environmental, and safety control measures. Self-administered questionnaires were distributed to all participants to assess their exposure to cleaning chemicals and their medical history. Spirometric parameters were measured for all nurses in 2012 (baseline) and again in 2014 (follow-up). The prevalence of work-related respiratory symptoms did not increase significantly over this time. Among all the spirometric parameters, only forced expiratory volume in 1 second (FEV1)/forced vital capacity (FVC) ratio decreased significantly, and only 10.7% of participants who were exposed to cleaning chemicals for more than 10 years had FEV1 and FVC less than their longitudinal normal limits at the end of the study. Smoking and gender were associated with statistically significant decreases in some of the spirometric parameters. Our 2-year follow-up study did not demonstrate significant association between exposure to cleaning chemicals among HCWs and changes in the prevalence of work-related respiratory symptoms, but indicated early effects on ventilatory function among them. The study highlights the importance of periodic spirometry, proper work practices, and effective control measures to protect HCWs against potentially harmful workplace chemicals for disinfection and sterilization.

Effect of high-fructose and high-fat diets on pulmonary sensitivity, motor activity, and body composition of brown Norway rats exposed to ozone

Diet-induced obesity has been suggested to lead to increased susceptibility to air pollutants such as ozone (O3); however, there is little experimental evidence. Thirty day old male and female Brown Norway rats were fed a normal, high-fructose or high-fat diet for 12 weeks and then exposed to O3 (acute – air or 0.8 ppm O3 for 5 h, or subacute – air or 0.8 ppm O3 for 5 h/d 1 d/week for 4 weeks). Body composition was measured non-invasively using NMR. Ventilatory parameters and exploratory behavior were measured after the third week of subacute exposure. Bronchoalveolar lavage fluid (BALF) and blood chemistry data were collected 18 h after acute O3 and 18 h after the fourth week of subacute O3. The diets led to increased body fat in male but not female rats. O3-induced changes in ventilatory function were either unaffected or improved with the fructose and fat diets. O3-induced reduction in exploratory behavior was attenuated with fructose and fat diets in males and partially in females. O3 led to a significant decrease in body fat of males fed control diet but not the fructose or fat diet. O3 led to significant increases in BALF eosinophils, increase in albumin, and reductions in macrophages. Female rats appeared to be more affected than males to O3 regardless of diet. Overall, treatment with high-fructose and high-fat diets attenuated some O3 induced effects on pulmonary function, behavior, and metabolism. Exacerbation of toxicity was observed less frequently.

Dynamics of the duration of tracheal forced expiratory noises during long-term isolation in the Mars-500 experiment

Dynamics of duration of tracheal forced expiratory noises in a group of volunteers was studied before, during and after 520-days confinement. The duration did not change in most volunteers. Two volunteers demonstrated significant changes of tracheal sounds duration and some spirometric parameters. Increase in duration of tracheal forced expiratory noises and decrease in spirometric parameters reveal ventilatory impairment of obstructive type. Analysis of duration of tracheal forced expiratory noises dynamics during prolonged confinement proves to be a sensitive technique to test ventilatory function changes.

Longitudinal decline in lung function in patients with primary immunoglobulin deficiencies

clinical symptoms in 90%. The variable disease penetrance within a given pedigree can only be explained by a ‘‘second signal.’’ In our patient the nature of this second signal was shown not to be one of the known genes involved in hemophagocytosis. Once intravenous immune globulin and prednisone were started, ferritin and sIL-2R levels did not completely normalize (ferritin, 600-750 mg/L [upper limit of normal, 350 mg/L]; sIL-2R, 4320 U/mL [upper limit of normal, 2400 U/mL]), even after almost 3 years of follow-up. Hemophagocytosis was detected in neither bone marrow smears nor in spleen and lymph node biopsy specimens. Clinically, the patient fulfilled the diagnosis of hemophagocytic lymphohistiocytosis but was not treated accordingly. The hemophagocytic lymphohistiocytosis parameters (ie, blood cell counts, ferritin, lactate dehydrogenase, sIL-2R, and triglycerides) were considered to be triggered by the pneumonia. The hypoimmunoglobulinemia and defective immunization responses were most compatible with CVID and highly unusual for ALPS. Increased susceptibility to malignancy, particularly hematological malignancy, is the most worrying consequence of ALPS. Lymphoma develops in about 10% of patients, and the relative risks of (non)Hodgkin lymphoma are 15to 50-fold, respectively. Also, patients who have CVID and granulomatous or lymphocytic interstitial lung disease are at high risk for early mortality and B-cell lymphomas. The absence of an increased risk among relatives suggests that the increased cancer morbidity in patients with CVID is related to the immunodeficiency per se rather than to specific genetic traits shared with their relatives. Whether the risk of lymphoproliferative malignancy in our family is increased remains uncertain. The grandfather has died from a mucosa-associated lymphoid tissue lymphoma but was healthy until he presented at old age. We do not know whether he carried the same FAS mutation. In conclusion, mutations in FAS (TNFRSF6) might not only result in clinical ALPS but also in hypogammaglobulinemia and reduced reactivity on immunization, which is defined as CVID. Similar phenotypic overlap was most recently suggested in a study including patients with ALPS and CVID, some of whom were carrying a FAS mutation. Our patient adds to this complex overlap syndrome, presenting with CVID and features of hemophagocytosis, whereas his FAS-mutated family members were without any clinical disease. Taco W. Kuijpers, MD, PhD Paul A. Baars, PhD Daan J. aan de Kerk, MD Machiel H. Jansen Natasja Dors, MD Rene A. W. van Lier, MD, PhD Steven T. Pals, MD, PhD

P101 Surface parasternal intercostal electromyogram (sEMGpara) as a monitoring tool in cystic fibrosis

Lung function has been traditionally accepted as the primary monitoring tool in cystic fibrosis. The rate of change in lung function however, is slowing and is now as low as...

Variáveis perioperatórias de função ventilatória e capacidade física em indivíduos submetidos a transplante cardíaco

Heart transplantation is currently the only widely accepted surgical alternative to treat patients with severe heart failure (HF) drug therapy cannot maintain optimal quality of life appropriate. To describe and to compare the values between pre-and postoperative physical capacity and pulmonary patients who underwent heart transplantation. A retrospective cohort composed of patients undergoing heart transplantation between January 2001 to March 2005 in IC-FUC/RS. Were included in the 21 individuals. We observed decreased levels of volume and lung capacity (FEV1 and FVC) in the first days after surgery compared to preoperatively (P <0.001) and recovery of these values in the 14th postoperative day (P <0.001). The values of muscle strength showed similar trends in reducing post-operative period compared to preoperative (P <0.001) and recovered on the 14th postoperative day (P <0.001). A useful functional capacity, measured by testing 6-minute walk test (T6') showed improvement in the 14th postoperative day in relation to pre-operatively (P <0.001). Changes in ventilatory function of subjects undergoing cardiac transplantation are predictable, but these recover respiratory muscle strength and lung capacity within two weeks, and improve functional capacity useful in relation to pre-operative, the transplantation, when indicated, associated with good functional rehabilitation is very god treatment strategy.

Changes in ventilatory function following surgery for bilateral abductor paralysis

Management of bilateral vocal fold immobility continues to remain a challenge for the Otolaryngologist who attempts to create a balance between creation of an adequate airway and preservation of voice. The flow volume loop obtained by spirometry provides an ideal objective assessment tool to evaluate the results of surgery for this condition. Our experience in using peak inspiratory flow rate (PIFR) and forced inspiratory flow with 50% of vital capacity (FIF(50)) in the lung in assessing the results of surgery is described. Seventeen patients were included in the study. The surgical procedures performed included laser posterior cordectomy with partial arytenoidectomy, endoscopic arytenoidectomy and posterior cordectomy-Kashima's technique. Twelve out of 17 patients were successfully decannulated, a success rate of 70.6%. All patients except one showed an increase in mid-inspiratory flow rates and peak inspiratory flow rates. The mean increase in FIF(50) was 0.44 l/sec (52.6%) and the mean increase in PIFR was 0.41l/sec (39.77%). No statistically significant difference in improvement of inspiratory flow rates was observed between the three surgical procedures used in the study.

How long do the systemic and ventilatory responses to toluene diisocyanate persist in dermally sensitized mice?

Years after removal from exposure, workers with occupational asthma still show respiratory symptoms and airway hyperresponsiveness on re-exposure to the offending agent. We investigated the persistence of the respiratory responsiveness to toluene diisocyanate (TDI) in a mouse model. BALB/C mice received dermal applications of TDI on days 1 and 8, and a single intranasal instillation of TDI on day 10, 15, 20, 25, 30, 40, 50, 60, or 90. After instillation, early (1 hour) changes in ventilatory function and methacholine responsiveness (22 hours) were assessed. Cell counts and macrophage inflammatory protein 2 were measured in bronchoalveolar lavage. Total serum IgE, IgG(1), and IgG(2a) were quantified. Lymphocyte subpopulations were assessed in auricular and cervical lymph nodes, and release of IL-4 and IFN-gamma by these lymph node cells was measured. Toluene diisocyanate-treated mice showed immediate ventilatory changes, increased methacholine reactivity, and an influx of neutrophils and macrophage inflammatory protein 2 in bronchoalveolar lavage as long as 50 days after initial treatment. These mice also showed a relative increase in CD19(+) cells and a decrease in CD4(+) and CD8(+) cells in auricular lymph nodes. Increased release of IL-4 and IFN-gamma in auricular lymph node cells was observed only until 20 days after sensitization. Total serum IgE, IgG(1), and IgG(2a) remained significantly elevated in TDI-sensitized mice until 90 days after dermal sensitization. Ventilatory and lung inflammatory responses decrease with increasing delay between sensitization and challenge, despite persistent humoral signs of sensitization.

Validation of a mouse model of chemical-induced asthma using trimellitic anhydride, a respiratory sensitizer, and dinitrochlorobenzene, a dermal sensitizer

Occupational asthma can be caused by chemicals. Previously, we established a murine model of immunologically mediated chemical-induced asthma using toluene diisocyanate. We sought to verify this model using trimellitic anhydride (TMA), a respiratory sensitizer, and 1-chloro-2,4-dinitrobenzene (DNCB), a dermal sensitizer. BALB/c mice received dermal applications (vehicle or chemical) on days 1 and 7. On day 10, they received an intranasal instillation (vehicle or chemical). Whole-body plethysmography (enhanced pause) was used to monitor changes in ventilatory function and methacholine reactivity. Pulmonary inflammation was assessed by using bronchoalveolar lavage (cells, TNF-alpha levels, and macrophage inflammatory protein 2 levels). Immunologic parameters included total serum IgE levels, lymphocyte distribution in auricular and cervical lymph nodes, and IL-4 and IFN-gamma levels in supernatants of lymph node cells incubated with or without concanavalin A. Mice dermally treated and intranasally challenged with TMA experienced markedly increased enhanced pause immediately after intranasal challenge and increased methacholine reactivity (24 hours later). Mice similarly treated with DNCB did not show any ventilatory changes. Neutrophil influx and increased macrophage inflammatory protein 2 and TNF-alpha levels were found in bronchoalveolar lavage fluid in both TMA- and DNCB-treated mice. The proportion of CD19+ B cells was increased in auricular and cervical lymph nodes of TMA-treated mice. IL-4 and IFN-gamma levels were increased in supernatants of concanavalin A-stimulated auricular and cervical lymph node cells of TMA- or DNCB-treated mice; however, the relative proportions of IL-4 and IFN-gamma levels differed between TMA- and DNCB-treated mice. Serum total IgE levels were increased in TMA-treated mice only. Both compounds induce a mixed T(H)1-T(H)2 response, but only TMA induced ventilatory changes. In the workplace avoiding skin contact with chemical sensitizers might be advised to prevent chemical-induced asthma.

Effect of High-Intensity Inspiratory Muscle Training on Lung Volumes, Diaphragm Thickness, and Exercise Capacity in Subjects Who Are Healthy

Previous investigations have demonstrated that a regimen of high-intensity inspiratory muscle training (IMT) resulted in changes in ventilatory function and exercise capacity in patients with chronic lung disease, although the effect of high-intensity IMT in subjects who are healthy is yet to be determined. The purpose of this study, therefore, was to examine whether high-intensity IMT resulted in changes in ventilatory function and exercise capacity in subjects who were healthy. Twenty subjects were randomly assigned to 2 groups. The training group completed an 8-week program of IMT set at 80% of maximal effort. The control group did not participate in any form of training. Baseline and posttraining measures of body composition, pulmonary function, inspiratory muscle function (including maximal and sustained maximal inspiratory pressures [MIP and SMIP]), relaxed and contracted diaphragm thickness and thickening ratio (Tdi.rel, Tdi.cont, and TR), and exercise capacity were determined. The training group demonstrated significant increases in MIP, SMIP, Tdi.cont, TR, VC, total lung capacity, and exercise capacity compared with the control group, which demonstrated no change from baseline measurements at 8 weeks. The findings of this study suggest that high-intensity IMT results in increased contracted diaphragm thickness and increased lung volumes and exercise capacity in people who are healthy.

Seguridad y eficacia de celiprolol en hipertensos con enfermedad pulmonar obstructiva crónica

Third generation beta blockers have an intrinsic simpatico-mimetic activity and are cardioselective. Therefore, they should not have adverse bronchial effects and could even have a slight bronchodilator activity. To test the efficacy and safety of celiprolol in hypertensive patients with chronic obstructive lung disease. Uncomplicated hypertensive patients with chronic obstructive lung disease received celiprolol during 12 weeks. They were subjected to monthly clinical assessment and ventilatory function was measured on the basal period and at the end of the trial. During the study period, blood pressure fell significantly from 179 +/- 6/112 +/- 8 to 161 +/- 4.7/98 +/- 1.6 mmHg. No changes were observed in forced expiratory volume in 1 s or in forced expiratory flow between 25 and 75% of the vital capacity. No subjective changes in respiratory function were reported during the trial. No changes in ventilatory function were observed in these patients with chronic obstructive lung disease, treated with celiprolol during 12 weeks.

Inquiry into Occurrence of Byssinosis in Jute Mill Workers

Inquiry into Occurrence of Byssinosis in Jute Mill Workers: B.P. Chattopadhyay, et al. Regional Occupational Health Center E—An epidemiological study was carried out on 196 jute mill workers to inquire into the occurrence of byssinosis and to study the pattern of pre‐shift and post‐shift changes in ventilatory functions during the working week. The respiratory symptoms were recorded in a questionnaire based on the definition of byssinosis. The pulmonary function tests (PFT) were done by means of a dry wedge bellows spirometer, Vitalograph. On each day, the PFT of the workers were done twice, i.e., half an hour before the beginning of work (pre‐shift record), and after five hours of work (post‐shift record) on six consecutive working days. In the present communication mainly the PFT results for the first working day are reported. The acute and chronic changes in ventilatory function were defined as recommended by the World Health Organization. Typical symptoms of byssinosis such as chest tightness and difficulty in breathing on the first day of the week (Monday) after a weekend rest were found in 18 (9.18%) workers. Another group of 28 (14.28%) workers complained of chest tightness and breathlessness after work on days other than Monday. This group of workers was referred to as having “atypical byssinosis”. A significant fall (post shift fall in FEV1 5% and more than the pre shift FEV1.0 value) was observed in 70 (35.71%) workers and chronic changes in FEV1.0 in 62 (31.63%) workers, respectively. It is concluded that the jute mill workers suffer from a specific respiratory morbidity which resemble the byssinosis observed in cotton, flax and hemp workers.

Longitudinal studies of active and passive smoking.

From the public health perspective, epidemiologic research on smoking and respiratory health can be considered a success. In addition to the identification of smoking as a cause of lung cancer, which is not a focus of this review, sufficient evidence has been obtained to causally link active and passive smoking to adverse respiratory effects in children and adults (1-3). Initially, much of this evidence, both for active and passive smoking, was derived from cross-sectional studies. The findings of these studies, some undertaken more than 40 yr ago, were compelling in their demonstration that active smoking could substantially reduce lung function and cause respiratory symptoms. The adverse effects of passive smoking on the lung function of children, although far more subtle, were first shown in cross-sectional data as well. The cross-sectional data on active smoking provided evidence sufficient to stand up to the yardstick of the criteria for causality. Although temporality cannot be met in cross-sectional data, the age-pattern of effect was consistent with the proper sequence, with smoking preceding its adverse consequences. The effects on symptoms and lung function level were also consistent among studies, biologically plausible, and strong, doseresponse relationships wereevident. Conclusions of the U.S. Surgeon General's reports mirrored this evidence (1-3). To better characterize the longitudinal effect of cigarette smoking on lung function, cohort studies wereinitiated that provided data on active smoking and respiratory health. These early studies, the London transport workers study and the Dutch cohort study, were implemented to address the early natural history of chronic airflow obstruction (4, 5). Information on active smoking also came secondarily from other cohort studies, including studies of occupational groups and studies of cardiovascular disease. The data from the early cohort studies wereanalyzed primarily to characterize change in ventilatory function and not disease incidence. The analytic approaches were straightforward, estimating change as simple difference measures or regression slopes. The findings from these cohort studies confirmed the cross-sectional evidence; cigarette smokers had accelerated decline compared with nonsmokers, and the degree of acceleration increased with the amount smoked. The longitudinal data further showed that the rate of decline after stopping smoking returned to that of the never smoker. By the end of the 1970s, the findings of this literature were extensive, and the findings were consistent among the investigations. These studies, which focused on adult smokers, did not examine the age at which effects of active smoking are first manifest. In the 1960s, the first studies were published on active smok-

Longitudinal Pattern of Reported Respiratory Symptoms and Accelerated Ventilatory Loss in Asbestos-Exposed Workers

Studies investigating the relation between respiratory symptoms and change in ventilatory function have been limited by use of reported symptoms at a single point in time. To assess the relation between the longitudinal pattern of reported cough, phlegm, wheeze, and dyspnea and ventilatory loss, we prospectively investigated changes in FVC and FEV1 associated with development, resolution, or persistence of these symptoms over a 3- to 5-year period in 446 asbestos-exposed workers. Longitudinally reported symptoms changed frequently, with 52 to 61% of subjects reporting a specific symptom noting resolution or development of that symptom during follow-up. Initially reported symptoms were not predictive of accelerated loss of FVC or FEV1. In contrast, development of any new respiratory symptom, and to a lesser extent persistence of symptoms during follow-up, were associated with significantly greater ventilatory losses compared with asymptomatic individuals, ranging from 28 mL/yr in FEV1 for newly developed dyspnea, to 67 mL/yr in FVC for developed wheeze (p < 0.01). We conclude that development or persistence of respiratory symptoms over time, rather than the presence of symptoms per se, is predictive of future ventilatory loss. Recognition of interval changes in symptom reporting during surveillance of asbestos-exposed workers may effectively identify groups at risk for progressive ventilatory impairment.

Changes in ventilatory function in grain processing and animal feed workers in relation to exposure to organic dust.

The effects of organic dust exposure on the configuration of the maximum expiratory flow volume (MEFV) curve was examined multivariately. Data from 390 male workers in the animal feed industry in The Netherlands were analyzed. A multivariate technique called nonlinear canonical correlation analyses was used to study the relationship between a set of organic dust exposure variables and a set of ventilatory function variables. The results indicate an almost independent effect of the overall mean organic dust exposure and the number of years of organic dust exposure on ventilatory function. Increasing mean organic dust exposure was associated with a decrease in both forced expiratory volume in 1 s (FEV1.0) and forced vital capacity (FVC) and decreased flows at high lung volumes only. Increasing number of years of dust exposure was associated with a decrease in FEV1.0 and a decrease in flow at all lung volumes, while the FVC seemed relatively constant. These two distinct patterns of reduction in ventilatory function may represent two different pathological processes. Whereas workers with prolonged exposure showed reduced values for all of the MEFV curve variables, except the FVC, those with only a few years of exposure especially showed a decrease in FVC and peak expiratory flow. The effect of current organic dust exposure was more evident for nonsmokers than for ex-smokers and current smokers. The major finding of this study was an independent effect of overall mean organic dust exposure and the number of years of organic dust exposure on the MEFV curve.

Pulmonary Function Among Cotton Textile Workers: A Study of Variability in Symptom Reporting, Across-Shift Drop in FEV1, and Longitudinal Change

Longitudinal variability in respiratory responses, including symptom reporting and across-shift change in ventilatory function, were examined in relation to long-term loss of ventilatory function in a group of 447 cotton textile workers in Shanghai, China. The study used a standardized respiratory questionnaire and standardized spirometric testing before and after a work shift on the first day of the workweek. Prediction equations for FEV₁ were generated from a group of silk textile workers from the same city. Environmental samples included both vertical elutriated cotton dust and endotoxin levels. There was considerable variability in symptom reporting between the baseline and 5-year follow-up survey for all symptoms. However, subjects who consistently reported symptoms had a significantly accelerated 5-year loss in FEV₁ compared with those who never reported symptoms. Subjects with symptoms of chest tightness or dyspnea at one survey lost FEV₁ at a rate intermediate between the never or both groups. Moreover, subjects with an across-shift change in FEV₁ of more than 5 percent at both surveys had the greatest loss in FEV₁ over 5 years (—267 ml) when compared with one-time responders (—224 ml), and nonresponders (—180 ml), though the differences were not significant. Workers with chest tightness and chronic bronchitis in both surveys were overrepresented in the high dust and endotoxin areas. Our results indicate that even with substantial survey-to-survey variability in responses, there is important information contained in both questionnaires and across-shift spirometry. Among cotton workers, consistent responders to either symptom questionnaire or across-shift FEV₁ decrements of ≥5 percent appear to be at increased risk for lung function impairment.

Discrepancies between longitudinal and cross-sectional change in ventilatory function in 12 years of follow-up.

We compared the age dependence of cross-sectional and longitudinal changes in ventilatory function. FEV1, FVC, and data on chronic respiratory symptoms were obtained from 4,395 adults in a longitudinal survey of normal populations in two different areas in the Netherlands. They participated in up to five surveys at 3-yr intervals between 1972 to 1973 and 1984 to 1985. The ventilatory function in the oldest cohorts is substantially lower than might have been expected from the longitudinal change in the youngest cohorts. This holds for males and females, smokers and nonsmokers, subjects with or without symptoms, and for both survey populations. The robustness of the findings is demonstrated by various data-analytic strategies or omitting one or two of the five surveys from the analysis. Selective loss to follow-up cannot explain the discrepancy. It is concluded that the main differences between our longitudinal and cross-sectional findings may be due to a cohort effect. The implication is that in longitudinal studies of populations at risk, reference equations based on cross-sectional surveys may overestimate longitudinal change and hence lead to underestimating effects of exposure. Similarly, in clinical studies, accelerated decline in ventilatory function may be underrated if it is compared with cross-sectional standards. In older people at any one age the ventilatory function seems to improve in successive birth cohorts.

Epidemiological study on respiratory effects of smoking in college students

To study the influence of smoking on the respiratory system in adolescents, we conducted a prospective study to look into the respiratory symptoms, changes in ventilatory function, and levels of expired CO of both smoking and nonsmoking college students. The subjects were 56 male students who entered Akita University in 1986. Thirty of the participants were smokers at entrance whereas the rest who were nonsmokers, served as controls. The smokers started smoking at an average age of 17.6 +/- 0.9 years. Physical examinations at 8 points during the study were performed periodically in May and November for four years, from 1986 to 1989. From these studies, the following conclusions were obtained. 1) The prevalence of respiratory symptoms, especially phlegm, was higher among the smokers compared with the nonsmokers; the differences not being significant. Among both the smokers and nonsmokers, no prevalence of persistent cough and phlegm was observed during the study period. 2) There were no differences in the levels of %FVC and %V50 between the smokers and the nonsmokers at any point during the study period. The FEV1% levels for smokers were decreased progressively, and the differences became significant at the 7th and 8th tests (p < 0.05). After the second test, %V25 levels were lower in the smokers than in the nonsmokers; the differences being significant at the 7th test (p < 0.05). 3) The dose-response relationships between smoking and pulmonary function were not statistically significant in any levels at the 7th and 8th tests. However, %V25 levels of the heavy smokers (15 < or = per a day) were lower than the those of the nonsmokers; the differences being significant at the 7th and 8th tests (p < 0.05). 4) Average expired CO concentrations of the smokers were 2.5-3.5 times higher than those of the nonsmokers during the study period, confirming exposure to tobacco smoke. These observations suggest that young smokers may develop obstructive changes, especially narrowed small airways during the first 5 years of exposure to tobacco smoke.