Acute Effect of Bronchodilator on Intrathoracic Airway Wall Compliance in COPD Patients

Abstract

Purpose In patients with chronic obstructive pulmonary disease (COPD), bronchial responsiveness after acute administration of short acting bronchodilators is conventionally assessed by measuring the improvement of forced expiratory volume in the first second (FEV1) during a maximal forced expiratory maneuver. This study aimed to measure the variation of intrathoracic airway wall compliance (AWC) after acute administration of short acting beta-2 agonist in COPD patients since this might influence the final modification of airway caliber during maximal expiratory effort and the resulting bronchodilation as inferred by FEV1 changes. Methods In a group of 10 patients suffering from COPD, intrathoracic AWC was measured at middle (50% of Forced Vital Capacity (FVC) and low (75% of FVC) lung volumes using the interrupter method during forced expiratory maneuver in basal conditions and after acute inhalation of albuterol (salbutamol) (400 mcg by MDI). Ten healthy subjects were examined similarly as a control group. Results Lower values of baseline intrathoracic AWC at both lung volumes were found in COPD patients (1.72 ± 0.20 ml/cmH2O and 1.08 ± 0.20 ml/cmH2O, respectively) as compared to controls (2.28 ± 0.27 ml/cmH2O and 1.44 ± 0.22 ml/cmH2O, respectively) (p < 0.001). In COPD patients, AWC increased significantly at both lung volumes after salbutamol, amounting to 1.81 ± 0.38 ml/cmH2O and 1.31 ± 0.39 ml/cmH2O, respectively (p < 0.01), but the relative change was not different from that observed in controls. Conclusion In COPD patients, AWC is reduced compared to controls, but after bronchodilator, the intrathoracic airways become more compliant. The consequent increased collapsibility under high positive pleural pressure could limit the airway caliber improvement seen after bronchodilator, as assessed by the FEV1 changes during the forced expiratory maneuver, underestimating the effective bronchodilation achieved in these patients.

Comparison of the Application of Vibrating Mesh Nebulizer and Jet Nebulizer in Chronic Obstructive Pulmonary Disease: A Systematic Review and Meta‐analysis

“…It has been suggested that in patients with COPD treated with the bronchodilator salbutamol, the assessment of effective bronchodilation and FEV 1 achieved in patients with COPD is underestimated due to the increased compliance of the airway wall within the chest cavity, which may be more collapsible at high thoracic pressures, limiting the improvement of the caliber of the airways. 41 Bronchodilator therapy (especially for small airways) may benefit these patients even if there is no significant change in FEV 1 . 42 It has also been shown that changes in FEV 1 and FVC do not correlate well after bronchodilator administration, and that FVC can improve independently of FEV 1 , possibly because FEV 1 is determined by the airflow at high to medium lung volumes, whereas FVC is mainly determined by airway narrowing and flow limitation at low lung volumes.…”

LUNG Year in Review: 2022

“…Studies of obstructive airway disease comprised a significant portion of articles published is 2022. Clinical studies of COPD examined diagnosis [ 2 ], risk factors [ 3 ], predictors of outcomes [ 4 – 9 ], and therapeutic interventions [ 10 , 11 ], whereas preclinical investigations evaluated chronic cigarette smoke-induced inflammation and airway remodeling [ 12 , 13 ]. Contributions in the field of asthma included physiological studies [ 14 – 18 ], effects of therapeutic interventions [ 19 ], social determinants of clinical outcomes [ 20 ], asthma-associated cough [ 21 , 22 ] and preclinical investigations [ 23 ].…”