bluuebunny/crossref_metadata_2025 huggingface dataset:
Intestinal permeability to chromium‐51 ethylenediamine tetraacetic acid in children with chronic obstructive respiratory disease: Relationship with clinical and duodenal biopsy findings
Authors: Hoyoux CI. , Forget P. P. , Borlee‐Hermans G. , Geubelle F.
Published: March 2007

Intestinal permeability (IP) to 51‐Cr ethylenediamine tetraacetic acid was investigated in 47 children with chronic obstructive respiratory disease (CORD). Endoscopic duodenal biopsies were performed in 22 of these patients. IP was significantly increased in CORD patients when compared to either control children or adults (P < 0.001). Mean ± 1 SD were 4.3 ± 1.71%, 2.5 ± 0.78%, and 2.3 ± 0.77% in the three groups, respectively.

IP was not related to the presence of atopy. Significant differences in IP results were found between CORD children with abdominal pain (4.5 ± 1.4%) and both control children and CORD patients without abdominal pain (2.5 ± 0.78% and 3.2 ± 1.49%, respectively). A significant correlation was found between small bowel injury on the one hand and IP on the other hand (P < 0.02). Furthermore, small bowel injury was significantly related to the presence of abdominal pain (P < 0.05).

We speculate that in CORD patients with abdominal pain, a factor exists that causes small bowel injury responsible for both abdominal pain and increased small bowel permeability. Food intolerance could, presumably, play a role in the mucosal damage‐linked IP increase found in the subset of CORD patients who complain of abdominal pain.
Noninvasive determination of respiratory mechanics during mechanical ventilation of neonates: A review of current and future techniques
Authors: Sly Peter D. , Brown Karen A. , Bates Jason H. T. , Spier Sheldon , Milic‐Emili Joseph
Published: March 2007

Study of the mechanical properties of the respiratory system is needed to help provide a better understanding of the pathogenesis of diseases causing respiratory failure. The nature of neonatal intensive care requires that any technique for monitoring respiratory mechanics be simple, noninvasive, and allow continued free access to the neonate. The peak airway pressure developed during volume cycled ventilation reflects the mechanical properties of the respiratory system but cannot distinguish between changes in the flow‐resistive or elastic properties. Similarly, dynamic compliance combines both the flow‐resistive and elastic components of the respiratory system in a single number and flow‐volume loops also reflect both elements. Extracting a single time‐constant from the expiratory limb of the latter assumes a single‐compartment model for the respiratory system and, as such, does not provide sufficient information to describe frequency dependence of resistance and compliance. Furthermore, flow‐volume loops are markedly distorted by the presence of an endotracheal tube, which must be corrected for, before calculating values of resistance and compliance. To provide the information to understand better the physiologic processes and adaptive mechanisms in diseased states causing acute respiratory failure, it is necessary to use a method that is based on a more detailed and realistic model of the respiratory system. Two such techniques that appear to warrant further investigation in ventilated infants are the interrupter technique and the forced‐oscillation technique.
Current techniques for assessing pulmonary function in the newborn and infant: Advantages and limitations
Authors: England Sandra J.
Published: March 2007

One of the major problems in pediatric pulmonology has been the shortage of tools to assess objectively the mechanical status of the lung and the effects of therapy. In the last few years this has changed; there are now a large number of methodologies to choose from. One method has rarely been tested against another, and as there does not appear to be a gold standard, the situation is becoming confused. Choice of the technique to be applied must be based on the characteristics of the patient to be studied. With the recent introduction of commercially available devices for performing some of these techniques, it is essential that those using them have a clear understanding of what they are measuring, the limitations of the measurements, and their interpretation.
Derepressed beta‐lactamase production as a mediator of high‐level beta‐lactam resistance in pseudomonas cepacia
Authors: Aronoff Stephen C.
Published: March 2007

A mechanism of high‐level resistance to readily and poorly hydrolyzable betalactam substrates in Pseudomonas cepacia was identified using a hypersusceptible, betalactamase‐inducible, non‐CF clinical isolate, 75–26, and a drug‐resistant mutant derived from this strain. Inoculation of 75–26 onto agar containing 16 μg/ml of ceftazidime produced a stable, beta‐lactam‐resistant mutant at a frequency of 1.7 × 10−5. Baseline beta‐lactamase production by a representative mutant isolate (75–26z) was almost 40‐fold greater than the parent. Both strains produced major beta‐lactamase bands with isoelectric points of 6.9, 7.8, 8.1, 8.5, and 9.2 by isoelectric focusing. Compared with the parental strain, multiple satellite bands associated with the major beta‐lactamase bands were present in the mutant. Growth of an indicator strain, E. coli ATCC 25922, was inhibited by ceftazidime and piperacillin but was not inhibited after the compounds were preincubated with the beta‐lactamase preparation from 75–26z. Preincubation of ceftazidime with beta‐lactamase, followed by the addition of a beta‐lactamase inhibitor, inhibited the growth of the indicator strain; piperacillin failed to inhibit growth of the indicator strain in a similar experiment. One mechanism of high‐level resistance to both poorly and readily hydrolyzable beta‐lactam substrates in P. cepacia is derepressed chromosomal beta‐lactamase production. Pediatr Pulmonol 1988; 4:72–77.
Cost savings and economic considerations using home intravenous antibiotic therapy for cystic fibrosis patients
Authors: Kane Robert E. , Jennison Karla , Wood Carol , Black Philip G. , Herbst John J.
Published: March 2007

Our Cystic Fibrosis (CF) Center made an effort to utilize home intravenous antibiotic therapy (HIVAT) as an alternative to continued hospitalization during a 1‐year study. After thorough individual clinical and financial evaluation, 27 of 41 CF patients admitted for treatment, including antibiotic therapy, were selected for HIVAT to complete a 14‐ to 21‐day treatment course (mean 15.1 days). The 27 patients (6–28 years old, mean 16 years) incurred a total of $698,587 in hospital charges and physician fees during 96 admissions. The average charge for 974 inpatient days was $717/day ($7,280 per admission). After an average of 10.2 days of inpatient care, the 27 patients underwent 79 courses of HIVAT for an additional 8 days; 21 additional HIVAT courses in six of these patients were initiated on an outpatient basis between frequent readmissions. The 811 days of HIVAT resulted in $85,027 total charges by two home care companies. The charges per day of HIVAT by one company were almost twice that of the other. The average daily cost of HIVAT was $108/day. If the HIVAT patients had remained hospitalized to complete the course of intravenous antibiotic therapy, the projected inpatient costs would have been $589,271. Therefore, the 811 days of HIVAT over a 1‐year period resulted in total estimated direct cost savings of $501,770. The average savings per course of HIVAT was $5,017, or $618/day. We concluded: 1) HIVAT was a safe, less expensive alternative to prolonged hospitalization with few complications; 2) the use of HIVAT at our center effected a 1‐year estimated cost saving of $501,770; and 3) additional cost savings could have been realized by cost comparison between home health care companies offering comparable services.
Lung pathology after high frequency jet ventilation combined with low rate intermittent mandatory ventilation in a canine model of meconium aspiration
Authors: Keszler Martin , Klappenbach R. Scott , Reardon Eileen
Published: March 2007

The microscopic appearance of lungs subjected to six hours of conventional ventilation (CV), standard high frequency jet ventilation (HFJV), and HFJV combined with low rate intermittent mandatory ventilation (CHFJV) was studied in 22 mongrel puppies. A lung injury model was created by insufflating 4 ml/kg of a 20% mixture of meconium into the trachea. The animals were initially ventilated at the same mean airway pressure (Paw). Subsequently, if Pco2 fell below 20 torr, peak and mean airway pressures were reduced. A scoring system was devised which assigned 0–3 points for each of eight lung injury parameters, and a total lung injury score (TLIS) was calculated.

CHFJV resulted in significantly less bronchopneumonia and edema, when compared to CV. A consistent, though not significant, trend toward lesser injury scores in CHFJV animals was noted for several other parameters. Six of eight lungs exposed to CV had TLIS > 5 compared to only 1 of 9 ventilated by CHFJV. (P= 0.02). It is concluded that CHFJV may have a protective effect on the lung, perhaps because effective gas exchange is achieved with a lower pressure amplitude and at lower Paw.
Evaluation of neonatal pulmonary mechanics and energetics: A two factor least mean square analysis
Authors: Bhutani Vinod K. , Sivieri Ms Emidio M. , Md Soraya Abbasi , Shaffer Phd Thomas H.
Published: March 2007

Pulmonary mechanics, using a two factor least mean square analysis technique, were determined in 22 preterm neonates with respiratory failure. The respiratory system is modelled as a linear mechanical system. Concurrent signals of airflow and transpulmonary pressure were utilized to calculate values of dynamic lung compliance and pulmonary resistances; these determinations were made over the entire tidal volume range. In addition, values of resistive work of breathing, pulmonary time constants, scalar records of sequential breaths, pressure‐volume and flow‐volume relationships were available for data review and interpretation. The mean ± SEM value of tidal volume was 7.4 ± 0.6 ml/kg; dynamic lung compliance was 0.44 ± 0.04 ml/cmH2O/kg; and the pulmonary resistance of the whole breath was 106 ± 9.1 cmH2O/liter/s. The resistive work of breathing (hysteresis) was 41.8 ± 5.9 gm.cm/kg. In correlating the measured values of pressure and flow to those predicted by the model, the mean value of the correlation coefficient for the least mean square analysis for all 22 studies was 0.995 ± 0.001; the standard error of estimate of the predicted pressure was <4.4% of the range of pressures measured. Thereby, the model was considered to be appropriate for the neonatal respiratory system. In addition to the traditional procedures of evaluating the respiratory status of a sick neonate, bedside analysis of pulmonary mechanics provide graphical information, and quantitative data which should be useful in day‐to‐day pulmonary management.
Airway obstruction and airway wall instability in cystic fibrosis: The isolated and combined effect of theophylline and sympathomimetics
Authors: Eber Ernst , Oberwaldner Beatrice , Zach Maximilian S.
Published: March 2007

Multiple aspects of lung function were measured in 17 cystic fibrosis (CF) patients on four occasions: without therapy (0); with oral theophylline medication (Th); after inhalation of salbutamol (β); and with combined medication (Th + β2). In addition to routine measurements, partial and maximum expiratory flow‐volume (MEFV) curves were superimposed, and the flow transient equivalent of the MEFV curve was determined. Its volume dimension (volume of airway contribution, VACMEFV) partially reflects airway distensibility. Changes in airway compressibility—the other consequence of airway wall instability—were assessed by observing changes in end‐expiratory flow rate. Airway resistance, expired volumes, and early expired flow rates, as well as VACMEFV improved significantly after β2 medication. Mean endexpiratory flow also increased after β2; in two patients, however, it decreased significantly, indicating that enhanced airway compression dominated over the release of bronchospasm. Th alone had only minor effects on lung function. Early expired volume and flow rates as well as VACMEFV showed no significant difference between β2 alone and Th + β2; airway resistance even decreased significantly with this drug combination. End‐expiratory flow rate, however, was significantly lower after Th + β2 than after β2 alone. Although theophylline does not alter lung function in most patients with CF, sympathomimetics relieve bronchospasm in many, but they enhance airway compressiblity and thereby decrease peripheral expiratory airflow in some. Th + β2 shows no clearcut therapeutic advantage over β2 alone but, due to destabilized bronchial walls, can lead to maximum expiratory airway compression in some patients; consequently, caution and detailed individualized assessment of induced lung function changes are recommended before considering such combined medication for treatment of hyperreactive airway disease in CF patients.
Effects on respiration of CPAP immediately after extubation in the very preterm infant
Authors: Andréasson Bengt , Lindroth Magnus , Svenningsen Nils W. , Jonson BjöN
Published: March 2007

The effects of continuous positive airway pressure (CPAP) on pulmonary function during weaning from ventilator treatment were examined immediately after extubation in 17 very preterm infants, who had been ventilator‐treated because of hyaline membrane disease (15 infants) and chronic pulmonary insufficiency of prematurity (two infants). Seven infants had bronchopulmonary dysplasia. Median birthweight was 920 g and median gestational age 26 completed weeks. The median duration of ventilator treatment was 10 days.

Application of CPAP by means of a face chamber device after endotracheal extubation significantly lowered the frequency of apnea (P = 0.02) and enhanced oxygenation (P = 0.001). The respiratory mechanical indices derived from flow rate and juxta‐diaphragmatic esophageal pressure measurements showed a reduced elastic (P = 0.03) and resistive (P = 0.02) load on the diaphragm. Even if the measured values do not accurately represent absolute resistances and compliances, the relative values of end‐inspiratory and end‐expiratory pressures differed significantly with and without CPAP (P = 0.001 and 0.002, respectively). We found CPAP applied via the face chamber technique immediately after extubation to be beneficial and to facilitate weaning from ventilator treatment in very preterm infants. Pediatr Pulmonol 1988; 4:213–218.
Mechanics of the ventilatory system in sedated infants: Forced oscillations versus single‐breath method
Authors: Marchal F. , Peslin R. , Duvivier C. , Gallina C. , Crance J. P.
Published: March 2007

The real—Re(Z)—and imaginary—Im(Z)—parts of the ventilatory system impedance were measured between 6 and 30 Hz in 18 normal infants and in 19 with airway obstruction. The intercept (RO) and slope (S) of the Re(Z)‐frequency function, as well as inertance (I) and compliance (C) estimated from Im(Z), were compared with ventilatory system resistance (Rrs) and compliance (Crs) (single‐breath method). RO correlated significantly with Rrs (r = 0.86), although the slope of the regression equation was significantly lower than 1 (P < 0.01). Negative frequency dependence of Re(Z) was observed in all subjects and a significant correlation was found between S and Rrs (r = ‐ 0.80). “Inertance” was negative in 20 subjects and correlated negatively with Rrs (r = ‐0.61). C correlated with Crs (r = 0.64) and with 1/Rrs (r = 0.85). The ratio of C to Crs (mean ± SD = 0.168 ± 0.082) also correlated with 1/Rrs (r = 0.51). The main characteristics of the total impedance/frequency function could be simulated with a model featuring the upper airway wall (Zuaw) in parallel with the ventilatory system (Zrs). It is suggested that the differential change in Zuaw and Zrs with growth accounts for the marked frequency dependence of Re(Z) as well as the inaccurate estimation of both I and C in this population.
Beta‐adrenergic receptors of lymphocytes in children with allergic respiratory diseases
Authors: Bittera István , Gyurkovits Kálmán , Falkay György , Eck Erna , Koltai Mátyás
Published: March 2007

The beta‐adrenergic receptor binding sites on peripheral lymphocytes in children with bronchial asthma (n = 16) and seasonal allergic rhinitis (n = 8) were examined in comparison with normal controls (n = 18) by means of 124l‐cyanopindolol. The number of beta‐adrenergic receptors was significantly lower in the asthmatic group (858 ± 460/lymphocyte) than in the controls (1564 ± 983/lymphocyte). The value (1891 ± 1502/lymphocyte in children with allergic rhinitis was slightly higher than that in healthy controls. Of the 24 patients suffering from allergic diseases of the lower or upper airways, the bronchial histamine provocation test was performed in 21; 16 gave positive results, while 5 were negative. No difference in beta‐adrenergic receptor count was found between the histamine‐positive and negative patients. Neither was there any correlation between the number of beta‐adrenergic receptors and the high (16/24) and low (8/24) serum IgE concentrations found in allergic patients. The significant decrease in beta‐adrenergic receptor count in asthmatic children lends support to Szentiványi's concept. Further qualitative and quantitative analysis of lymphocyte beta‐adrenergic receptors may provide an individual approach to the treatment of bronchial asthma with beta‐sympathomimetic drugs.
The effect of age on postpneumonectomy growth in rabbits
Authors: Cagle Philip T. , Langston Claire , Thurlbeck William M.
Published: March 2007

To assess the effect which age at pneumonectomy has on pulmonary compensatory growth, male New Zealand white rabbits underwent left pneumonectomy or sham thoracotomy at 10, 18, or 26 weeks of age. Morphometric and biochemical evaluation of the remaining lungs was carried out four weeks later. There was significant compensatory growth in terms of lung volume, weight, DNA, RNA, and protein in all three age groups. Lung volume response was incomplete, i.e., right lung volume of the experimental animals did not match the volume of both lungs of controls; other variables were not significantly different between the right lung of experimentals and both lungs of the controls. An unchanged surface area per unit volume accompanied by a stable mean linear intercept indicated that alveolar multiplication occurred in the 10 and 18 week age groups. The oldest group had significantly decreased surface area per unit volume and significantly increased mean linear intercept, suggesting an increase in the size of existing alveoli at 26 weeks of age.
Mechanisms of bronchial hyperreactivity in cystic fibrosis
Authors: Van Asperen Peter P. , Manglick Patricia , Allen Hugh
Published: March 2007

We studied 14 patients with cystic fibrosis (CF) who had evidence of bronchial hyperreactivity on a standardized histamine challenge. Patients had a histamine challenge on the first day. Then they were pretreated with either 0.25 mg ipratropium bromide or 0.5 mg fenoterol hydrobromide on 2 separate days, and the histamine challenge was repeated. Baseline forced expiratory volume in 1 sec was similar on the 3 days; however, there was a small but significant (P<0.05) improvement after fenoterol. Mean PC20 on the control day was 1.50 mg/ml, which increased significantly after pretreatment with ipratropium (2.88 mg/ml, P<0.01) and fenoterol (3.64 mg/ml, P<0.005), indicating protection against histamine‐induced bronchial hyperreactivity. The six CF patients with “coexistent asthma,” as defined by recurrent episodes of wheezing responsive clinically to bronchodilator therapy, had no significant protection from ipratropium, whereas the eight “nonasthmatic” CF patients were protected by both ipratropium and fenoterol. We postulate that at least two mechanisms contribute to histamine‐induced bronchial hyperreactivity in patients with CF, one related to vagally mediated reflex bronchoconstriction and another that acts independently of this mechanism.
Inherent variability of pulmonary function tests in infants with bronchiolitis
Authors: Mallol Javier , Hibbert Marienne E. , Robertson Colin F. , Olinsky Anthony , Phelan Peter D. , Sly Peter D.
Published: March 2007

During the last decade, many new methods of assessing pulmonary function in infants have been introduced. However, considerable controversy has arisen when these different techniques are used to assess the efficacy of various inhaled medications. The currently employed measures of pulmonary function have been reported to have coefficients of variation of less than 10%. However, these figures refer to repeated measurements made in individual babies over a short period of time, with the infant in a constant position. They may not be applicable to studies on the effects of drugs when a significant time interval elapses between measurements, particularly if the infant is repositioned during this time. In the present study, we found that the variability of measurements of thoracic gas volume (TGV), passive respiratory mechanics, and forced expiration approximately doubled if the infant was taken out of the plethysmograph, or repositioned within the plethysmograph, between sets of measurements. The between‐test coefficients of variation ranged from 4.8% to 18.9% for TGV, 7.8% to 23.5% for respiratory system resistance, from 5.0% to 24.1% for respiratory system compliance, and from 10.8% to 36.1% for maximal flow at functional residual capacity. These results demonstrate that the commonly employed infant pulmonary function tests have wide variability in infants with acute wheezing illnesses. Before studying the efficacy of therapeutic interventions in such infants, it is necessary to establish the individual variability of the tests in the infants under the conditions of the study. Failure to do so may result in erroneous conclusions and recommendations.
Activation of alveolar macrophages from children with the acquired lmmunodeficiency syndrome‐related complex
Authors: Clement A. , Sardet A. , Chadelat K. , Grimfeld A. , Tournier G.
Published: March 2007

The ability of alveolar macrophages (AM) to release hydrogen peroxide (H2O2), an indicator of AM function, was studied in five children with the acquired immunodeficiency syndrome (AIDS) related complex and, for comparison, in 11 children without disorders of the lung parenchyma. In the AIDS‐related complex group, pulmonary manifestations were mild, and lung involvement was suspected by moderate clinical and/or radiological features. None had a past history of opportunistic infections; neither did any have lymphopenia. Cytologic study of the bronchoalveolar lavage (BAL) fluid revealed increased cellularity with increased percentage of lymphocytes. The study of H2O2 release was performed on unstimulated AM and on AM stimulated by phorbol myristate acetate (PMA). Under both experimental conditions, the amount of H2O2 accumulated in the medium was significantly increased in the group with AIDS‐related complex (P < 0.001). As no enhanced oxidative activity has been reported in AM from patients with full‐blown AIDS, an increased ability of AM to release oxygen metabolites from children with AIDS‐related complex may reflect an initial and temporary step in the course of the LAV/HTLV‐III pulmonary disease. Determining AM activation might be a reliable method of assessing the evolution of lung disorder in AIDS.
Pulmonary function following mild respiratory tract infections (“common cold”) in teenagers
Authors: Teculescu Dan B. , Pham Quang Thieu , Chau Nearkasèn , Aubry Catherine , Kuntz Claude
Published: March 2007

Ventilatory function—forced vital capacity (VC)—forced expiratory volume (in 1‐sec forced expiratory flows) static lung volumes, closing volume, and phase III slope (singlebreath N2 test) were compared in 94 children with and 436 children without a history of recent mild acute respiratory infection. Their age ranged from 10 to 16 years; subjects with symptoms on the day of the study were excluded. We found no difference in lung function between the two groups, with the exception of a slight (inconsistently significant) increase in closing volume (CV) and the CV/VC ratio. Although the influence of a persistent increase in interstitial lung pressure leading to early small airways closure cannot be ruled out, this isolated functional abnormality probably represents a spurious positive result, arising by chance when a large number of statistical tests are done.
Respiratory control during nipple feeding preterm infants
Authors: Mathew Oommen P.
Published: March 2007

The present study was designed to investigate the development of respiratory control during feeding in premature infants. Cardiorespiratory disturbances during feeding were evaluated with polygraphic monitoring in 24 premature infants within 1 week of beginning nipple feeds. During the initial study, 15 infants exhibited one or more episodes of short apnea (≥ 10 sec) and three infants exhibited prolonged apnea (≥20 sec). Bradycardia developed in seven infants; apnea and decreases in oxygen saturation invariably preceded the development of bradycardia. In contrast, short apnea occurred during sleep in five infants and associated bradycardia developed in four infants. Occurrence of apnea during sleep was significantly lower than that observed during feeding (P < 0.05). Subsequently, 18 of these infants were reevaluated 7–10 days later. Seven infants developed one or more episodes of short apnea, five developed prolonged apnea, and four developed bradycardia. These occurrences were not significantly different from those observed during the initial study (P > 0.05). Short apnea persisted during sleep in four infants during reevaluation. Most of the apneic episodes in both studies were mixed apnea. The high frequency of cardiorespiratory disturbances during the first 2 weeks of nipple feeding indicates that in most preterm infants respiratory control during feeding is still immature at the postconceptional age of 35–36 weeks.
Airway pressures during crying in healthy infants
Authors: Shardonofsky Felix R. , Perez‐Chada Daniel , Carmuega Esteban , Milic‐Emili Joseph
Published: March 2007

Maximal inspiratory and expiratory airway pressures (PI max and PE max) were measured in 100 healthy infants (51 males, 49 females; age range, 0.06–3.76 years) by occluding the airway with a suitable face mask during a crying effort. Mean values ± SD for PI max and PE max were 118 ± 21 cm H2O and 125 ± 35 cm H2O, respectively. Maximal inspiratory pressure was independent of age, sex, and anthropometrics, while maximal expiratory pressure showed a low but statistically significant positive correlation with body weight (P < 0.001).
Predicting arterial oxygen tension from maximum expiratory flow volume curves in cystic fibrosis
Authors: Stecenko Arlene A. , Postotnik Linda , Thomas Ronald G.
Published: March 2007

Measurements of arterial oxygen tension (PaO2) while breathing room air, and maximum expiratory flow volume curves were performed in 34 patients with cystic fibrosis (age range 7–27 years, 24 males and 10 females). Logistic regression was performed using forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow rate (PEFR), and forced expiratory flow at 75% of expired vital capacity (FEF75) to model an equation for predicting when PaO2 would be less than 55 mmHg (severe hypoxemia). Equations were modelled using one, two, three, or all four of the variables. For the univariate logistic regression, each of the four variables was a significant (P < 0.001) predictor for severe hypoxemia. FVC was the best predictor with an R2 = 0.56, sensitivity of 100% (false negative rate = 0%), and a specificity of 88.5% (false positive rate = 27%). The model predicted that patients with an FVC < 35% of the predicted normal were at risk of having PaO2 ≤ 55 mmHg. Adding FEV1, FEF75, or PEFR in various combinations to FVC made the model equation more complicated but did not add significantly to the ability to predict severe hypoxemia.
Reducing inadvertent peep by controlling end‐tidal pressures in the trachea
Authors: Gonzalez Felipe , Carlstrom Jeffrey , Richardson Peter
Published: March 2007

Mechanical ventilation using exhalation times too brief for completion of exhalation results in inadvertent positive end‐expiratory pressure (IPEEP) and increased functional residual capacity (FRC). The endotracheal (ET) tube with side lumen allows us to monitor tracheal airway pressures and to determine the contributions of the ET tube to IPEEP. We hypothesized that, during rapid rate ventilation, controlling the positive end‐expiratory pressure (PEEP) level in the trachea rather than at the ET tube adaptor will counter effects of the ET tube on IPEEP and result in less increase of FRC.

Thirteen anesthetized rabbits were ventilated at rates of 30, 60, 90, and 120 breaths per minute (BPM). Peak inspiratory pressure was held constant, and PEEP was adjusted to 2 cmH2O, measured conventionally at the proximal end of the ET tube. Pulmonary function tests were made and then repeated while PEEP was held constant in the trachea, measured at the distal end of the ET tube.

Controlling PEEP conventionally resulted in mean (± SE) FRC values of 13.7 ± 3.8, 14.8 ± 3.9, 17.1 ± 4.5, and 21.1 ± 5.3 ml/kg at 30, 60, 90, and 120 BPM, respectively. Controlling PEEP at the trachea yielded FRC values of 13.7 ± 3.8, 13.6 ± 3.4, 15.3 ± 4.4, and 16.3 ± 5.4 ml/kg, respectively. Increasing the ventilator rate above 60 BPM did not affect minute ventilation or blood gases.

These results suggest that controlling PEEP in the trachea reduces effects of IPEEP on FRC by countering the contribution of the ET tube to the resistance of gas flow during exhalation.
Mechanics and energetics of breathing in newly diagnosed infants with cystic fibrosis: Effect of combined bronchodilator and chest physical therapy
Authors: Hardy Karen A. , Schidlow Daniel V. , Wolfson Marla R. , Shaffer Thomas H.
Published: March 2007

Response to bronchodilator (BD) and chest physical therapy (CPT) was evaluated in newly diagnosed infants with cystic fibrosis (n = 13; age, 6.9 ± 1.5 SE months) who were asymptomatic for lung disease at the time of the study. Lung function was assessed from the mechanics and energetics of breathing prior to and following combined BD and CPT. After therapy, respiratory rate, tidal volume, minute ventilation, and pulmonary compliance were not statistically different from values under baseline conditions. In contrast, there was a significant decrease in pulmonary resistance (‐34%; P <0.05) and the resistive work of breathing (‐26%; P <0.05) following the combined treatment. The effect of combined BD and CPT in decreasing the resistive respiratory load may be related to relief of subclinical bronchospasm, reduction in mucosal edema, and mobilization of mucous secretions.
Prenatal relationship of surfactant lipid and protein constituents in infants with respiratory distress syndrome: A preliminary communication
Authors: Wilbur Deborah B. , Kanarek Keith S. , Balis John U. , Paciga June E. , Shelley Sue A. , Cohen Gary
Published: March 2007

The prenatal relationships between surfactant disaturated phosphatidylcholine (DSPC) and surfactant‐associated proteins of preterm infants with respiratory distress syndrome (RDS) have not been well documented. In the present study we measured the concentration of DSPC, surfactant glycoproteins (GP), and surfactant proteolipids (PLP) in amniotic fluids obtained within 6 hours prior to delivery of 16 newborn infants with gestational ages between 27 and 32 weeks. In control infants of 27–32 weeks gestation without RDS, the values of DSPC, GP, and PLP per milliliter of amniotic fluid were 20 ± 2.9 μg, 684 ± 115.3 ng and 289 ± 62.5 ng, respectively. These values were significantly higher, threefold for PLP, fourfold for DSPC, and fivefold for GP, than amniotic fluid levels in infants with RDS. The findings support the concept that immaturity of surfactant in RDS involves both phospholipids and surfactant‐associated proteins. Measurements of surfactant lipid‐protein complex appear to enhance the reliability for identifying prenatally, infants at risk of developing hyaline membrane disease. More extensive studies are warranted to assess the usefulness of these assays for clinical application.
The reproducibility and agreement of three indices of airway responsiveness to histamine in asthmatic children
Authors: van Aalderen W. M. C. , Gerritsen J. , Knol K. , Koëter G. H. , Postma D. S. , van der Weele L. T.
Published: March 2007

In 12 asthmatic children, aged 8–14 years, we investigated the possibility of using a provocation concentration of histamine (PC) causing a 10% or 15% fall in baseline forced expiratory volume in 1 sec (FEV1), instead of a PC20 histamine, in the assessment of bronchial hyperreactivity. Inhalation challenge tests were performed on days 6 and 7 after withdrawal of medication. PC10, PC15, and PC20 were calculated from the dose‐response curves.

Reproducibilities for PC10, PC15, and PC20, values for both days, determined by Student's t‐test, were not significantly different. Correlation coefficients between PC20 and PC15 values on days 6 and 7 and between PC10 values on days 6 and 7 were 0.82 and 0.76, respectively; between PC20 values on day 6 and PC15 values on day 7; and between PC20 values on day 6 and PC10 values on day 7 they were 0.84 and 0.82, respectively. (P <0.01 for all r values).

The predictive value of PC20 for PC10 and PC15 was determined by a least‐squares regression line with 95% confidence intervals. Variances between PC10, PC15, and PC20, were not significantly different on either day 6 or 7.

Our data show that a PC10, as well as a PC15, can be used in the assessment of the degree of bronchial hyperreactivity in children with asthma.
A correction formula for computing specific airway resistance from a single‐step measurement
Authors: Haluszka Janusz , Willim Grzegorz , Filtcher Slavi , Cutrera Renato , Ronchetti Roberto
Published: March 2007

Specific airway resistance (SRaw) is conventionally determined by multiplying the plethysmographically measured values of airway resistance and functional residual capacity (FRC). An alternative single‐step method, which avoids the need for airway occlusion during determination of FRC, has been described by Dab and Alexander.5,6 The single‐step method provides no correction for resistance or dead space of the apparatus and, as a result, systematically overestimates SRaw. Using 1,000 paired measurements, it was possible to compute a formula for correcting the single‐step measurement. This correction formula can be adjusted and applied to measurements made in any laboratory. The unlimited applicability of the proposed correction has been demonstrated by 234 plethysmographic measurements made in the Pediatric Clinic in Rome.
Estimation of maximum expiratory flow‐volume variables in children
Authors: Houthuijs Danny , Remijn Bregt , Brunekreef Bert , Koning Rian De
Published: March 2007

Different protocols for pulmonary function testing were evaluated in 611 children, 6–9 years old. Attention was paid to the necessary minimum number of acceptable maneuvers, the necessary maximum number of attempts, and the best of seven different methods for summarizing variables from maximum expiratory flow‐volume (MEFV) curves. The results of the study indicate that it is not useful to continue pulmonary function testing after eight attempts. The differences between the results from three or five acceptable maneuvers are not substantial for any method; in children, obtaining three acceptable curves seems sufficient. When flow variables are selected from one acceptable curve, as in the American Thoracic Society (ATS) guidelines, the reproducibility is somewhat less good than in methods in which results of various curves are averaged or selection is made from different curves. The method that has been recommended by the European Community for Coal and Steel for the selection of MEFV variables in teenagers and adults in Europe, was also demonstrated to be suitable for younger children.
Nontypable Haemophilus influenzae nosocomial pulmonary infections in children following intubation
Authors: Hicks Ralph A. , Burry V. Fred , Olson Lloyd C. , Jackson Mary Anne
Published: March 2007

Twenty‐nine intubated pediatric patients were prospectively studied to determine whether nontypable Haemophilus influenzae (NTHI) is associated with the development of nosocomial pneumonia. Throat cultures and tracheal Gram stains, leukocyte counts and cultures were obtained immediately following intubation, then serial studies on tracheal secretions were performed. Median patient age was 13 months. One patient had preexisting lung disease and 14 (48%) had pneumonia when intubated. There were five deaths. NTHI was recovered from the initial throat or tracheal culture in seven patients (24%); none developed a nosocomial lower respiratory tract infection. NTHI was not associated with any of three cases of nosocomial pneumonia. Three of 12 NTHI isolates were beta‐lactamase producers. Tracheal leukocyte counts and Gram stains were not predictive of pneumonia, either at the time of intubation or subsequently. We conclude that NTHI in the oropharynx or trachea is not predictive of pneumonia among intubated pediatric patients.
Characterization of prolonged apneic episodes associated with respiratory syncytial virus infection
Authors: Pickens Deborah L. , Schefft Georgia L. , Storch Gregory A. , Thach Bradley T.
Published: March 2007

We used high‐speed polygraphic recordings to document in detail the sequence of events during prolonged apneic spells in two infants with respiratory syncytial viral (RSV) infection. Also, we elicited upper airway reflexes by stimulating the airway with saline during sleep. Spontaneous prolonged apneic spells were recorded in both infants, and these consisted of two distinctly different apnea types. A number of similarities between apnea of prematurity, upper aiway reflex apnea and the apneas in these two infants with RSV infection suggests the possibility that these various kinds of apnea may have related causal mechanisms.
Changes in the spatial distribution of pulmonary blood flow during the fetal/neonatal transition: an in vivo study in the rabbit
Authors: Lipsett Jill , Hunt Kerri , Carati Colin , Gannon Bren
Published: March 2007

The spatial distribution of pulmonary blood flow was investigated in term fetal and neonatal rabbit littermates, using the plasma tracer fluorescein‐isothiocyanate bovine serum albumin (FITC‐BSA). A tracer bolus was injected intravenously and allowed 2 minutes to circulate in vivo, prior to arrest of the circulation and tissue preparation.

In the fetus, fluorescence was only present in 43% of the lung volume, contained within discrete regions or “lobules.” Some 57% of lung volume received no tracer inflow at all (during 2 min). In the fetal lung, the size of the potential airspaces in the perfused regions was 1.5 times larger than those in the nonperfused regions.

In the fetus, a high pulmonary vascular resistance (PVR) is maintained. It is generally accepted that pulmonary blood flow in the fetus is evenly distributed to the entire vascular bed. Our results show that fetal pulmonary blood flow is distributed to discrete “lobules,” while (over a 2 min period) the majority of “lobules” receive no flow at all. Thus, by directing flow to a lesser proportion of the vasculature, greater flow rates are achieved, and the risk of blood sludging and stasis is reduced. Alternation of perfusion with nonperfusion in each “lobule,” perhaps regulated by the lobular arterioles, would permit both maintenance of the high fetal PVR and uniform lung development.

In the neonatal lung, the plasma tracer was distributed uniformly to the entire vascular bed. This suggests that some of the reduction in PVR at birth is due to recruiting 50–60% of lung vasculature.
Cough flow‐volume relationships in normal and asthmatic children
Authors: Beardsmore Caroline S. , Park Alan , Wimpress Stephen P. , Thomson Anne H. , Simpson Hamish
Published: March 2007

The flow‐volume profile of a maximum voluntary cough resembles that of a maximum expiratory flow‐volume (MEFV) curve with superimposed transient peak flows at the onset of each cough effort and portions of zero flow corresponding to periods of glottis closure. A straight line (the cough slope) can be drawn through the transient peak flows, and the ratio of MEFV‐equivalent flow to the cough peak flow can be calculated. This cough ratio has been shown to fall during adult life and may be related to changes in airway compliance and crosssectional area with age. The present study investigated the cough ratio, cough slope, and maximum flows measured from the cough flow‐volume curve in a group of normal children aged 7 to 16 years. Maximum flows and the cough slope increased with height, but the cough ratio did not change with growth or age. In a similar group of asthmatic children, baseline measurements of cough showed a reduction in cough peak flow rates, MEFV‐equivalent flow, and the cough ratio. These changes are related to alterations in airway compliance and cross‐sectional area and are partly reversed following inhalation of a bronchodilator.
Expression of results of histamine challenge
Authors: Reiser J. , Wadsworth J. , Nunn A. , Warner J. O.
Published: March 2007

Different aspects of standardization of histamine challenges have been extensively investigated. However, several methods have been used for the actual derivation of the provocation concentration causing a 20% fall in lung function (PC20) from the results of the serial lung function tests (e.g. forced expiratory volume in 1 second [FEV1]). We have compared these methods on a series of 21 histamine challenges to see if any were systematically inconsistent with the others. The simplest method, with least potential for further error, is interpolation of two points, on either side of the line for 20% fall in lung function, calculated by computer. We conclude that, as this method was consistent with the majority of others, it is the method of choice for deriving the PC20.
Subglottic inflammatory pseudotumor in a 6‐year‐old child
Authors: Zapatero J. , Lago J. , Madrigal L. , Baschwitz B. , Rodriguez E. Perez , Penalver R. , Candelas J.
Published: March 2007

Inflammatory pseudotumors have been given diverse—no fewer than 19—names in the literature. The most frequent localization is in the lung, the gastrointestinal tract, and salivary glands. The case presented here at the subglottic level is exceptional. Although the intraoperative diagnosis is not easy, the prognosis is usually good. Malignant degenerations have not been described. In those cases that cannot be operated on or that extend into the mediastinum, radiotherapy is indicated.
Changes in functional residual capacity in response to bronchodilator therapy among young asthmatic children
Authors: Greenough Anne , Pool Jeni , Price J. F.
Published: March 2007

Measurements of functional residual capacity (FRC) by helium gas dilution and peak expiration flow rate (PEFR) were made in 63 young asthmatic children aged 2 and 7 years before and after bronchodilator therapy. All 63 children tolerated two measurements of FRC, but only 33 children were able to perform the peak flow maneuver. Bronchodilator therapy was associated with significant change in FRC in the majority (80%) of children; in some, however, this change was an increase rather than a decrease. The change in FRC was significantly correlated with both prebronchodilator FRC and the change in PEFR. An increase in FRC following bronchodilator therapy was more common in children with severe and symptomatic asthma. We suggest that changes in FRC may be used in asthmatic children to demonstrate bronchodilator responsiveness, particularly in those too young to perform other respiratory function tests. Pediatr Pulmonol. 1989; 7:8–11.
Costal and crural diaphragm, and intercostal and genioglossal electromyogram activities during spontaneous augmented breaths (sighs) in kittens
Authors: Watchko Jon F. , Brozanski Beverly S. , O'Day Terrence L. , Klesh Kenneth W. , Guthrie Robert D.
Published: March 2007

Spontaneously occurring augmented breaths (sighs) are common in infants. The pattern of electrical activity of the inspiratory muscles of the thorax and upper airway during augmented breaths, however, has not been fully characterized in this less than fully mature age group. We therefore examined costal and crural diaphragm and external intercostal and genioglossal EMG activities during spontaneous augmented breaths (n = 46) in 10 anesthetized (1.35% halothane) 1‐month‐old kittens breathing room air. EMG responses were assessed by comparing the spontaneous augmented breaths (AB) to the five immediately preceding breaths (control). The peak moving time average EMG activity observed during the AB was 240 ± 32% (mean ± SD) of control for the costal diaphragm, 279 ± 66% of control for the crural diaphragm, and 274 ± 68% of control for the external intercostal muscle. The mean increase in EMG activity during the AB was not significantly different among these three muscle groups (P > 0.25). Genioglossal EMG activity during AB was observed in only 1 of 10 study animals. These results document that during AB in anesthetized kittens, activity of the thoracic inspiratory muscles (costal/crural diaphragm and external intercostal muscles) increase in parallel, suggesting that they are modulated in a uniform manner. The infrequent observance of genioglossal activity during AB suggests that either (1) halothane anesthesia depresses genioglossal activity more than diaphragmatic and intercostal activity during AB or (2) that genioglossal recruitment is not necessary to maintain upper airway patency during this period of heightened respiratory drive. Pediatr Pilmonol. 1989; 7:94–100.
Exercise tolerance and effects of training in young patients with cystic fibrosis and mild airway obstruction
Authors: Braggion C. , Cornacchia M. , Miano A. , Schena F. , Verlato G. , Mastellay G.
Published: March 2007

We evaluated the effects of an 8‐week aerobic training (1 hr, three times a week) on physical performance of ten patients with cystic fibrosis (CF) (median age, 12.5 yr; range 11.1–15.3 yr), with mild airway obstruction (FEV1 = 77 ± 22% pred.), and ten healthy age‐matched children (CONTR) (median age, 12.7 yr; range 12.2–15.2 yr). Physical performance was tested with maximal incremental (MAX) and submaximal (SMAX) (fixed workload of 1.7 W/kg during 6 min) exercise tests on a cycle ergometer. These and standard spirometric and anthropometric measurements were performed at the beginning and end of a period with usual daily activity and one with the training program. The kinetics of ventilatory parameters at the onset and end of SMAX were displayed by fitting data on oxygen uptake and minute ventilation by monoexponential curves (least‐squares method). At the start and the end of the training period, all children were timed for endurance run to voluntary exhaustion and for sprinting through an obstacle course. A pattern of relative hyperventilation during SMAX and of poor performance in endurance and obstacle runs were evident at the start of the training period in patients with CF. The effects of training on MAX and SMAX were small and partial; the improvement in field test performances was significant only for CF and could be attributed to improvement of skill and motivation. Pediatr Pilmonol. 1989; 7:145–152.