Evaluation of Acute Exogenous Hypoxia Impact on the Fraction of Exhaled Nitric Oxide in Healthy Males

Abstract

IntroductIon:Exogenous hypoxia increases ventilation and contracts the pulmonary vessels. Whether those factors change the values of nitric oxide in exhaled air has not yet been evaluated. objectIve: To examine the effect of exogenous normobaric hypoxia on the values of the fraction of nitric oxide in exhaled breath (FeNO). SubjectS аnd MethodS: Twenty healthy non-smoker males at mean age of 25.4 (SD = 3.7) were tested. The basal FeNO values were compared with those at 7 min. and 15 min. after introducing into the hypoxic environment (hypoxic tent), imitating atmospheric air with oxygen concentration corresponding to 3200 m above sea level. Exhaled breath temperature was measured at baseline and at 10-12 min. of the hypoxic exposition. Heart rate and oxygen saturation were registered by pulse-oximetry. results: All the subjects had FeNO values in the reference range. The mean baseline value was 14.0 ± 3.2 ppb, and in hypoxic conditions -15.5 ± 3.8 ppb (7 min.) and 15.3 ± 3.6 ppb (15 min.), respectively, as the elevation is statistically significant (p = 0.011 and p = 0.008). The values of exhaled breath temperature were 33.79 ± 1.55°С and 33.87 ± 1.83°С (p = 0.70) at baseline and in hypoxic conditions, respectively. Baseline oxygen saturation in all subjects was higher than that, measured in hypoxia (96.93 ± 1.29% vs. 94.27 ± 2.53%; p < 0.001). conclusIons: Exogenous hypoxia leads to an increase of FeNO values, but does not affect the exhaled breath temperature. . Исходные показатели FeNO были сопоставлены с показателями, полученными через 7 и 15 мин. после помещения в гипоксическую среду (гипоксическую палатку), которая имитировала атмосферный воздух с концентрацией кислорода, соответствующей концентрации на высоте 3200 м над уровнем моря. Температура выдыхаемого воздуха была измерена в начале и по истечении 10-12 мин. гипоксической экспозиции. Частота сердечных сокращений и сатурация кислорода были зарегистрированы при помощи записывающего пульсоксиметра. результаты: Все лица имели показатели FeNO в рамках референтного диапазона. Средний исходный показатель составлял 14.0 ± 3.2 ppb, а в гипоксических условиях -15.5 ± 3.8 ppb (7 мин.) и 15.3 ± 3.6 ppb (15 мин.), соответственно, при этом повышение было статистически значимым (p = 0.011 и p = 0.008). Показатели температуры выдыхаемого воздуха составляли 33.79 ± 1.55 °С и 33.87 ± 1.83 °С (p = 0.70), соответственно в начале и в условиях гипоксии. Исходная сатурация кислорода у всех лиц была выше измеренной в гипоксической палатке (96.93 ± 1.29 % vs. 94.27 ± 2.53 %;

Effects of COVID-19 protective face masks and wearing durations on respiratory haemodynamic physiology and exhaled breath constituents

“…In our setup, we did not measure the fraction of exhaled nitric oxide ( F eNO ), which is known to regulate vasomotor tone, blood pressure and is regarded as a marker for oxidative stress [ 81 ]. The F eNO in breath increases under acute exogenous hypoxia [ 82 ] and pilot findings have indicated inverse relationship between isoprene and nitric oxide [ 83 ]. Thus, future examination of breath nitric oxide under the same/improved experimental conditions may reveal its clearer relationship to isoprene and other endogenous VOCs that are associated with oxidative stress and systemic microbial activity.…”

Fractional Exhaled Nitric Oxide in Normoxic Adult Patients With COVID-19 Infection in the Emergency Department: A Preliminary Observation

“…Conceivably, differences in patient characteristics, such as age, sex, race/ethnicity, disease severity, and therapeutic interventions at the time of FeNO testing could account, in part, for these observations. For instance, hypoxia has been shown to increase FeNO levels while short-term hyperoxia decreases FeNO levels for several hours in human subjects [ 6 , 7 ].…”