Small airway disease in chronic obstructive pulmonary disease: insights and implications for the clinician.

PURPOSE OF REVIEW: Small airway disease (SAD) is a common feature in chronic obstructive pulmonary disease (COPD) patients. Chronic exposure to cigarette smoking causes inflammation, damage, tissue remodelling and eventually airway loss. These features lead to airflow limitation and defective alveolar ventilation. The aim of this review is to provide clinicians with an up-to-date perspective of SAD in COPD. RECENT FINDINGS: In this review, we will discuss the key pathological features of SAD. We also review state-of-the-art techniques for measuring SAD, including impulse oscillometry and lung imaging methods. We discuss emerging concepts such as SAD in the earlier stages of COPD and the relationship between SAD and emphysema. SUMMARY: The current review highlights the importance of targeting small airways early in the course of COPD to tackle disease progression.

Effect of airway acidosis and alkalosis on airway vascular smooth muscle responsiveness to albuterol.

BACKGROUND: In vitro and animal experiments have shown that the transport and signaling of ß2-adrenergic agonists are pH-sensitive. Inhaled albuterol, a hydrophilic ß2-adrenergic agonist, is widely used for the treatment of obstructive airway diseases. Acute exacerbations of obstructive airway diseases can be associated with changes in ventilation leading to either respiratory acidosis or alkalosis thereby affecting albuterol responsiveness in the airway. The purpose of this study was to determine if airway pH has an effect on albuterol-induced vasodilation in the airway. METHODS: Ten healthy volunteers performed the following respiratory maneuvers: quiet breathing, hypocapnic hyperventilation, hypercapnic hyperventilation, and eucapnic hyperventilation (to dissociate the effect of pH from the effect of ventilation). During these breathing maneuvers, exhaled breath condensate (EBC) pH and airway blood flow response to inhaled albuterol (ΔQ̇aw) were assessed. RESULTS: Mean ± SE EBC pH (units) and ΔQ̇aw (µl.min(-1).mL(-1)) were 6.4 ± 0.1 and 16.8 ± 1.9 during quiet breathing, 6.3 ± 0.1 and 14.5 ± 2.4 during eucapnic hyperventilation, 6.6 ± 0.2 and -0.2 ± 1.8 during hypocapnic hyperventilation (p = 0.02 and <0.01 vs. quiet breathing), and 5.9 ± 0.1 and 2.0 ± 1.5 during hypercapnic hyperventilation (p = 0.02 and <0.02 vs quiet breathing). CONCLUSIONS: Albuterol responsiveness in the airway as assessed by ΔQ̇aw is pH sensitive. The breathing maneuver associated with decreased and increased EBC pH both resulted in a decreased responsiveness independent of the level of ventilation. These findings suggest an attenuated response to hydrophilic ß2-adrenergic agonists during airway disease exacerbations associated with changes in pH. TRIAL REGISTRATION: Registered at clinicaltrials.gov: NCT01216748 .

The impact of sugar cane-burning emissions on the respiratory system of children and the elderly.

We analyzed the influence of emissions from burning sugar cane on the respiratory system during almost 1 year in the city of Piracicaba in southeast Brazil. From April 1997 through March 1998, samples of inhalable particles were collected, separated into fine and coarse particulate mode, and analyzed for black carbon and tracer elements. At the same time, we examined daily records of children (<13 years of age) and elderly people (>64 years of age) admitted to the hospital because of respiratory diseases. Generalized linear models were adopted with natural cubic splines to control for season and linear terms to control for weather. Analyses were carried out for the entire period, as well as for burning and nonburning periods. Additional models were built using three factors obtained from factor analysis instead of particles or tracer elements. Increases of 10.2 microg/m3 in particles