Resumen:
To examine the correlation DCO2/PaCO2 on high-frequency oscillatory ventilation (HFOV) combined with volume guarantee (VG) throughout increasing frequencies in two different respiratory conditions, physiological and low compliance. Neonatal animal model was used, before and after a bronchoalveolar lavage (BAL). HFOV combined with VG was used. The frequency was increased from 10 to 20 Hz, and high-frequency tidal volume (VThf) was gradually decreased maintaining a constant DCO2. Arterial partial pressure of carbon dioxide (PaCO2) was evaluated after each frequency and VThf change. Six 2-day-old piglets were studied. A linear decrease in PaCO2 was observed throughout increasing frequencies in both respiratory conditions while maintaining a constant DCO2, showing a significant difference between the initial PaCO2 (at 10 Hz) and the PaCO2 obtained at 18 and 20 Hz. A new DCO2 equation (corrected DCO2) was calculated in order to better define the correlation between DCO2 and the observed PaCO2. Conclusion: The correlation DCO2/PaCO2 throughout increasing frequencies is not linear, showing a greater CO2 elimination efficiency at higher frequencies, in spite of maintaining a constant DCO2. So, using frequencies close to the resonant frequency of the respiratory system on HFOV combined with VG, optimizes the efficiency of gas exchange.What is Known: center dot The efficacy of CO(2)removal during high-frequency oscillatory ventilation (HFOV), described as the diffusion coefficient of CO2(DCO2) is related to the square of the high-frequency tidal volume (VThf) and the frequency (f), expressed as DCO2= VThf(2)x f.What is New: center dot The correlation between DCO(2)and PaCO(2)throughout increasing frequencies is not linear, showing a greater CO(2)elimination efficiency at higher frequencies. So, using very high frequencies on HFOV combined with volume guarantee optimizes the efficiency of gas exchange allowing to minimize lung injury.
