bluuebunny/crossref_metadata_2025_split huggingface dataset:
Flow‐pressure looping during plethysmography in wheezy infants
Authors: Beardsmore C. S. , Maayan Ch. , Bar‐Yishay E. , Godfrey S. 
Published: March 2007

AbstractMarked looping of the expiratory portion of the flow‐pressure relationship was noted in some infants during measurements of airway resistance in a whole‐body plethysmograph while the respired air was maintained at body temperature and humidity. An investigation of 13 infants who had varying degrees of airway obstruction showed that there was a negative correlation (r = 0.72) between the severity of the looping and specific airway conductance (SGaw). An even stronger correlation (r = 0.85) was found between the tangent of the angle of phase lag between flow and pressure (θ) and the forced expiratory time constant (t) obtained from the partial forced expiratory flow‐volume curve. Such a relationship would be predicted from a model in which the lung behaved as a simple electrical resistance‐capacitance network during expiration. It is suggested that the looping is the result of small airway closure during expiration in wheezy infants, with a consequent rise in resistance and prolongation of the time constant of the lung.
Pressure‐flow curves in infancy
Authors: Stocks Janet , Thomson Anne , Wong Charles , Silverman Michael 
Published: March 2007

AbstractCalibrated pressure‐flow (P‐V) curves were plotted by computer using data from both the plethysmographic method for measuring airway resistance and the esophageal balloon technique for measuring lung resistance. P‐V curves from 100 sick, healthy, and convalescent infants (age range 2 days to 19 months, weight range 0.9–10.4 kg) were classified into five distinctive types according to shape and direction of looping. Two of these patterns, one with a virtually closed, the other with a narrow figure‐of‐eight loop, reflected the normal physiologic changes in airway caliber that may occur during tidal breathing. The remaining three patterns, with far more marked changes in resistance, were associated with particular pathophysiologic mechanisms of airway obstruction. A wide figure‐of‐eight configuration, in which the expiratory loop rotated clockwise with marked flow limitation toward end expiration, was found for infants with chronic lung disease. By contrast, a rise in initial expiratory resistance due to dynamic glottic narrowing, with an anticlockwise rotated expiratory P‐V loop, occurred in infants with reduced or unstable lung volumes. A clockwise inspiratory loop was observed only for infants intubated during the neonatal period, many of whom had clinical evidence of extrathoracic airway obstruction. Inspection and analysis of P‐V curves provides more information about the state of the airways than does a single numerical expression of resistance. However, since normal patterns of P‐V curves are not restricted to infants with healthy airways, a combined qualitative and quantitative approach to these measurements is recommended.
Endogenous opiates and response to exercise in asthmatic children and adolescents
Authors: Tal Asher , Pasterkamp Hans , Chernick Victor 
Published: March 2007

AbstractWhether endorphins secreted during stressful exercise may play a role in the physiologic response of asthmatics was investigated. Thirteen asthmatic subjects were studied: seven (mean age 16 years ± 2.8 SEM) had perennial asthma and exercise‐induced bronchospasm (EIB), and six (mean age 18 years ± 2) had mild seasonal asthma without EIB. Each subject performed two matched progressive exercise challenges on consecutive days. Baseline lung function was measured before each challenge and was measured again after exercise at regular intervals for 30 minutes. One minute before exercise each subject received intravenously either i.v. naloxone (0.04 mg/kg), an opiate receptor blocker, or saline, in a double‐blind crossover fashion. Heart rate, oxygen consumption, minute ventilation, tidal volume, and arterial oxygen saturation were recorded throughout the tests. During the two challenges these parameters were not significantly different for all 13 patients. The mean percentage reduction in FEV1 after exercise for the seven subjects with EIB was slightly but not significantly less with naloxone (25% ± 7 SEM) than with placebo (32% ± 7) during the first 10 minutes after exercise. Naloxone had no obvious effect on EIB or the other parameters measured in association with strenuous exercise in asthmatic patients.
Parental smoking and respiratory illness during early childhood: A six‐year longitudinal study
Authors: Fergusson D. M. , Hons Ba , Horwood L. J. 
Published: March 2007

AbstractThe relationship between parental smoking habits and lower respiratory illness and symptoms during the first 6 years of life was studied in a birth cohort of New Zealand children. This showed that maternal (but not paternal) smoking was associated with significant increase in rates of lower respiratory infection and lower respiratory symptoms during the child's first 2 years. This association persisted when a range of perinatal, social, and familial factors were taken into account statistically. After two years there was no detectable association between parental smoking habits and lower respiratory infection. Further, there was no evidence to suggest that children whose parents smoked had increased risks of asthma or rates of asthmatic attacks during early childhood.
Calculation of mean airway pressure during neonatal intermittent positive pressure ventilation and high frequency positive pressure ventilation
Authors: Field D. , Milner A. D. , Hopkin I. E. 
Published: March 2007

AbstractBecause mean airway pressure (MAP) is extensively used to quantify ventilation administered during the neonatal period, the accuracy and reproducibility of the techniques currently used to define MAP were assessed. All techniques were found to compare closely with MAP measured by integration of the pressure wave form even at ventilator rates in excess of 100 breaths per minute. It was therefore concluded that all methods currently used are satisfactory for clinical use.
Exponential analysis of the lung pressure‐volume curve in newborn mammals
Authors: Saetta Marina , Mortola Jacopo P. 
Published: March 2007

AbstractThe compliance of the lung (per unit of lung weight) is less in newborn mammals than in adults. This could result from a smaller volume of airspaces per unit weight and/or a lower lung distensibility. The isolated role of lung distensibility was evaluated by using a mathematical description of the pressure‐volume (P‐V) curve during lung deflation. Deflation limbs of static P‐V curves in newborns of six species (four experimentally obtained and two taken from the literature) ranging from total lung capacity to the resting volume (Vr) were fitted by a monoexponential function of the type V = B − Ae−KP, where B equals Vmax at infinite P, A equals the difference between Vmax and V at P = O, and K is a constant representing lung distensibility. Unlike in adults, in newborns the monoexponential fitting provided an adequate description of the P‐V curve for only a relatively small range of transpulmonary pressure (from P at Vr to 10–15 cm H2O). The K value of this portion of the curve was similar among species but higher than in adult mammals, averaging 0.240 cm H2O−1. This suggests a similar lung structure in the different species. Since lung distensibility in newborns is larger than in adults, the fact that a unit mass of lung in the newborn is less compliant should be due to the smaller volume of its airspaces.
Alterations of airway smooth muscle cell membrane by sensitization
Authors: Souhrada M. , Souhrada J. F. 
Published: March 2007

AbstractThe sensitization of guinea pigs with ovalbumin and Bacillus pertussis vaccine caused an increase (P < 0.001) in the resting membrane potential (Em) of airway smooth muscle (ASM) cells, from −61.3 ± 0.5 mV (± SE) to −72.7 ± 0.6 mV (± SE). One, two, and three weeks after resensitization of sensitized animals with ovalbumin, Em further increased (P < 0.001) to −76.2 ± 0.2 mV (± SE), −77.4 ± 0.3 mV, and −78.1 ± 0.5 mV, respectively. Similarly, both in vivo and in vitro passive sensitization caused an increase (P < 0.001) in Em of ASM cells to −69.5 ± 0.3 mV and −68.5 ± 0.4 mV, respectively. ASM preparations isolated from rabbits showed a similar increase (P < 0.001) in Em after passive in vitro sensitization with serum from ovalbumin‐sensitized rabbits. An increase in the contribution of the electrogenic Na+‐pump was found to be responsible for the observed changes in Em following both active and passive sensitization. The presence of diphenhydramine (anti‐H1), methysergide, indomethacin, 5,8,11,14‐eicosatetraenoic acid (ETYA), FPL 55712 (a leukotriene receptor blocker), phenoxybenzamine, and disodium cromoglycate (a stabilizing agent) during passive in vitro sensitization failed to prevent an increase in the Em of ASM cells. However, incubation of normal guinea pig and rabbit ASM preparations with heated serum (60°C for 2 hours) from ovalbumin‐sensitized guinea pigs or rabbits partially inhibited (in guinea pigs) or completely abolished (in rabbits) such an increase. From these data, it is concluded that the hyperpolarization of ASM cells, as observed after sensitization, seems to result from direct interaction of serum heatsensitive factors (presumably specific antibodies) and ASM cell membrane rather than from the interaction of ASM cells with specific mediator(s) of anaphylaxis. The results suggest that sensitization directly alters the ASM cell membrane.
Apnea and periodic breathing in normal full‐term infants during the first twelve months
Authors: Kelly Dorothy H. , Stellwagen Lisa M. , Kaitz Ellen , Shannon Daniel C. 
Published: March 2007

AbstractThe pediatric pneumogram is a frequently used tool in the diagnosis and management of apnea during infancy. We analyzed 287 pneumographic recordings from 123 full‐term infants (63 males) obtained during the first 12 months of life to establish normative values for apnea, periodic breathing, and bradycardia. The results of the analysis were compared by sex and age. The number of infants who exhibited periodic breathing decreased significantly over time (78% at 0–2 weeks vs 29% at 39–52 weeks; P < 0.05). However, for those infants who did breathe periodically, the percent of sleep time spent in this breathing pattern did not change with age. No apnea ≥ 15 seconds was recorded in any infant, and apnea density (total apnea ≥ 10 seconds in minutes/100 minutes sleep time) did not change with age or sex. Using our definitions, no bradycardia was identified. Normal full‐term infants occasionally have apnea of 10, 11, or 12 seconds, and, until 6 months of age, the majority will have a small amount of periodic breathing (< 1% of sleep time) during sleep at home.
Cardiorespiratory response to physical conditioning in children with bronchial asthma
Authors: Ramazanoglu Yildirim M. , Kraemer Richard 
Published: March 2007

AbstractThe relationship of physical conditioning to changes in static lung volumes (hyperinflation) and airway dynamics (bronchoconstriction) as well as to ventilatory gas exchange, heart rate reserve, breathing reserves, and working capacity at a heart rate of 170/min (WC 170) was evaluated in 23 children (16 girls, 7 boys) between 6 and 15 years of age who had perennial asthma. Lung function tests including incremental cycle ergooxymetry were performed before and after a 15‐week period of regular physical training (RPT). Lung function data obtained after RPT showed a significant improvement (P< 0.05) in both hyperinflation and specific airway conductance, whereas oxygen consumption only increased related to lean body mass and heart rate. However, WC 170 and work tolerance during the endurance phase of the exercise test were significantly increased (P< 0.05 and < 0.01, respectively). In view of the relationship that has recently been found between exercise tolerance and lung mechanics in adults, the decreased hyperinflation and bronchoconstriction observed in our population after RPT is striking. This finding was presumably a consequence of the effect of RPT on breathing technique and chest wall mechanics. Ventilation of the lungs may improve because of mobilization of the costovertebral articulations, inspiratory muscle relaxation, an optimized force‐length relationship of the respiratory muscles, and closer linkage between the diaphragm and intercostal muscles. Therefore, RPT might be an effective addition to standard drug regimens in the management of childhood asthma.
The bronchodilator effect of a fixed‐combination metered aerosol (fenoterol and ipratropium bromide)
Authors: Berdel D. , Kellersmann U. 
Published: March 2007

AbstractThe fixed‐combination metered aerosol IK6 (fenoterol 0.05 mg/puff, ipratropium bromide 0.02 mg/puff‐Berodual, Boehringer‐Ingelheim Ltd., Ridgefield, Conn.) was administered to 12 children (8 boys, 4 girls) aged 3 1/2 to 6 1/12 years who had extrinsic bronchial asthma. Three forms of administration, each with a different site of action, were compared: 1) Two puffs during inspiration. Probable site of action: oral cavity, pharynx, larynx, trachea, and bronchi. 2) Two puffs using an inhalational aid during inspiration. Probable site of action: pharynx, larynx, trachea, and bronchi. 3) Two puffs in the breathing interval after deep inspiration. Probable site of action: oral cavity and pharynx. The resistance of the respiratory system (Rrs) was measured using oscillometry for up to 360 minutes after administration. A significant decrease of the median resistance was found with all three forms of administration. The changes were Form 1–48% of baseline after 120 minutes; Form 2–47.9% of baseline after 60 minutes; Form 3–44.4% of baseline after 30 minutes. The greatest decrease was observed with form 1. The study indicates that significant bronchodilation was achieved in small children using the combination of fenoterol and ipratropium bromide administered by metered aerosol even when inhalation and the release of the puff were not synchronized. A significant bronchodilator effect was also observed in cases of severe bronchial obstruction in which transport of the active ingredients to the lower airways could not be sufficiently guaranteed.
Peripherally inserted central venous catheters for treatment of cystic fibrosis
Authors: Zann Robert L. , Shutack John G. , Schuler Pamela M. , Christie Deborah , Holsclaw Douglas S. 
Published: March 2007

AbstractPatients who have cystic fibrosis (CF) are frequently hospitalized for long‐term intravenous(IV) treatment. We evaluated clinical effectiveness of the Drum‐Cartridge Catheter (Abbott Laboratories) for such patients. The catheter is placed peripherally under local anesthesia via an antecubital vein into the superiorvena cava or right atrium. Patients who were more than 10 years of age and who were hospitalized for IV antibiotic therapy and/or IV hyperalimentation were studied. All but 2 patients had CF. Using an aseptic technique the catheters were inserted into the basilic or cephalic vein. Chest radiographs were used to confirm the final location of the catheter. Catheters were used to administer IV antibiotics, hyperalimentation, and lipids. There were 38 catheterizations in 23 patients; several patients had repeated insertions at later admissions. The success rate of insertion was 86% with 31 of the 38 insertions initially located either in the superior vena cava or right atrium. Mean duration of catherization was 15.4 days (range 5–49 days). No major complications such as sepsis, catheter or clot embolism, pneumothorax, vascular perforation, or hemorrhage occurred in the patients who had CF. Complications that required catheter removal were thrombophlebitis (1 patient), clot occlusion (1 patient), displacement of catheter into the axillary vein (1 patient), and cracked catheter hub (1 patient). This study shows that the Drum‐Cartridge Catheter can be used easily for IV therapy of patients who have CF for a long duration, repeatedly, and with no major complications.
The accuracy of esophageal pressure measurements in convalescent and sick intubated infants
Authors: Heaf D. P. , Turner H. , Stocks J. , Helms P. 
Published: March 2007

AbstractAssessment of the esophageal pressure technique for measuring dynamic lung compliance (Cdyn) showed that accurate results were obtained in only 5 of 15 studies of sick intubated infants, whereas they were obtained in 6 of 6 studies of convalescent nonintubated infants. In sick infants, inaccuracy was due to large variations in esophageal pressure change (APes) at different esophageal depths and difficulties validating Pes using the occlusion test. Methods of assessing lung stiffness that depend on the measurement of esophageal pressure are unreliable and should not be used in sick intubated infants.
The functional response of infants with persistent wheezing to nebulized beclomethasone dipropionate
Authors: Maayan C. , Itzhaki T. , Bar‐Yishay E. , Gross S. , Tal A. , Godfrey S. 
Published: March 2007

AbstractLung function was measured in nine infants, ages 15‐36 weeks, who had persistent wheezing, apparently following acute bronchiolitis, before and after 2 weeks of treatment with either inhaled nebulized beclomethasone dipropionate (BDP) or placebo in a randomized, double blind, crossover trial. The effect of nebulized albuterol (Salbutamol) was measured before and after the steroid treatment. Thoracic gas volume (TGV) and specific airway conductance (SGaw) were determined using a whole body plethysmograph, and forced expiratory flow at resting lung volume (VmaxFRC) was determined with a thoracoabdominal compression jacket. All infants had marked airways obstruction before treatment with mean ± SE VmaxFRC of 24 ± 4% predicted and SGaw of 37 ± 5% predicted. Two weeks of placebo treatment had no significant effect on lung function, but after 2 weeks of BDP inhalation there was a significant rise in SGaw to 61 ± 7% (P < 0.005). VmaxFRC increased to 42 ± 13% but the difference did not reach significance. Respiratory rate and clinical score for retractions and wheezing also fell significantly with BDP therapy (P < 0.01 and P < 0.001 respectively). Albuterol had no effect on lung function either before or during steroid therapy. Steroids may have a role in the management of persistent wheezing following bronchiolitis.
Bronchial sensitivity to inhaled histamine in healthy, nonatopic children
Authors: Riedel Frank , Hardt Horst von der 
Published: March 2007

AbstractBronchial reactivity was determined in 38 healthy children by histamine inhalation challenge using forced expiratory and body plethysmographic methods. The histamine concentrations which produced a 20% decrease in forced expiratory volume in 1 second (PC20, FEv1), were comparable to the concentrations producing a 60% fall in specific airway conductance (PC60,SGaw). There was a significant difference in bronchial reactivity between the healthy children and a group of 29 asthmatic children (P < 0.001), although there was some overlap. Bronchial reactivity in healthy children was found to be much higher than expected from surveys of adults. External influences or intrinsically increased bronchial reactivity in childhood are discussed as possible explanations.
Cardiorespiratory status in long‐term survivors of prematurity, with and without hyaline membrane disease
Authors: Maclusky I. B. , Stringer D. , Zarfen J. , Smallhorn J. , Levison H. 
Published: March 2007

AbstractForty‐eight children, born at less than 33 weeks' gestation and without bronchopulmonary dysplasia (BPD) or Wilson‐Mikity syndrome (WM) were studied at a mean age of 9.1 years, to identify the incidence and possible factors contributing to the development of long‐term abnormalities in pulmonary function. As neonates, 30 children had hyaline membrane disease (HMD) of whom 21 required ventilation. Eighteen did not have HMD, of whom 9 required ventilation for nonrespiratory reasons. All patients had grown normally. Four of the 48 (8.3%) had clinical asthma, 5 had persisting chest x‐ray abnormalities (10.6% of 47 chest x‐rays performed), each having been ventilated for HMD. There was a close association between duration of ventilation, oxygen administration, and subsequent abnormal chest x‐ray. Electrocardiogram and M‐mode echocardiograms were normal in all but 2 patients. Only 3 patients had significant restrictive lung disease, 3 had evidence of significant airways obstruction, and 13 (27.7%) had signs of air trapping. Methacholine challenge was positive in 30 of 46 patients (65.2%). The incidence of a positive methacholine challenge did not correlate with history of HMD, duration of ventilation, or high oxygen administration. There is an increased incidence of airway hyperreactivity in survivors of prematurity, not associated with any identified therapeutic maneuver during the neonatal period.
Trapped gas and airflow limitation in children with cystic fibrosis and asthma
Authors: Desmond Katharine J. , Coates Allan L. , Martin James G. , Beaudry Pierre H. 
Published: March 2007

AbstractTrapped gas (TG) has been shown to be present in cystic fibrosis (CF) and asthma, but its relationship with airflow limitation (AL) has not been explored. TG was defined as the difference between the functional residual capacity measured by body plethysmography [FRC(BP)] and that measured by helium dilution [FRC(He)] expressed as a percentage of total lung capacity (TLC). We studied 21 children with CF and 15 with asthma who had a similar degree of AL and hyperinflation, however the children with CF had greater amounts of TG compared with asthma [15% ± 2 (mean ± 1SE) vs 8 ± 2, P < 0.05]. Mixing efficiency (ME), an index of the distribution of ventilation, was found to be lower in the CF children than in those with asthma (34 ± 4 vs 54 ± 4). In CF, TG correlated with forced expiratory flow between 25 and 75% of vital capacity (FEF25‐75), ME, RV/TLC, and maximal expiratory flow rates at 25 and 50% of vital capacity (V̇max25 and 50, respectively; r = −0.66, −0.61, 0.72, −0.71, −0.74). ME also correlated with the above measures. In asthma, TG did not correlate with the FEF25‐75, ME, RV/TLC, V̇max25, or V̇max50. Furthermore, TG was frequently found in patients with asthma with moderate AL while it was often absent in patients with severe AL. For both CF and asthma, neither the severity of AL nor the magnitude of the TG could be predicted from the increase in V̇max 50 with helium (ΔV̇50). In CF, TG and ME correlated, thus allowing for an assessment of the validity of FRC(He) in determining hyperinflation. In asthma, the presence or absence of TG could not be anticipated from tests of ME or AL, and hence the validity of FRC(He) in determining hyperinflation could not be anticipated.
Magnetic resonance imaging of inflammatory lung disorders: Preliminary studies in children
Authors: Cohen Mervyn D. , Cory David A. , Smith John A. , Eigen Howard , Scott Peter H. , Tepper Robert , Scales Richard L. 
Published: March 2007

AbstractMagnetic resonance (MR) scans were performed on 14 children with a variety of inflammatory disorders of the lungs. MR successfully identified disease in all of the children and accurately localized the disease within the lung fields. In patients with pneumonia and luns abscesses the acute inflammation was associated with a marked increase in signal intensity on T2 when compared with T1 weighted images. One patient with an inflammatory pseudotumor demonstrated a smaller increase in signal intensity on T2 weighted images than was seen in acute pneumonia. Abscess cavities were well identified along with the wall thickness. In patients with diffuse lung disease (diffuse histoplasmosis, miliary tuberculosis, Letterer‐Siwe disease, and allergic alveolitis), each disease appeared different on the MR images. These preliminary studies indicate that magnetic resonance imaging is effective for identifying pulmonary disease in children and may improve the radiologist's ability to differentiate pulmonary disorders.