Problems associated with collecting breath condensate for the measurement of exhaled hydrogen peroxide from neonates on respiratory support

We developed a bedside method for collecting exhaled breath condensate (EBC) from neonates who were ventilated or receiving nasal continuous positive airway pressure (CPAP) and analyzed their EBC for hydrogen peroxide levels. A sufficient volume for analysis could be collected over 25-40 min from neonates on the ventilator and nasal CPAP (medians 5.3 and 2.7 ml, respectively). There was no significant difference between hydrogen peroxide levels from neonates on a ventilator or CPAP (median 0.28 vs. 0.38 microM, p = 0.06) and these were no different from a background with the ventilator or CPAP system alone (median for each 0.31 microM). The dilution of breath condensate by humidified gases plus the existence of background hydrogen peroxide resulted in this collecting setup being insufficiently sensitive to use for the detection of exhaled hydrogen peroxide in infants who were ventilated or on nasal CPAP.