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PubMed1996

Increased bronchial responsiveness in workers sawing Scots pine.

The purpose of the present investigation was to study bronchial responsiveness and pulmonary function in Swedish sawmill workers, who are not exposed to plicatic acid, the sensitizer in red wood cedar asthma. Bronchial responsiveness, transfer factor, spirometry, and precipitating antibodies in serum against sawmill fungi were measured in 164 workers at five sawmills. The results from workers inside the sawing area (sawyers, n=59), in the trimming department (trimmers, n=66), and from other workers in the sawmill (sawyer-referents, n=39) were compared. Sawyers had higher bronchial responsiveness than referents. In 55% of the sawyers FEV1 decreased by 20% or more within the highest dose of methacholine compared with 31% of sawyer-referents and 41% of trimmers (p<0.01, sawyers/referents). Sawyers decreased 74% more in FEV1 per milligram of inhaled methacholine compared with referents (geometric means, p<0.01). The transfer test in never-smokers was 13% lower in sawyers than in trimmers (p<0.01) and 8% lower compared with sawyer-referents (nonsignificant p<0.1). Presence of precipitating antibodies was not associated with changes in pulmonary function. Some agents in the sawing area of sawmills appear to increase bronchial responsiveness and decrease diffusion capacity.

Adult↗
PubMed1987

Accuracy of spirometric and flow-volume indices obtained by digitizing volume-time tracings.

We tested the accuracy of a new system for deriving standard spirometric indices, maximal expiratory flow rates, and slope ratios from volume-time tracings. A computer-based technique employing a hand-operated cursor was used to put discrete values of volume and time into a memory array. Spirometric values obtained on 102 subjects using the computer system were compared with the corresponding "hand-read" values. The difference between the 2 measuring techniques were not significant for the FVC, the FEV75, and the FEF25-75; however, the average FEV1 differed by 6.7 ml (SD, 20.3 ml), which was significant. In addition, 10 subjects performed FVC maneuvers through a spirometer and flowmeter connected in series. Flows and slope ratios obtained from the volume-time tracings were compared with those obtained directly from the flowmeter. There was a high degree of correlation between the 2 types of flow measurements (r = 0.989), whereas slope ratios were less well correlated (r = 0.589). Configurational detail such as the presence of "bumps" on slope ratio versus volume plots were recovered with the computer technique. Using this new system, it is possible for 1 operator to process 10 to 12 sets of spirometry tracings per hour.

Adolescent↗
PubMed1988

Dichotomous airway response to exercise in asthmatic patients.

The extent and location of airway narrowing in asthmatic subjects are usually inferred from measurements of maximal expiratory flow rates and airway resistance. In the present study, we used the acoustic reflection technique to measure the airway cross-sectional area in 14 asthmatic subjects and 8 normal controls before and following treadmill exercise tests. In normal subjects, exercise caused no significant change in FEV1 and bronchial area, but did cause a significant increase in the intrathoracic tracheal area from 2.0 +/- 0.7 cm2 to 3.1 +/- 0.7 cm2 (p less than 0.002). In the asthmatics, exercise was followed by a 37 +/- 15% reduction in forced expiratory volume in 1 s(FEV1), and a 36% decrease in bronchial area from 8.5 +/- 2.8 cm2 to 5.4 +/- 1.1 cm2 (p less than 0.001); however, extra- and intrathoracic tracheal areas increased significantly. These findings provide direct and quantitative evidence that the bronchi are the main site of airway narrowing in exercise-induced asthma, and draw attention to the phenomenon of tracheal dilatation that occurs concomitant with bronchoconstriction in asthmatic patients.

Adult↗
PubMed1989

Hard-rock mining exposures affect smokers and nonsmokers differently. Results of a community prevalence study.

The physiologic consequences of occupational dust exposure, their relation to smoking, and their reversibility with cessation of exposure remain controversial. To address these questions, we studied a random sample of male residents of Leadville, Colorado when the major employer, a hard-rock mine, had been closed for 5 to 11 months. Subjects were interviewed for respiratory symptoms and occupational history, underwent plethysmographic measurements of lung volume and airflow, and performed a single breath diffusing capacity procedure. Dyspnea was the only respiratory symptom exacerbated by mining exposures. Cumulative dust exposure, estimated with historic respirable dust measurements for mining job titles and weighted by time at the job, was associated with decreases in maximal expiratory flow rates when controlled for smoking, age, and height. However, determinations of plethysmographic lung volume that allowed calculation of flow rates at equivalent absolute lung volume indicated that dust effects differed in never-smokers and smokers. In never-smokers, dust exposure was associated with decreased lung volume, increased flow rates, and increased DLCO/VA. In smokers, dust exposure was associated with increased lung volume, lower flow rates, and lower DLCO/VA than that accounted for by smoking. We suggest that hard-rock mining exposures result in irreversible pulmonary function changes of airflow limitation in smokers and of a restrictive nature in never-smokers.

Adult↗
PubMed1979

Changes in the forced expiratory spirogram in young male smokers.

Forced expiratory spirograms and peak expiratory flow were measured in 102 resident male medical students (60 nonsmokers and 42 smokers). Forced vital capacity; forced expiratory volume in 1 sec; forced expiratory volume in 1 sec expressed as a percentage of forced vital capacity; forced expiratory flows between 80 and 70 per cent, between 55 and 45 per cent, between 30 and 20 per cent, and between 15 and 5 per cent of the forced vital capacity; forced expiratory time for the last 0.5 liter of the forced vital capacity; and maximal mid-expiratory flow were determined from the forced expiratory spirogram. Peak expiratory flow, all forced expiratory flows (except the forced expiratory volume in 1 sec), and the ratio of forced expiratory volume in 1 sec to forced vital capacity were significantly lower, and forced expiratory time for the last 0.5 liter of the forced vital capacity was significantly higher in the heavy smokers (those who had smoked a lifetime total of more than 10,000 cigarettes) than the nonsmokers. The light smokers (those who smoked a lifetime total of fewer than 10,000 cigarettes) had values between those of nonsmokers and the heavy smokers. Thus, a definite dose-related response to smoking was seen. Flows at lower lung volumes showed greater percentage changes than flows at higher lung volumes. The forced expiratory flow between 30 and 20 per cent of the forced vital capacity was the most sensitive test for detecting abnormality in smokers. Among heavy smokers, 58 per cent had abnormally low forced expiratory flow between 30 and 20 per cent of the forced vital capacity, whereas only 47 per cent had abnormally low ratio of forced expiratory volume in 1 sec to forced vital capacity, and 32 percent had abnormally low maximal mid-expiratory flow. The results show that even subjects with short smoking histories may have changes in pulmonary function that probably reflect narrowing of small airways. Moreover, these changes can easily be detected by simple tests, such as evaluation of a forced expiratory spirogram.

Adult↗
PubMed1980

Effect of layoff and rehire on respiratory variables of grain elevator workers.

A group of 77 grain elevator workers was examined at monthly intervals over a 7-month period. Approximately half of the workers were temporarily laid off for several months of this period, during which those who were steadily employed were involved in processing a reduced throughput of grain. The men who were laid showed a transient decrease in some respiratory symptoms during the months of layoff, followed by an increase after rehire. Those who were steadily employed showed a corresponding increase in these symptoms during the period of reduced grain movement, which did not change when the elevator returned to full activity. All of them demonstrated the greatest maximal expiratory flow rates during the midportion of the period of reduced work status, and the lowest values after either rehire or the restoration of full elevator activity. These longitudinal changes in respiratory variables are largely consistent with the effects of grain dust exposure, which may be at least partially reversible.

Absenteeism↗
PubMed1981

Smoking and lung function.

In a cross-sectional survey of 3 separate communities, we studied the white residents 7 year of age and older in order to determine the relation between cigarette smoking and lung function. We identified 2,817 nonsmokers, 664 ex-smokers, and 1,209 smokers who were further classified as light smokers (1 to 20 cigarettes per day) and heavy smokers (greater than 20 cigarettes per day). Residual lung function (observed-predicted) was examined in these groups for forced expiratory volume in one second (rFEV1) and for maximal expiratory flow rates at 50% and 25% of the vital capacity (rVmax50% and rVmax 25%). Mean residuals by sex, age, and smoking category were compared and revealed an increasing progression of lung function loss with advancing age in males and females in all smoking categories. These age-related trends were due primarily to the amount smoked by persons in each group. The age of onset of these abnormalities was found to be as early as the age group 15 to 24 yr. Abnormalities were greater in smokers than ex-smokers, even when the amount smoked was taken into account. This is suggested improvement in lung function after cessation of smoking. Men and women were found to experience the same relative degree of gain. Also, the contribution of the various smoking habits to lung function loss was assessed using regression analyses and accounted for no more than 15% of the variation of the residual lung function. Combinations of variables were found to explain only slightly more variation than a single variable. The two most important variables were duration of smoking and pack-years. Inhalation and use of filters were not significant. Although the same amount of variation explained by the smoking variables after accounting for age, height, weight, and sex was small, this variation accounted for almost all of the decrease, over age, in residual lung function for smokers and ex-smokers.

Adolescent↗
PubMed1982

A longitudinal study of respiratory health in a rural community.

We studied the white residents of Lebanon, Connecticut, a rural community, cross-sectionally in 1972 and a follow-up survey in 1978. In this community, we examined prospectively the growth and decay of lung function and the prevalence, attack, and remission of respiratory symptoms in 1,262 persons. These longitudinal findings were related to sex, age, and smoking habits. Respiratory symptoms and 3 lung function variables were examined: forced expiratory volume in one second (FEV1) and maximal expiratory flow rates at 50 and 25% of vital capacity (Vmax50 and Vmax25). The representativeness of the follow-up population was examined by an extensive analysis of the respondents and nonrespondents based on their cross-sectional characteristics. These analyses did not, in general, reveal any consistent results indicating that a healthier population was followed. The longitudinal data showed that lung growth continued into early adulthood (25 to 34 yr of age) with a leveling off and decline beginning at 35 yr and older. This is in contrast to cross-sectional studies of growth and decay of lung function, which show less growth among the young and more decay among adults. The rates of growth in both males and females were affected by their smoking status, with smokers having less growth and greater decline than nonsmokers. In particular, lung function growth was impaired in young smokers as early as 15 to 24 yr of age, and an actual decline was seen in the females of this age group.

Adolescent↗
PubMed1982

Exponential analysis of the lung pressure-volume curve as a predictor of pulmonary emphysema.

To compare the predictive value of different pulmonary function tests in the diagnosis of morphologic emphysema, we performed measurements of subdivisions of lung volume, gas exchange, maximal expiratory flow rates, and static deflation pressure-volume curves on 55 subjects prior to surgery for removal of an isolated peripheral pulmonary lesion. Emphysema was graded on the resected lung specimen and the pressure-volume data were fitted to an exponential equation (V = A - Be-KP). By chi-square analysis, K was the best predictor of emphysema in individual subjects and it was the only test that distinguished subjects with moderate emphysema from subjects with mild or without emphysema, but K did not distinguish those with mild emphysema from those without emphysema. As a group those with mild emphysema were distinguishable from predicted normal with K and elastic recoil pressures at 90 and 60% of predicted total lung capacity. We conclude that minimal emphysema may be detected by exponential analysis of the lung pressure-volume curve.

Adult↗
PubMed1986

Nonspecific airway reactivity in cigarette smokers. Relationship to airway pathology and baseline lung function.

To examine the relationship of cigarette smoking, starting airway caliber, and airway pathology to nonspecific airway reactivity, we performed inhalation dose-response curves in 40 patients prior to lung surgery. Airway reactivity was assessed by the provocative concentration of methacholine (n = 30) or histamine (n = 10) resulting in a 20% fall in FEV1 (PC20). All patients had measurements of maximal expiratory flow, diffusing capacity, and lung volumes preoperatively. After resection, the specimens were graded for small and large airways pathology and emphysema. The patients were divided into 4 groups: PC20 less than or equal to 1 mg/ml (n = 6), PC20 1 mg/ml to less than or equal to 4 mg/ml (n = 11), PC20 4 mg/ml to less than or equal to 16 mg/ml (n = 14), and PC20 greater than 16 mg/ml (n = 9). Subjects with PC20 less than or equal to 1 mg/ml had reduced measurements of maximal expiratory flow (FEV1, FEV1/FVC, Vmax50, and Vmax25). There were no differences in measurements of cartilaginous airway disease among the 4 reactivity groups. We found significant independent correlations of cigarette consumption, membranous bronchiole inflammation, and maximal expiratory flow rates (FEV1 and Vmax50) to PC20. The data suggest that cigarette smoking, starting airway caliber, and airway inflammation are associated with nonspecific airway reactivity and that each exerts an effect on airway reactivity that is not dependent on the contribution of the other 2 factors.

Aged↗
PubMed1987

"Sensitive tests" are poor predictors of the decline in forced expiratory volume in one second in middle-aged smokers.

In 1978, we studied 3 groups of steelworkers 45 to 55 yr of age who were all smokers: "obstructive" smokers (OS) with a FEV1/VC less than 66.6% (59.8% in average) (n = 37), smokers with "small airways disease" (SAD) and an abnormal closing capacity and/or slope of phase III (delta N2) but normal FEV1/VC (n = 32), and "resistant" smokers (RS) with normal functional indices (n = 36). Smokers with SAD had a lower (p less than 0.05) FEV1/VC (71.7%) than did RS (74.9%). We studied again 6 yr later about 85% of survivors in each group. Analysis of variance showed that FEV1 decreased significantly (p less than 0.001) only in OS (from 2.67 to 2.46 L). In RS and smokers with SAD, FEV1 declined from 3.34 to 3.26 L and from 2.95 to 2.85 L, respectively (p greater than 0.05). In all 3 groups, delta N2 increased (p less than 0.001) from 0.77 to 1.30% N2/L in RS, 1.41 to 2.43% N2/L in smokers with SAD, and 2.22 to 4.20% N2/L in OS. A multivariate analysis showed that the initial N2 explained about 30% (p less than 0.001) of the decline in FEV1 in OS, but only 10% (p less than 0.001) in the 3 groups together. In fact, the link between delta N2 and fall in FEV1 was restricted to OS. Closing volume and maximal expiratory flow rates were not related to decline in FEV1. The link between uneveness of ventilation and subsequent loss of FEV1 is of physiopathologic interest.(ABSTRACT TRUNCATED AT 250 WORDS)

Forced Expiratory Volume↗
PubMed1977

Peripheral airways as a determinant of ventilatory function in the human lung.

We have investigated the morphological differences responsible for the variability in two tests of pulmonary function, maximal expiratory flow rates (MEF) and the frequency dependence of dynamic compliance (CDYN ratio). Functional measurements were obtained from 53 normal and minimally diseased postmortem human lungs. Morphological measurements performed on these same lungs included airway diameter at three levels in the bronchial tree, the amount of bronchial gland mass, and the alveolar surface to volume ratio. Multiple regression analysis suggests that the diameter of the peripheral conduction airways (membranous bronchioles) is the major morphological determinant for both MEF and the CDYN ratio in lungs at any particular age. Age-dependent changes in both functional tests were associated primarily with differences in the alveolar surface to volume ratio. Minimal emphysema and a lesion associated with cigarette smoking, respiratory bronchiolitis, have no demonstrable effect on either MEF or the CDYN ratio. These studies provide further evidence that the peripheral conducting airways are a major determinant of ventilatory function in the normal human lung.

Adolescent↗
PubMed1984

Kyphosis and pulmonary function in cystic fibrosis.

Spine deformity and chronic pulmonary disease are commonly seen in patients with cystic fibrosis (CF). In order to assess the prevalence of kyphosis, a retrospective evaluation of all initial standing chest radiographs of our CF patients matched with our "reference" population was undertaken. We also studied the possible correlation between the degree of kyphosis and the pulmonary function tests ( PFTs ), consisting of thoracic gas volume and maximal expiratory flows. In our population, the study confirmed an increased prevalence of kyphosis in CF patients (p less than .01), which occurred mostly in girls after 12 years of age (p less than .018). The kyphosis appeared to be, in most instances, of mild degree and was not related to any of the PFTs . No measurable increase of kyphosis was observed over a 3-year period in the group. Longer prospective study and the relationship of kyphosis to endocrine function in CF at puberty should be undertaken.

Adolescent↗
PubMed1998

Attenuation of isocapnic hyperpnoea-induced guinea-pig bronchoconstriction by chronic hypoxia.

Chronic hypoxia has been shown to augment the production of antioxidants in rat lungs and to reduce airway hyperreactivity in patients with asthma. This study investigated indirectly whether this increase in antioxidants occurs in guinea-pig lungs and whether the increased antioxidants affect hyperpnoea-induced bronchoconstriction (HIB). Guinea-pigs were divided into four groups: control (n=8); chronic hypoxia (n=7); capsaicin pretreatment (n=7); and capsaicin pretreatment plus chronic hypoxia (n=8). Control animals were not treated. Animals in the hypoxia group were intermittently exposed to an ambient pressure of 380 mmHg for 7 days. A five day pretreatment of capsaicin was used to deplete tachykinins. In the last group, animals were pretreated with capsaicin, followed by a seven day hypoxic exposure. On the day of the study, airway function was examined in the anaesthetized and paralysed animal. Fifteen minutes of hyperpnoea caused marked decreases in the maximal expiratory flow rate at 15% vital capacity, forced expiratory volume in one second, and dynamic respiratory compliance, indicating HIB. This HIB and plasma substance P levels were significantly attenuated by chronic hypoxia, capsaicin pretreatment, and capsaicin pretreatment plus chronic hypoxia. Furthermore, chronic hypoxia attenuated airway constriction induced by xanthine-xanthine oxidase. The results suggest that chronic hypoxia attenuates hyperpnoea-induced bronchoconstriction via a decrease in the oxygen radical-mediated release of tachykinins.

Animals↗
PubMed1998

Identification of smokers susceptible to development of chronic airflow limitation: a 13-year follow-up.

BACKGROUND: Cigarette smoking is the cardinal cause of COPD, but only a relatively small percentage of smokers have development of clinically overt disease. OBJECTIVES: To identify high-risk subjects and to assess the prognostic significance of "small airways" tests. SETTING: University teaching hospital. SUBJECTS: Fifty-six smokers and ex-smokers of mean age 62.5 years (SD, 2.7) with a smoking history of 40.6 (18.9) pack-years were studied at the end of a 13-year follow-up period. MEASUREMENTS: Questionnaire and lung function tests, including static and dynamic lung volumes, airway resistance, maximal expiratory flow rates, and small airways tests, such as nitrogen slope of the alveolar plateau (N2 slope) and closing volume. RESULTS: Eighty-two percent of subjects with a normal FEV1/vital capacity (VC) ratio at the start of the study (half of them with abnormal results of small airways tests) still had a normal FEV1/VC ratio 13 years later. In the remainder, all but one had final FEV1/VC values >60%. About 80% of subjects with a decreased FEV1/VC at the start (subjects with airflow obstruction) reached at the end of study lower than predicted FEV1/VC values. Only about 10% of these subjects showed an accelerated loss of FEV1, reaching end FEV1/VC values of <45%. Initial N2 slope predicted about 80% of end FEV1 values. CONCLUSION: Middle-aged smokers are at no evident risk of functional deterioration if their FEV1/VC ratio is normal. This is so even if results of small airways tests are abnormal. A decreased FEV1/VC ratio has no serious implications in itself. Only an associated high N2 slope adds the necessary information to predict a low FEV1. Present data suggest that a subgroup of smokers in their 50s, characterized by a low FEV1/VC ratio and a high N2 slope, are probably the susceptible smokers at high risk for development of COPD.

Airway Obstruction↗
PubMed2000

Airway hyperreactivity in subjects with tetraplegia is associated with reduced baseline airway caliber.

OBJECTIVES: We administered aerosolized histamine to 32 subjects with tetraplegia to determine whether there were differences in spirometric and/or lung volume parameters between responders and nonresponders. RESULTS: Baseline pulmonary function parameters revealed mild to moderate restrictive dysfunction. We found that 25 subjects (78%) were hyperreactive to histamine (mean provocative concentration of a substance causing a 20% fall in FEV(1) [PC(20)], 1.77 mg/mL). Responders (PC(20), < 8 mg/mL) had significantly lower values for forced expiratory flow between 25% and 75% of the outflow curve (FEF(25-75)), FEF(25-75) percent predicted, and FEF(25-75)/FVC ratio. Among all 32 subjects, the natural logarithmic transformation performed on PC(20) values (lnPC(20)) correlated with FEF(25-75) percent predicted, FEV(1) percent predicted, and FEF(25-75)/FVC ratio but not with FVC percent predicted. Responders with PC(20) values < 2 mg/mL (n = 13) had significantly reduced values for FVC, FVC percent predicted, FEV(1), and FEV(1) percent predicted compared to those with PC(20) values between 2 mg/mL and 8 mg/mL. In addition, among responders, there was a significant correlation between lnPC(20) and FVC percent predicted. A significant relationship was found between maximal inspiratory pressure (PImax) and both FEV(1) percent predicted and FEF(25-75) percent predicted, but not between lnPC(20) and either PImax or maximal expiratory pressure (PEmax). CONCLUSIONS: These findings demonstrate that subjects with tetraplegia who exhibit airway hyperreactivity (AHR) have reduced baseline airway caliber and that lower values for lnPC(20) are associated with parallel reductions in surrogate spirometric indexes of airway size (FEV(1) percent predicted and FEF(25-75) percent predicted) and airway size relative to lung size (FEF(25-75)/FVC ratio). The absence of an association between lnPC(20) and FVC percent predicted for the entire group or between lnPC(20) and either PImax or PEmax indicates that reduced lung volumes secondary to respiratory muscle weakness cannot explain the mechanism(s) underlying AHR. Among responders, however, a possible role for reduction in lung volume, as it pertains to increasing AHR, cannot be excluded. Proposed mechanisms for reduced baseline airway caliber relative to lung size in subjects with tetraplegia include unopposed parasympathetic activity secondary to the loss of sympathetic innervation to the lungs and/or the inability to stretch airway smooth muscle with deep inhalation.

Adult↗
PubMed1975

Cough dynamics in the post-thoracotomy state.

A series of 24 adult male patients undergoing thoracotomy were found to have a reduction in their cough pressures in the immediate postoperative period to 29 percent of their preoperative values. Cough pressures still averaged only 50 percent of control values one week following surgery, with slow return toward normal over the ensuing three weeks. Pain associated with the surgical wound appeared to be primary factor in the patients' inability to cough effectively. The degree of impairment appeared to be related to the extent of the procedure, pressures being altered less in those with limited incision thoracotomies. Ultrasonically nebulized water mist was found to be effective in all but one patient in inducing significantly higher cough pressures and more effective sputum expectoration. Its use should be considered as a simple method of inducing more effective coughs in the postoperative patient.

Adult↗