Abstract
In asthma elevated rates of exhaled breath temperature changes (Δe°T) and bronchial blood flow (Qaw) may be due to increased vascularity of the airway mucosa as a result of inflammation.We investigated the relationship of Δe°T with Qaw and airway inflammation as assessed by exhaled nitric oxide (NO). We also studied the anti-inflammatory and vasoactive effects of inhaled corticosteroid and β2-agonist.Δe°T was confirmed to be elevated (7.27 ± 0.6 Δ°C/s) in 19 asthmatic subjects (mean age ± SEM, 40 ± 6 yr; 6 male, FEV1 74 ± 6 % predicted) compared to 16 normal volunteers (4.23 ± 0.41 Δ°C/s, p < 0.01) (30 ± 2 yr) and was significantly increased after salbutamol inhalation in normal subjects (7.8 ± 0.6 Δ°C/ s, p < 0.05) but not in asthmatic patients. Qaw, measured using an acetylene dilution method was also elevated in patients with asthma compared to normal subjects (49.47 ± 2.06 and 31.56 ± 1.6 μl/ml/min p < 0.01) and correlated with exhaled NO (r = 0.57, p < 0.05) and Δe°T (r = 0.525, p < 0.05). In asthma patients, Qaw was reduced 30 minutes after the inhalation of budesonide 400 μg (21.0 ± 2.3 μl/ml/min, p < 0.05) but was not affected by salbutamol.Δe°T correlates with Qaw and exhaled NO in asthmatic patients and therefore may reflect airway inflammation, as confirmed by the rapid response to steroids.
Highlights
Age Sex (M/F) FEV1 (% predicted) Smokers Ex smokers Therapy: Inhaled β-drenergics Theophylline Inhaled steroids Oral steroids
In a recent study we have found that patients with asthma have higher increases of exhaled breath temperature (∆e°T) compared with normal subjects and that this is correlated to the concentration of exhaled nitric oxide (NO) [5]
Effect of budesonide and salbutamol inhalation Bronchial blood flow In asthmatic patients Qaw was significantly reduced 30 minutes after the inhalation of budesonide compared to baseline (53.0 ± 5.0 μl/ml/min and 21.3 ± 2.32 μl/ml/ min respectively, p < 0.05 Figure 4 Panel A) and returned to baseline levels at 60 minutes (52.6 ± 4.0 μl/ml/min)
Summary
Age (years) Sex (M/F) FEV1 (% predicted) Smokers Ex smokers Therapy: Inhaled β-drenergics Theophylline Inhaled steroids Oral steroids. 0 0 0 0 between airway inflammation as assessed by exhaled NO, with Qaw and ∆e°T measured non-invasively. Qaw is an expression of bronchial blood flow, whereas ∆e°T reflects the rate of temperature increase in the exhaled breath. We hypothesised that Qaw changes may contribute to the levels of ∆e°T and we studied their relationship considering that, potentially, minor changes of bronchial blood flow may not affect exhaled breath temperature. Because NO regulates bronchial vascular tone [9] and may increase bronchial blood flow [10,11] we measured its concentration in the exhaled breath as a marker of inflammation and we analysed its relationship with Qaw and ∆e°T. ∆e°T and bronchial blood flow (Qaw) were measured non-invasively allowing us to make repeated measurements and to study the interactions of these two markers and exhaled NO The measurement of Qaw is non-invasive and was standardised and adapted from a previously validated technique [12,13]. ∆e°T and bronchial blood flow (Qaw) were measured non-invasively allowing us to make repeated measurements and to study the interactions of these two markers and exhaled NO
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