Analysis of induced sputum to examine the effects of prednisone on airway inflammation in asthmatic subjects

Status asthmaticus

Despite improved understanding of the pathophysiology and treatment of asthma, significant morbidity and mortality exist for both the pediatric and adult patient. The critical care practitioner must understand the chronic as well as the acute nature of the condition in order to provide effective intervention. This article reviews the epidemiology and pathophysiology of asthma, clinical assessment, management principles, therapeutic modalities, and future approaches to the management of asthma.

Safety of one method of sputum induction in asthmatic subjects

To assess the safety of sputum induction in asthmatic subjects, we conducted a retrospective review of data from 351 sputum inductions in 78 subjects from our institution. The sputum induction protcol consisted of baseline FEV1, pretreatment with albuterol 180 micrograms, postbronchodilator spirometry 15 min later, the induction procedure itself (inhalation of 3% saline for 20 min), and postsputum induction spirometry. We found that sputum induction was usually well tolerated, although some subjects developed wheeze and dyspnea. Overall, 11 of the 78 subjects (14%) had a fall in FEV1 of > or = 20% from the postbronchodilator baseline ("excessive bronchoconstriction") during their first sputum induction (range: -20 to -69%); no subject developed refractory bronchoconstriction requiring hospitalization or emergency room treatment. Only one of the 54 subjects (1.9%) with a baseline prebronchodilator FEV1 > 80% had excessive bronchoconstriction, whereas 10 of the 24 subjects (42%) whose baseline FEV1 was < or = 80% predicted did so. The change in FEV1 during sputum induction was significantly correlated with the baseline prebronchodilator FEV1% predicted, the baseline postbronchodilator FEV1% predicted, the PC20 for methacholine, and the percentage of eosinophils in induced sputum. We conclude that 180 micrograms albuterol does not prevent excessive bronchoconstriction in all asthmatic subjects undergoing sputum induction, especially in asthmatic subjects with a low baseline FEV1. Pulmonary function should be monitored regularly during sputum induction in asthmatic subjects to monitor for excessive bronchoconstriction.

High-resolution computed tomography of airway changes after induced bronchoconstriction and bronchodilation in asthmatic volunteers

RATIONALE AND OBJECTIVES

We examined whether high-resolution computed tomography (HRCT) would detect and quantify induced airway changes in asthmatic volunteers.

METHODS

We performed pulmonary function tests and HRCT on eight asthmatic adults and two nonasthmatic control adults under three conditions: baseline, after methacholine inhalation, and after albuterol inhalation. Changes in pulmonary function, airway internal luminal diameter (AILD), and airway wall thickness (AWT) in the three conditions were compared.

RESULTS

After methacholine inhalation, pulmonary function showed significant airflow obstruction in the asthmatic volunteers compared with two nonasthmatic control volunteers. The median value for AILD decreased by 17% (p = .04). After subsequent inhalation of albuterol, pulmonary function improved to above the baseline levels in the eight asthmatic volunteers. The median value for AILD increased by 18% above the baseline value (p = .001). No changes in pulmonary function or AILD were seen in the two nonasthmatic volunteers. AWT did not change significantly in either the asthmatic or nonasthmatic volunteers after inhalation of methacholine or albuterol.

CONCLUSION

HRCT can quantify changes in the internal luminal diameter of asthmatic airways provoked by methacholine and albuterol inhalation.