Exhaled Nitric Oxide in Pregnant Healthy and Asthmatic Women

Background. Measurement of fractioned exhaled nitric oxide (FENO) is useful for monitoring airway inflammation in asthma. Asthma is one of the most common diseases complicating pregnancy, and FENO may be helpful for monitoring asthma in pregnancy. However, some physiological alterations of FENO may be expected during healthy pregnancy due to vascular nitric oxide production. Until now no study assessed the level of FENO in asthmatic pregnant patients. Objective. We aimed to assess the possible use and reproducibility of FENO measurements in pregnant asthmatic women. We compared FENO concentrations between four groups of subjects: healthy nonpregnant and pregnant females and asthmatic nonpregnant and pregnant patients. We also investigated the relationship between FENO values and the level of asthma control in pregnant asthmatic patients. Methods. A total of 102 female subjects (35 healthy nonpregnant and 27 healthy pregnant females; 20 nonpregnant and 20 pregnant asthmatic women) were included in this cross-sectional study. Two FENO measurements were performed in each subject using an electrochemical sensor based device (NIOX MINO, Aerocrine, Solna, Sweden). Data are given as median with range. Results. The repeatability of FENO measurement was similar in pregnant and nonpregnant subjects. FENO levels did not differ significantly between healthy pregnant versus nonpregnant subjects (16.0 [8, 31] vs. 16.0 [9, 35] ppb). FENO levels were significantly increased in asthmatic women compared to healthy females (nonpregnant asthmatics: 38 [9, 54] ppb, p < 0.001 vs. healthy nonpregnant; pregnant asthmatic patients: 28 [10, 56] ppb; p < 0.05 vs. healthy pregnant). Conclusions. FENO level is not influenced by healthy pregnancy. In pregnant asthmatic patients FENO level is elevated compared to healthy pregnant subjects and correlates with the level of asthma control. Further studies are required to assess the use of FENO measurement to monitor asthma in this patient group.