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

M. Yamaya, K. Sekizawa, S. Ishizuka, M. Monma, K. Mizuta, H. Sasaki

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109 Citations (Scopus)


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.

Original languageEnglish
Pages (from-to)311-314
Number of pages4
JournalAmerican journal of respiratory and critical care medicine
Issue number1
Publication statusPublished - 1998

ASJC Scopus subject areas

  • Pulmonary and Respiratory Medicine
  • Critical Care and Intensive Care Medicine


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