Carbon dioxide clearance using bubble CPAP with superimposed high-frequency oscillations in a premature infant lung model with abnormal lung mechanics

摘要

Background High-frequency (HF) oscillatory ventilation has been shown to improve carbon dioxide (CO2) clearance in premature infants. In a previous in vitro lung model with normal lung mechanics we demonstrated significantly improved CO(2)washout by HF oscillation of bubble continuous positive airway pressure (BCPAP). Objective To examine CO(2)clearance in a premature infant lung model with abnormal lung mechanics via measurement of end-tidal CO(2)levels (EtCO2) while connected to HF oscillated BCPAP. Design andMethods A 40 mL premature infant lung model with either: normal lung mechanics (NLM): compliance 1.0 mL/cm H2O, airway resistance 56 cm H2O/(L/s); or abnormal lung mechanics (ALM): compliance 0.5 mL/cm H2O, airway resistance 136 cm H2O/(L/s), was connected to BCPAP with HF oscillation at either 4, 6, 8, 10, or 12 Hz. EtCO(2)was measured at BCPAPs of 4, 6, and 8 cm H2O and respiratory rates (RR) of 40, 60, and 80 breaths/min and 6 mL tidal volume. Results HF oscillation decreased EtCO(2)levels at all BCPAPs, RRs, and oscillation frequencies for both lung models. Overall mean +/- SD EtCO(2)levels decreased (P < .001) from nonoscillated baseline by 19.3 +/- 10.2% for NLM vs 14.1 +/- 8.8% for ALM. CO(2)clearance improved for both lung models (P < .001) as a function of oscillation frequency and RR with greatest effectiveness at 40 to 60 breaths/min and HF at 8 to 12 Hz. Conclusions In this in vitro premature infant lung model, HF oscillation of BCPAP was associated with improved CO(2)clearance as compared with nonoscillated BCPAP for both NLM and ALM. The significant improvement in CO(2)clearance in an abnormal lung environment is an important step towards clinical testing of this novel respiratory support modality.