Increased blood carboxyhaemoglobin concentrations in inflammatory pulmonary diseases.
BACKGROUND
Exhaled carbon monoxide has been reported to increase in inflammatory pulmonary diseases and to be correlated with blood carboxyhaemoglobin (Hb-CO) concentration. A study was undertaken to determine whether arterial blood Hb-CO increases in patients with inflammatory pulmonary diseases.


METHODS
The Hb-CO concentration in arterial blood was measured with a spectrophotometer in 34 normal control subjects, 24 patients with bronchial asthma, 52 patients with pneumonia, and 21 patients with idiopathic pulmonary fibrosis (IPF).


RESULTS
The mean (SE) Hb-CO concentrations in patients with bronchial asthma during exacerbations (n=24, 1.05 (0.05)%), with pneumonia at the onset of illness (n=52, 1.08 (0.06)%), and with IPF (n=21, 1.03 (0.09)%) were significantly higher than those in control subjects (n=34, 0.60 (0.07)%) (mean difference 0.45% (95% confidence interval (CI) 0.23 to 0.67), p<0.01 in patients with bronchial asthma, mean difference 0.48% (95% CI 0.35 to 0.60), p<0.0001 in patients with pneumonia, and mean difference 0.43% (95% CI 0.26 to 0.61) p<0.001 in patients with IPF). In 20 patients with bronchial asthma the Hb-CO concentration decreased after 3 weeks of treatment with oral glucocorticoids (p<0.001). In 20 patients with pneumonia the Hb-CO concentration had decreased after 3 weeks when patients showed evidence of clinical improvement (p<0.001). The values of C-reactive protein (CRP), an acute phase protein, correlated with Hb-CO concentrations in patients with pneumonia (r=0.74, p<0.0001) and in those with IPF (r=0.46, p<0.01). In patients with bronchial asthma changes in Hb-CO concentrations were significantly correlated with those in forced expiratory volume in 1 second (FEV(1)) after 3 weeks (r=0.67, p<0.01). Exhaled carbon monoxide (CO) concentrations were correlated with Hb-CO concentrations (n=33, r=0.80, p<0.0001).


CONCLUSIONS
Hb-CO concentrations are increased in inflammatory pulmonary diseases including bronchial asthma, pneumonia, and IPF. Measurement of arterial Hb-CO may be a useful means of monitoring pulmonary inflammation.
Yasuda
H
H
Department of Geriatric and Respiratory Medicine, Tohoku University School of Medicine, Sendai 980-8574, Japan. yasuda@geriat.med.tohoku.ac.jp
Yamaya
M
M
Yanai
M
M
Ohrui
T
T
Sasaki
H
H
D000368:Aged; D001249:Asthma / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D002248:Carbon Monoxide / Q000378:metabolism; D002263:Carboxyhemoglobin / Q000378:metabolism*; D005260:Female; D006801:Humans; D008297:Male; D011014:Pneumonia / Q000097:blood*; D011658:Pulmonary Fibrosis / Q000097:blood*
D015415:Biomarkers; D002248:Carbon Monoxide; D002263:Carboxyhemoglobin