Variation In Pulmonary Function Research Articles

Study of pulmonary function tests in workers of rurally located flour mills

Background: Agro-based industrial works like flour milling are a significant component in the industrial arena of Kerala. In milling industry, dusts are produced in substantial quantities and inhalation of which can result in pulmonary impairment in workers. In such situations, spirometric evaluation can aid in the diagnosis and prognosis of pulmonary diseases. Aims and Objectives: The aims of this study were to assess the effect of flour dust on pulmonary function among flour mill workers and to study the variation in pulmonary function among workers according to duration of exposure and their working environment in the factory. Materials and Methods: A cross-sectional study was conducted in three wheat flour mills. Subjects were selected after proper exclusion and after getting informed consent. In the present study, 79 flour mill workers aged more than 20 years and employed for more than 1year, were considered and their FVC,FEV1,FEV1/FVC,PEFR and FEF25-75% values were assessed. The objective was to find out the effect of their duration of employment and exposure to dust on their spirometric parameters based on their type of job and age. These parameters were tested using a portable electronic spirometer in the factory premises. Results: The study showed no significant relation of these parameters with duration of employment and dust exposure. However, there was significant reduction in FVC and FEV1 with increasing age. Conclusion: Even though apparently normal PFT values are obtained in many subjects, these may be on the extremes of normal spectrum.

Dose to High Ventilating Lung Predicts Radiation-Induced Pneumonitis in Lung Cancer Patients

<h3>Purpose/Objective(s)</h3> Current lung cancer radiotherapy (RT) planning does not account for regional variation in pulmonary function. Functional avoidance RT is being studied as a technique to limit pulmonary toxicity. There is limited data on useful dose parameters for avoiding high ventilating lung. Our objective was to identify metrics of radiation dose delivered to high ventilating lung predictive of radiation-induced pneumonitis. <h3>Materials/Methods</h3> A combined prospective and retrospective cohort of 108 patients with locally advanced non-small cell lung cancer treated with standard fractionated RT of 60-66 Gy in 30-33 fractions were evaluated. Regional lung ventilation was determined from pre-RT 4-dimensional computed tomography (4DCT) using the Jacobian determinant of a B-spline deformable image registration to estimate lung tissue expansion during respiration. Lung voxels with greater expansion than the voxel-wise population median expansion were defined as high ventilating. Mean dose and volumes receiving dose over thresholds of 5-60 Gy were analyzed for both total lung-ITV (MLD, V5-V60) and high ventilating functional lung-ITV (fMLD, fV5-fV60). The primary endpoint was symptomatic grade 2+ (G2+) pneumonitis. Differences in dose metrics were compared and receiver operator curve (ROC) analyses were used to identify predictors of pneumonitis. <h3>Results</h3> G2+ pneumonitis occurred in 20.4% of patients. There were no differences between stage, smoking, COPD or chemo or immunotherapy use between G<2 or G2+ pneumonitis patients. Total lung median MLD, V5 Gy and V20 Gy were 15.4 Gy, 58.0% and 25.7%, respectively. Each metric was significantly different between patients with G<2 and G2+ pneumonitis (p<0.016). Optimal ROC points predicting pneumonitis from total lung dose were MLD < 17 Gy, V5 < 59% and V20 < 25%. Regional ventilation calculated from 4DCTs had a population-wide median of 18% voxel-level expansion. The median amount of high ventilating (≥ 18% expansion) lung per patient was 52.4% ± 23.0%. All functional dose metrics (fMLD, fV5-fV60) were significantly different between G<2 and G2+ patients (p<0.04). Optimal ROC points of fMLD < 15 Gy, fV5 < 53% and fV20 < 19% of functional lung were predictive of G2+ pneumonitis. Patients with fMLD ≥ 15 Gy had a 41% risk of developing G2+ pneumonitis. Similarly, pneumonitis risk increased from 9% to 33% for fV5 ≥ 53% and 11% to 33% for fV20 ≥ 19%. Spared functional lung volume receiving < 5 Gy was significantly different between G<2 and G2+ pneumonitis patients (671 cc vs 935 cc, p=0.04). <h3>Conclusion</h3> This work produced dosimetric values for ventilating lung associated with symptomatic pneumonitis. Predictive functional lung dose cut-offs were lower than total lung metrics; indicating planning could focus on limiting dose to functional regions. These findings provide important metrics to be used in functional lung avoidance RT planning and designing clinical trials.

Evidence of seasonal changes in airborne particulate matter concentration and occupation-specific variations in pulmonary function and haematological parameters among some workers in Enugu Southeast Nigeria: a randomized cross-sectional observational study

BackgroundUpsurge in cardiopulmonary dysfunctions in Enugu, Nigeria, involved mainly cement workers, automobile spray painters, woodworkers, and Cleaners and was worsened in the dry season, suggesting the need for an occupation-specific characterization of the disease features and seasonal evaluation of air quality for prevention and management.MethodsWe conducted a randomized cross-sectional study of eighty consenting participants (in Achara Layout, Enugu), comprising 20 cement workers (39.50 ± 14.95 years), 20 automobile spray painters (40.75 ± 9.85 years), 20 woodworkers (52.20 ± 9.77 years), and 20 cleaners (42.30 ± 9.06 years). The air quality, some haematological (fibrinogen-Fc, and C-reactive protein-CRP), and cardiopulmonary parameters were measured and analyzed using ANCOVA, at p < 0.05.ResultsThe dry season particulate matter (PM) in ambient air exceeded the WHO standards in the New layout [PM10 = 541.17 ± 258.72 µg/m3; PM2.5 = 72.92 ± 25.81 µg/m3] and the University campus [PM10 = 244 ± 74.79 µg/m3; PM2.5 = 30.33 ± 16.10 µg/m3], but the former was twice higher. The PM differed significantly (p < 0.05) across the sites. Forced expiratory volume at the first second (FEV1) (F = 6.128; p = 0.001), and Peak expiratory flow rate (PEFR) (F = 5.523; p = 0.002), differed significantly across the groups. FEV1/FVC% was < 70% in cement workers (55.33%) and woodworkers (61.79%), unlike, automobile spray painters (72.22%) and cleaners (70.66%). FEV1 and work duration were significantly and negatively related in cement workers (r = -0.46; r2 = 0.2116; p = 0.041 one-tailed). CRP (normal range ≤ 3.0 mg/L) and Fc (normal range—1.5–3.0 g/L) varied in cement workers (3.32 ± 0.93 mg/L versus 3.01 ± 0.85 g/L), automobile spray painters (2.90 ± 1.19 mg/L versus 2.54 ± 0.99 mg/L), woodworkers (2.79 ± 1.10 mg/L versus 2.37 ± 0.92 g/L) and cleaners (3.06 ± 0.82 mg/L versus 2.54 ± 0.70 g/L).Conclusion(s)Poor air quality was evident at the study sites, especially in the dry season. Cement workers and automobile spray painters showed significant risks of obstructive pulmonary diseases while woodworkers had restrictive lung diseases. Cement workers and cleaners recorded the highest risk of coronary heart disease (CRP ≥ 3.0 mg/L). The similarity in Fc and CRP trends suggests a role for the inflammation-sensitive proteins in the determination of cardiovascular risk in cement workers and cleaners. Therefore, there are occupation-specific disease endpoints of public health concern that likewise warrant specific preventive and management approaches among the workers.

Circadian molecular clock disruption in chronic pulmonary diseases.

The circadian clock is the biochemical oscillator with a near 24-h period that is responsible for generating the circadian rhythms in peripheral organs including the lung. Mounting evidence suggests that circadian clock disruption during chronic lung diseases plays an essential role in augmented oxidative stress, inflammatory response, metabolic imbalances, hypoxia/hyperoxia, mucus secretion, dysregulated autophagy, and alters pulmonary function. Here, we review circadian clock disruption and discuss candidate clock genes that are altered at the transcriptional or translational level in chronic pulmonary diseases. This review aims to provide the current knowledge and understanding of the circadian molecular clock disruption in chronic pulmonary diseases which will further advance the development of novel clock-based therapeutics in the future.

Variations in Pulmonary Function in Relation with the Menstrual Cycle in Healthy Adult Female

Objective: To compare the respiratory parameters during different menstrual versus luteal phases of the menstrual cycle in healthy adult female. Methodology: This comparative study was conducted in research lab physiology department of Liaquat University of medical and health sciences Jamshoro, from January 2018 July 2018. Adult healthy non-pregnant females aged between 18 and 24 years were Included. Each participant was advised to visit the Physiology Lab on a particular date for pulmonary function test during menstrual (1-5th day) and luteal (19-22th day) phases, based on their menstrual history. Using the Power lab AD tools 15:HT Computerized Spirometer and parameters recorded on Labtutor software, the participants were made to undertake pulmonary function testing in distinct menstrual cycle stages. All the data was collected via study proforma. Results: Mean age of the cases was 20.03+6.30 years and mean duration of menstrual cycle was 28.62±1.35 days. Mean FVC value was significantly higher in luteal phase (2.57) as compared to menstrual phase (2.50) (p-0.016). Average FEV1 value was significantly higher in luteal phase (2.61) compared to menstrual phase (2.53) (p-0.009). Average values of PEF and FEV1/FVC were also significantly higher in luteal phase as compared to menstrual phase (p-&lt;0.05). Conclusion: Pulmonary functions as well as respiratory efficiency were significantly improved in luteal phase compared to menstrual phase of menstrual cycle, which were enumerated in this study thus suggesting a possible beneficial role of progesterone in improvement of respiratory parameters. The reason could be the bronchodilator effect of progesterone, its level remains higher during this phase.

Evaluation of pulmonary function tests in allergic rhinitis patients attending a rural tertiary care hospital in South India

Background: Pulmonary function tests (PFTs) include a variety of tests such as spirometry, the volume of lung measurement, and diffusing capacity of lung quantification. Allergic rhinitis (AR) is a kind of rhinitis related to complex symptomatology characterized by rhinorrhea, obstruction of the nasal cavity, attacks of sneezing, and irritation of the nose, palate, and eyes. PFT could be deranged in AR patients, as they sustain anomalous airway function, determined by obstruction. Hence, assessing PFT's are a crucial part of the patient workup with AR. Aim: The current study evaluated the variations in pulmonary function among AR patients. Materials and Methods: A sum of 100 people were included in the study, of which 50 people were with AR meeting inclusion criteria, whereas the same age- and gender-matched 50 persons were regarded as a “control group.” PFTs were performed after getting informed consent from both groups. Data were charted and analyzed for statistical significance by the Student's t-test. Results: P value of maximal voluntary ventilation (MVV) has been observed to be the most significant, pointing toward a marked reduction of MVV in the AR patients in comparison to the control group. The P value of forced expiratory volume 1 (FEV1) is moderately significant, depicting a mild decrease in FEV1 among the study group. The P value of FEV1% has been highly significant, pointing toward a marked decrease in FEV1% among the study group participants. The P value of peak expiratory flow rate (PEFR) has been highly significant, denoting a substantial decrease in PEFR in the study group. Conclusion: Alterations in the pulmonary function were evaluated by applying the PFT's among the AR patients of Salem. It was observed that PFT values such as “FEV1, FEV1%, MVV, and PEFR” demonstrated a notable reduction in the allergic patients compared to control.

Vascular Endothelial Function as a Valid Predictor of Variations in Pulmonary Function in T2DM Patients Without Related Complications.

To assess the variations in pulmonary function and vascular endothelial function in their early stages (without related complications). A total of 162 type 2 diabetes mellitus (T2DM) patients without diabetes complications and 55 healthy people were selected, comprising the T2DM group and the control group, respectively, to evaluate changes in vascular endothelial function and lung function and determine the correlation between them. In this study, the T2DM group exhibited significantly lower pulmonary function than that of the control group (P < 0.05). The T2DM group also showed significantly lower flow-mediated dilation (FMD) and nitric oxide (NO) (P < 0.05) than those of the control group. Pulmonary functional indexes correlated positively with FMD and NO (P < 0.05) and correlated negatively with endothelin-1 (ET-1) (P < 0.05). FMD and NO correlated negatively with diabetes duration/HbA1c (P < 0.05), whereas ET-1 correlated positively with glycosylated hemoglobinA1c (HbA1c)/diabetes duration (P < 0.05). Pulmonary functional indexes negatively correlated with HbA1c/diabetes duration (P < 0.05). Multiple linear regression was used to analyze the relationship between vascular endothelial function indexes (FMD, ET-1, and NO) and pulmonary functional indexes. The results indicated that each vascular endothelial function index (FMD, ET-1, and NO) was significantly correlated with the pulmonary functional index (P < 0.05). The patients with T2DM presented changes in the subclinical vascular endothelial and pulmonary function. They also had impaired vascular endothelial functions, which were characterized by reduced vascular endothelial function relative to those of healthy people. Regulating glycemia may improve vascular endothelial and pulmonary functions. Moreover, microvascular lesions in preclinical stages, vascular endothelial function indexes (FMD, ET-1, and NO) were valid predictors of alterations in pulmonary function in T2DM patients without related complications.Clinical Trial Registration ClinicalTrials.gov, identifier NCT03575988.

Pulmonary function and high-resolution computed tomography examinations among offshore drill floor workers

PurposeThe aim of this study was to assess short-term changes in pulmonary function in drill floor workers currently exposed to airborne contaminants generated as a result of drilling offshore. We also aimed to study the prevalence of pulmonary fibrosis using high-resolution computed tomography (HRCT) scans of another group of previously exposed drill floor workers.MethodsPulmonary function was measured before and after a 14-day work period in a follow-up study of 65 drill floor workers and 65 referents. Additionally, 57 other drill floor workers exposed to drilling fluids during the 1980s were examined with HRCT of the lungs in a cross-sectional study.ResultsThe drill floor workers had a statistically significant decline in forced expiratory volume in 1 s (FEV1) across the 14-day work period after adjustment for diurnal variations in pulmonary function (mean 90 mL, range 30–140 mL), while the small decline among the referents (mean 20 mL, range − 30 to 70 mL) was not of statistical significance. Larger declines in FEV1 among drill workers were associated with the fewer number of days of active drilling. There were no signs of pulmonary fibrosis related to oil mist exposure among the other previously exposed drill floor workers.ConclusionAfter 14 days offshore, a statistically significant decline in FEV1 was observed in the drill floor workers, which may not be related to oil mist exposure. No pulmonary fibrosis related to oil mist exposure was observed.

Heritability of pulmonary function estimated from pedigree and whole-genome markers.

Asthma and chronic obstructive pulmonary disease (COPD) are major worldwide health problems. Pulmonary function testing is a useful diagnostic tool for these diseases, and is known to be influenced by genetic and environmental factors. Previous studies have demonstrated that a substantial proportion of the variation in pulmonary function phenotypes can be explained by familial relationships. The availability of whole-genome single nucleotide polymorphism (SNP) data enables us to further evaluate the extent to which genetic factors account for variation in pulmonary function and to compare pedigree- to SNP-based estimates of heritability. Here, we employ methods developed in the animal breeding field to estimate the heritability of forced expiratory volume in one second (FEV1), forced vital capacity (FVC), and the ratio of these two measures (FEV1/FVC) among subjects in the Framingham Heart Study dataset. We compare heritability estimates based on pedigree-based relationships to those based on genome-wide SNPs. We find that, in a family-based study, estimates of heritability using SNP data are nearly identical to estimates based on pedigree information, and range from 0.50 for FEV1 to 0.66 for FEV1/FVC. Therefore, we conclude that genetic factors account for a sizable proportion of inter-individual differences in pulmonary function, and that estimates of heritability based on SNP data are nearly identical to estimates based on pedigree data. Finally, our findings suggest a higher heritability for FEV1/FVC compared to either FEV1 or FVC.

Diurnal Variability of Lung Function and Its Association with Sleep among Patients with Asthma

This prospective exploratory story examined diurnal variations in pulmonary function and their association with sleep and quality of life (QOL) in 20 adult asthmatics. Peak expiratory flow (PEF) was assessed for 7 days, before bedtime and upon awakening. There was no association between PEF variability and QOL. Six of 13 polysomnographic measures were significantly correlated with overnight decline in PEF. Individuals with greatest decline took longer to fall asleep and enter Stage 1 sleep, spent less time asleep, and experienced poorer sleep efficiency. Diurnal variations in PEF reflect adverse sleep quality, yet impact on QOL is often unnoticed.

Inflammatory changes associated with circadian variation in pulmonary function in subjects with mild asthma.

Nocturnal enhancement of airway inflammation has been demonstrated in patients with asthma who have a significant drop in pulmonary function at night. To investigate the circadian changes in airway inflammation and their relationship with variations in pulmonary function in subjects with mild atopic asthma. Twelve asthma subjects were admitted to the hospital for two separate 24-h visits. Bronchoalveolar lavage (BAL) was performed at 04:00 hours during one visit, and at 16:00 hours during another visit. BAL cells were analysed for lymphocyte phenotype and the capacity to secrete cytokines following ex vivo stimulation with phytohaemagglutinin (PHA). The numbers of BAL lymphocytes and the percentage of CD4+ T cells were higher at 04:00 hours compared with 16:00 hours. At 04:00 hours, the forced expiratory volume in 1 s (FEV1) was inversely correlated with BAL lymphocytes and CD4+ cells. PHA-induced generation of IL-5 by BAL cells correlated with BAL eosinophils and CD4+ cells. Moreover, there was a linear relationship between the relative change (16:00-04:00 hours) in IL-5 and circadian variation in FEV1. These data suggest that the circadian variation in lung function in asthma is associated with increased airway CD4+ lymphocyte numbers and their capacity to generate IL-5. Furthermore, in mild asthma, these circadian changes appear to fall into a continuous range, suggesting that day/night variations in airway inflammation and lung function occur on a continuum, rather than as an all-or-none phenomenon.

Review of therapeutically equivalent alternatives to short acting β2 adrenoceptor agonists delivered via chlorofluorocarbon-containing inhalers

BACKGROUNDTo study the transition from metered dose inhalers using chlorofluorocarbons as propellants (CFC-MDIs) to non-CFC containing devices, a systematic review was conducted of clinical trials which compared the delivery of...

Diurnal variation in lung function in subgroups from two Dutch populations: consequences for longitudinal analysis.

We studied circadian variation in FVC, FEV1, PEF, TLC, VC, and RV between 9:00 A.M. and 9:00 P.M. and analyzed how this variation affected estimated longitudinal change. Data from 876 adults were obtained in a longitudinal survey of samples from two Dutch areas. Subjects participated in four surveys held at 3-yr intervals between 1975 and 1985. FVC, FEV1, PEF, and VC increased from 9:00 A.M. until noon and decreased afterwards. TLC was constant over the day, whereas RV decreased from 9:00 A.M. to noon. Average variation in FVC, FEV1 and PEF, expressed as percentages of average level, was 4. 8% (200 ml), 2.8% (86 ml), and 3.1% (250 ml/s), respectively. These results are compatible with circadian changes in airway size. No differences in variability were found between men and women. Significantly larger changes between 9:00 A.M. and noon were found in young adults, smokers, and those with respiratory symptoms than in other subgroups. Adjustment for diurnal variation reduced, albeit slightly, residual standard deviations of estimated longitudinal declines. Average diurnal change was large relative to underlying longitudinal change. Its effect on longitudinal change within an individual can therefore be large depending on age, smoking habits, symptomatology, number of visits, time of measurement, and difference in time between measurements. However, when people are measured at random times during the day for at least three visits, or when measurements are made after 11:00 A.M., effects of diurnal variation in pulmonary function on estimated average longitudinal decline are minimal.

Influence of Age on Diurnal Variability in Measurements of Spirometric Indices and Respiratory Pressures

We evaluated variations in spirometric indices (i.e., forced vital capacity [FVC], peak expiratory flow [PEF], and forced expiratory volume in 1 sec [FEV,1]) and static respiratory muscle pressures (i.e., maximum static inspiratory pressure [PImax] and maximum static expiratory pressure [PEmax]) within a span of 12 hr in 60 healthy elderly subjects, 60 young subjects, and 30 Chronic Obstructive Pulmonary disease (COPD) patients. There were no differences among data of FVC, PEF, FEV1, Plmax, and PEmax on three separate occasions within a day in the elderly or the young. The mean coefficient of variation (CV) values of PEF and Plmax on three occasions were 3.0 ± 0.3% and 4.2 ± 0.4% in the elderly, and 2.4 ± 0.2% and 3.7 ± 0.3% in the young, respectively. No subjects had more than 9% CV on each measurement in the study, suggesting that there is no significant daytime variation in measurement of expiratory flow and respiratory pressures in young and elderly people. However, FVC, PEF FEV1, and Plmax values in the morning were smaller than those measured at the other two occasions in COPD patients. The results indicate that COPD affects diurnal variation in pulmonary function, but age alone has little impact on diurnal variation.

Factors Associated With Variations in Pulmonary Function Among Elderly Japanese-American Men

To identify lifestyle, anthropometric, biochemical, and clinical characteristics associated with pulmonary function in elderly men. Cross-sectional population-based study. Japanese-American men (n=3,111) aged 71 to 93 years, who completed spirometry at the fourth examination of the Honolulu Heart Program (1991 to 1993). Pulmonary function measurements (FEV1 and FVC) were obtained using American Thoracic Society guidelines. Potential factors associated with pulmonary function were examined using Pearson correlation coefficients and general linear models. Age- and height-adjusted mean levels of FEV1 and FVC were compared across quintiles of continuous variables and by status of prevalent disease and medication or vitamin use. Stepwise multiple linear regression was used to identify factors independently associated with pulmonary function overall and among never smokers. A number of correlates of pulmonary function were initially identified. In multivariate analyses, age, current smoking, pack-years of smoking, emphysema, asthma, wheezing without colds, subscapular skinfold thickness, ECG abnormality, heart rate, WBC count, and eosinophil count were all negatively and independently associated with FEV1, while height, grip strength, physical activity, and mean corpuscular hemoglobin concentration were positively associated. With a few exceptions, similar relations were observed with FVC and among never-smokers. Cigarette smoking, respiratory symptoms and disease, and several cardiovascular risk factors were independently associated with pulmonary function in elderly Japanese-American men. In most cases, inadequate control for smoking does not appear to account for these associations. Results suggest that a number of factors that are correlates of FEV1 and FVC in younger age groups are also associated with pulmonary function beyond the age of 70 years.

Nocturnal Asthma: Circadian Rhythms and Therapeutic Interventions

The pathophysiology of nocturnal asthma is closely associated with chronobiology, the science of biologic processes that have time-related rhythms. The 24-h cycle (circadian rhythm) is especially important in understanding the changes in pulmonary function that occur in sleeping asthmatics. Nocturnal asthma can be seen as representing an exaggerated amplitude of normal circadian patterns, including increased airway responsiveness and decreased lung function at night and in the early morning. Circadian changes in epinephrine, AMP, histamine and other inflammatory mediators, cortisol, vagal tone, body temperature, and lower airway secretions are potential mechanisms that favor nocturnal bronchoconstriction. Circadian variation in pulmonary function, as well as the effect of therapeutic interventions, can be readily demonstrated by having patients record peak expiratory flow rate values at different times of the day and night, using a peak flow meter. The treatment of nocturnal asthma requires a chronopharmacologic approach, in which more intense therapy is targeted to coincide with the time that the disease is the worst. Chronopharmacology includes the strategic use of longer-acting beta-agonists, theophylline, corticosteroids, and anticholinergics. Understanding the kinetics of the different drug preparations is necessary for most effective timing of dose. Future treatment of nocturnal asthma will continue to be guided by increased understanding of circadian and sleep-related events.

Detection of Circadian Variation in Pulmonary Function Using peak Expiratory Flow and Forced Expiratory Volume Measurements

IN the clinical environment, pulmonary function tests are used to monitor the progression of respiratory disorders and the patient's response to treatment. The t w o most commonly used by physiotherapists are those of forced expiratory volume (FEV, and peak expiratory flow rate (PEFR); both of these tests are considered indices of airway resistance. The purpose of this study was to determine whether FEV, and PEFR measurements could detect the presence of a circadian variation in airway resistance in healthy subjects. Circadian variation (variation occurring within a 24-hour period) is considered to be larger than the response of the airways to bronchodilator drugs. Hence an improvement in the results of these two tests may not necessarily reflect an improvement in a patient's condition. Measurements of FEV, and PEFR were recorded by a Vitalograph spirometer and function analyser, and a Wright peak f low meter. The validity and reliability of the equipment were confirmed prior to the main study. Measurements of FEV,, PEFR and oral temperature were recorded from eight healthy subjects at three-hourly intervals over a 24-hour period. This procedure was repeated on three days to determine the reliability of the data. Oral temperature was monitored as it is considered to be one of the main influencing factors on the 'body clock'. The activities and food/drink intake of the subjects was restricted and they were encouraged to maintain their normal sleep/wakefulness patterns. The data were analysed using cosinor analysis and t-tests. The former considers a mathematical model of the rhythm which is best approximated by a sine or cosine wave and tests the fit. The group of subjects demonstrated significant circadian rhythm (p<0.05) in oral temperature on all three days, while the measurements of PEFR and FEV, were non-significant (p<0.05) for each day. The circadian variation in oral temperature, PEFR and FEV, was significant (p<0.05) for the group of subjects on each of the three days. The analysis of the individual results revealed five significant rhythms (p<0.05) in FEV, and three in PEFA during the three days. These rhythms only occurred concomitantly on one day in one subject. This study indicates that airway resistance does vary significantly during the day. An interesting feature is the lack of concomitant rhythms between PEFR and FEV,. It suggests the t w o tests are not measuring the same aspects of pulmonary function. This has many clinical implications and requires further investigation.

Variation of lung function during the workshift among cotton and jute workers.

Cotton and jute dust exposure is known to induce reversible airway obstruction. We compared 50 exposed workers to 99 non exposed workers for the prevalence of respiratory symptoms and ventilatory impairment, and for variations in pulmonary function after five working days and after inhalation of salbutamol. The prevalence of respiratory symptoms was not significantly different between the two groups. Pulmonary function was not different on Monday morning, however, significant differences were observed on Friday afternoon. The exposed workers had a lower flow rate at 75% of exhaled forced vital capacity than controls (P less than 0.01). Salbutamol induced greater bronchodilatation in the exposed group. Comparison with a control group is necessary to take into account the change in pulmonary function. Repeated tests, combined with pharmacological tests, are able to differentiate the lung function pattern of exposed and non exposed workers.

Comparison of clinical effects and pharmacokinetics of once daily uniphyl and twice-daily theo-dur in asthmatic patients

A pharmacokinetic study using theophylline syrup in adult asthmatic patients demonstrated a mean apparent volume of distribution of 0.38 liters/kg, mean elimination rate constant of 0.10 hours −1, and variable rates of clearance of theophylline (total body clearance of 0.38 to 0.96 ml/kg per minute). Subsequently, the asthmatic patients were compared using a cross-over design after maintenance Uniphyl (once daily at 8 a.m. or at 8 p.m.) and Theo-Dur (twice daily at 8 A.M. and 8 P.M.). Total daily maintenance theophylline dosage, calculated from the pharmacokinetic data, was identical in all three cross-over phases. At the end of each phase, plasma theophylline levels were measured every two hours and spirometric determinations were made every four hours (excluding 4 A.M.) for 24 hours. The following results were observed: (1) highest peak and mean plasma theophylline concentration and area under the concentration-time curves with evening Uniphyl (p < 0.05); (2) prolonged time-to-peak theophylline concentration after nocturnal compared with daytime dosing; (3) diurnal variation in pulmonary function and plasma theophylline concentrations; (4) no significant differences between the three maintenance treatments in asthmatic symptoms or spirometric results.

Biochemical changes in acute respiratory failure.

A study has been carried out on patients presenting respiratory failure from chronic obstructive lung disease. Acid-base balance, electrolytes and amino acids levels have been studied in plasma and in cerebrospinal fluid (CSF) of patients in hypercapnic coma and results compared with those observed in patients with primary acute hypercapnia. Additional cardiopulmonary measurements were made. The study has shown evidence of significant modification of the distribution ratios of plasma and CSF electrolytes and amino acids, particularly in the patients with coma. The changes seem to be related to variations of the transmembrane potentials and alterations of some metabolic pathways involved in the homeostasis and in neurotransmission. Finally some of the changes of amino acid in plasma and CSF appear significantly correlated to variations in pulmonary function and to modification of acid-base balance observed both in plasma and CSF.