Relation between exhaled carbon monoxide levels and clinical severity of asthma

Abstract

Carbon monoxide (CO) can be detected in exhaled air and is increased in asthmatic patients not treated with corticosteroids. However, it is uncertain whether exhaled CO is related to severity of asthma. To study whether exhaled CO is related to severity of asthma in clinical courses, exhaled CO concentrations were measured on a CO monitor by vital capacity manoeuvre in 20 mild asthmatics treated with inhaled beta2-agonists alone, 20 moderate asthmatics treated with inhaled corticosteroids, and 15 stable asthmatics treated with high dose inhaled corticosteroids and oral corticosteroids once a month over 1 years. Exhaled CO concentrations were also measured in 16 unstable severe asthmatics who visited the hospital every 7 or 14 days for treatment with high dose inhaled corticosteroids and oral corticosteroids. The mean values of exhaled CO in severe asthma over 1 year were 6.7 +/- 9.5 p.p.m. (n = 31, mean +/- SD) and significantly higher than those of non-smoking control subjects (1.2 +/- 0.9 p.p.m., n = 20, P < 0.01). Exhaled CO concentrations in unstable severe asthmatics were significantly higher than those in stable severe asthmatics. However, exhaled CO concentrations in mild and moderate asthmatics did not differ significantly from those in non-smoking control subjects (P > 0.20). There was a significant relationship between the exhaled CO concentrations and forced expiratory volume in one second in all asthmatic patients. These findings suggest that exhaled CO concentrations may relate to the severity of asthma and measurements of exhaled CO concentrations may be a useful means of monitoring airway inflammation in asthma.

The role of oxidative stress in ambient particulate matter-induced lung diseases and its implications in the toxicity of engineered nanoparticles

“…This study has provided most direct in vivo evidence that PM induce ROS generation and cause oxidative tissue damage. In humans, experimental DEP exposures result in increased CO in exhaled air; CO is the catalytic product of HO-1, which acts as a sensitive marker for PM-induced oxidative stress [69][70][71][72].…”

Quantum cascade laser-based sensors for the detection of exhaled carbon monoxide

“…In 1972, Nikberg et al [5] were the first to describe exhaled CO (eCO) as a marker to assess different diseases such as cardiovascular diseases, diabetes, and nephritis. Moreover, high levels of eCO have been observed for many diseases [6,7], such as asthma [8][9][10][11] and cystic fibrosis [12,13], but these findings are still subject of controversy [14].…”

Does the Finding of Small Airway Obstruction in Pulmonary Function Tests Effect End-Expiratory Carbonmonoxide Level?

“…In two studies conducted by a Japanese group, the exhaled CO level was found to be higher in patients with asthma than in healthy individuals (2,3). In a meta-analysis that also referred to two studies conducted in Turkey (23,24), it was reported that the exhaled CO level was found to be higher in asthma patients who did not smoke than in those without asthma, and the CO level displayed a correlation with the severity of asthma (4).…”

“…CO is absorbed through smoking or can be produced endogenously in alveolar macrophages, endothelial cells, and other lung cells as a product of local inflammation and oxidative stress in individuals with airway diseases (1). In many studies, it was revealed that the end-expiratory CO (exhaled CO) level was higher in patients with severe asthma and lower in asthma patients receiving inhaled steroid therapy than in those not having therapy (2)(3)(4). Therefore, the exhaled CO level has recently begun to be used as an inflammatory biomarker in airway diseases such as asthma, chronic obstructive pulmonary disease (COPD), cystic fibrosis, and bronchiectasis (1,5).…”