Background: Mainstream airflow sensors used in neonatal ventilators to synchronize mechanical breaths with spontaneous inspiration and measure ventilation increase dead space and may impair carbon dioxide (CO2) elimination. Objective: To evaluate a technique consisting of a continuous gas leakage at the endotracheal tube (ETT) adapter to wash out the airflow sensor for synchronization and ventilation monitoring without CO2 rebreathing in preterm infants. Design: Minute ventilation (V′ E) by respiratory, inductance plethysmography, end-inspiratory and end-expiratory CO2 by side-stream microcapnography, and transcutaneous CO2 tension (TcPCO2) were measured in 10 infants (body weight, 835 ± 244 g; gestational age, 26 ± 2 weeks; age, 19 ± 9 days; weight, 856 ± 206 g; ventilator rate, 21 ± 6 beats/min; PIP, 16 ± 1 centimeters of water (cmH 2O); PEEP, 4.2 ± 0.4 cmH2O; fraction of inspired oxygen (FIo2), 0.26 ± 0.6). The measurements were made during four 30-minute periods in random order: IMV (without airflow sensor), IMV + Sensor, SIMV (with airflow sensor), and SIMV + Leak (ETT adapter continuous leakage). Results: Airflow sensor presence during SIMV and IMV + Sensor periods resulted in higher end-inspiratory and end-expiratory CO2, TcPCO 2, and spontaneous V′E compared with IMV. These effects were not observed during SIMV + Leak. Conclusions: The significant physiologic effects of airflow sensor dead space during synchronized ventilation in preterm infants can be effectively prevented by the ETT adapter continuous lea leakage technique.
ASJC Scopus subject areas
- Pediatrics, Perinatology, and Child Health