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Multi-center studies provide advantages in clinical research but differences between centers can introduce bias. Three specialist pediatric respiratory laboratories standardized their methodology and examined differences between centers. The specific aims were to (i) assess the variability of measurements on adults within and between centers and (ii) to exchange and cross-analyze data from children to assess the extent of agreement between centers. Each laboratory used identical equipment and software. Inter-laboratory visits were used to (i) standardize protocols for data collection and analysis and (ii) make spirometric and plethysmographic measurements on participating staff at each location. Staff also had repeat measurements in their home laboratories. Measurements from children in each laboratory were exchanged on disk, cross-analyzed, and data compared by ANOVA. There were no significant within-subject, between-center differences in FVC, FEV1, FEF50, FRCpleth, or VC. There was a slight trend for TLC and RV (P=0.07) to be higher at one center. The 95% limits of agreement within and between centers were similar for all parameters. There were no differences between centers in cross-analyzed data from 10 children. By standardizing hardware, software, and protocol, potential inter-laboratory differences can be minimized. We recommend that this approach be adopted prior to multi-center studies., ((c) 2006 Wiley-Liss, Inc.)

Pneumomediastinum is uncommon in pediatric medical practice, outside the neonatal period. While asthma or respiratory infections are the most frequent underlying causes, it is important not to forget the possibility of foreign body aspiration, particularly after the clinical presentation., (Copyright 2003 Wiley-Liss, Inc.)

Cough is common in childhood, resulting in significant morbidity and frequent medical consultation. Despite this, little is known about the frequency or development of cough, particularly in infants and young children. Recent progress in monitoring has enabled cough to be measured objectively both day and night. However, to date, objective measurement has only been used in adults and older children. The aim of this study was to see whether such methods could be extended to allow objective cough monitoring in infants. Thirty infants were recruited: 13 with coughing illnesses (group 1), and 17 normal, healthy babies (group 2) born to nonatopic, nonsmoking parents. Group 2 infants were studied when well, several times in the first year of life. Coughs were recorded using an adapted commercial cough monitor (Logan Research LR100) and simultaneous infrared video and sound recording. Thirty-eight recordings with simultaneous cough monitor and video data were analyzed: 9 from group 1, and 29 from group 2. Overall, the sensitivity of the monitor when compared to video was 81%, with a positive predictive value of 0.8. There was good agreement between the two methods for infants with infrequent cough (<5 coughs per hour). Agreement in infants with more frequent cough was not as good, because more coughs were consistently identified by the cough monitor. The portability and small size of the cough monitor made it easy to use, although there were difficulties in keeping the leads attached in older, more mobile infants. In conclusion, objective assessment of cough is practical in infants, enabling the pattern of cough in illness and in health to be studied further., (Copyright 2003 Wiley-Liss, Inc.)

The correlation between digital clubbing and certain pulmonary function derangements (hypoxemia and FEV(1)) was previously described. However, the relationship between digital clubbing and other measures of pulmonary function or the presence of liver disease in patients with cystic fibrosis (CF) is poorly defined. Hence we compared the digital clubbing index (CI: ratio of distal phalangeal depth to interphalangeal depth) of 100 patients with CF (43 males, 57 females; mean age, 15.7 +/- 7.3 years) with that of 100 age- and gender-matched healthy controls. Digital clubbing was defined as a CI > or = 1.00 (mean + 2.6 SD; 99% of normal subjects). The CI and its relationship to pulmonary function and to liver disease was then evaluated in the CF patients. Digital clubbing was present in 75/100 (75%) of CF patients but was absent in all controls (P < 0.0001). In CF patients, CI was inversely correlated with PaO(2) (r = -0.555; P < 0.001), FEV(1) (r = -0.499; P < 0.001), and FEF(25-75%) (r = -0.404; P < 0.001), and was positively correlated with RV (r = 0.285; P < 0.05) and the slope of phase 3 of single-breath nitrogen washout (SP3N(2)) (r = 0.532; P < 0.01). There was no significant correlation between CI and age (r = 0.020; P = 0.84), TLC (r = -0.097; P = 0.34), PaCO(2) (r = 0.167; P = 0.10), or history of liver disease (P = 0.08). We conclude that in CF, the degree of digital clubbing is related to degree of hypoxemia, airways obstruction, hyperinflation, and nonuniformity of ventilation.

Asthmatic athletes (adults and junior) have competed successfully at the highest level for many years assisted by pre-event medication with beta 2-agonists. To examine the impact of beta 2-agonists upon submaximal running economy (oxygen consumption at a given submaximal work load), we studied 10 nonasthmatic boys (age, 10.4 +/- 0.48 years, mean +/- SD). They each completed submaximal (speeds, 7.2, 8.0 and 8.8 km/hr) and peak treadmill running protocols preceded by treatment with beta 2-agonist (terbutaline, 500 micrograms via nebuhaler) or placebo in a randomized, crossover single-blind study. No significant differences were found between running economy and heart rate during the submaximal exercise tests or between peak oxygen consumption (VO2), peak respiratory exchange ratio, peak heart rate (HR), or total running time during the peak VO2 test. Pretreatment with terbutaline did produce small but nonsignificant increases in aerobic fractional utilization (percent peak VO2 on drug: 65.9%, 72.6%, and 76.7% vs. placebo: 65.1%, 70%, and 75.5%), at the three submaximal work loads. Respiratory exchange ratio (RER) values were elevated throughout the submaximal tests (on drug: 0.94, 0.93, and 0.94 vs placebo: 0.91, 0.92, and 0.91, P < 0.05). No significant differences were found between drug and placebo for minute ventilation (VE) and ventilatory equivalent for oxygen (VE/VO2), at both submaximal and peak exercise intensities.(ABSTRACT TRUNCATED AT 250 WORDS)

Digital clubbing and pulmonary function tests were measured in children, adolescents, and adults with chronic lung diseases to determine pulmonary function correlates with a quantitative measure of clubbing. The group had a mean age of 13.8 +/- 6.0 (SD) years, mean PaO2 of 81 +/- 21 mm Hg, and mean FEV1 of 60% +/- 26% predicted. Digital clubbing was diagnosed in 43 cases when the distal phalangeal depth to interphalangeal depth (DPD/IPD) ratio, measured on a finger cast, was greater than or equal to 1 (greater than 3 SD above mean from 85 controls; no history of pulmonary disease; mean age, 14.8 +/- 7.6). The PaO2 of patients with digital clubbing was 69.4 +/- 2.1 (SEM) mm Hg compared with 88.3 +/- 1.3 mm Hg in those without digital clubbing (P less than 0.0001). Digital clubbing was present in 39 of the 84 (46%) hypoxic patients (PaO2 less than or equal to 88) but only four of the 78 (5%) normoxic patients (P less than 0.0001). The DPD/IPD ratio was negatively correlated with PaO2 in subjects with cystic fibrosis and interstitial fibrosis. Weak negative correlations were seen for all other subjects except asthmatics. Overall, the DPD/IPD ratio was significantly correlated with PaO2 (r = -0.53; P less than 0.0001). The DPD/IPD ratio was correlated with other lung function abnormalities (increased RV, decreased FEV1, and FEF25%-75%) only for the subjects with cystic fibrosis. We conclude that digital clubbing is associated with hypoxemia and airway obstruction. The relation is seen most clearly in subjects with cystic fibrosis, possibly reflecting the prolonged duration of hypoxemia. Digital clubbing is rarely seen in normoxic subjects.