Hypocarbia in preterm infants with periventricular leukomalacia: The relation between hypocarbia and mechanical ventilation

Objective. The aim of this study was to elucidate the relationship between mechanical ventilation and hypocarbia in infants with periventricular leuko malacia (PVL). Study Design. Matched pair analysis was conducted for 26 infants with PVL a nd 26 with normal development, who were born between 27 and 32 weeks' gesta tional age and required mechanical ventilation. The time-averaged carbon di oxide (CO2) index, PaCO2, and pH were calculated every 24 hours for samples obtained from indwelling arterial catheters within the first 72 hours of l ife. The time-averaged respiratory rate of the ventilator (RR), peak inspir atory pressure (PIP), mean airway pressure (MAP), and ventilator index (VI) were also determined. The time-averaged total respiratory rate (TRR) was d etermined by observing the movement of the chest wall. The patients' charac teristics, antenatal and neonatal variables, and electroencephalographic fi ndings were also compared. Results. The time-averaged CO2 index was larger, the time-averaged CO2 lowe r and the time-averaged pH higher in infants with PVL than in those with no rmal development on the third day of life. There was no significant differe nce in the time-averaged RR, PIP, MAP, or VI on any day. TRR was larger in the PVL group than in the control group on each day, but there was no signi ficant difference. No significant difference was observed in the clinical c haracteristics or neonatal variables. Electroencephalographic abnormalities within 48 hours of life were more frequent in infants with PVL than in tho se with normal development. Conclusion. Hypocarbia was associated with PVL because the time-averaged CO 2 index was larger and the time-averaged PaCO2 lower in infants with PVL th an in those with normal development. However, the ventilator settings were similar among the infants with and without PVL.