High inspired oxygen during mechanical ventilation may influence the exhalation of the
previously proposed breath biomarkers pentanal and hexanal, and additionally induce systemic
inflammation. We therefore investigated the effect of various concentrations of inspired oxygen on
pentanal and hexanal exhalation and serum interleukin concentrations in 30 Sprague Dawley rats
mechanically ventilated with 30, 60, or 93% inspired oxygen for 12 h. Pentanal exhalation did not
differ as a function of inspired oxygen but increased by an average of 0.4 (95%CI: 0.3; 0.5) ppb per hour,
with concentrations doubling from 3.8 (IQR: 2.8; 5.1) ppb at baseline to 7.3 (IQR: 5.0; 10.8) ppb after
12 h. Hexanal exhalation was slightly higher at 93% of inspired oxygen with an average difference
of 0.09 (95%CI: 0.002; 0.172) ppb compared to 30%. Serum IL-6 did not differ by inspired oxygen,
whereas IL-10 at 60% and 93% of inspired oxygen was greater than with 30%. Both interleukins
increased over 12 h of mechanical ventilation at all oxygen concentrations. Mechanical ventilation at
high inspired oxygen promotes pulmonary lipid peroxidation and systemic inflammation. However,
the response of pentanal and hexanal exhalation varies, with pentanal increasing by mechanical
ventilation, whereas hexanal increases by high inspired oxygen concentrations
