Exercise intolerance in cystic fibrosis (CF) is attributed to diminished nutritional and pulmonary function. We studied the pathophysiology of such intolerance in relation to muscle force and fat-free mass (FFM), in 15 children with moderately severe symptoms of CF (FEV1 < 80% predicted and/or weight for age < -1 SD of reference median), 13 children with mild symptoms of CF (FEV1 and weight above these thresholds), and 13 healthy controls. Cycle maximal workload (Wmax) and V O2max were assessed. Maximal peripheral muscle force was measured, and FFM was calculated from skinfolds. Patients with mild CF, as compared with matched controls, had lower values of Wmax per kilogram of FFM (3.9 +/- 0.5 versus 4.6 +/- 0.3 W/kg [mean +/- SD], respectively; difference = 0.7 [95% CI = 0.4 to 1.1]), and diminished maximal muscle force (2.7 +/- 0.4 kN versus 3.1 +/- 0.7 kN; difference = 0.44 [95% CI = 0.03 to 0.87]), but similar V O2max. Patients with moderate CF had lower FFM, muscle force, and exercise tolerance than did the other groups. Oxygen cost of work was elevated in both groups of CF patients. Muscle force showed a strong positive correlation with Wmax in patients and controls, with disproportionately lower regression slopes in the CF patients. In children with CF, muscle force is decreased and associated with diminished maximal work load, even in the absence of diminished pulmonary or nutritional status.

The impulse oscillometry system (IOS) was introduced as a new technique to assess airflow obstruction in patients who are not able to perform forced breathing maneuvers, e.g., subjects with cerebral palsy or severe mental retardation, and young children. This study evaluates the sensitivity and specificity of IOS parameters to quantify changes in airflow obstruction in comparison with forced expiratory volume in the first second (FEV(1)) and peak expiratory flow (PEF) measurements. Measurements of FEV(1), PEF, and resistance (R) and reactance (X) at frequencies of 5-35 Hz were performed in 19 children with asthma before, during, and after methacholine challenge and subsequent bronchodilatation. All parameters changed significantly during tests. Values of R5 and R10 correlated with FEV(1) (r = -0.71 and -0.73, respectively, P < 0.001), as did values of X5 and X10 (r = 0.52 and 0.57, respectively, P < 0.01). Changes in R preceded changes in PEF and FEV(1) during methacholine challenge. The area under the receiver operating characteristic (ROC) curve to predict a 15% fall in FEV(1) showed better sensitivity and specificity for R5 (area under the curve, 0.85) compared to PEF (0.79) or R10 (0.73). We conclude that IOS parameters can be easily used as an indirect measure of airflow obstruction. This might be helpful in patients who are not able to perform forced breathing maneuvers. In individual subjects, R values measured at 5 Hz showed to be superior to PEF measurements in the detection of a 15% fall in FEV(1).

Background The increase in the prevalence of allergic diseases in countries with a so-called western lifestyle may be due to a decrease in exposure to infectious agents in early life. Objective To establish the effect of Bacille-Calmette-Guerin (BCG) vaccination in 6-week-old high-risk infants in a prospective single-blind, randomized, placebo-controlled trial on the prevalence of allergic disease at the age of 4 and 18 months. Methods Subjects were 121 predominantly Caucasian high-risk newborns, having either a mother, or both a father and at least one sibling with past or present allergic disease. BCG or placebo was administered at the age of 6 weeks, and repeated once when both a post-vaccination scar and a positive TB skin test were absent at the age of 4 months. Results At the age of 18 months, the prevalence of allergic disease was not significantly different between the two groups. A trend towards less eczema (P = 0.07) and significantly less use of medication for eczema was shown in the BCG group compared with the placebo group (P = 0.04). Conclusion A single (or once repeated) BCG vaccination in 6-week-old high-risk Caucasian infants was not associated with a 50% reduction in the prevalence of allergic disease. However, there could be a smaller beneficial effect of BCG, especially because a trend towards less eczema and significantly less use of medication for eczema was shown. For definite proof, a larger study should be carried out.

This study was designed to evaluate the value and applicability of tidal breathing pattern analysis to assess airflow obstruction in young children. The time needed to reach maximal tidal expiratory flow (TME) divided by total expiratory time (TE) was measured in 228 healthy children 3 to 11 yr of age, 64 patients with asthma, and 12 children with cystic fibrosis. In 70 patients both TME/TE and forced maximal expiratory flow volume (MEFV) parameters were measured. The mean TME/TE in healthy subjects was 43.0 +/- 7.6%. The within-subject reproducibility was high (repeatability index, 5.3%). In the asthmatic patients the mean TME/TE was significantly lower (30.0 +/- 8.2%, p < 0.001), and it increased to 36.5 +/- 7.9% after bronchodilation (n = 44, p < 0.001). The TME/TE level of the subgroup of patients with asthma and FEV1/FVC > or = 0.80 was lower when compared with age-matched normal subjects (30.9 +/- 8.5, p < 0.0001), but it was in a higher range when compared with asthmatics with FEV1/FVC < 0.80 (25.9 +/- 7.9, p < 0.001). In the cystic fibrosis group the mean TME/TE was 27.4 +/- 10.7% without a significant change after bronchodilation. TME/TE correlated significantly with MEFV parameters. Tidal breathing analysis proved easy to perform in children older than 3 yr of age. The TME/TE ratio may be a reliable and simple indicator for airway obstruction.