Impact of Cigarette Smoking on Maximal Expiratory Flows in a General Population: the Takahata Study

Abstract

Background Maximal expiratory flows (MEFs) depend on the elastic recoil pressure in the alveoli, airway resistance and bronchial collapsibility. MEFs at lower levels of vital capacity [MEFs at x% FVC (MEFx)] would indicate the patency of peripheral airways. In Japan, a ratio of MEF50 to MEF25 (MEF50/MEF25) greater than 4.0 is used as an index of injury to the small airways in subjects without airflow limitation. However, to date there have been no epidemiological investigations relating to this index. The aim of this study was to evaluate the impact of cigarette smoking on MEFs in a general population, and to assess the validity of using this index to evaluate injury to the small airways. Methods Subjects aged 40 years or older (n=2,917), who had participated in a community-based annual health-check in Takahata, Japan, were enrolled in the study. MEF75, MEF50 and MEF25 were measured in these subjects. Results In smokers, as compared with never-smokers, the percentage predicted MEFs (%MEFs) decreased according to the aging of the population, except in the case of %MEF25 in females. In males, but not in females, %MEFs decreased significantly with an increase in cigarette consumption. In both genders, MEF50/ MEF25 was slightly, but significantly, elevated with aging of the population. In addition, 36.5% of subjects who participated in this health-check had MEF50/MEF25 values greater than 4.0. No difference in MEF50/ MEF25 was observed between smokers and never-smokers. Conclusion Cigarette smoking enhanced the age-related decline in MEFs. Since many healthy subjects aged 40 years or older have MEF50/MEF25 values greater than 4.0, the use of this criterion may over-estimate the presence of small airway disease.

Pulmonary Function Parameters in High-resolution Computed Tomography Phenotypes of Chronic Obstructive Pulmonary Disease

“…In this study, 63 stable COPD patients were classified into 3 phenotypes according to HRCT assessments. 12 Narrowing and disappearance of small conducting airways before the onset of emphysematous destruction can explain the increasing peripheral airway resistance and airflow limitation reported in COPD severity. These results were in line with the observation described by Martinez that most males and patients with lower BMI had emphysematous forms of COPD, 25,26 whereas most females had asthmatic bronchitis.…”

“…10 Maximum expiratory flows (MEF) at forced vital capacity (FVC) impairments can reflect various pathological changes of small airway. 12 MEF 50 /MEF 25 ratio depends on the elastic recoil pressure in the alveoli, airway resistance and bronchial collapsibility instead of emphysema. 12 MEF 50 /MEF 25 ratio depends on the elastic recoil pressure in the alveoli, airway resistance and bronchial collapsibility instead of emphysema.…”

Nicotine enhances both excitatory and inhibitory synaptic inputs to inspiratory‐activated airway vagal preganglionic neurons

“…In the present study, however, the overall effect of nicotine on IA-AVPNs was excitatory, indicating that the direct postsynaptic excitatory effect of nicotine plays a predominant role in the nicotine-mediated modulation of IA-AVPNs. The nicotinic excitation of IA-AVPNs might play a role in the maintenance of physiological airway cholinergic tone, and might account, at least in part, for the acute increase of airway resistance after cigarette smoke inhalation (Higenbottam et al 1980) and the age-related decrease in the maximal expiratory flows in smokers (Nemoto et al 2011).…”

Hyperhomocysteinaemia predicts the decline in pulmonary function in healthy male smokers

“…The study was approved by the institutional ethics committee and all participants gave written informed consent [2]. Cross-sectional analyses of spirometry data for subjects who were enrolled from 2004 to 2005 (n53165) have been reported previously [2,[25][26][27]. Enrolment of subjects continued through 2006, and the additional data for these subjects became available recently.…”