Restrictive Lung Function Pattern Research Articles

Individual and mixture analyses of the associations of phenols and phthalates with lung function among US adults

ABSTRACT The effects of endocrine disruptors including phenols and phthalates on adult lung function remain unclear. In the present study, data from 2007–2012 National Health and Nutrition Examination Survey (NHANES) were extracted, and 4338 participants were included in the final analyses. The associations of three phenols and four phthalate metabolites with six lung function parameters were investigated. In generalized linear regression models (GLM) and restricted cubic spline (RCS) analyses, bisphenol A (BPA) was associated with decreased forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC), and 2,5-dichlorophenol (DCP) was associated with reduced FEV1, FVC and peak expiratory flow rate (PEF), and increased prevalence of restrictive lung function (RLF) in adults. Furthermore, weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) models demonstrated that mixed exposures to phenols and phthalates were linked to reduced FEV1, FVC and PEF and increased prevalence of RLF, and these associations were mainly driven by BPA and 2,5-DCP. In conclusion, mixed exposure to phenols and phthalates was linked to compromised and a restrictive pattern of lung function. The mechanisms of the effects of phenol and phthalate exposures on lung function and respiratory diseases need to be further investigated.

Real-world therapeutic performance of pirfenidone for connective tissue disease-associated interstitial lung diseases.

Pirfenidone (PFD) is commonly applied for antifibrotic treatment in patients with idiopathic pulmonary fibrosis but has rarely been studied in cases with connective tissue disease-associated interstitial lung diseases (CTD-ILDs). We aimed to examine the efficacy of PFD in patients with CTD-ILD based on real-world data. A retrospective cohort study. This study assessed the clinical features of CTD-ILD patients with or without a 6-month PFD treatment. A linear mixed effects model was employed to evaluate the effectiveness of PFD in alleviating lung function changes. Differences in response to PFD were analyzed based on CTD subtype, imaging classification, and pattern of pulmonary function at baseline. A total of 289 patients with CTD-ILD were included, with 155 (53.6%) receiving PFD treatment and the remaining constituting the control group. Patients with the usual interstitial pneumonia (UIP) pattern were more likely to receive PFD treatment, and a relatively lower proportion of cases in the PFD group received immunosuppressive therapies compared to the control group (p < 0.05). At the 6-month follow-up, patients in the PFD group demonstrated a more significant improvement in forced vital capacity (FVC) and diffusion capacity for carbon monoxide (DLCO) (ΔFVC%: 2.9% vs 0.45%, p = 0.009; ΔDLCO%: 1.9% vs -1.1%, p = 0.004). In the linear mixed model analysis, there was a statistically significant group-time interaction between FVC% and DLCO% changes over time (FVC%: β = 4.52, p < 0.001; DLCO%: β = 4.13, p = 0.003). Furthermore, subgroup analysis indicated that pirfenidone may have superior therapeutic effects in patients with systemic sclerosis (SSc)-associated ILD, non-UIP pattern, and restrictive pattern of lung function at baseline. This study provided real-world data demonstrating the effectiveness of PFD in terms of lung function improvement in patients with CTD-ILD.

Assessment of Lung Function of People, Chronically Exposed to Air Pollution in Delhi/NCR, India

Background: Air pollution in India is a serious issue with the major sources being motor vehicle emissions, thermal power stations, cooling towers, biomass burning, fuel adulteration, factory smoke, and stubble burning. Chronic exposure to ambient air pollution has obtunded effects on the development of lung function in children and detrimental effects on lung function of adults. The adverse effects of pollution on lung function increase the development of lung diseases in the future. Aims and Objective: The aim of the study was a comparison of lung function between two groups of population with different occupations, one group with outdoor occupation (high exposure) and second group with indoor occupation (low exposure). Settings and Design: It was a cross-sectional study and the sampling approach was Quota sampling. Quota sampling is a type of non-probabilistic sampling. There are certain groups of people who are particularly vulnerable to ambient air pollution because of their sustained high exposure like traffic police personnel deputed at traffic junctions, auto rickshaw driver/Taxi driver, E-Rickshaw driver plying in this area, and road side vendors this group. Low exposure group chosen were employee of offices and showrooms who are working indoor. Methods and Materials: This study was a two groups of 245 participants in each. First group with outdoor occupation and second group with indoor occupation having different level of exposure to air pollution due to their nature of occupation. Lung function parameters FEV1, FVC, FEV1/FVC, PEFR, and FEF were compared between two groups. Statistical Analysis: SPSS 26 software was used. Independent “T” test for continuous data type for different population, paired “T” test within the group, and Chi-square test for categorical data were applied. Results: Among high exposure group, 62.7% and 9.4% were found to have restrictive and normal lung function pattern, respectively. In comparison, among low exposure group, 31% and 59.5% were found to have restrictive and normal lung function pattern, respectively. Among outdoor group, there was a significant decline of lung function parameters such as FEV1, FVC, FEV1/FVC, PEFR, and FEF in comparison to indoor group. Conclusion: In this study, the lung function parameters were decreased in population working outdoor and chronically exposed to air pollution, in comparison to indoor subjects.

Deterioration and Mortality Risk of COPD Patients Not Fitting into Standard GOLD Categories: Results of the COSYCONET Cohort

Background: Patients with COPD-specific symptoms and history but FEV₁/FVC ratio ≥0.7 are a heterogeneous group (former GOLD grade 0) with uncertainties regarding natural history. Objective: We investigated which lung function measures and cutoff values are predictive for deterioration according to GOLD grades and all-cause mortality. Methods: We used visit 1–4 data of the COSYCONET cohort. Logistic and Cox regression analyses were used to identify relevant parameters. GOLD 0 patients were categorized according to whether they maintained grade 0 over the following 2 visits or deteriorated persistently into grades 1 or 2. Their clinical characteristics were compared with those of GOLD 1 and 2 patients. Results: Among 2,741 patients, 374 GOLD 0, 206 grade 1, and 962 grade 2 patients were identified. GOLD 0 patients were characterized by high symptom burden, comparable to grade 2, and a restrictive lung function pattern; those with FEV₁/FVC above 0.75 were unlikely to deteriorate over time into grades 1 and 2, in contrast to those with values between 0.70 and 0.75. Regarding mortality risk in GOLD 0, FEV₁%predicted and age were the relevant determinants, whereby a cutoff value of 65% was superior to that of 80% as proposed previously. Conclusions: Regarding patients of the former GOLD grade 0, we identified simple criteria for FEV₁/FVC and FEV₁% predicted that were relevant for the outcome in terms of deterioration over time and mortality. These criteria might help to identify patients with the typical risk profile of COPD among those not fulfilling spirometric COPD criteria.

A cross-sectional study connecting obesity and pulmonary function test among young adult in Northern India region

Background: One of the world’s biggest health threats is obesity. This can contribute to various health conditions such as diabetes, vascular disorders, and osteoarthritis. Yet, there has been less focus on the impact of obesity on the respiratory system. Pulmonary function tests (PFTs) are commonly associated with the body’s size and age, where height is a predictor for the size of the chest, and age represents maturity. Aim and Objective: This research was designed to show that any body mass index (BMI) rise would affect lung function. Materials and Methods: We, therefore, tried to investigate the relationship between obesity and different variable of PFTs. Results: The variable of pulmonary function tests such as forced vital capacity (FVC) and forced expiratory volume in one second (FEV1)/FCV ratio was significantly decreased in obese individuals than normal individuals. However, FEV1, FEF25-75%, and peak expiratory flow rate (L/sec) were comparable among obese and normal-weight individuals. The linear correlation between BMI with FVC [r(43) = −0.033; P = 0.0829] and BMI with FEV1/FVC ratio [r(43) = −0.111; P = 0.4666] was not observed. This suggests that BMI does not determine the significant change in the FVC and FEV1/FVC ratio among obese individuals. Conclusion: We discovered a significant relationship between obesity and PFT and concluded that, as shown by the significant decrease in FVC, obesity induces significant changes in respiratory function, and the significant increase in FEV1/FVC ratio indicates a restrictive lung function pattern among obese individuals. However, the correlation analysis suggests that BMI is not a detrimental factor for PFT alteration in obesity. BMI is, therefore, not a significant predictor of PFT. When interpreting PFT outcomes in patients, our findings will assist clinicians.

Impact of continuous positive airway pressure on the pulmonary changes promoted by immersion in water.

ABSTRACTObjective:To determine whether different levels of CPAP improve the lung volumes and capacities of healthy subjects immersed in water. Methods:This was a randomized clinical trial, conducted between April and June of 2016, involving healthy female volunteers who were using oral contraceptives. Three 20-min immersion protocols were applied: control (no CPAP); CPAP5 (CPAP at 5 cmH2O); and CPAP10 (CPAP at 10 cmH2O). We evaluated HR, SpO2, FVC, FEV1, the FEV1/FVC ratio, peak expiratory flow rate (PEFR), and FEF25-75%) at three time points: pre-immersion; 10 min after immersion; and 10 min after the end of each protocol. Results:We evaluated 13 healthy volunteers. The CPAP10 protocol reversed the restrictive pattern of lung function induced by immersion in water, maintaining pulmonary volumes and capacities for a longer period than did the CPAP5 protocol. Conclusions:When the hemodynamic change causing a persistent lung disorder, only the application of higher positive pressures is effective in maintaining long-term improvements in the pulmonary profile.

Disease Severity Prediction by Spirometry in Adults with Visceral Leishmaniasis from Minas Gerais, Brazil.

Visceral leishmaniasis (VL) is associated with interstitial pneumonitis according to histology and radiology reports. However, studies to address the functional impact on respiratory function in patients are lacking. We assessed pulmonary function using noninvasive spirometry in a cross-sectional study of hospitalized adult VL patients from Minas Gerais, Brazil, without unrelated lung conditions or acute infections. Lung conditions were graded as normal, restrictive, obstructive, or mixed patterns, according to Brazilian consensus standards for spirometry. To control for regional patterns of lung function, we compared spirometry of patients with regional paired controls. Spirometry detected abnormal lung function in most VL patients (70%, 14/20), usually showing a restrictive pattern, in contrast to regional controls and the standards for normal tests. Alterations in spirometry measurements correlated with hypoalbuminemia, the only laboratory value indicative of severity of parasitic disease. Abnormalities did not correlate with unrelated factors such as smoking or occupation. Clinical data including pulmonary symptoms and duration of therapy were also unrelated to abnormal spirometry findings. We conclude that the severity of VL is correlated with a restrictive pattern of lung function according to spirometry, suggesting that there may be interstitial lung involvement in VL. Further studies should address whether spirometry could serve as an index of disease severity in the management of VL.

A rare case of postpoliomyelitis quadriparetic patient with severe kyphoscoliosis.

A rare case of postpoliomyelitis quadriparetic patient with severe kyphoscoliosis.

Reduced respiratory muscle strength and endurance in type 2 diabetes mellitus

A restrictive lung function pattern is frequently observed in patients with diabetes mellitus (DM) and has been related to respiratory muscle dysfunction in type 1 DM or in mixed population. We aimed to verify whether such a relationship applies also to type 2 DM patients. The respiratory muscle function was explored in 75 non-smoking patients with type 2 DM without pulmonary or cardiac diseases and compared with that of 40 healthy non-smoking control subjects matched by age and sex. Maximal inspiratory and expiratory pressures (MIP, MEP) and maximum voluntary ventilation (MVV), which reflect respiratory muscle strength and endurance, respectively, were measured, and a complete respiratory function assessment was recorded. Patients were in stable metabolic conditions and had, on average, normal total lung capacity and diffusing lung capacity for carbon monoxide. However, MIP and MVV were significantly reduced in comparison with those of control subjects. Both MIP/MEP and MVV significantly correlated with lung volumes and diffusing lung capacity for carbon monoxide. The multiple regression analysis identified age (beta coefficient = -0.238, p = 0.046), glycated haemoglobin (beta coefficient = -0.245, p = 0.047) and total lung capacity (beta coefficient = 0.430, p = 0.016) as independent correlates of MIP, whereas male sex (beta coefficient = 0.423, p = 0.004) and diabetic complications (beta coefficient = -0.248, p = 0.044) were independent correlates of MVV. In type 2 DM, respiratory muscle strength was reduced and significantly related to lung volumes and quality of metabolic control, whereas impaired endurance of respiratory muscles prevailed in patients with microvascular complications.

Pulmonary Complications of Congenital Heart Disease

Cardiac and pulmonary pathophysiologies are closely interdependent, which makes the management of patients with congenital heart disease (CHD) all the more complex. Pulmonary complications of CHD can be structural due to compression causing airway malacia or atelectasis of the lung. Surgical repair of CHD can also result in structural trauma to the respiratory system, e.g., chylothorax, subglottic stenosis, or diaphragmatic paralysis. Disruption of the Starling forces in the pulmonary vascular system in certain types of CHD lead to alveolar-capillary membrane damage and pulmonary oedema. This in turn results in poorly compliant lungs with a restrictive lung function pattern that can deteriorate to cause hypoxemia. The circulation post single ventricle palliative surgery (the so called "Fontan circulation") poses a unique spectrum of pulmonary pathophysiology with restrictive lung function and a low pulmonary blood flow state that predisposes to thromboembolic complications and plastic bronchitis. As the population of patients surviving post CHD repair increases, the incidence of pulmonary complications has also increased and presents a unique cohort in both the paediatric and adult clinics.

Azithromycin reduces pulmonary fibrosis in a bleomycin mouse model

ABSTRACTIdiopathic pulmonary fibrosis (IPF) is a devastating disease without proper treatment. Despite intensive research, the exact underlying pathogenesis remains elusive. It is regarded as a continuous injury, resulting in inflammation, infiltration, and proliferation of fibroblasts and extracellular matrix deposition, leading to an irreversible restrictive lung function deterioration and death. In this study the effect of azithromycin, a macrolide antibiotic on bleomycin-induced pulmonary fibrosis was investigated. C57BL/6 mice were intratracheally instilled with bleomycin (0.5 mg/kg) or saline. In the bleomycin group, half of the animals received azithromycin every other day from day 1 on. Bronchoalveolar lavage and histology were performed at days 7 and 35, and pulmonary function tests on day 35. At day 35, fibrotic lesions (spindle cell proliferation/collagen I deposition) were paralleled by a restrictive lung function pattern. Alterations were found in neutrophils and macrophages (innate immunity) and in TH2, TH17, and Treg cytokines (adaptive immunity). Azithromycin significantly reduced both fibrosis and the restrictive lung function pattern. This study demonstrated a beneficial effect of azithromycin on bleomycin-induced pulmonary fibrosis. A possible mechanism could be a modulation of both innate immunity and adaptive immunity. These findings might suggest a potential role for azithromycin in the treatment of IPF.

True Restrictive Ventilatory Pattern in Asthma

Asthma is characterized by a reversible bronchial obstruction. Some patients may present a restrictive lung function pattern. Most often, this is due to extrapulmonary causes such as obesity, scoliosis, etc. As in chronic obstructive pulmonary disease (COPD), a “pseudorestriction,” a lowered forced vital capacity (FVC) due to dynamic hyperinflation with air trapping, may be seen. This article presents two patients suffering from asthma who had an considerable impairment of total lung capacity (TLC) and FVC when their asthma was poorly controlled, showing a complete reversibility of restriction when treated properly for the asthma.

Mechanical effects of obesity on airway responsiveness in otherwise healthy humans

We investigated whether obesity is associated with airway hyperresponsiveness in otherwise healthy humans and, if so, whether this correlates with a restrictive lung function pattern or a decreased number of sighs at rest and/or during walking. Lung function was studied before and after inhaling methacholine (MCh) in 41 healthy subjects with body mass index ranging from 20 to 56. Breathing pattern was assessed during a 60-min rest period and a 30-min walk. The dose of MCh that produced a 50% decrease in the maximum expiratory flow measured in a body plethysmograph (PD50MCh) was inversely correlated with body mass index (r2=0.32, P<0.001) and waist circumference (r2=0.25, P<0.001). Significant correlations with body mass index were also found with the maximum changes in respiratory resistance (r2=0.19, P<0.001) and reactance (r2=0.40, P<0.001) measured at 5 Hz. PD50MCh was also positively correlated with functional residual capacity (r2=0.56, P<0.001) and total lung capacity (r2=0.59, P<0.001) in men, but not in women. Neither PD50MCh nor body mass index correlated with number of sighs, average tidal volume, ventilation, or breathing frequency. In this study, airway hyperresponsiveness was significantly associated with obesity in otherwise healthy subjects. In obese men, but not in women, airway hyperresponsiveness was associated with the decreases in lung volumes.

Lung function and bronchial hyper‐responsiveness 11 years after hospitalization for bronchiolitis

Aim: Atopic infants hospitalized for wheezing not caused by respiratory syncytial virus (RSV) carry the highest risk for later asthma. In the present paper, early risk factors for later lung function abnormalities and for bronchial hyper‐responsiveness (BHR) were evaluated in 81 children, hospitalized for bronchiolitis in infancy, at the median age of 12.3 years.Methods: The basic data, including data on atopy in children and viral aetiology of bronchiolitis, had been collected on entry to the study at less than 2 years of age. Lung function was studied by flow‐volume spirometry (FVS), and BHR by methacholine and exercise challenge tests 11.4 years after hospitalization during infancy.Results: RSV aetiology of bronchiolitis was associated with reduced forced vital capacity (FVC; 93.65% of predicted ± 11.05 vs. 99.57%± 12.59, p = 0.009). Early sensitization to inhalant allergens (OR 12.59, 95% CI 2.30–68.77) and maternal smoking during pregnancy (OR 4.58, 95% CI 1.28–16.39) were associated with BHR to exercise, and early atopic dermatitis (OR 3.48, 95% CI 1.09–11.10) was associated with BHR to methacholine.Conclusions: RSV bronchiolitis was associated with a restrictive pattern of lung function. Early atopy and maternal smoking during pregnancy may play a role in the development and persistence of BHR.

Satisfactory Results of Diaphragmatic Plication for Bilateral Phrenic Nerve Paralysis

Bilateral diaphragmatic plication was performed in a 44-year-old man who underwent complete resection of a thymoma infiltrating the right lung, bilateral brachiocephalic vein, pericardium, and bilateral phrenic nerves. The plication procedure allowed him to be weaned from the ventilator on postoperative day 4. He demonstrated no restrictive or obstructive pattern of lung function, and after respiratory rehabilitation he returned to work full time 5 weeks after the operation. The present results indicate that ventilatory movement of the thoracic cage can compensate for loss of bilateral diaphragmatic ventilation for at least 18 months.

Radiation induced lung injury in survivors of childhood cancer

20017 Background: The purpose of this study was to examine survivors of childhood cancer, treated with whole lung irradiation (WLI), for signs of pulmonary insufficiency and to correlate pulmonary function test (PFT) results to symptoms of pulmonary dysfunction as detected using the St. George’s Respiratory Questionnaire (SGRQ). Methods: A cross-sectional study was conducted on eligible patients (&gt;2 years from WLI and &lt;18 years at time of diagnosis) who are followed in our institution’s cancer survivor program. Participating patients had a history and physical examination and PFTs performed pre and post bronchodilator challenge. Patients (or their guardians) also completed the SGRQ. The SGRQ, validated for patients 17 to 80 years, generates four values that define respiratory dysfunction: a Symptoms score, an Activity Score, an Impact score, and a Total score. Results: Twenty eligible patients were identified, 12 of whom consented to participate in this study (11 Wilms, 1 Ewing sarcoma). The median current age was 18.4 years (7.5 to 43 years; n=6 &lt; 14 yrs), while patients received WLI (1,200 cGy n=10, 1500 cGy n=2) at a median age of 4.4 years of age (1.7 to 8.7 years). The median time from radiation therapy was 12.6 years (4.7 to 34.3 years). All patients denied smoking, 4 had a history of asthma and all had a normal lung exam. Ten patients had PFTs, 5 of whom (4/5 adults and 1/5 children) had a restrictive pattern noted by PFTs. One further patient (7.5 yrs of age) had a total lung volume 70% predicted but a forced vital capacity 86% predicted. In the pediatric patients (&lt;14 years currently) the FEF 25–75 (4/5) and SGaw (5/5) were increased following treatment with bronchodilator. Twelve participants completed the SGRQ, 4 had elevated total scores (22, 32, 37 and 64). 1 patient with echocardiographic evidence of a dilated cardiomyopathy had an elevated total score but normal symptom score. One patient with a recorded acute pneumonitis after WLI, now 18 years later had normal PFTs and normal SGRQ scores. No correlation was seen between PFT results and SGRQ scores. Conclusions: A restrictive lung function pattern is more common at a later age following WLI in childhood. Mid-expiratory flow and airway conductance following bronchodilator were increased in children. The functional significance of these findings requires further study. No significant financial relationships to disclose.

Mid-term follow-up in patients with diaphragmatic plication after surgery for congenital heart disease

Diaphragmatic palsy (DP) is a rare but severe complication after surgery for congenital heart disease. Transthoracic diaphragmatic plication is an effective means of treatment for those with respiratory impairment due to DP, but little is known about the mid-term effects of diaphragmatic plication. We performed a study in 24 patients with history of DP. Diaphragm movement was assessed using ultrasound. Patients with DP who were old enough were additionally followed-up with lung function and exercise testing. A group of patients with similar age, diagnoses and operations served as controls. Ultrasound showed that in the majority of cases with history of DP the paralysed diaphragm was static, independently of whether it was plicated or not. Patients with DP had a more restrictive lung function pattern (VC: 54.3 vs. 76.4% predicted, p<0.001; FEV(1): 58.4 vs. 86.2% predicted, p<0.001) and a lower exercise capacity compared with the control group (peak VO2: 24.5 vs. 31.3 ml/kg/min, p=0.03). Comparing patients with and without plication for DP, only a tendency towards lower lung function values in patients after diaphragmatic plication, but no differences regarding exercise capacity, could be found. Our results provide evidence that DP is a serious surgical complication with a reduction in lung function and exercise capacity, even at mid-term follow-up; however, diaphragmatic plication, a useful tool in treating post-surgical DP in children with respiratory impairment, seems to be without mid-term risk in terms of recovery of phrenic nerve function, lung function values, and exercise capacity.

Schwimmbadlunge - Exogen-allergische Alveolitis oder Mykobakteriose?

There have been several recent reports of pulmonary disease resulting from exposure to Mycobacterium avium complex in indoor hot tubs. The disease is thought to be due either to infection or extrinsic allergic alveolitis (EAA). In this report we describe the case of a patient who developed episodes of fever, dyspnea and cough 4-6 hours after cleaning his indoor swimming pool. A diagnosis of EAA was made on finding a restrictive lung function pattern with gas exchange abnormalities, a predominant lymphocytosis in the bronchoalveolar lavage, diffuse ground-glass opacities in the lower lobes on high-resolution computer tomography, and specific IgG antibody activity to the swimming pool water. There was no precipitin reaction or specific IgG antibody activity to microbes extracted from the water. Interestingly, the water contained Mycobacterium avium complex (MAC) in huge amounts and in this case the histopathological features of the lung biopsy specimens differed from those seen in typical EAA, but were similar to those described in "hot tub lung" caused by mycobacteria. Solely by avoidance of cleaning the swimming pool, without any pharmacological treatment, the patient recovered completely within three months. To the best of our knowledge, this is the first report of EAA possibly associated with MAC exposure in a swimming pool environment.

Respiratory findings in workers employed in the brick-manufacturing industry.

We studied 233 male workers employed in two brick-manufacturing plants and 149 matched control workers. The mean age of the brick workers was 35 years, with a mean duration of employment in this industry of 16 years. The prevalence of chronic respiratory symptoms as well as acute symptoms during the work shift were recorded. Lung function was measured on Monday during the work shift by recording maximum expiratory flow-volume (MEFV) curves, from which the forced vital capacity (FVC), the one-second forced expiratory volume (FEV1) and flow rates at 50% and the last 75% of the FVC (FEF50, FEF75) were measured. The results of periodic chest roentgenograms were reviewed. There was a significantly higher prevalence of chronic cough (31.8%), chronic phlegm (26.2%), and chest tightness (24.0%) in exposed workers, compared with control workers (20.1%; 18.1%; 0%) (P < 0.05). This increased symptom frequency was also documented among nonsmokers studied by age and by length of employment, suggesting a work-related effect. Among work shift-related symptoms, high prevalences were noted for upper respiratory tract symptoms (e.g., dry throat, eye irritation, throat irritation). The measured FVC and FEV1 were significantly lower than predicted for brick workers and suggested a restrictive pattern. The mean FVC (as a percent of predicted) was 78.1% and FEV1 was 88.1%. The FEF50 and FEF25 were not significantly decreased. A multiple regression analysis with age, exposure, and smoking as predictors and lung function parameters as response variables showed a significant effect between exposure and FVC. Significant chest roentgenographic abnormalities were not documented. These findings of a restrictive lung function pattern in brick workers with normal chest roentgenograms may suggest early interstitial disease. Additionally, a bronchitic component, as suggested by the respiratory symptoms, may also be present.

Respiratory muscle weakness and normal ventilatory drive in dilative cardiomyopathy.

In dilative cardiomyopathy several factors influence dyspnoea. Patients with chronic heart failure may demonstrate impairment of breathing pattern, ventilatory drive and respiratory muscle strength, as well as reduction of ventilatory efficiency. The purpose of this study was to evaluate whether dilative cardiomyopathy is accompanied by changes in breathing pattern, respiratory muscle weakness and ventilatory neural drive. We investigated 47 patients (36 men, mean age = 47.8 +/- 11.2 years) with chronic heart failure due to dilative cardiomyopathy, and 30 healthy subjects (10 men, mean age = 35.4 +/- 11.7 years) served as controls. Patients and controls underwent evaluation of left ventricular ejection fraction by 2D echocardiography, spirometry, body plethysmography, mouth occlusion pressure and respiratory muscle strength, as well as by submaximal treadmill exercise testing with gas exchange measurements. The patients' results were compared to controls and predicted standard normal values, and evaluated for differences according to the degree of severity of functional impairment. Patients with dilative cardiomyopathy demonstrated a slight reduction in lung volumes (15% of the patients with obstructive and 15% with restrictive lung function pattern) and diffusion capacity (20.4 +/- 6.8 vs 15.4 +/- 6.7 ml.min-1.kPa-1; P < 0.01). In neural drive, as assessed by mouth occlusion pressure, there was no significant difference between patients and controls. There was a slight but significant reduction in respiratory muscle strength, as assessed by measuring maximal inspiratory pressure in patients with dilative cardiomyopathy (6.7 +/- 2.4 kPa vs 8.6 +/- 3.5 kPa; P < 0.01). The observed changes were more pronounced in the severe chronic heart failure patients (with a reduction in ventilatory efficiency) whereas no relationship among indices of cardiac or respiratory function was found. Patients with chronic heart failure due to dilative cardiomyopathy develop respiratory muscle weakness without changes in neural ventilatory drive, and slight changes in breathing pattern related to the severity of the disease.