bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of air pollution on the respiratory tract of children.
Authors: Schmitzberger R. , Rhomberg K. , Büchele H. , Puchegger R. , Schmitzberger‐Natzmer D. , Kemmler G. , Panosch B. 
Published: March 2007

AbstractThe effects of air pollution on pulmonary function and respiratory status was evaluated in 1,626 school aged children from a European Alpine region. Based on measurements of SO2, NO2 and O3 as well as infrared imaging and lichen mapping, three zones of exposure were defined. Results of standardized respiratory questionnaires, medical examinations, and lung function tests were compared among the children in the three different exposure zones. After controlling for age, sex, height, socioeconomic status, and exposure to environmental tobacco smoking, areas of increased SO2 and NO2 as well as areas of increased ozone (max. half hourly mean value, 146 ppb) were significantly associated with decrements of forced expiratory volume in 1 s (FEV1) and flow rates at 50 and 75% of vital capacity (FEF50 FEF75). In addition, areas with increased ozone had a higher prevalence of asthma In all regions, maternal smoking was associated with reduced expiratory flow rates and increased prevalence of asthma. The results provide evidence that outdoor pollution and exposure to passive smoking are risk factors for childhood respiratory health. © 1993 Wiley‐Liss, Inc.
Respiratory resistance and transcutaneous P during histamine provocation in children with bronchial asthma
Authors: Holmgren D. , Engström I. , Bjure J. , Sixt R. , Åberg N. 
Published: March 2007

AbstractBronchial reactivity was assessed in 66 children with bronchial asthma (aged 8–15 years) by provocation with histamine‐HCl during a symptom‐free period. A significant bronchial reaction to histamine was defined as a 50% increase in the resistance of the respiratory system (Rrs) determined by the forced oscillation technique. The provocative dose causing a 50% increase in the Rrs (PD50Rrs) was interpolated from the log dose‐response curve. The mean PD50Rrs was significantly lower in children with asthma (0.22 mg/mL) compared with a group of healthy children in the same age range (1.55 mg/mL) (P < 0.001). In children with clinically severe asthma, the mean PD50Rrs was lower (0.13 mg/ml) than in children with mild asthma (0.34 mg/mL) (P < 0.001). Transcutaneous Po2 (Ptco2) was monitored in 25 of the children with asthma. In this group the proportion of mild and severe asthma, the baseline lung function variables, and the PD50Rrs were not significantly different from those of the whole group of children. During the reaction, the Ptco2 fell on average by 29% of the baseline value (P < 0.001); in 88% of the children, the fall in Ptco2 was 20% or more of the baseline value. We conclude that histamine provocation tests using the forced oscillation technique and transcutaneous Po2 to assess a bronchial reaction have a good discriminatory capacity for different degrees of clinical severity of asthma in children. © 1993 Wiley‐Liss, Inc.
A nonlinear regression analysis of nonlinear, passive‐deflation flow‐volume plots
Authors: Jarriel W. Scott , Richardson Peter , Knapp Roger D. , Hansen Thomas N. 
Published: March 2007

AbstractWhen studying lung mechanics of intubated premature infants, by the passive‐deflation technique we noted that in many flow‐volume plots the descending limb was curvilinear with a convexity toward the volume axis. By conventional linear analysis lung mechanics of these patients did not change after the administration of terbutaline, but Mead's tangent‐chord slope ratio method for quantifying the amount of curvature showed that the shape of the flow‐volume plots did change. Because of the limitations of this method, we developed a microcomputer based, reiterative regression algorithm which optimizes a nonlinear function for the best fit to any given set of data. We then studied six very low birth weight infants with clinical evidence of pulmonary gas trapping (weight at study, 1.22 ± 0.29 kg; age, 26 ± 16 days). We measured respiratory system resistance (Rrs), compliance (Crs), and expiratory time constants (TCrs), by the passive deflation technique before and after subcutaneous administration of 0.02 mg/kg of terbutaline. No effect of terbutaline in a dose sufficient to increase heart rate > 25 beatshin was observed. The same data analyzed using the nonlinear regression technique with a function based upon a two compartment model of parallel inhomogeneities revealed one compartment with relatively normal Rrs, Crs, and TCrs, values, and a second compartment with a very high Rrs. The latter fell by 50% after terbutaline. These data suggest that abnormalities of airway resistance in ventilated preterm infants are not easily identifiable by classic linear analysis of lung mechanics. We propose that in such patients the two compartment analysis of passive exhalation mechanics measurements can provide better information about Rrs. © 1993 Wiley‐Liss, Inc.
Increased physiological dead space during exercise after bronchodilation in cystic fibrosis.
Authors: Kusenbach G. , Friedrichs F. , Skopnik H. , Heimann G. 
Published: March 2007

AbstractBicycle ergospirometry was performed on 14 patients with cystic fibrosis (CF), for evaluating the effects of salbutamol and theophylline on the ventilatory response to exercise. After 1 week without bronchodilator therapy the patients cycled at 1/3 and 2/3 of their individual maximal working capacity (Wmax). The test was repeated three times after treatment with salbutamol, theophylline, or both drugs, respectively. After the combined therapy, physiological deadspace, ventilation, ventilatory equivalent of oxygen, and end‐expiratory oxygen pressure increased significantly during steady state exercise at 1/3 Wmax. Similar, although not statistically significant changes, were observed after monotherapy with salbutarnol or theophylline and during exercise at 2/3 Wmax. These effects could not be predicted by any lung function tests at rest or by the Shwachman‐Kulczycki score. The results indicate that in some patients with CF bronchodilators can impair lung function during exercise. In conclusion the effects of medication on exercise performance of patients with CF have to be considered. Especially, the use of bronchodilators requires a careful evaluation of their real benefit in each individual patient. © 1993 Wiley‐Liss, Inc.
Assessment of passive respiratory compliance in healthy preterm infants: A critical evaluation
Authors: Gappa M. , Rabbette P. S. , Costeloe K. L. , Stocks J. 
Published: March 2007

AbstractThe airway occlusion techniques for assessing passive respiratory mechanics have become well established methods in fullterm neonates and older infants. The single breath technique (SBT) is frequently used for assessing lung function in intubated infants on neonatal intensive care units. However, less is known about the reliability of these quick and noninvasive techniques in healthy preterm infants. The aim of this study was to evaluate these methods in healthy unintubated preterm infants to facilitate both establishment of reference values and more meaningful interpretation of lung function assessments in the neonatal unit. Forty‐seven studies were attempted in 31 healthy preterm infants (gestational age 29–36 weeks; body weight 1.88 ± 0.28 kg; mean ± SD) during the first 2 weeks of life, using both the multiple occlusion technique (MOT) and the SBT. Whereas technically acceptable respiratory system compliance (Crs) data from either the MOT or the SBT were obtained on 37 occasions in 25 infants, satisfactory results from both techniques were achieved only on 22 occasions. In these infants mean ± SD Crs was 28.1± 5.2 mL kPa−1 when assessed by MOT and 29.1± 5 6.0 mL kPa−1 when using the SBT. The mean difference between technically satisfactory paired Crs values obtained with MOT and SBT was less than 5% (range, +28 to −18%). By contrast, in infants in whom data were invalidated as a result of expiratory airflow braking, failure to relax or instability of the end‐expiratory level, gross discrepancies occurred between the techniques. In conclusion, assessment of passive respiratory compliance is feasible in healthy, unintubated preterm infants, but strict criteria for quality control should be applied to avoid gross errors in the results. Ideally, passive respiratory mechanics should be assessed using both MOT and SBT in order to increase confidence in the reported results. © 1993 Wiley‐Liss, Inc.
Prognostic value of clinical and radiological status on day 28 of life for subsequent course in very low birthweight (< 1,500g) babies with bronchopulmonary dysplasia
Authors: Hansen Thor W. R. , Wallach Michael , Dey Achintya N. , Boivin Paul , Vohr Betty , Oh William 
Published: March 2007

AbstractTo test the hypothesis that the shortn‐term (= 6 months) course of babies with bronchopulmonary dysplasia (BPD) could be predicted from the clinical and radiological status on day 28 of life, we retrospectively examined the medical records of 79 infants born between 1985 and 1988 who required supplemental oxygen and/or ventilatory support on day 28. Chest roentgenographs taken close to day 28 (± 7 days) were scored on a scale of 0–10. Four babies died from causes not related to BPD. Four of the remaining 75 died from BPD, and the rest are alive. Forty‐six of 71 were weaned from supplementary oxygen by 37 weeks corrected gestational age, and only 13/71 remained on supplemental oxygen after 40 weeks gestational age. To determine which variables contributed most to the outcome, defined as total days on supplemental oxygen, a multiple regression analysis was performed, including only those variables the tolerance of which exceeded 0.7 (sex, Fi, ventilatory mode, and infectious status). Fi, and ventilatory mode together predicted 15% of the variability in outcome, so that a high Fi, and ventilator dependence on day 28 of life were highly correlated with a prolonged need for supple‐mental oxygen (F = 4.28, P < 0.05). © 1993 Wiley‐Liss, Inc.
Evaluation of cold air challenge data in a population sample using a model of bronchial hyperreactivity and disposition to bronchial obstruction
Authors: Wjst Matthias , Dold Sigrid , Reitmeir Peter , Wulff Andrea , Nicolai Thomas , von Mutius Erika 
Published: March 2007

AbstractTo explore the role of bronchial hyperreactivity and obstruction after cold air challenge, data from a cross‐sectional study of more than 7,000 10‐year‐old children were used. Current knowledge of hyperreactivity is primarily based on pharmacological provocation tests with variable prechallenge flow rates and their decrease relative to baseline. Using forced expiratory volume (FEV) in 1 sec values before and after cold air challenge, however, it is possible to define a subsample of children with predominant hyperreactivity and a subsample with predominant obstruction after challenge. The prevalence of respiratory symptoms and the diagnoses in the two subsamples were compared. The analysis showed that children with bronchial obstruction have nearly the same frequency of respiratory symptoms as those with bronchial hyperreactivity. A combined model of bronchial obstruction and hyperreactivity was, therefore, more predictive of symptoms than a model of hyperreactivity alone. © 1993 Wiley‐Liss, Inc.
Use of pulse oximetry in the hospital management of acute asthma in childhood
Authors: Connett G. J. , Lenney W. 
Published: March 2007

AbstractOxyhemoglobin saturation values were recorded before and 10 minutes after 5 mg of nebulized salbutamol in 75 children (age, 1.5–14.6 years) admitted to hospital with acute asthma. Other assessments included heart rate, respiratory rate, peak expiratory flow rate, pulsus paradoxus, and an asthma severity score. All assessments were performed by the same observer (GC) and subsequent hospital care was transferred to the on‐call pediatricians, who were not told the initial saturation values. Six children required intravenous therapy after hospital admission when their symptoms were not improved after nebulized salbutamol. Cutoff points for each continuous variable were selected so that they identified at least 5 of these 6 children (i.e., with a sensitivity of at least 83 percent). The resulting specificities and positive predictive values were calculated for each variable before and after nebulized therapy. A postnebulizer saturation of less than 91 % had a sensitivity of 100% [95% confidence interval (CI), (54–1001 with a specificity of 98%] (95% CI, 92–100) and a positive predictive value of 86%. This was the best predictor of the need for intravenous (IV) therapy. Correlation coefficients were calculated for the 75 admissions and 2 others who required immediate IV treatment to determine how closely saturation values were related to the other recorded clinical variables. Saturation values were significantly, though weakly, correlated with asthma severity scores and prenebulizer heart rate, but they were not associated with any of the other variables. These results highlight the difficulties encountered when assessing acute asthma in a hospital population with a large number of preschool children. Saturation measurements are easy to obtain in all age groups and help identify those children who require intensive therapy and close supervision after hospital admission. © 1993 Wiley‐Liss, Inc.
Relationship between exposure to dust mite allergen and bronchial response to exercise in schoolchildren sensitized to dust mites
Authors: Frischer T. H. , Kuehr J. , Meinert R. , Karmaus W. , Urbanek R. 
Published: March 2007

AbstractWe assessed the relationship between the exposure to dust mite allergens and a bronchial response to exercise in 8‐year‐old schoolchildren. Dust was collected from the mattresses of 1, 291 children and the concentration of mite allergens was estimated by a commercially available ELISA test using monoclonal antibodies (ALK, Copenhagen) against the major allergens of Dermatophagoides pteronyssinus (Der pt) and Dermatophagoides farinae (Der f). A positive bronchial response to exercise (decrease of peak expiratory flow ≥ 5% after exercise) occurred in 21 (22.6%) of 101 children sensitized to mite allergens (wheal size ≥4 mm) and in 51 (4.8%) of 1, 070 nonsensitized children. In the highest exposure groups (>10 μg allergen/g dust), 15% of children sensitized to Der f and 20% of children sensitized to Der pt were responsive to exercise. Corresponding figures for the lowest exposure groups (< 0.4 μg allergen/g dust) were 11 and 28%, respectively. This negative finding may indicate that measurement of allergen concentration in mattresses does not reflect true exposure or alternatively that at the age of 8 years high exposure to dust mite allergens does not affect bronchial response to exercise in sensitized children. Pediatr Pulmonol. 1993; 16:13–18. © Wiley‐Liss, Inc.
Maturation affects the maximal pulmonary response to methacholine in rabbits
Authors: Tepper Robert S. , Kisling Jeff , Brearton Linda 
Published: March 2007

AbstractMaximal bronchoconstriction in normal adults produces only small reductions in pulmonary function; however, in normal infants severe airway obstruction limits testing to low agonist concentrations. In this study, maximal pulmonary response to methacholine was evaluated in 5 immature (1 month old) and 5 mature (6 months old) rabbits. Animals were anesthetized, paralyzed, and mechanically ventilated via a tracheostomy tube. Changes in pulmonary function were assessed from maximal deflation flow volume curves following inhalation of doubling concentrations of methacholine between 0.6 and 320 mg/mL. Following 320 mg/mL methacholine, the immature rabbits had a greater percent decline in forced vital capacity (FVC) than the mature animals (55 ± 15% vs. 36 ± 10%; P < 0.05). At 50% FVC, isovolume flows were measurable in the 5 mature rabbits, and 4 of 5 had plateaus in their dose‐response curves. At the higher methacholine doses, only 1 of 5 immature animals had measurable isovolume flows because of the decrease in FVC. There was no significant difference between immature and mature animals in the methacholine dose required to decrease baseline flows by 50%. We conclude that in rabbits maturation affects maximal pulmonary response but not the sensitivity to methacholine. Pediatr Pulmonol. 1993; 16:48–53. © 1993 Wiley‐Liss, Inc.
Airway responsiveness in infants: Comparison of inhaled and nasally instilled methacholine
Authors: Tepper Robert S. , Steffan Michael 
Published: March 2007

AbstractAirway responsiveness of infants is evaluated during sleep and the infants inhale the bronchial challenge agent via the nasal airway. Since stimulation of the nasal airway may produce bronchoconstriction, it is unclear whether the observed response in the infants results from deposition of the aerosol in the lower airways or from stimulation of nasal receptors. Therefore, in 6 healthy infants we compared the changes in partial expiratory flow‐volume (PEFV) curves produced by aerosol inhalation of methacholine and the changes produced by instillation of equivalent doses of methacholine liquid into the nares. Following aerosol, the peak expiratory flow and the flow at functional residual capacity decreased, PEFV curves became concave in shape, and the oxygen saturation (Sao2) decreased. The highest methacholine concentration inhaled by any infant was 1.25 mg/mL. In contrast to aerosol delivery, a maximal methacholine concentration of 10.0 mg/mL was instilled into the nares of all 6 infants without any change in maximal flow at functional respiratory capacity (VmaxFRC) or Sao2. There was a significant decrease in peak flow and flattening of the PEFV curves at higher lung volumes; however, the PEFV curve remained convex in shape at the lower lung volumes. The changes in the PEFV curve following nasal instillation of methacholine are consistent with an increase in nasal resistance and no change in the lower airways. We conclude that the bronchoconstriction observed following inhaled methacholine does not result from stimulation of nasal receptors. Pediatr Pulmonol. 1993; 16:54–58. © 1993 Wiley‐Liss, Inc.
Chest wall motion before and during mechanical ventilation in children with neuromuscular disease
Authors: Diaz Carlos E. , Deoras Kiran S. , Allen Julian L. 
Published: March 2007

AbstractPatients with neuromuscular disease can display paradoxic motion of the rib cage (RC) and abdomen (AB), which increases the work of breathing and predisposes to respiratory muscle fatigue. Long‐term mechanical ventilation can reverse chronic hypercapnea and decrease the work of breathing in these patients. Changes in chest wall motion (CWM) that occur during mechanical ventilation have not been studied. We have assessed CWM using a calibrated respiratory inductive plethysmograph before and during mechanical ventilation in 5 children and young adults with neuromuscular disease and paradoxic breathing at rest. Asynchrony of CWM was quantitated by measuring the phase shift, 0, between RC and AB motion (0° = synchronous motion, 180° = paradoxic motion). The volume contribution of the paradoxing compartment totidal volume (PC/VT,) was calculated. Before mechanical ventilation, mean±SEM VT was 122±17 mL, 0 was 131±15°C, and PC/VT was −27±6%. During mechanical ventilation, VT increased to 274±17 mL (P < 0.05), 0 decreased to 41±14° (P < 0.05), and PC/VT increased to +39±9% (P < 0.02). We conclude that mechanical ventilation improves RC/AB asynchrony and reverses the negative contribution to tidal volume of the paradoxing compartment in children and young adults with neuromuscular disease. This implies that mechanical ventilation assumes most or all the role of the respiratory pump in these patients, which provides a rationale for the use of chronic or nighttime ventilation in the treatment of respiratory muscle fatigue. Assessment of CWM may be useful in the determination of optimal ventilator settings in this population. Pediatr Pulmonol. 1993; 16:89–95. © 1993 Wiley‐Liss, Inc.
Meconium aspiration syndrome: Physiological and inflammatory changes in a newborn piglet model
Authors: Davey Andrew M. , Becker Jennifer D. , Davis Jonathan M. 
Published: March 2007

AbstractIn order to evaluate further the physiological and inflammatory changes of meconium aspiration syndrome (MAS), 25 newbom piglets (1‐2 days old, 1.5±0.4 kg) were studied. Piglets were briefly ventilated with 100 % oxygen and then received an intratracheal bolus of 3 mL/kg of a 20% suspension of human meconium. They were then further ventilated, keeping PaCO2, at approximately 40 torr and PaO2 at 70 torr during 4, 12,24, and 48 h studies. Pulmonary function studies and tracheal aspirates were obtained at time zero and serially throughout the study. Bronchoalveolar lavage was performed at the end of the study to examine endogenous surfactant function. Control piglets received 3 mL/kg of intratracheal saline and were then ventilated for 48 h at an inspired oxygen concentration and mean airway pressure matched to the meconium treated group (to control for the effects of hyperoxia and barotrauma on the lung). MAS caused acute decreases in gas exchange and dynamic lung compliance, which returned toward baseline by 48 h (P<0.001, ANOVA). Tracheal aspirate absolute neutrophil count, neutrophil chemotactic activity, albumin, and total protein concentrations also increased significantly over time (P<0.001). Endogenous surfactant function appeared to be significantly inhibited by the meconium. All variables of lung injury were significantly higher in the meconium group compared to the saline control group over the 48 h study. Newborn piglets provide a clinically relevant model of MAS, demonstrating physiological and inflammatory changes with apparent alterations in endogenous surfactant function. Effective therapies for MAS may require interventions directed at all of these components of lung injury. Pediatr Pulmonol. 1993; 16:101–108. © 1993 Wiley‐Liss, Inc.
Lung function and bronchial challenges in infants: Repeatability of histamine and comparison with methacholine challenges
Authors: Stick S. M. , Turner D. J. , Lesouéf Peter N. 
Published: March 2007

AbstractLimited information exists regarding the repeatability of lung function and bronchial challenge tests using the rapid thoracic compression technique (RTC) in infants. Aims: To determine the repeatability of lung function and histamine challenge test results using the RTC technique and to compare the results obtained for bronchial challenges using histamine (H) and methacholine (M). Methods: Twelve infants 7 healthy, 5 with cystic fibrosis (CF) had pairs of H challenges 1 week apart. Eleven infants (7 healthy, 4 CF) had one H and one M challenge a week apart. The provocative concentration of H or M to cause a 40% fall in maximum flow at functional residual capacity (PC40) was determined using the RTC technique. Twenty‐three comparisons were possible between maximal expiratory flow at functional residual capacity (VmaxFRC) measurements made l week apart. Results: The mean difference between pairs of VmaxFRC measurements was 6.4% of baseline, and the coefficient of repeatability was 31.1% of baseline. The mean difference between PC40(H) measurements was 0.163 doubling concentrations, with a coefficient of repeatability of 1.66 doubling concentrations. The mean difference between PC40(H) and PC40(M) was 0.75 doubling concentrations, with 95% of PC40(H) between −0.18 to 1.69 doubling concentrations of the PC40(M). Conclusions: Although the repeatability of VmaxFRC using the RTC technique is less than for voluntary forced expiratory flow parameters in older children, similar results were obtained for infants as observed in older subjects for repeatability of H challenges and agreement between measures of bronchial responsiveness using H or M. Pediatr Pulmonol. 1993; 16:177–183. © 1993 Wiley‐Liss, Inc.