Carbon Dioxide Levels in Extremely Preterm Neonates Ventilated With High Frequency Jet Ventilation

Background: Close monitoring of carbon dioxide (CO 2 ) levels is crucial in extremely preterm neonates; however, a consensus on the optimal CO 2 thresholds is lacking. We aimed to evaluate the impact of P aCO 2 levels during the first 24 h of life on the outcomes of extremely preterm neonates ventilated with first-intention high frequency jet ventilation (HFJV). Methods: We retrospectively examined neonates ≤26 weeks of gestational age who were ventilated with first-intention HFJV, during 2022–2024, comparing the lowest P aCO 2 , peak P aCO 2 , P aCO 2 fluctuations, and P aCO 2 deviation from the target (40–50 mm Hg) during the first 24 h of life between neonates who survived without severe intraventricular hemorrhage (IVH) and neonates who developed severe IVH or died. Results: Among 50 extremely preterm neonates of gestational age 24.3 ± 1.5 weeks and birthweight 656 ± 170 g, 33 (66%) survived without severe IVH. Neonates who survived without severe IVH were of greater gestational age (24.7 ± 1.3 vs 23.6 ± 1.5 weeks, P = .01) and birthweight (696 ± 159 vs 577 ± 167 g, P = .02), compared to neonates who developed severe IVH or died. The latter had significantly higher peak P aCO 2 (66.7 ± 17.0 vs 54.6 ± 10.2 mm Hg, P = .006), P aCO 2 fluctuations (30.8 ± 17.3 vs 16.6 ± 8.8 mm Hg, P = .001), and P aCO 2 deviation from the target (20.0 ± 14.9 vs 9.7 ± 7.3 mm Hg, P = .003), compared to neonates who survived without severe IVH. A higher peak P aCO 2 , P aCO 2 fluctuation, and P aCO 2 deviation from the target were significantly associated with severe IVH, death, or severe IVH/death. A cutoff of a peak P aCO 2