The aim of this prospective study of a population of children (age, 2-15 years) hospitalized for severe asthma was to test them for acute infection due to Mycoplasma pneumoniae and acute infection due to Chlamydia pneumoniae. Of 119 patients with previously diagnosed asthma, acute M. pneumoniae infection was found in 24 (20%) and C. pneumoniae infection was found in 4 (3.4%) of the patients during the current exacerbation. Of 51 patients experiencing their first asthma attack, acute M. pneumoniae infection was proven in 26 (50%) of the patients (P<.01) and C. pneumoniae in 4 (8.3%). In the control group of 152 children with stable asthma or rhinitis, 8 (5.2%) had M. pneumoniae infection (P<.005). Of the 29 patients experiencing their first asthma attack and infected with M. pneumoniae or C. pneumoniae, 18 (62%) had asthma recurrences but only 6 (27%) of the 22 patients who did not have such infections had asthma recurrences (P<.05). M. pneumoniae may play a role in the onset of asthma in predisposed children and could be a trigger for recurrent wheezing.

Inspiratory muscle strength is an important variable in patients with neuromuscular or skeletal disorders. It is usually assessed by measuring maximal inspiratory pressure (PI(max)), but this test may prove difficult for some patients, and low values may originate from incomplete effort or air leaks. We assessed the usefulness of the novel sniff nasal pressure (Pn(sn)) test in 126 patients with a neuromuscular or a skeletal disorder, aged 5 to 49 yr. Pn(sn) was measured in an occluded nostril during maximal sniffs performed through the contralateral nostril. All patients performed the Pn(sn) maneuver easily, whereas 10 young and weak patients with neuromuscular disorders could not perform the PI(max) maneuver. Data were analyzed for the 116 patients who could perform both tests (92 patients with neuromuscular and 24 with skeletal disorders). When expressed as percents of the predicted values, Pn(sn) was similar to PI(max) in patients with neuromuscular disorders (54 +/- 25% predicted [mean +/- SD] versus 52 +/- 24% predicted), and was higher than PI(max) in patients with skeletal disorders (70 +/- 25% predicted versus 61 +/- 27% predicted, p < 0.05). Pn(sn) appeared to be the main determinant of VC in patients with neuromuscular disorders, whereas the Cobb angle and PI(max) were the main determinants of VC in patients with skeletal disorders. We conclude that inspiratory muscle strength can be easily assessed with Pn(sn) in children and adults with various neuromuscular and skeletal disorders. This new muscular parameter appears particularly useful in neuromuscular disorders, in which it represents a major determinant of VC.

Pulmonary function tests are seldom performed in preschool children with asthma. The aim of this multicenter study was to compare pulmonary function in 74 preschool children with asthma (height of 90-130 cm) and 84 healthy control subjects. Functional residual capacity (helium dilution technique) and expiratory interrupter resistance (interrupter technique) were measured. As compared with control children, children with asthma had a significantly higher resistance (0.77 +/- 0.20 vs. 0.92 +/- 0.22 kPa. L-1. second, p < 0.001) and significantly lower specific expiratory interrupter conductance (p < 0.005) values. Resistance values were significantly higher in children with asthma with than without symptoms on exertion (p < 0.05). The effect of bronchodilator administration, expressed as the percentage of baseline and predicted resistance values, was significantly greater in children with asthma than in control subjects (-18.6 +/- 13.6% vs. -11.2 +/- 15.2%, p