Levels of fractional exhaled nitric oxide (FeNO), a measure of how much nitric oxide a person exhales, could be used to diagnose pulmonary hypertension (PH) in patients with acute exacerbation of COPD. In a recent study published in the journal Emergency Medicine International, the researchers observed a reduction of mean FeNO levels as PH severity increased, with those in the mild group showing significantly higher FeNO levels compared with those in the moderate group and severe group. The study reviewed data from 56 AECOPD patients and 27 AECOPD participants, also with PH, admitted to the Harrison International Peace Hospital. The team said that the mean levels of FeNO were significantly lower in the AECOPD-PH (18.78 parts per billion, ppb) compared with the AECOPD group (33.14 ppb).