Changes In Bronchoconstriction Research Articles

Bronchoprotective effect of deep inspirations in cough variant asthma: A distinguishing feature in the spectrum of airway disease?

PurposeTo assess the effect of deep inspirations (DIs) on airway behaviour in individuals with classic asthma (CA), cough variant asthma (CVA), and methacholine (MCh)-induced cough but normal airway sensitivity (COUGH) during bronchoprovocation. MethodsTwenty-five adults (18 female; 44.8 ± 12.3 years (Mean ± SD); n = 9 CA, n = 9 CVA, and n = 7 COUGH) completed two single-dose MCh challenges, with and without DIs. Bronchoprotection was assessed by comparing changes in bronchoconstriction (FEV1, FVC, FEV1/FVC, FEF50, FEF25-75), gas trapping (RV, RV/TLC) and impulse oscillometry (IOS) measurements. ResultsThe% changes in FEV1 with and without DIs were not significantly different within any group. Decreases in FEF50 and FEF25-75 were greater in CA (p = 0.041 and p = 0.029), decreases in FVC (% predicted) and FEV1/FVC(%) were less in CVA (p = 0.048 and p = 0.010), and increases in RV (L) and RV/TLC (% predicted) were less in COUGH (p = 0.007 and p = 0.028), respectively. No differences in IOS measurements were noted. ConclusionsDIs triggered bronchoconstriction in CA, bronchoprotection in CVA, and prevented gas trapping in COUGH.

Thorax and Abdomen Motion Analysis in Patients with Obstructive Diseases

Objective: We evaluated changes in bronchoconstriction by a new approach based on respiratory inductive plethysmography (RIP) signal analysis. Methods: Thoracic and abdominal motions were recorded (5 min) by uncalibrated RIP in 44 adult subjects with a diagnosis of moderate bronchial obstruction (Obstructive group) and 50 healthy adult controls (Healthy group). In the Obstructive group, two series of measurements were performed before (Obstructive PRE) and after (Obstructive POST) a bronchodilation protocol. Airway resistance (Raw) and lung function data (forced vital capacity (FVC), forced expiratory volume in one second (FEV1 ) and FEV1 /FVC) were measured with a body plethysmograph. A breath-bybreath analysis was performed to calculate distances between normalized thorax and abdomen RIP signals and a mean distance (D) was calculated for each recording. Results: D and Raw were higher in the Obstructive group than in the Healthy group in both PRE and POST conditions. Both D and Raw significantly decreased after bronchodilation in the Obstructive group. D and Raw were also positively and significantly correlated in the Obstructive group in both PRE and POST conditions. Conclusion: D, as calculated from signals recorded by RIP, appears to be a useful non-invasive parameter for continuous monitoring of changes in bronchoconstriction.

Acute changes in bronchoconstriction influences exhaled nitric oxide level.

In previous studies the exhaled nitric oxide (NO) level of asthma patients was investigated only in association with bronchial inflammation, and whether the degree of bronchoconstriction itself influences the exhaled NO level has never been investigated. We therefore evaluated the effect of inhalation of a bronchoconstrictor (methacholine) or a bronchodilator (salbutamol) on the exhaled NO level of healthy volunteers and asthma patients. The exhaled NO level of the healthy volunteers decreased after methacholine inhalation. The exhaled NO level of patients with mild or moderate persistent asthma, who had no asthma attacks on the day of measurement, increased after salbutamol inhalation, and the exhaled NO level of asthma patients during asthma attacks increased after salbutamol inhalation followed by intravenous drip infusion of aminophylline. It is suspected that large amounts of NO are trapped in the lung distal to the constricted airway, contributing little to the exhaled NO level at the mouth. However, we expect that the trapped NO is exhaled at a larger fraction after the dilatation of the constricted small airway, thereby increasing the exhaled NO level at the mouth. In conclusion, the results of this study suggest that acute changes in bronchoconstriction themselves influence the exhaled NO level independently of the change in NO synthase activity associated with airway inflammation.

Vagal stimulation and aerosol histamine increase hysteresis of lung recoil

Bronchoconstriction changes pulmonary resistance and dynamic compliance by altering both airway properties and dynamic lung tissue recoil. To assess the contribution of recoil, we measured transpulmonary pressure in anesthetized open-chest dogs during sinusoidal ventilation with gas flow and during sinusoidal compression of intrapulmonary gas without flow. Measurements with gas flow characterized total pulmonary behavior, including the contribution of gas flow in airways, whereas measurements during gas compression characterized lung tissue recoil alone. Histamine aerosol produced a 54% decrease in dynamic compliance, a 465% increase in total pulmonary resistance, and a 153% increase in pressure-volume hysteresis of dynamic recoil. Vagal stimulation produced a 31% decrease in dynamic compliance, a 135% increase in total pulmonary resistance, an 82% increase in the hysteresis of recoil, and a 15% increase in mean recoil pressure. At slow oscillation frequencies (0.2 Hz) and high transpulmonary pressures (10 cmH2O), hysteresis of lung recoil contributes substantially to total pulmonary resistance, and changes in dynamic lung recoil can account for much (35%) of the increase in pulmonary resistance seen with bronchoconstriction.