A new approach to detect early lung functional impairment in very light smokers

Lung function impairment and cardiometabolic risks among rural adults: implication for an aging society

BACKGROUND

Early detection and prevention of cardiometabolic risk factors in an increasingly aging society are a global public health concern. Maintaining adequate lung function is important for healthy aging. Few studies exist on lung function impairment and decline in primary healthcare settings, especially among rural adults with cardiometabolic risks. This study aimed to explore the prevalence of impaired lung function and its association with cardiometabolic risks among rural adults.

METHODS

A community-based, cross-sectional study was conducted between March and December 2019 in western coastal Yunlin County, Taiwan. The lung function test was measured by spirometry, based on the American Thoracic Society recommendations. Three lung function parameters were obstructive lung impairment, restrictive lung impairment, and mixed lung impairment. Restrictive, obstructive, and mixed type lung function was categorized as impaired. Cardiometabolic risk factors and metabolic syndrome were based on the national standard and include five abnormal biomarkers, including abdominal obesity, blood pressure, fasting plasma glucose, triglycerides, and decreased high-density cholesterol levels.

RESULTS

The median age of the 1653 (92.9%) participants with complete data was 66 years (interquartile range: 55 to 75 years). The prevalence of impaired lung function was 37%, including 31.7% restrictive, 2.5% obstructive, and 2.7% mixed type. Adults with impaired lung function (86% restrictive type) engaged more in smoking and betel nut chewing, ate fewer vegetables and fruit, and drank less water compared to the normal lung function group. After adjusting for potential confounding variables, multivariate logistic regression analysis showed that cardiometabolic risk factors were independently associated with restrictive lung impairment, while cigarette smoking (OR = 2.27, 95% CI = 1.14-4.53) and betel nut chewing (OR = 2.33, 95% CI = 1.09-5.01) were significantly associated with the obstructive type of lung impairment.

CONCLUSIONS

A high prevalence of restrictive lung impairment, cardiometabolic risks, and unhealthy lifestyles among rural adults were found in this study. For adults with cardiometabolic risks in rural areas, initiating lifestyle modifications with culture-tailored programs to improve lung function should be an important issue for clinicians and primary healthcare providers.

A new ventilatory efficiency index and accuracy for early lung diffusion impairment in non-COPD smokers

In smokers without manifest airway obstruction, early emphysema and endothelial dysfunction has been related to minute-ventilation/carbon dioxide output ratio (V'_E/V'CO₂). Thus, smokers with reduced lung carbon monoxide diffusion capacity (D_Lco) have a heightened V'_E/V'CO₂ ratio. We hypothesized that ventilatory inefficiency could contribute to the suspicion of impaired diffusive capacity in the absence of significant airway obstruction. Thus, 15 smokers with impaired D_Lco were compared to 15 smokers with normal D_Lco. Accuracy through sensibility and specificity for V'_E/V'CO₂ slope and nadir was compared with a new index for ventilatory efficiency (ηV'_E,%), to uncover early diffusive changes in smokers without COPD.

Incorporating Lung Diffusing Capacity for Carbon Monoxide in Clinical Decision Making in Chest Medicine

Lung diffusing capacity for carbon monoxide (Dlco) remains the only noninvasive pulmonary function test to provide an integrated picture of gas exchange efficiency in human lungs. Due to its critical dependence on the accessible "alveolar" volume (Va), there remains substantial misunderstanding on the interpretation of Dlco and the diffusion coefficient (Dlco/Va ratio, Kco). This article presents the physiologic and methodologic foundations of Dlco measurement. A clinically friendly approach for Dlco interpretation that takes those caveats into consideration is outlined. The clinical scenarios in which Dlco can effectively assist the chest physician are discussed and illustrative clinical cases are presented.

Cardiopulmonary and Muscular Interactions: Potential Implications for Exercise (In)tolerance in Symptomatic Smokers Without Chronic Obstructive Pulmonary Disease

Smoking and physical inactivity are important preventable causes of disability and early death worldwide. Reduced exercise tolerance has been described in smokers, even in those who do not fulfill the extant physiological criteria for chronic obstructive pulmonary disease (COPD) and are not particularly sedentary. In this context, it is widely accepted that exercise capacity depends on complex cardio-pulmonary interactions which support oxygen (O₂) delivery to muscle mitochondria. Although peripheral muscular factors, O₂ transport disturbances (including the effects of increased carboxyhemoglobin) and autonomic nervous system unbalance have been emphasized, other derangements have been more recently described, including early microscopic emphysema, pulmonary microvascular disease, ventilatory and gas exchange inefficiency, and left ventricular diastolic dysfunction. Using an integrative physiological approach, the present review summarizes the recent advances in knowledge on the effects of smoking on the lung-heart-muscle axis under the stress of exercise. Special attention is given to the mechanisms connecting physiological abnormalities such as early cardio-pulmonary derangements, inadequate oxygen delivery and utilization, and generalized bioenergetic disturbances at the muscular level with the negative sensations (sense of heightened muscle effort and breathlessness) that may decrease the tolerance of smokers to physical exercise. A deeper understanding of the systemic effects of smoking in subjects who did not (yet) show evidences of COPD and ischemic heart disease - two devastating smoking related diseases - might prove instrumental to fight their ever-growing burden.