Bronchodilator responsiveness assessed by forced oscillometry and multiple breath washout techniques in preschool children.

IMPORTANCE: The forced oscillation (FOT) and multiple breath washout (MBW) techniques are passive tests of lung function, and are reliable for preschool-age children. There has not been comparison testing to determine which test could more accurately differentiate between healthy controls and poorly controlled asthmatics, or differentiate a response to bronchodilator administration. OBJECTIVE: To determine whether the MBW and/or FOT could differentiate between healthy controls and poorly controlled asthmatics, and whether the two tests could detect a response to bronchodilator administration. METHODS: Twenty-eight healthy controls and 23 poorly controlled asthmatics 3-6 years of age participated. All subjects were administered the MBW followed by the FOT. A bronchodilator was then administered and testing was repeated. Wilcoxon Rank Sum tests were used to compare the difference between healthy controls and poorly controlled asthmatics. Wilcoxon Signed Rank tests were used to compare the pre- and post-bronchodilator values. RESULTS: Neither MBW nor FOT differentiated healthy controls from poorly controlled asthmatics (pre-bronchodilator data); both groups had similar baseline gas mixing and airway mechanics. There was no improvement in any MBW outcomes post-bronchodilator administration. FOT detected a significant and similar degree of improvement in the airway mechanics in both groups. INTERPRETATION: Neither MBW nor FOT differentiated between poorly controlled asthmatics (when well) and healthy controls. MBW did not detect a significant bronchodilator response in either subject group, whereas FOT detected a similar degree of bronchodilator responsiveness in both groups. This discrepancy may reflect differential changes in airway mechanics and gas mixing properties in response to bronchodilators.

Tracheobronchomalacia Is Associated with Increased Morbidity in Bronchopulmonary Dysplasia.

RATIONALE: Tracheobronchomalacia is a common comorbidity in neonates with bronchopulmonary dysplasia. However, the effect of tracheobronchomalacia on the clinical course of bronchopulmonary dysplasia is not well-understood. OBJECTIVE: We sought to assess the impact of tracheobronchomalacia on outcomes in neonates with bronchopulmonary dysplasia in a large, multi-center cohort. METHODS: We preformed a cohort study of 974 neonates with bronchopulmonary dysplasia admitted to 27 neonatal intensive care units participating in the Children's Hospital Neonatal Database who had undergone bronchoscopy. In hospital morbidity for neonates with bronchopulmonary dysplasia and tracheobronchomalacia (N=353, 36.2%) was compared to those without tracheobronchomalacia (N=621, 63.8%) using mixed-effects multivariate regression. RESULTS: Neonates with tracheobronchomalacia and bronchopulmonary dysplasia had more comorbidities, such as gastroesophageal reflux (OR=1.65, 95%CI 1.23- 2.29, P=0.001) and pneumonia (OR=1.68, 95%CI 1.21-2.33, P=0.002) and more commonly required surgeries such as tracheostomy (OR=1.55, 95%CI 1.15-2.11, P=0.005) and gastrostomy (OR=1.38, 95%CI 1.03-1.85, P=0.03) compared with those without tracheobronchomalacia. Neonates with tracheobronchomalacia were hospitalitized (118 ± 93 vs 105 ± 83 days, P=0.02) and ventilated (83.1 ± 91.1 vs 67.2 ± 71.9 days, P=0.003) longer than those without tracheobronchomalacia. Upon discharge, neonates with tracheobronchomalacia and BPD were more likely to be mechanically ventilated (OR=1.37, 95CI 1.01-1.87 P=0.045) and possibly less likely to receive oral nutrition (OR=0.69, 95%CI 0.47-1.01, P=0.058). CONCLUSIONS: Tracheobronchomalacia is common in neonates with bronchopulmonary dysplasia who undergo bronchoscopy and is associated with longer and more complicated hospitalizations.