The effects of 100% oxygen on breathing pattern are not limited to young children

Abstract

Breathing 100% oxygen has been reported to decrease tidal volume (VT) in infants [1] and recent evidence published in the European Respiratory Journal suggest that transient less pronounced effects are also seen in preschool children [2]. It is unclear whether there is an age dependency beyond infancy in the response to 100% oxygen or whether it is limited to young children. Here we investigate the effects of 100% oxygen on breathing pattern across a spectrum of ages to identify the change in VT that occurs when subjects breathe 100% oxygen during a multiple breath nitrogen washout (MBNW) test.MBNW testing was performed [3] with the Exhalyzer® D using Spiroware 3.1 software (EcoMedics AG, Dürnten, Switzerland). Preschool children were tested using a mask whereas older children and adults used a mouth piece. All trials were re-run through Spiroware 3.2.0 to obtain breath-by-breath output of VT, respiratory rate (RR) and minute ventilation (V′E) for all pre-washout and washout breaths. The average VT , RR and V′E of the last 5 breaths of the pre-phase was compared to each washout breath to calculate a relative change in each parameter. We also compared the final 5 breaths of the pre-phase to the average all of breaths collected during the washout phase. A non-linear regression analysis was used to model the breath-by-breath changes. In total data collected from 112 preschool children (50 healthy and 62 with cystic fibrosis (CF)) [4], 18 school age children (all with CF) [5] and 10 adults (all healthy) were include in the analysis. Combined, the subjects ranged from 2.5 years to 29 years of age (median 4.8 years, interquartile range (3.7-17.5)) and 63% of participants were male.Exposure to 100% oxygen resulted in an initial decrease in VT, RR and V′E in all three age groups (figure 1), followed by a return to pre-phase levels. This effect was observed in both healthy subjects and those with CF. The average VT of the entire washout was not significantly different when compared to the pre-phase in all groups (0.8% decrease in healthy preschool children, 3.2% and 3.9% decrease in preschool and school age children with CF, respectively, and a 1.6% decrease in healthy adults).Our findings are thus consistent with two recent studies that compared the average pre-phase VT to the average VT during the washout phase in preschool [2] and school age children [6]. FOONG et al.[2] observed a 13 mL (4.8%) decrease in VT whereas JOST et al.[6] observed a 9.7 mL (3.5%) decrease in VT. In infants, breath-by-breath analysis demonstrated temporary hypoventilation driven by a decrease in VT after 2-4 breaths, which remained low for 10-25 breaths before returning to baseline [1]. Therefore, changes in tidal breathing in response to exposure to 100% oxygen observed in infants are not unique to this age group. Rather, they are a phenomena exhibited by subjects of all ages with the magnitude of the effect being small after early infancy. This is important for longitudinal studies with MBNW measurements, as breathing 100% oxygen is unlikely...

Comparison of lung clearance index determined by washout of N2 and SF6 in infants and preschool children with cystic fibrosis

“…Taking all into account, it seems unlikely that the different software versions used in our study with their inherent algorithms to process signals to MBW parameters are a major determinant contributing to differences between N 2 -and SF 6 -LCI observed. Some studies detected a decrease in VT during inhalation of 100% O 2 in infants, preschool children, and even young adults of up to 29 years [34,[42][43][44]. However, these studies observed a minimal effect on breathing pattern after early infancy, which is in line with our study in older infants and children demonstrating no difference in VT and RR between N 2 -and SF 6 -MBW (Table 2).…”

Difference between SF6 and N2 multiple breath washout kinetics is due to N2 back diffusion and error in N2 offset

“…Although we previously identified NBD as one factor (19) contributing to the differences between the two methodologies, we have speculated that NBD alone may be inadequate to account fully for the differences. Other studies (13,17,19,21) have also demonstrated a significant effect of NBD on N 2 washout kinetics, but other factors such as the use of 100% oxygen for washout (16) may also contribute to the difference between SF 6 and N 2 washout kinetics.…”

“…For example, the individual systems normally use different washout gases (100% O2 vs. air). A recent study (16) has reported a considerable effect on breathing pattern (lower tidal volume) of 100% oxygen in all age groups, which may affect CEV and LCI. Furthermore, it remains unknown whether there is an influence of pure oxygen on gas exchange.…”