bluuebunny/crossref_metadata_2025_split huggingface dataset:
Rib cage to abdominal asynchrony in children undergoing polygraphic sleep studies
Authors: Sivan Yakov , Ward Sally Davidson , Deakers Timothy , Keens Thomas G. , Newth Christopher J. L. 
Published: March 2007

AbstractWe assessed rib cage (RC) to abdominal (AB) asynchrony in 110 children, aged 1 to 50 months who underwent diagnostic daytime polygraphic sleep studies (PSG), and correlated the results. RC—AB asynchrony was calculated by the phase angile (PA) technique and compared to normal values (0–24°) derived from a separate group of 45 control children, matched for age and weight. Eighty‐two of the 110 patients had PSG as part of their evaluation for obstructive sleep apnea. There was a high association between the phase angles and the PSG results (P < 0.01; Fisher's exact test). PSG was abnormal in 38/82 patients (46%) and the phase angle was increased in 51/82 (62%) (mean ± SD, 68° ± 39°; range 28°–168°) compared to the normal controls (P < 0.001). Fourteen of the 110 patients had bronchopulmonary dysplasia; of these, PSG and PA results agreed in six normal and seven abnormal studies and disagreed in only one (P = 0.002). Six of 110 patients had Down's syndrome; 5 of 6 had increased RC—AB asynchrony, compared to 3 of 6 who had abnormal PSG. Eight of 110 patients were evaluated for central apnea and hypoventilation; PA was abnormal in 4 of 8, who also had abnormal PSG and in 1 with normal PSG. We conclude that RC—AB measurement by the PA technique may be an important adjunct to the evaluation of breathing disorders during sleep in small children and it may be a good screening test for small children who need PSG.
Importance of using lung function regression equations appropriate for ethnic origin
Authors: Greenough A. , Hird M. F. , Everett L. , Price J. F. 
Published: March 2007

AbstractFunctional residual capacity (FRC) can be assessed reliably in young children using a helium gas dilution technique. The aim of the present study was to determine if differences in lung volume are found in asthmatic children of different ethnic origins. Eighty‐eight children were studied, 53 of Caucasian origin and 35 of Afro‐Caribbean origin. Their median age was 6.1 years (range, 5.3–9.0 years). FRC measured by helium gas dilution is reported as a percentage of predicted for height, using a published regression equation as well as regression equations appropriate for the ethnic origin of the child. In the majority of both groups FRC was elevated above the ethnically appropriate regression equation for healthy children. The Caucasian children apparently had higher FRCs than the Afro‐Caribbean children if comparing the absolute lung volume, and if lung volume was expressed as percent of predicted for height, by a regression equation uncorrected for ethnic origin (P < 0.02). This difference disappeared when ethnically appropriate regression equations were used. We conclude that lung volumes are similar in asthmatic children of different ethnic origin and that it is important to use ethnically appropriate regression equations.
Antineutrophil elastase activity in cystic fibrosis serum
Authors: Cantin André M. , Lafrenaye Sylvie , Bégin Raymond O. 
Published: March 2007

AbstractThe antigenic concentrations of alpha‐1‐antitrypsin (α1AT) were measured in 13 patients with cystic fibrosis (CF) and in 11 healthy subjects. Serum α1AT was purified by immunoaffinity chromatography and the antielastase activity of the purified α1AT was determined by measuring the molar ratio necessary to inhibit human neutrophil elastase (HNE). The association rate constant of α1AT with HNE was determined in a timed assay. The capacity of CF serum α1AT to form complexes with porcine pancreatic elastase was studied by polyacrylamide gel electrophoresis. Antigenic concentrations of α1AT μmol/L were markedly increased in the serum of all patients with CF (61.9 ± 4.3 μmol/L) in comparison to a reference standard (36.7 ± 1.8 μmol/L; P < 0.0001). CF serum α1AT was fully active against HNE, and its association rate constant in the presence of HNE was similar to that of healthy subjects. In addition, CF serum α1AT formed complexes with porcine pancreatic elastase that were electrophoretically indistinguishable from those of normal serum α1AT. These results indicate that patients with CF have increased serum α1AT concentrations and that this antiprotease, when purified from serum, functions normally.
Variability of dynamic compliance measurements in spontaneously breathing and ventilated newborn infants
Authors: Ratjen F. A. , Wiesemann H. G. 
Published: March 2007

AbstractWe studied reproducibility and variability of dynamic pulmonary compliance (Cdyn) by making measurements with the esophageal balloon at multiple locations within the esophagus, in both spontaneously breathing and mechanically ventilated newborn infants. Reliable measurements could be obtained over a range similar to that reported for measurements with a liquid‐filled catheter. In spontaneously breathing infants Cdyn was found to be highly variable. This variability was unrealated to catheter position but was associated with concomitant changes in pulmonary resistance. Probably because of the high variability, the correlation of Cdyn with a measurement of respiratory system compliance (Crs) was rather poor (r = 0.63). Cdyn measured in mechanically ventilated infants was significantly less variable and compared favorably to Crs (r = 0.86), but its accuracy could not be adequately assessed since the comparison of esophageal and airway occlusion pressure was not feasible in all infants. In addition, significant differences in Cdyn were found between spontaneous and ventilated breaths during mechanical ventilation. Further studies in both ventilated and spontaneously breathing infants are needed to assess the variability of Cdyn over extended time periods. Pediatr pulmonol.1992; 12:73–80.
Time course of lipid‐laden pulmonary macrophages with acute and recurrent milk aspiration in rabbits
Authors: Colombo John L. , Hallberg Timothy K. , Sammut Paul H. 
Published: March 2007

AbstractHigh levels of lipid‐laden macrophages (LLM) in bronchial washings have been associated with food aspiration. We studied the time course of appearance and clearance of LLM in rabbits undergoing either a single milk instillation, five weekly milk instillations or saline (control) instillations into the airways. Cells were obtained by bronchoalveolar lavage of intubated rabbits at uniform time intervals following the single or the last of five milk/saline instillations. LLM semi‐quantitative indexes were derived using oil‐red‐O staining. Significantly elevated indexes were found in both milk groups 6 hr after milk instillation. In the single saline and milk instillation groups the indexes were not different beginning on the 4th day, and indexes from 8 of 9 rabbits had returned to baseline by the 6th day. However, indexes remained significantly elevated up to 17 days in the group receiving weekly milk instillations. Indexes from all rabbits in the repeat milk instillation group remained elevated for 12 days or longer. This group also developed increased numbers of binucleated macrophages. Quantitation of LLM in this model appears to be a sensitive indicator of recurrent lipid aspiration, these cells remaining in the airways for several days after the last aspiration event.
Lung function measurements in awake compared to sleeping newborn infants
Authors: Lødrup K. C. , Mowinckel P. , Carlsen K. H. 
Published: March 2007

AbstractTidal breathing flow‐volume loops were recorded in 19 healthy newborn infants when awake and asleep. This preceded and followed measurements of passive lung mechanics (by single breath occlusion). Our aim was to evaluate possible differences in lung function due to state of arousal or any influence of the occlusion technique. Expiratory volumes and flow rates were larger in awake than in sleeping infants before, but not after occlusion measurements. In sleeping, but not in awake infants, expiratory volumes and flow rates were higher after occlusion than before. Respiratory system compliance was significantly larger in sleeping than awake infants, while differences in respiratory system resistance and airway plateu pressure did not reach a significant level. Our results show that lung function can be measured in awake as well as sleeping infants, but differs significantly according to their arousal state, and whether tidal expiratory flow measurements are performed before or after airway occlusion measurements. Separate reference values for awake and sleeping infants may, therefore, be required. Marked intrasubject variability was found in the occlusion measurements, and criteria for acceptable measurements need to be defined.
Estimation of arterial carbon dioxide by end‐tidal and transcutaneous P measurements in ventilated children
Authors: Sivan Yakov , Eldadah Maher K. , Cheah Teik‐ee , Newth Christopher J. L. 
Published: March 2007

AbstractSimultaneous measurements of arterial, end‐tidal, and transcutaneous carbon dioxide (Pa, Pet, Ptc, respectively) were obtained in 134 children receiving mechanical ventilation (ages, 2 days to 16 years; mean, 2.5 years). The mean ± SD Pet± bias (Pa − Pet) was 3.4 ± 6.6 mmHg. When the Pet bias was plotted against the Pa/P ratio, a change in the scatter was obvious at about 0.3. The Pet bias for patients with Pa/P under 0.3 was 7.8 ± 7.3 mmHg compared to 0 ± 3.4 in patients with Pa/P above 0.3 (P < 0.001). Pet differed significantly from Pa (P < 0.001) only for patients with Pa/P under 0.3. The slope (Pa versus Pet) for these patients was 1.59, while the slope for patients with Pa/P above 0.3 coincided with the line of identity (1.00). The mean ± SD Ptc bias (Pa − Ptc) was − 1.3 ± 7.2 mmHg. Skin perfusion was recorded at the area close to the transcutaneous CO2 monitor electrode and was defined as normal when capillary refill was below 3 seconds. The Ptc bias for patients with normal skin perfusion was −0.2 ± 5.4 mmHg (P = 0.73) compared to −4.1 ± 9.9 for patients with decreased skin perfusion (P = 0.01). The slope of Ptc against Pa was closer to identity in patients with normal skin perfusion (1.17) than in patients where it was decreased (slope, 1.40). We suggest that Pa estimation by both Pet and Ptc is sufficiently precise and reliable for clinical use in critically ill children. Certain limitations stem from the nature of the techniques. Measurement of alveolar to arterial O2 ratio may improve the precision of Pa estimation by capnography; assessment of skin perfusion is important in order to increase the accuracy of the transcutaneous method, especially in critically ill children.
Airway responsiveness in infants following bronchiolitis
Authors: Tepper Robert S. , Rosenberg David , Eigen Howard 
Published: March 2007

AbstractAirway responsiveness to inhaled methacholine was assessed in 18 infants, 4 and 10 months old, following bronchiolitis. Pulmonary function was measured from partial expiratory flow‐volume curves generated by the rapid compression technique. Sleeping infants inhaled increasing concentrations of methacholine until maximal expiratory flows at functional residual capacity (VmaxFRC) decreased by 30% or 2.5 mg/mL was inhaled. Airway responsiveness was quantitated by: 1) the threshold concentration (log TC) required to decrease VmaxFRC by 2 standard deviations from baseline; 2) the concentration required to decrease VmaxFRC by 30% (log PC30); and 3) the slope of the dose‐response curve between TC and PC30 (log SPC30). At both the first and second evaluation, the bronchiolitic infants had lower baseline VmaxFRC (% pred.) than 24 control infants. In addition, the bronchiolitic infants had heightened airway responsiveness compared to controls, demonstrating lower values for logTC and logPC30 and steeper slopes to their dose‐response curves (logSPC30). After accounting for the relationship between airway responsiveness and age, the occurrence of bronchiolitis was found to be a significant independent factor 10 months but not 4 months following bronchiolitis. The bronchiolitic infants did not demonstrate the decline in airway responsiveness with increasing age that occurs in normal infants. We conclude that infants exhibit heightened airway responsiveness following bronchiolitis. © 1992 Wiley‐Liss, Inc.
Prediction of the acute response to surfactant therapy by pulmonary function testing
Authors: Wallenbrock Mark A. , Sekar K. C. , Toubas Paul L. 
Published: March 2007

AbstractWe tested the hypothesis that pretreatment pulmonary function values would be predictive of the response to the synthetic pulmonary surfactant, Exosurf® (Burroughs Wellcome Co.) treatment of infants with respiratory distress syndrome (RDS). Pulmonary compliance and resistance were measured prior to Exosurf treatment in 40 infants with severe RDS. In 36 patients who survived for at least 24 hr the acute response to therapy was quantitated by calculated post‐treatment/pretreatment ratios of ventilator efficiency index (VEI) and arterial/alveolar oxygen tension ratios [Pa/A]. The values of these calculated response ratios 24 and 48 hr after treatment varied widely among individual patients. The magnitude of the response was not related to birthweight, gestational age, age at treatment, pretreatment VEI, pretreatment Pa/A, or pretreatment pulmonary compliance. However, the response to Exosurf as measured by improvements in Pa/A at 24 and 48 hr was related to pretreatment pulmonary resistance (r = −0.34, P < 0.05 and r = −0.60, P < 0.001), high pretreatment pulmonary resistance was associated with a poor response to Exosurf 24 and 48 hr after treatment. © 1992 Wiley‐Liss, Inc.
Nonbronchoscopic approach to bronchoalveolar lavage in children with artificial airways
Authors: Alpert Brad E. , O'Sullivan Brian P. , Panitch Howard B. 
Published: March 2007

AbstractBronchoalveolar lavage (BAL) performed with a fiberoptic bronchoscope (FOB) is a useful method for sampling alveolar contents. Since the smallest FOB with a channel has a diameter of 3.6 mm, BAL is difficult to accomplish through artificial airways (AA) < 5.0 mm I.D. We used a 4F balloon wedge pressure catheter to perform BAL through small AA. Supplemental O2 or ventilatory support was delivered via an adaptor through which the catheter was introduced. After it was passed distal to the AA, the balloon was inflated with normal saline (NS) to a predetermined volume, and advanced until resistance was felt. The balloon was deflated, advanced slightly, and then reinflated to achieve airway occlusion. Five aliquots of 0.75 mL/kg of NS were used for BAL. The procedure was performed in 20 children from 1 month (950 g) to 6½ years of age (median, 9 months). All specimens contained abundant alveolar macrophages, indicating good recovery of alveolar contents. Clinically significant information was obtained in 17 (85%) cases, and no patient required an open lung biopsy. In conclusion, nonbronchoscopic bronchoalveolar lavage is a valuable method for obtaining alveolar contents in children with small AA that preclude the use of an FOB, and it obviates the need for open lung biopsy in many patients. This technique could be used as a research tool for measuring constituents of alveolar contents in infants and small animals. © 1992 Wiley‐Liss, Inc.
Compact apparatus for measurement of ventilatory response to carbon dioxide in newborns and infants
Authors: Kobayashi Keiko , Katayama Masao , Miyasaka Katsuyuki 
Published: March 2007

AbstractWe developed a rebreathing system for measuring response to carbon dioxide (CO2) of newborns and infants for use at the bedside. The system based on Read's method is small, easy to operate, and includes a computer‐controlled gas switching sequence, computerized calculation, and display functions. © 1992 Wiley‐Liss, Inc.We measured the CO2 response in 11 infants with or without apnea, who were born at 26–33 weeks gestation and were 12 to 215 days old at the time of the study. Our results suggest that the presence of apnea in premature infants may correspond to a low CO2 response.The method was convenient for clinical use because it allowed an investigator to carry out bedside tests in only a few minutes. With our system we were able to assess respiratory center function in newborns and infants.
The effects of airway hyperresponsiveness, wheezing, and atopy on longitudinal pulmonary function in children: A 6‐year follow‐up study
Authors: Sherrill Duane , Sears Malcolm R. , Lebowitz Michael D. , Holdaway M. David , Hewitt Chris J. , Flannery Erin M. , Herbison G. Peter , Silva Phil A. 
Published: March 2007

AbstractWe examined growth of spirometric lung function in 696 children of European ancestry who were followed from ages 9 to 15 years and stratified according to their degree of responsiveness to methacholine inhalation challenge, atopic status, and respiratory symptoms. Subjects were participants in the longitudinal Multidisciplinary Health and Development Study in Dunedin, New Zealand. Forced expired volume in 1 second (FEV1), and vital capacity (VC) were measured at 9, 11, 13, and 15 years of age, concurrently with assessment of airway responsiveness determined by the concentration of methacholine causing a 20% fall in FEV1 (PC20 FEV1). Atopic status was assessed at age 13 by skin‐prick testing to 11 allergens. In children demonstrating airway hyperresponsiveness, FEV1 increased with age at a slower rate, and the FEV1/VC ratio had a faster rate of decline through childhood, compared to non‐responsive children. Subjects with positive skin tests to house dust mite and cat dander also had lower mean FEV1/VC ratios than the control group. Any reported wheezing was associated with slower growth of FEV1 and VC in males. We conclude that in New Zealand children with airway responsiveness and/or atopy to house dust mite or cat growth of spirometric lung function is impaired. © 1992 Wiley‐Liss, Inc.
A bench test evaluation of a neonatal closed tracheal suction system
Authors: Monaco Frank J. , Meredith Keith S. 
Published: March 2007

AbstractWe tested the hypothesis that a possible mechanism for reduced hypoxia during suctioning with closed tracheal suction systems (CTSS) is the provision of uninterrupted gas delivery and the maintenance of airway pressures. This was accomplished by using a neonatal ventilator and test lung model to permit the insertion of a CTSS (with and without suction applied), measurements of inspiratory and end‐expiratory airway pressures proximal and distal to the endotracheal tube (ETT) and measurements of inspired and expired tidal volumes (sampled distal to the ETT). An 8 Fr CTSS was evaluated with 4.5, 4.0, and 3.5 mm ETT, and a 6 Fr CTSS with a 3.5, 3.0, and 2.5 mm ETT. We found that catheter placement without suction caused no changes in proximal airway pressures but distal peak inspiratory pressures decreased as the relationship between suction catheter size and ETT lumen increased, while distal end‐expiratory pressures were unchanged. Similarly, distal tidal volumes progressively decreased as the size of the suction catheter occupied more of the ETT lumen. During suctioning with the 6 Fr catheter, proximal airway pressures were virtually unchanged; however, as ETT size decreased, distal airway pressures also decreased. The application of suction only modestly augmented the substantial decrement in measured tidal volumes when compared to catheter insertion alone. For the 8 Fr catheter, suction markedly reduced both proximal and distal airway pressures and tidal volumes. We conclude that the use of the CTSS tested in this neonatal ventilator/test lung model does not preserve continuity of volume or pressure delivery during suction procedures; therefore these cannot be the sole explanation for the reported reduction in suction related hypoxia. © 1992 Wiley‐Liss, Inc.
Spontaneous desaturations in intubated very low birth weight infants with acute and chronic lung disease
Authors: Durand Manuel , McEvoy Cindy , MacDonald Kelvin 
Published: March 2007

AbstractPatients with chronic lung disease (CLD) have frequent episodes of spontaneous desaturations. Utilizing computerized pulse oximetry (CPO) we quantified the frequency and severity of spontaneous desaturations in very low birth weight (VLBW) infants with CLD. Thirty‐four studies by CPO were performed in intubated infants for 4 hours; 17 patients (birth weight, 550–980 g; postnatal age 28–85 days) had CLD, and 17 (birth weight, 520–980 g; postnatal age, 1–7 days) had acute lung disease. Oxygen saturation (Sa) was measured with the Nellcor N‐200 oximeter, its serial output (updated once a second) captured by a computer. Pulse rate, pulse amplitude, and heart rate were also monitored continuously. We measured respiratory system mechanics in 23 patients. Tidal volume (VT), respiratory system compliance (Crs), and resistance (Rrs) were obtained by the PeDS system. Spontaneous desaturation to Sa < 90% occurred for 4.5% of the time in acute patients vs. 27.1% of the time in chronic patients (P < 0.0001); to Sa < 85%, 0.7% vs. 7.6% of the time in acute vs. chronic patients (P < 0.002); and to Sa < 80%, 0.4% vs. 2.6% of the time in acute vs. CLD patients (P < 0.05). Rrs was significantly higher in the ventilated patients with CLD (174 cmH2O/L/s) than in the ventilated patients with acute lung disease (94 cmH2O/L/s, P < 0.0001). The mean Crs values of the two groups were comparable. Our preliminary data indicate that VLBW infants with CLD receiving assisted ventilation have a greater number of spontaneous desaturation episodes, as compared to patients with acute lung disease. © 1992 Wiley‐Liss, Inc.
Evaluation of the multiple linear regression method to monitor respiratory mechanics in ventilated neonates and young children
Authors: Rousselot J. M. , Peslin R. , Duvivier C. 
Published: March 2007

AbstractA potentially useful method to monitor respiratory mechanics in artificially ventilated patients consists of analyzing the relationship between tracheal pressure (P), lung volume (V), and gas flow (\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^. $\end{document}) by multiple linear regression (MLR) using a suitable model. Contrary to other methods, it does not require any particular flow waveform and, therefore, may be used with any ventilator. This approach was evaluated in three neonates and seven young children admitted into an intensive care unit for respiratory disorders of various etiologies. P and V were measured and digitized at a sampling rate of 40 Hz for periods of 20–48 s. After correction of P for the non‐linear resistance of the endotracheal tube, the data were first analyzed with the usual linear monoalveolar model: P = PO + E.V + R.\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm V}\limits^. $ \end{document} where E and R are total respiratory elastance and resistance, and PO is the static recoil pressure at end‐expiration. A good fit of the model to the data was seen in five of ten children. PO, E, and R were reproducible within cycles, and consistent with the patient's age and condition; the data obtained with two ventilatory modes were highly correlated. In the five instances in which the simple model did not fit the data well, they were reanalyzed with more sophisticated models allowing for mechanical non‐homogeneity or for non‐linearity of R or E. While several models substantially improved the fit, physiologically meaningful results were only obtained when R was allowed to change with lung volume. We conclude that the MLR method is adequate to monitor respiratory mechanics, even when the usual model is inadequate. © 1992 Wiley‐Liss, Inc.