Influence of Flow Rate Change on CO2 Levels During High Flow Nasal Ventilation (HFNV) in Preterm Infants.

Background: Preterm Births: About 10% of births are preterm, with infants at risk for respiratory distress. Respiratory Support: Endotracheal ventilation has improved survival but increased the risk of bronchopulmonary dysplasia. Non-Invasive Support: Nasal CPAP minimizes complications. Heated, humidified high-flow nasal ventilation (HFNV) is an alternative, providing advantages like reduced nasal trauma and improved oral feeding. Aim: Primary Goal: Examine changes in transcutaneous CO2 (tcCO2) levels in preterm infants when using HFNV at low (2 LPM) versus high (6 LPM) flow rates. Hypothesis: Different HFNV flow rates will show minimal change in tcCO2 (≤5 mmHg). Methods: Design: Prospective, crossover observational study in Rambam NICU. Participants: Preterm newborns (24-33.6 weeks' gestation) needing HFNV. Inclusion Criteria: Stabilized HFNP settings and tcCO2, parental consent. Exclusion Criteria: Specific flow and CO2 levels, unstable conditions, or congenital malformations. Procedure: Randomize infants into two groups starting with 2 or 6 LPM flow rates, monitoring tcCO2 over three consecutive hours with alternating flow rates. Measurements: Primary Outcome: Change in tcCO2 levels. Secondary Outcomes: Number of study terminations due to pCO2/TcCO2 out of safety range, changes in respiratory parameters, and episodes of desaturation or bradycardia. Statistical Analysis: Sample Size: 45 infants needed to detect no difference with 90% power and 5% significance level. Data Analysis: Use paired and unpaired Student's t-tests to compare results within and between groups. Safety Protocol: The study will terminate if significant desaturation, bradycardia, or pCO2 levels outside the safety range occur.