Determining the diagnostic value of endogenous carbon monoxide in chronic obstructive pulmonary disease exacerbations

To determine whether endogenous carbon monoxide levels in exacerbations of Chronic Obstructive Pulmonary Disease patients were higher compared to healthy individuals and to investigate alteration of carbon monoxide levels across the three different severity stages of Global Initiative for Chronic Obstructive Lung Disease criteria related to Chronic Obstructive Pulmonary Disease exacerbations.

The prospective study was conducted from January to March 2011 at two medical institutions in Ankara, Turkey, and comprised patients of acute Chronic Obstructive Pulmonary Disease exacerbations. The severity of the exacerbations was based on the Global Initiative for Chronic Obstructive Lung Disease criteria. Patients with active tobacco smoking, suspicious carbon monoxide poisoning and uncertain diagnosis were excluded. healthy control subjects who did not have any comorbid diseases and smoking habitus were also enrolled to compare the differences between carboxyhaemoglobin levels A two-tailed Mann-Whitney U test with Bonferroni correction was done following a Kruskal-Wallis test for statistical purposes.

There were 90 patients and 81 controls in the study. Carboxyhaemoglobin levels were higher in the patients than the controls (p < 0.001). As for the three severity stages, Group 1 had a median carboxyhaemoglobin of 1.6 (0.95- 2.00). The corresponding levels in Group 2 (1.8 [1.38-2.20]) and Group 3 (1.9 [1.5-3.0]) were higher than the controls (p < 0.001 and p < 0.005 respectively). No statistically significant difference between Group 1 and the controls (1.30 [1.10-1.55]) was observed (p < 0.434).

Carboxyhaemoglobin levels were significantly higher in exacerbations compared with the normal population. Also, in more serious exacerbations, carboxyhaemoglobin levels were significantly increased compared with healthy individuals and mild exacerbations.