Combined Use of Alkaline Agents With Low-Flow Extracorporeal Carbon Dioxide Removal in Carbon Dioxide Inhalation Models Preserving Inspiratory Efforts.

Background: Low-flow extracorporeal CO ₂ removal (ECCO ₂ R), managed using a renal replacement platform, is useful in achieving lung-protective ventilation with low tidal volume. However, its capacity for CO ₂ elimination is limited. Whether this system is valuable in reducing strong inspiratory efforts in respiratory failure is unclear. The combined use of alkaline agents with low-flow ECCO ₂ R might be useful in hypercapnic subjects preserving inspiratory efforts.

Methods: This study examined the effects of low-flow ECCO ₂ R on respiratory status and investigated the effects of NaHCO ₃ , trometamol, and saline on respiratory status during low-flow ECCO ₂ R in CO ₂ inhalation models.

Results: Although low-flow ECCO ₂ R did not significantly change the respiratory rate (92.2% ± 24.3% [mean ± standard deviation] of that before ECCO ₂ R), it reduced minute ventilation (MV) (78.9% ± 13.5% of that before ECCO ₂ R). The addition of NaHCO ₃ improved acidemia but did not change MV compared with that of the saline group (0.451 ± 0.026 L/min/kg body weight [BW] vs. 0.556 ± 0.138 L/min/kg BW, respectively). The addition of trometamol improved acidemia and reduced MV compared with that of the saline group (0.381 ± 0.050 L/min/kg BW vs. 0.556 ± 0.138 L/min/kg BW, respectively). The total amounts of CO ₂ removed during ECCO ₂ R in the NaHCO ₃ group were lower than those in the saline and trometamol groups.

Conclusion: The low-flow ECCO ₂ R reduced MV in subjects preserving spontaneous breathing efforts with CO ₂ overload. The addition of NaHCO ₃ improved acidemia but did not change MV, whereas the addition of trometamol improved acidemia and reduced MV.