Exhaled Carbon Monoxide Concentration Research Articles

Increased carbon monoxide in exhaled air of patients with seasonal allergic rhinitis.

Carbon monoxide (CO) can be detected in exhaled air and is increased in asthmatic patients. However, it is uncertain whether exhaled CO is increased in patients with allergic rhinitis. To study whether exhaled CO is increased in patients with allergic rhinitis, exhaled CO concentrations were measured on a CO monitor by vital capacity manoeuvre in 86 patients with seasonal allergic rhinitis during and out of the cedar pollen season. During the season, exhaled CO concentrations were 3. 6 +/- 0.3 p.p.m. and decreased to 1.2 +/- 0.1 p.p.m. out of the season. The values of exhaled CO out of the season were similar to those in age-matched non-smoking healthy control subjects (1.2 +/- 0. 1 p.p.m.). Exhaled CO concentrations were significantly higher in patients with symptoms than in those without symptoms (P < 0.01). Exhaled CO concentrations in patients did not differ significantly among oral and nasal exhalation, and oral exhalation with an expiratory resistance (P > 0.20). These findings suggest that allergic rhinitis increases the concentration of CO in exhaled air and increases in exhaled CO may be derived from lower airways.

Exhaled carbon monoxide in childhood asthma

Objectives: Oxidative stress and inflammation induce the expression of heme oxygenase-1, which produces carbon monoxide (CO), and nitric oxide synthase, which produces nitric oxide (NO). Exhaled CO and NO levels are elevated in asthmatic patients and are decreased after corticosteroid treatment, suggesting that they may be useful as noninvasive markers of airway inflammation. Study design: We measured forced expiratory volume in the first second, PC 20, and exhaled CO and NO levels in 29 children (18 boys, mean age 11.5 ± 0.53 years) with asthma of different severity and 40 nonsmoking children without asthma (21 boys, mean age 8.1 ± 0.35 years). We also studied whether upper respiratory tract infections were associated with elevated exhaled CO. Results: Exhaled CO levels (ppm) were significantly higher (2.17 ± 0.21) in children with persistent asthma compared with those in children with infrequent episodic asthma (1.39 ± 0.18, P < .05) and healthy children (1.01 ± 0.12, P < .001). The CO levels in children with infrequent episodic asthma and the normal control group, however, were not different. In contrast, exhaled NO levels (ppb) were higher in children with persistent asthma (24.2 ± 5.9, P < .001) and infrequent episodic asthma (14.5 ± 3.73, P < .05) than in normal subjects (5.1 ± 0.24), but no significant difference was seen between the 2 asthmatic groups. In healthy children with upper respiratory tract infections (n = 12), exhaled CO concentrations were significantly elevated (2.16 ± 0.33) during the acute symptomatic phase. No correlation was found between exhaled CO and forced expiratory volume in the first second or PC 20. Conclusions: Noninvasive measurement of exhaled CO may provide complementary data for assessment of asthma control in children. However, elevated CO levels are nonspecific and may be found in association with an acute viral illness. (J Pediatr 1999;135:569-74)

Increased carbon monoxide in exhaled air of patients with cystic fibrosis

BACKGROUNDInflammation, oxidative stress, and recurrent pulmonary infections are major aggravating factors in cystic fibrosis. Nitric oxide (NO), a marker of inflammation, is not increased, however, probably because it is metabolised...

Exhaled Carbon Monoxide Levels Elevated in Diabetes and Correlated With Glucose Concentration in Blood: A New Test for Monitoring the Disease?

In diabetes, the interaction of glycated proteins with their cell-surface binding sites leads to oxidative stress and induction of the stress protein heme oxygenase (HO)-1. Considering that carbon monoxide (CO) is a product of HO activity, we studied the level of exhaled CO as a marker of oxidative stress in diabetes. Eight patients with insulin-dependent diabetes mellitus (type 1) (4 men, 4 women; [mean +/- SEM] age, 50 +/- 8 years) were studied, of whom 2 had peripheral neuropathy and 1 had renal failure. Sixteen patients with non-insulin-dependent diabetes mellitus (type 2) (5 men, 11 women; age 63 +/- 8 years) were studied, of whom 2 had peripheral neuropathy. Glycosylated hemoglobin (HbA(1)c) levels were higher (7.4 +/- 0.3%) in patients with type 1 (mean duration of the disease, 20 +/- 5 years) than in type 2 (4.9 +/- 0.4%; p < 0.05; mean duration of the disease, 11 +/- 2 years). All of the patients were lifelong nonsmokers. Levels of exhaled CO were higher in patients with diabetes (type 1, 4.0 +/- 0.7 ppm; type 2, 5.0 +/- 0.4 ppm) when compared to 37 nonsmoking healthy subjects (20 men, 17 women; age, 33 +/- 3 years) (2.9 +/- 0.2 ppm; p < 0.05). There was a positive correlation between exhaled CO levels and the incidence of glycemia in all subjects (r = 0.52, p < 0.05) and the duration of diabetes (r = 0.48, p < 0.05), but there was not a strong correlation with concentrations of HbA(1)c (r = 0.06, p = 0.8). In addition, an oral glucose tolerance test was performed in five healthy nonsmoking volunteers (three men; age, 33 +/- 4 years). The maximal glucose increase (from 3.9 +/- 0.2 to 5.5 +/- 0.1 mmol/L at 15 min; p < 0.05) was associated with a significant increase in exhaled CO concentration (from 3.0 +/- 0.5 to 6.3 +/- 1.0 ppm; p < 0. 05). Both parameters returned to the baseline at 40 min after glucose administration. Elevated levels of exhaled CO in diabetes may reflect HO-1 induction and oxidative stress. The measurement of CO may be a new tool for disease monitoring.

Pulmonary function and respiratory symptoms in a population of airport workers.

OBJECTIVES: To assess the prevalence of respiratory symptoms and to measure spirometry in a sample of employees of Birmingham International Airport, United Kingdom, to examine whether occupational exposure to aircraft...

Increased carbon monoxide in exhaled air of subjects with upper respiratory tract infections.

Viral infection may induce the expression of heme oxygenase, resulting in increased carbon monoxide (CO) formation. CO may be produced by various cells of the upper and lower respiratory tract and may be detected in the exhaled air. Therefore, exhaled CO concentrations were measured on a CO monitor by vital capacity maneuver in subjects with upper respiratory tract infections (URTIs) and in nonsmoking and smoking healthy control subjects. At the time of symptoms of URTI, exhaled CO concentrations were 5.6 +/- 0.4 ppm and decreased to 1.0 +/- 0.1 ppm during recovery. Recovery values of exhaled CO were similar to those in age-matched nonsmoking healthy control subjects (1.2 +/- 0.3 ppm). Smoking healthy control subjects had the highest levels of exhaled CO concentration among the groups (18.5 +/- 2.5 ppm). These findings suggest that symptomatic URTIs increase the concentration of CO in exhaled air. This may reflect the induction of heme oxygenase that has an antiviral effect in the airways.