Maximal Expiratory Flow-volume Research Articles

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.

The use of a neural network to detect upper airway obstruction caused by goiter.

Goiter is a common condition and can cause upper airway obstruction (UAO), which may be difficult to detect. We have studied maximal expiratory and inspiratory flow volume loops using a neural network to see if this offers a better way to identify patients with UAO. The flow-volume loops from 155 patients with goiter were assessed by a human expert and sorted into those with and without UAO. The reliability of this assessment was judged by using two observers who repeated the sorting 8 wk apart. A set of 46 patients with loops suggesting UAO and a set of 51 patients with normal flow loops were taken from these 155, and the loops from a further 50 subjects with airflow limitation caused by chronic obstructive pulmonary disease were used for training and testing the neural network. Novel and standard indices were derived from the loops and used by the neural network. The kappa score for agreement between each of the observers and the original classification were 0.5 and 0.46, respectively, with the agreement between the observers at each reading of 0.58 and 0.68. The neural network found that a combination of four novel scores for flatness of the expiratory loop, the moment ratio, and the FEV1/PEF ratio was best at identifying UAO with a kappa score of 0.81, a sensitivity of 88%, specificity of 94% and an accuracy of 92%. We conclude that a neural network using only six indices taken from the expiratory limb of a flow-volume loop was better than human experts at identifying flow loops with UAO.

Effect of Cold Air on Exercise Capacity in COPD: Increase or Decrease?

To clarify the effect of cold air on exercise capacity in COPD. Cycle ergometer tests under different environmental conditions. Pulmonary function laboratory and an environmental chamber at a university hospital. Eighteen patients with stable COPD; 14 completed the study. A preliminary cycle ergometer test followed by two incremental, symptom-limited cycle ergometer tests, one at 24 degrees C and the other at -20 degrees C. On the first study day: arterial blood gas analysis, 12 to 15 s maximal voluntary ventilation, maximal expiratory flow-volume curves before and 1 h after inhalation of 80 microg of ipratropium bromide, and diffusion capacity of the lung. During the exercise challenges: spirometric indices, minute ventilation (VE), oxygen consumption (VO2), carbon dioxide production (VCO2), facial skin temperature, and heart rate. The feeling of dyspnea was assessed with a visual analogue scale. The maximal work load was 87.5+/-7.3 W at -20 degrees C compared with 96.4+/-6.9 W at 24 degrees C (p<0.05). Accordingly, the exercise duration was shorter in the cold. Exercise dyspnea was more severe in the cold at equal work loads. The shortening of exercise duration induced by cold air correlated with the enhancement of exercise dyspnea. Furthermore, cold air cooled the facial skin and induced immediate bronchoconstriction. VE, VO2, VCO2, and heart rate did not differ between the warm and cold challenges. Cold air decreases exercise capacity in COPD, probably by increasing exercise dyspnea.

Effect of a Nasal Dilatator on Nasal Patency During Normal and Forced Nasal Breathing

A nasal dilatator contains two elastic strips, which provide the dilatator with a spring action. The aimed function of the nasal dilatator is to slightly open the nares and hereby facilitate nasal breathing. The aim of this study was to evaluate the effect of a nasal dilatator by measuring nasal airway resistance during normal breathing and nasal forced expiratory and inspiratory flows and volumes with and without use of the nasal dilatator. Nasal resistance was measured with a whole body plethysmograph; maximal expiratory and inspiratory flow-volume curves were obtained with a pneumotachometer. These measurements were performed in ten healthy volunteers. No significant difference was found between nasal resistance with and without the nasal dilatator. However, values for forced inspiratory volume in 1 s (FIV 1) with the nasal dilatator, proved to be significantly higher (p=0.045,paired t-test) than values obtained without the nasal dilatator; mean improvement was 0.26 L (sd = 0.36). No significant improvement in peak inspiratory flow (PIF) was found, as was the case for the other flows and volumes. It is concluded that the nasal dilatator causes no appreciable improvement of nasal patency during normal breathing. In view of the fact that FIV 1 values increased significantly, we believe that the nasal dilatator prevents collapse of the external nares during forced inspiration. A beneficial effect during exercise when ventilation is increased is however doubtful because in that situation most volunteers switch to oronasal breathing already at submaximal exercise.

Postoperative complications after coronary bypass operations in patients with pulmonary impairment

The postoperative courses of 112 patients with pulmonary disease (59 with obstructive disease = Group 0, 38 with restrictive disease = Group R and 15 with mixed disease = Group M) who underwent elective coronary artery bypass grafting were retrospectively reviewed. Preoperative pulmonary function test (percentage of vital capacity = %VC and percentage of forced expiratory volume at 1 second = FEV1.0%) of these group showed typical abnormal values, and velocity ratio of 50% and 25% of maximum expiratory flow volume (V50/V25) of each groups were measured abnormal values (3.99 +/- 1.44 of Group O, 4.26 +/- 1.42 of Group R and 3.74 +/- 1.82 of Group M). The our strategy for these groups were a). Using skeletonization method for harvesting internal mammary artery (IMA) b) Take care not to injure the phrenic nerve and open the pleural cavity as surgical techniques (Harvesting IMA) and c) Administration of theophylline derivatives and corticosteroids to prevent bronchospasm d) Administration of concentrated serum albumin and diuretics to prevent pulmonary edema as therapeutic measures. The length of stay in the intensive care unit and ventilation time of each groups were not significantly longer. Patients of group M had more respiratory complications (atelectasis, pleural effusion, pneumothrax, bronchospasm, and pneumonia) than did patients of group R (p < 0.05), but did not more nonpulmonary complications and hospital deaths. The four in hospital deaths (2 with group O, 1 with group R and 1 with group M) were not directly related to pulmonary complications. Thus, result of CABG in patients with pulmonary impairment definitely proved to be satisfactory by our strategy, but mixed pulmonary diseased significantly had more pulmonary complications.

Small Airways Function in Patients with Inflammatory Bowel Disease

It has been reported that in patients with inflammatory bowel disease (IBD), the airways are involved, and a number of clinical manifestations have been described. The aim of this study was to investigate the function of the small airways in IBD. Thirty patients with IBD (mean age, 47 yr), 12 with Crohn's disease and 18 with ulcerative colitis, were studied and compared with a control group of 16 normal subjects. Maximal expiratory flow-volume curves were performed breathing room air and a mixture of 80% helium, 20% oxygen. The differences of flows at 50% of FVC (delta Vmax50) and the volume of equal flows (Visov) were calculated as indices of small airways function. In addition, spirometry, lung volumes, and diffusing capacity were measured. Visov was statistically significantly greater in patients with either CD or UC than in control subjects (x +/- SD) (24.99 +/- 1.35 and 25.95 +/- 1.5 versus 20.1 +/- 1.39), (p < 0.01 and p < 0.001, respectively). A reduction in TL(CO) was noticed in the active stage of the disease in both groups of patients (p < 0.05). This may indicate that lung parenchyma is also involved in active IBD. Our results suggest that the function of the small airways and diffusion capacity of the lungs are affected in patients with IBD.

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

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

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

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

Comparison of the functional results of single lung transplantation for pulmonary fibrosis and chronic airway obstruction.

BACKGROUND: Single lung transplantation (SLT) is now a treatment option for patients with both pulmonary fibrosis and advanced chronic airway obstruction. Lung function after transplantation might be expected to be...

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

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

Dependence of forced vital capacity manoeuvre on time course of preceding inspiration in patients with restrictive lung disease

In normal subjects and patients with airway obstruction, flows during a forced vital capacity (FVC) manoeuvre are higher after a fast inspiration without an end-inspiratory pause (manoeuvre 1) as compared to a slow inspiration with an end-expiratory pause of approximately 5 s (manoeuvre 2). In this study, we investigated the influence of these manoeuvres on maximal expiratory volume-time and flow-volume curves in patients with restrictive lung disease. Eleven patients with restrictive lung disease were studied. Their average (+/-SD) lung function test results were: FVC=55+/-12% predicted value, forced expiratory volume in one second (FEV1) 52+/-20% pred, FEV1/FVC 85+/-6%, total lung capacity 55+/-8% pred, and carbon monoxide transfer factor 47+/-18% pred. The patients performed the two FVC manoeuvres in random order. We compared the ensuing spirograms and maximal expiratory flow-volume curves from which peak expiratory flow, FEV1, FEV1/FVC, maximal mid-expiratory flow, and maximal flows were computed. All spirometric indices were significantly higher with manoeuvre 1 than 2. Maximal expiratory flows at the same lung volume were also significantly higher with manoeuvre 1 than 2, in all patients. Routine spirometric indices, obtained during a forced vital capacity manoeuvre depend on the time course of the preceding inspiration in patients with restrictive lung disease. Therefore, the forced vital capacity manoeuvre should be standardized if used in clinical, epidemiological and research studies.

Expiratory flow limitation in stable asthmatic patients during resting breathing.

Application of negative pressure at the mouth during tidal expiration (NEP) provides a simple, rapid, noninvasive method for detecting expiratory flow limitation during spontaneous breathing. Patients in whom NEP elicits an increase in flow throughout expiration are not flow-limited (FL). In contrast, patients in whom application of NEP does not elicit an increase in flow during most or part of tidal expiration are considered FL. We have used the NEP technique to assess the prevalence of expiratory flow limitation during resting breathing in sable asthmatic patients in both the seated and supine positions. In patients in the sitting position, we have also assessed flow limitation with the conventional method, based on comparison of tidal and maximal expiratory flow-volume (MEFV) curves. We studied 13 patients (FEV1 range: 48 to 94% predicted) with both the NEP and conventional techniques. According to the NEP technique, none of the patients was FL in the seated and only two were FL in the supine position. By contrast, on the basis of the conventional method, six of the patients would have been classified as FL in the sitting position. We conclude that: (1) most stable asthmatic patients do not exhibit tidal expiratory flow limitation during resting breathing; and (2) the conventional method for assessing flow limitation may lead to erroneous conclusions.

Influence of endotracheal tube diameter on forced deflation flow-volume curves in rhesus monkeys.

The forced deflation (FD) technique is the recommended gold standard to generate forced expiratory vital capacity (FVC) curves and to measure maximum expiratory flow-volume (MEFV) relationships in intubated infants and children. However, the influence of the endotracheal tube (ETT) on the site of flow limitation, the shape and the analysis of the resultant MEFV curves have not been defined. Nine anaesthetized (thiopentone, 8 mg x kg(-1) x h(-1)) rhesus monkeys (mean weight (+/-SEM) 10+/-1 kg) were intubated consecutively with ETTs of different internal diameters (ID 3.0-5.5 mm, at intervals of 0.5 mm); the largest representing the appropriate ETT size for the animal. Quadruplicate MEFV curves were generated by FD using the standard +40 cmH2Oinsp/-40 cmH2Oexp pressures and recorded at each ETT diameter. The effect of the different ETT diameters on the FD flow-volume curve was analysed by comparing maximum expiratory flows at isovolume points at 50, 25 and 10% FVC (MEF50, MEF25 and MEF10, respectively). The shape of the resulting MEFV curves could be divided into an initial horizontal part (tube-dependent), and a final descending slope (airway-dependent). No difference in FVC occurred irrespective of the ETT size (p>0.05 by analysis of variance (ANOVA)). MEF50 increased with increasing tube diameter (p<0.05). MEF25 remained unchanged using ETTs which were less than 1.5 mm smaller than the largest ETT. Smaller ETTs resulted in significantly reduced MEF25 (p<0.05). MEF10 was not influenced by the ETT size. We conclude that maximum expiratory flows measured by the forced deflation technique are not influenced by an appropriately sized endotracheal tube at lung volumes below 25% forced vital capacity in our monkey model with normal lungs. We postulate that the effect of endotracheal tubes on maximum expiratory flow volume curves in intubated infants might be of similar or even smaller magnitude, which remains to be established.

Lung function and airway responsiveness in children and adolescents after hyaline membrane disease: a matched cohort study

Some investigators consider prematurity to be responsible for the lung function abnormalities found in prematurely born children and adolescents who had neonatal respiratory diseases. This study attempts to measure the effect of neonatal respiratory disease on lung function during school age and adolescence, by controlling the confounding effect due to prematurity. Lung volumes, airway resistance and specific airway conductance measured by plethysmography, maximum expiratory flow-volume curves, pulmonary diffusion of carbon monoxide, and the airway responsiveness to a challenge with methacholine, were determined in a cohort of children aged 8-14 yrs, who had suffered from hyaline membrane disease but who did not develop bronchopulmonary dysplasia. The values obtained were compared with those of children without hyaline membrane disease, not ventilated for other causes, and matched for gestational age, sex and age. Thirty six pairs of children were enrolled, of which 26 participated in the methacholine test. Compared to their paired controls, children with hyaline membrane disease had a significantly lower forced expiratory volume in one second (FEV1), forced mid-expiratory flow (FEF25-75), and maximal expiratory flow when 75, 50 and 25% of the forced vital capacity remained in the lung (MEF75, MEF50 and MEF25, respectively), and a significantly higher airway resistance (Raw). The effect was less in children born more prematurely, who showed less difference in FEF25-75, MEF75 and MEF25. The duration of treatment with steroids in the neonatal period was associated with a reduction in the differences in FEV1, MEF25 and Raw. Independent of prematurity, hyaline membrane disease and its treatment is associated with alterations in long-term lung function, even in children who do not develop bronchopulmonary dysplasia. The effect can be less in more premature children, and neonatal steroids can have a long-term preventive effect.

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

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

Acute respiratory distress syndrome caused by respiratory syncytial virus.

Acute respiratory distress syndrome (ARDS) complicating severe respiratory syncytial virus (RSV) infection has been described in only a few infants. In contrast to the low mortality rates usually associated with RSV infections (< 5%), mortality rates in the range of 40-70% have been reported in pediatric patients with ARDS. However, studies on patients with ARDS are usually lumped with respect to causation, and the disease course of RSV-induced ARDS has not been previously studied. We examined the pulmonary function abnormalities of 37 infants with RSV-induced respiratory failure who were admitted to our pediatric intensive care unit for assisted ventilation. Measurements included respiratory mechanics, maximum expiratory flow-volume curves, and lung volumes. These allowed the calculation of a Murray lung injury score (modified for pediatric use) in which radiographic findings, ventilator settings, lung compliance, and blood gas results were considered. We identified ten infants with severe restrictive lung disease who fulfilled the clinical criteria for classification as ARDS. All had lung injury scores above 2.5, compatible with a diagnosis of ARDS. Twenty-seven infants had obstructive patterns of lung function consistent with a clinical diagnosis of RSV bronchiolitis. The patients with RSV-induced ARDS were significantly younger, and had a longer time on assisted ventilation (P < 0.05) and a higher proportion of predisposing illnesses (P < 0.05, odds ratio = 6.67, two-tailed Fisher's exact test) when compared with the patients who had obstructive disease. Only one patient (who had immunodeficiency) died, and all others were successfully managed on conventional mechanical ventilation. We conclude that RSV-induced respiratory failure represents a relatively benign cause of ARDS in pediatric patients. Our observations support the notion of differentiating ARDS with respect to causation, especially when novel and experimental therapy is considered and mortality rates are analyzed.

Assessment of pulmonary function in the early phase of ARDS in pediatric patients.

Scant data are available on lung function in acute respiratory distress syndrome (ARDS) in pediatric patients. We measured respiratory mechanics by single-breath occlusion and maximum expiratory flow-volume curves by forced deflation in ten critically ill infants with clinical ARDS. Ten mechanically ventilated infants without lung disease served as the control group. To assess the severity of the lung injury in the infants with ARDS, we modified an adult scoring system that calculates a score (from 0 to 4; > 2.5 indicates severe lung injury) based on the extent of chest radiographic changes, degree of hypoxemia, amount of positive end-expiratory pressure (PEEP), and total respiratory system compliance. The lung injury scores of our patients were in the range of 2.75 to 3.75. The lung injury scores of the control group were zero. The predominant alteration in lung function was restrictive, as characterized by a significant decrease in total respiratory system compliance (0.41 +/- 0.13 ml/cmH2O/kg versus 1.12 +/- 0.16 ml/cmH2O/kg of controls; P < 0.001) and forced vital capacity (21.5 +/- 6.5 ml/kg versus 59.2 +/- 6.3 ml/kg of controls; P < 0.001). Maximum expiratory flow rates at 10% forced vital capacity were significantly increased (23.6 +/- 20.1 ml/kg/sec versus 8.4 +/- 2.5 ml/kg/sec of controls; P < 0.05), confirming the absence of any significant obstructive abnormalities. The passive expiratory flow-volume curves were curvilinear and convex in shape, indicating inhomogeneous lung pathology. The inhomogeneous distribution of lung injury in ARDS restricts the validity of respiratory mechanics measurements that rely on a single-compartment model. However, the forced deflation technique allows accurate spirometric assessments of the severity of restrictive (and obstructive) lung function changes in intubated infants with severe ARDS. Such measurements can be incorporated into lung injury scoring systems to classify the severity of the disease process for the purpose of outcome evaluation and to evaluate the effect of therapeutic interventions.

Airway function tests and vocal cord paralysis in lung transplant recipients

Maximum expiratory and inspiratory flow-volume (MEFV, MIFV) curves, specific airway conductance (sGaw), and flexible fiberoptic laryngoscopy were examined in 8 pediatric lung transplant recipients with vocal cord paralysis (VCP). Six were heart-lung (H-L) and 2 double-lung (D-L) recipients, 7 had left VCP, and 1 had right VCP. Based on the pulmonary function tests (PFT), 2 subgroups could be distinguished in the 8 recipients with VCP. Group A (5/8 recipients; mean age, 13 +/- 3.4 years; mean height, 144.3 +/- 12.3 cm) had significantly reduced specific airway conductance (sGaw; < 2 SD from predicted) and normal MEF25, MEF50, peak expiratory flow (PEF), forced expiratory volume in 1 second (FEV1), and %FEV1/forced vital capacity (FVC); this pattern suggested variable extrathoracic airway obstruction. PIF was normal in 4/5 and reduced in 1/5 of these recipients. Group B (3/8 recipients with VCP; mean age, 17 +/- 2.4 years; mean height, 156.3 +/- 12.0 cm) had significantly reduced sGaw, MEF25, MEF50, PEF, FEV1, and %FEV1/FVC, implying primarily small airway obstruction. These recipients had bronchiolitis obliterans. The results suggest that a pattern of reduced sGaw and normal MEFs, PEF, FEV1, and PIF should raise the possibility of VCP in patients after lung transplantation. sGaw is more sensitive than PIF and PEF in identifying airway obstruction due to VCP, and should be routinely included in the follow-up evaluation of lung transplant recipients.

Theoretical basis for improvement following reduction pneumoplasty in emphysema.

Reduction pneumoplasty may improve flow rates, comfort, and exercise tolerance in severe emphysema. The basis for improvement has not been systematically addressed. The major disability of emphysema stems from impairment of maximal expiratory flow-volume performance of the lung (MEFV). This requires the chest wall to operate at high volumes, which in turn severely compromises inspiratory muscle function. Clinical benefit, then, requires that MEFV performance improve so that the operating lung volume is reduced. This study presents theory and illustrative calculations. Removing nonventilating lung (e.g., bullae) simply displaces the MEFV curve down the volume axis. Removing ventilating parenchyma reduces both volume and maximal expiratory flow at iso-lung recoil pressure, and shortens the curve on the volume axis. The critical beneficial effect in both cases is reduction of the volume for a given limiting flow, VL (Vmax). Removing a given fraction of lung from the ventilating compartment is nearly as effective as removing it from the nonventilating compartment. Lowering of operating volumes benefits the strength, efficiency, endurance, and reserve of the inspiratory muscles and thus extends the metabolic scope of the emphysematous patient.

Respiratory function in shoe manufacturing workers.

A study of respiratory findings was performed on 376 female workers employed in a shoe manufacturing plant. The mean age of the workers was 32 years and the mean duration of their employment was 12 years. These workers were predominantly nonsmokers. Acute and chronic respiratory symptoms were recorded for each worker, and lung function was measured before and after the work shift. Maximum expiratory flow-volume (MEFV) curves were performed on which forced vital capacity (FVC), 1-second forced expiratory volume (FEV1), and flow rates at 50% and the last 25% (FEF50, FEF25) were measured. Significantly higher prevalences of all chronic respiratory symptoms were recorded in exposed compared to control workers; in particular, chest tightness (exposed: 44.7%; control: 0%), dyspnea (exposed: 42.6%; control: 2.0%), and rhinitis (exposed: 46.3%; control: 2.4%) were far more prevalent in workers than in controls. Among the shoe workers, there was also a high prevalence of acute symptoms that developed during the work shift, being most pronounced for nose and throat irritation (61.4%). The prevalence of acute and chronic respiratory symptoms increased with duration of employment. Statistically significant across-shift reductions were recorded for all ventilatory capacity tests for the group as a whole. In comparison to predicted, the measured ventilatory capacity parameters were significantly lower for all workers (p < 0.01). Lung function abnormalities increased with duration of employment. Environmental measurements demonstrated that benzene, fur, and synthetic fibers were found at higher than allowable maximal concentrations (Croatian standards). The data suggest that work in the shoe manufacturing industry may be responsible for the development of acute and chronic respiratory impairment.