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Abstract Background Chronic obstructive pulmonary disease (COPD) is a critical public health issue. Spirometric measurements are used to diagnose chronic obstructive lung disease, as per the guidelines of the GOLD initiative. Post-bronchodilator forced expiratory volume in 1 s (FEV1) is a predictor of mortality from COPD and helps to classify the disease’s severity. Smoking contributes to the high levels of exhaled CO. Evidence suggests that the exhaled CO level in COPD patients varies with degree of blockage and can be used to assess treatment response. Estimating the exhaled CO level can help assess airway inflammation and severity of airflow obstruction in individuals with COPD. Aim Evaluate role of exhaled CO in assessment of severity of COPD. Materials and methods This cross-sectional study included 132 patients who visited the outpatient clinics or were admitted to the Chest Department, Kasr Alainy Hospital, Faculty of Medicine, Cairo University. The study participants were divided into three groups: group 1 nonsmoker healthy control, group 2 smoker non-COPD, and group 3 smoker COPD which further divided according to GOLD 2023 into mild, moderate, and severe COPD. The smoking status, exhaled CO, and spirometry test including FEV1/FVC and FEV1 were measured for each patient. Results Exhaled CO was significantly increased in the smoker group (mean 9.69, SD 3.11) compared to the nonsmoker group (mean 2.19, SD 0.98) with p-value

Background: Chronic obstructive pulmonary disease (COPD) is a critical public health issue. Spirometric measurements are used to diagnose chronic obstructive lung disease, as per the guidelines of the GOLD initiative. Post-bronchodilator forced expiratory volume in 1 s (FEV1) is a predictor of mortality from COPD and helps to classify the disease's severity. Smoking contributes to the high levels of exhaled CO. Evidence suggests that the exhaled CO level in COPD patients varies with degree of blockage and can be used to assess treatment response. Estimating the exhaled CO level can help assess airway inflammation and severity of airflow obstruction in individuals with COPD. Aim: Evaluate role of exhaled CO in assessment of severity of COPD. Materials and methods: This cross-sectional study included 132 patients who visited the outpatient clinics or were admitted to the Chest Department, Kasr Alainy Hospital, Faculty of Medicine, Cairo University. The study participants were divided into three groups: group 1 nonsmoker healthy control, group 2 smoker non-COPD, and group 3 smoker COPD which further divided according to GOLD 2023 into mild, moderate, and severe COPD. The smoking status, exhaled CO, and spirometry test including FEV1/FVC and FEV1 were measured for each patient. Results: Exhaled CO was significantly increased in the smoker group (mean 9.69, SD 3.11) compared to the nonsmoker group (mean 2.19, SD 0.98) with p-value < 0.001. Exhaled CO was also statistically significantly higher in the smoker COPD group (mean 10.45, SD 3.03) compared to the smoker non-COPD group (mean 7.05, SD 1.56) with p-value < 0.001. Although exhaled CO was increased in the severe COPD group compared to the mild and moderate group, there is no statistically significant difference between them. Conclusion: Exhaled CO is a fast, sensitive, noninvasive, and well-established method test that can be used to identify smokers from nonsmokers with 98.9% sensitivity at 4.5 cutoff value. Also, exhaled CO levels in COPD patients vary with different degrees of airway obstruction. [ABSTRACT FROM AUTHOR]

Background Exhaled carbon monoxide has been related to the degree of inflammation. An easy, inexpensive, and non-invasive test to measure exhaled CO levels (eCO) may help in supporting the diagnosis of asthma and allergic rhinitis (AR) in children. Objective To compare the eCO levels in children with asthma, AR, or both asthma and AR, to children without asthma or AR. Methods This was a cross-sectional study involving 450 children aged 13-14 years in Yogyakarta. Asthma and AR were determined according to the International Study of Asthma and Allergies in Childhood (ISAAC) study criteria, while eCO level was examined using a Smokerlyzer®. The levels of eCO between groups were analyzed using Kruskal-Wallis and Mann-Whitney tests. Results Of 450 children, 48 (10.67%) had asthma only, 91 (20.22%) had AR only, 67 (14.89%) had both asthma and AR, and 244 (54.22%) had neither asthma nor AR. The eCO levels of children with asthma or AR were not significantly different compared to those without asthma and AR (P=0.33 and P=0.19, respectively). However, children with both asthma and AR had significantly higher eCO level compared to children without asthma and AR (P< 0.001). Conclusion The levels of eCO in children with asthma only or AR only are similar to those without both diseases. Children with both asthma and AR have significant higher eCO compared to healthy children.

Background: COVID-19, caused by the SARS-CoV-2 virus, has infected nearly 270 million people over the past two years. We aimed to determine the exhaled CO levels of patients hospitalized with COVID-19 pneumonia and its correlation with parenchymal involvement. Methods: Between September 2021 and December 2021, 74 patients who were hospitalized in the infectious diseases service of our hospital and whose delta variant COVID-19 infection was confirmed with real-time PCR method were included in the study. The patients were analyzed in 3 groups: moderate COVID-19 (group 1), severe COVID-19 without macrophage activation syndrome (MAS) (group 2), and severe COVID-19 with MAS (group 3). Results: While it was observed that the exhaled CO levels were higher in patients in Group 3 at the time of hospitalization than in patients in Group 1 and 2, it was determined that no significant difference was observed between the groups at the time of discharge (p < 0.001, 0.213). CT scores obtained at the time of hospitalization were also observed to be statistically significantly higher in patients in Group 3 when compared to patients in Group 1 and 2 (p = 0.002). In the correlation analysis of the exhaled CO levels and the CT scores at the time of hospitalization, a statistically significant positive correlation was observed (r = 0.628, p < 0.001). Conclusions: In COVID-19, which has a high affinity for lung tissue compared to other known viral lower respiratory tract infections, the exhaled CO level may be a non-invasive parameter that can be used in the evaluation of parenchymal involvement and clinical course. [ABSTRACT FROM AUTHOR]

Background Exhaled carbon monoxide has been related to the degree of inflammation. An easy, inexpensive, and non-invasive test to measure exhaled CO levels (eCO) may help in supporting the diagnosis of asthma and allergic rhinitis (AR) in children. Objective To compare the eCO levels in children with asthma, AR, or both asthma and AR, to children without asthma or AR. Methods This was a cross-sectional study involving 450 children aged 13-14 years in Yogyakarta. Asthma and AR were determined according to the International Study of Asthma and Allergies in Child- hood (ISAAC) study criteria, while eCO level was examined using a Smokerlyzer®. The levels of eCO between groups were analyzed using Kruskal-Wallis and Mann-Whitney tests. Results Of 450 children, 48 (10.67%) had asthma only, 91 (20.22%) had AR only, 67 (14.89%) had both asthma and AR, and 244 (54.22%) had neither asthma nor AR. The eCO levels of children with asthma or AR were not significantly different compared to those without asthma and AR. However, children with both asthma and AR had significantly higher eCO level compared to children without asthma and AR. Conclusion The levels of eCO in children with asthma only or AR only are similar to those without both diseases. Children with both asthma and AR have significant higher eCO compared to healthy children. [ABSTRACT FROM AUTHOR]

Background and objectives: During the last decade, conventional tobacco smoking is experiencing a decline and new smoking products have been introduced. IQOS (“I-Quit-Ordinary-Smoking”) is a type of “heat-not-burn” (HNB) tobacco product. The impact of IQOS on respiratory health is currently not defined. The objectives of this study were to evaluate the acute effects of IQOS on pulmonary function in non-smokers and current smokers. Materials and Methods: Fifty male healthy non-smokers and current smokers with no known co-morbidity underwent an exhaled CO measurement, oximetry (SaO2%), pulmonary function tests (flows, volumes and diffusion capacity), and a measurement of respiratory resistances with an impulse oscillometry system (IOS) before and immediately after IQOS use. Results: In the whole group of 50 participants, SaO2%, forced expiratory flow at 25% and 50% of vital capacity (FEF 25%, FEF 50%, respectively), peak expiratory flow (PEF), and diffusion lung capacity for carbon monoxide/VA (KCO) decreased significantly after IQOS use, whereas exhaled CO and airway resistance (R5 Hz, R10 Hz, r15 Hz, R20 Hz, R25 Hz, R35 Hz) increased. When the groups of smokers and non-smokers were compared, in both groups (all males, 25 smokers and 25 non-smokers), exhaled CO increased and SaO2% decreased after IQOS use (p < 0.001). In the group of non-smokers, PEF (pre 8.22 ± 2.06 vs. post 7.5 ± 2.16, p = 0.001) and FEF 25% (pre 7.6 ± 1.89 vs. 7.14 ± 2.06, p = 0.009) decreased significantly; respiratory resistances R20 Hz (pre 0.34 ± 0.1 vs. post 0.36 ± 0.09, p = 0.09) and R25 Hz (pre 0.36 ± 0.1 vs. post 0.38 ± 0.09, p = 0.08) increased almost significantly. In smokers, PEF (pre 7.69 ± 2.26 vs. post 7.12 ± 2.03, p = 0.007) and expiratory reserve volume (ERV) (pre 1.57 ± 0.76 vs. post1.23 ± 0.48, p = 0.03) decreased and R35 Hz (pre 0.36 ± 0.11 vs. post 0.39 ± 0.11, p = 0.047) increased. The differences in the changes after the use of IQOS did not differ between groups. Conclusions: IQOS had an impact on exhaled CO, SaO2%, and airways function immediately after use. Even though these changes were rather small to be considered of major clinical importance, they should raise concerns regarding the long-term safety of this product. Further research is needed for the short- and long-term effects of IQOS, especially in patients with respiratory disease.

Objectives: The main goal of the study was to assess possible association between fetal exposure to fi ne particulate matter (PM2.5) and exhaled carbon monoxide (eCO) measured in non-asthmatic children. Material and Methods: The subjects include 118 children taking part in an ongoing population-based birth cohort study in Kraków. Personal samplers of PM2.5 were used to measure fi ne particle mass in the fetal period and carbon monoxide (CO) in exhaled breath from a single exhalation effort at the age of 7. In the statistical analysis of the effect of prenatal PM2.5 exposure on eCO, a set of potential confounders, such as environmental tobacco smoke (ETS), city residence area, sensitization to house dust allergens and the occurrence of respiratory symptoms monitored over the seven-year follow-up was considered. Results: The level of eCO did not correlate with the self-reported ETS exposure recorded over the follow-up, however, there was a positive signifi cant relationship with the prenatal PM2.5 exposure (non-parametric trend p = 0.042). The eCO mean level was higher in atopic children (geometric mean = 2.06 ppm, 95% CI: 1.58–2.66 ppm) than in non-atopic ones (geometric mean = 1.57 ppm, 95% CI: 1.47–1.73 ppm) and the difference was statistically signifi cant (p = 0.036). As for the respiratory symptoms, eCO values were associated positively only with the cough severity score recorded in the follow-up (nonparametric trend p = 0.057). In the nested multivariable linear regression model, only the effects of prenatal PM2.5 and cough severity recorded in the follow-up were related to eCO level. The prenatal PM2.5 exposure represented 5.1%, while children’s cough represented only 2.6% of the eCO variability. Conclusion: Our study suggests that elevated eCO in non-asthmatic children may result from oxidative stress experienced in the fetal period and that heme oxygenase (HO) activity in body tissues may be programmed in the fetal period by the exposure to fi ne particulate matter.

Aim: This study compared exhaled carbon monoxide (CO) levels in patients hospitalized for bacterial and COVID-19-related viral community-acquired pneumonia. Materials & methods: The study included a total of 150 patients: 50 patients hospitalized for COVID-19 between February 2021 and March 2022, 50 patients with bacterial community-acquired pneumonia and 50 healthy controls. Results: In comparisons of exhaled CO levels among the groups, there was no significant difference between patients with bacterial pneumonia and controls, whereas patients with COVID-19 pneumonia had significantly higher exhaled CO levels compared with both the bacterial pneumonia and control groups (p < 0.001). Conclusion: Viral agents can directly affect the heme oxygenase system of the lower respiratory tract, leading to greater increases in ferritin and exhaled CO levels compared with bacterial pneumonia.

Background: COPD is largely under-diagnosed and once diagnosed usually at a late stage. Early diagnosis is thoroughly recommended but most attempts failed as the disease is marginally known and screening marginally accepted. It is a rare cause of concern in primary care and spirometry is not very common. Exhaled carbon monoxide (eCO) is a 5-seconds easy-to-use device dedicated to monitor cigarette smoke consumption. We aimed to assess whether systematic eCO measurement in primary care is a useful tool to improve acceptance for early COPD diagnosis. Methods: This was a two-center randomized controlled trial enrolling 410 patients between March and May, 2013. Whatever was the reason of attendance to the clinic, all adults were proposed to measure eCO during randomly chosen days and outcomes were compared between the two different groups of patients (performing and not performing eCO). Primary outcome was the rates of acceptance for COPD screening. Results: Rate of acceptance for COPD screening was 28% in the eCO group and 26% in the other (P = 0.575). These rates increased to 48 and 51% in smokers (current and former). eCO significantly increased the rate of clinics during which a debate on smoking was initiated (42 vs. 24%, P = 0.001). eCO at 2.5 ppm was the discriminative concentration for identifying active smokers (ROC curve AUC: 0.935). Smoking was the only independent risk factor associated with acceptance for early COPD screening (OR = 364.6 (82.5-901.5) and OR = 78.5 (18.7-330.0) in current and former smokers, respectively) while eCO measurement was not. Conclusions: Early COPD diagnosis is a minor cause of concern in primary care. Systematic eCO assessment failed to improve acceptance for early COPD screening. [ABSTRACT FROM AUTHOR]

Background: Measurement of biological indicators of physiological change may be useful in evaluating the effectiveness of stove models, which are intended to reduce indoor smoke exposure and potential health effects. Objectives: We examined changes in exhaled carbon monoxide (CO), percentage carboxy-hemoglobin, and total hemoglobin in response to the installation of a chimney stove model by the Juntos National Program in Huayatan, Peru in 2008. Methods: Biomarkers were measured in a convenience sample comprising 35 women who met requirements for participation, and were measured before and three weeks after installation of a chimney stove. The relationships between exposure to indoor smoke and biomarker measurements were also analyzed using simple linear regression models. Results: Exhaled CO reduced from 6.71 ppm (95% CI 5.84-7.71) to 3.14 ppm (95% Cl 2.77-3.66) three weeks after stove installation (P < 0.001) while % COHb reduced from 1.76% (95% Cl 1.62-1.91) to 1.18% (95% Cl 1.12-1.25; P < 0.001). Changes in exhaled CO and % COHb from pre- to post-chimney stove installation were not correlated with corresponding changes in exposure to CO and PM2.5 even though the exposures also reduced after stove installation. Conclusion: Exhaled CO and % COHb both showed improvement with reduction in concentration after the installation of the chimney cook stoves, indicating a positive physiological response subsequent to the intervention. [ABSTRACT FROM AUTHOR]

The article focuses on a study which aims to assess the possible association of fetal exposure to fine particulate matter (PM2.5) with exhaled carbon monoxide (eCO) measured in non-asthmatic children. Material and methods of the study are presented, as well as the statistical analysis of the effect of prenatal PM2.5 exposure on eCO. It suggests that elevated eCO in non-asthmatic children may result from oxidative stress experienced during the fetal period.

The aim of this study was to show the interactions between nicotine dependency, exhaled carbon monoxide (CO) and smoking status including environmental passive tobacco smoke exposure in a sample of Turkish adolescents. This study was a cross-sectional research conducted among high school students of Erzurum province (n=536). The level of exhaled CO of all participants who accepted to participate in the study was measured by Microbio CO Analyzer (Microbio Med). Nicotine dependency was measured by a six-item version of the Fagerstrom Tolerance Questionnaire. Mean age of the adolescents was 17.0±1.6 (median: 17) and 77.1% were male. Of the study population, 30.2% and 11.4% of the students were regular and occasional smokers, respectively. Non-smokers who were exposed to environmental tobacco smoke had significantly (p<0.01) higher exhaled CO levels (2.8±2.6 ppm) than not-exposed non- smokers (1.8±1.9 ppm). Only 8.6% of adolescents who reported themselves to be a regular smoker had 7 ppm and higher exhaled CO. There was a statistically significant and positive correlation between exhaled CO levels and nicotine dependency after controlling for environmental tobacco smoke exposure and cigarettes per day (partial correlation, r=0.334, p=0.004). Exhaled CO can be used as a predictor of smoking status and environmental tobacco smoke exposure and an indicator of nicotine dependency in adolescents. [ABSTRACT FROM AUTHOR]