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 leukomalacia (PVL). Study Design. Matched pair analysis was conducted for 26 infants with PVL and 26 with normal development, who were born between 27 and 32 weeks' gestational age and required mechanical ventilation. The time-averaged carbon dioxide (CO₂) index, Paco₂, and pH were calculated every 24 hours for samples obtained from indwelling arterial catheters within the first 72 hours of life. The time-averaged respiratory rate of the ventilator (RR), peak inspiratory pressure (PIP), mean airway pressure (MAP), and ventilator index (VI) were also determined. The time-averaged total respiratory rate (TRR) was determined by observing the movement of the chest wall. The patients' characteristics, antenatal and neonatal variables, and electroencephalographic findings were also compared. Results. The time-averaged CO₂ index was larger, the time-averaged CO₂ lower and the time-averaged pH higher in infants with PVL than in those with normal development on the third day of life. There was no significant difference 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 significant difference. No significant difference was observed in the clinical characteristics or neonatal variables. Electroencephalographic abnormalities within 48 hours of life were more frequent in infants with PVL than in those with normal development. Conclusion. Hypocarbia was associated with PVL because the time-averaged CO₂ index was larger and the time-averaged Paco₂ lower in infants with PVL than in those with normal development. However, the ventilator settings were similar among the infants with and without PVL.