Perception of bronchoconstriction in smokers with airflow limitation

Abstract

To our knowledge, no data have been provided as to whether and to what extent dynamic hyperinflation, through its deleterious effect on inspiratory muscle function, affects the perception of dyspnoea during induced bronchoconstriction in patients with chronic airflow obstruction. We hypothesized that dynamic hyperinflation accounts in part for the variability in dyspnoea during acute bronchoconstriction. We therefore studied 39 consecutive clinically stable patients whose pulmonary function data were as follows (% of predicted value): vital capacity (VC), 97.8% (S.D. 16.0%); functional residual capacity, 105.0% (18.8%); actual forced expiratory volume in 1 s (FEV(1))/VC ratio, 56.1% (6.3%). Perception of dyspnoea using the Borg scale was assessed during a methacholine-induced fall in FEV(1). The clinical score and the treatment score, the level of bronchial hyper-responsiveness and the cytological sputum differential count were also assessed. In each patient, the percentage fall in FEV(1) and the concurrent Borg rating were linearly related, with the mean slope (PD slope) being 0.09 (0.06). The percentage fall in FEV(1) accounted for between 41% and 94% of the variation in the Borg score. At a 20% fall in FEV(1), the decrease in inspiratory capacity (Delta IC) was 0.156 (0.050) litres. Patients were divided into three subgroups according to the PD slope (arbitrary units/% fall in FEV(1)): subgroup I [eight hypoperceivers; PD slope 0.026 (0.005)], subgroup II [26 moderate perceivers; 0.090 (0.037)] and subgroup III [five hyperperceivers; 0.200 (0.044)]. By applying stepwise multiple regression analysis with the PD slope as the dependent variable, and other characteristics (demographic, clinical and functional characteristics, smoking history, level of bronchial hyper-responsiveness and sputum cytological profile) as independent variables, Delta IC (r(2)=45%, P<0.00001) and to a lesser extent treatment score (r(2)=17.3%, P<0.0006), and to an even lesser extent age (r(2)=3%, P<0.05), independently predicted a substantial amount (r(2)=65.27%, P<0.00001) of the variability in the Borg slope. Thus acute hyperinflation, and to a lesser extent treatment score and age, account in part for the variability in the perception of dyspnoea after accounting for changes in FEV(1) during bronchoconstriction in patients with chronic airflow obstruction.

Smoking Affects Response to Inhaled Corticosteroids or Leukotriene Receptor Antagonists in Asthma

“…These findings are consistent with previous studies that have described worse clinical status in subjects with asthma who smoke (8,16,17). Although several studies have reported that smokers with chronic airflow obstruction have fewer symptoms with induced bronchoconstriction than patients with asthma with similar obstruction (49,50), perhaps due to depletion of neurotransmitters from sensory nerves (50), the ability to perceive induced bronchoconstriction could not be predicted by smoking history (49). Taken together, these data demonstrate that laboratory-based testing does not capture the impact of cigarette smoking on disease severity in asthma such as is captured by daily symptom diaries and quality-of-life measures.…”

Relation between inflammation and symptoms in asthma

“…Asthmatic smokers or nonsmokers had variable perception without relationship with bronchial inflammation (114). The data of Ottanelli et al (110) do not seem to show that neutrophils in the sputum have an important independent effect on the perception of bronchoconstriction by patients with permanent bronchial obstruction.…”

“…The perception of dyspnoea is abnormal in COPD, but the situation seems to be different from that observed in asthma (108,109). Ottanelli et al (110) suggested that tobacco has an effect on abnormal perception associated with the sputum neutrophilia, which is often observed during persistent obstruction in severe asthma and smoker COPD (111)(112)(113). Asthmatic smokers or nonsmokers had variable perception without relationship with bronchial inflammation (114).…”

Psychological Co-morbidities of Physical Illness

“…The diagnosis of COPD is based upon data from medical history, physical examination, and results from pulmonary function testing (Kumar & Gross, 2002). One barrier to accurate diagnosis in older patients is that age seems to reduce the perception of bronchoconstriction leading to less reporting of milder symptoms and thus underdiagnosis (Ottanelli et al, 2001).…”