Accuracy of a battery-powered portable capnometer in premature infants

Carbon dioxide measurement is useful for confirmation of successful tracheal intubation and ensuring adequate ventilation. There are two types of CO₂ detectors, i.e., single-use-only colorimetric devices and capnometers. Although portable capnometers are widely used for resuscitation, there have been no reports regarding their clinical utility in neonates. The correspondence between end-tidal CO₂ (PetCO₂) level determined using a battery-powered portable capnometer and arterial CO₂ (PaCO₂) was investigated using paired data obtained simultaneously from 26 neonates weighing 1262 ± 589 g at examination on mechanical ventilation. PetCO₂ level and PaCO₂ showed a strong correlation (r = 0.839, P < 0.001), and the correlation equation was: PetCO₂ = 0.8 × PaCO₂ + 1.1. Therefore, PetCO₂ readings obtained with a battery-powered portable capnometer were likely to be underestimated. This became more pronounced with decreasing infant body weight at examination as the net difference in measurements of PaCO₂ and PetCO₂ was significantly positively correlated with infant body weight at examination (r = 0.451, P < 0.001). The observations presented here may be helpful in the use of battery-powered portable capnometers in neonates requiring controlled ventilation with tracheal intubation.