DCO/PaCO correlation on high-frequency oscillatory ventilation combined with volume guarantee using increasing frequencies in an animal model.

To examine the correlation DCO/PaCO 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 DCO. Arterial partial pressure of carbon dioxide (PaCO) was evaluated after each frequency and VThf change. Six 2-day-old piglets were studied. A linear decrease in PaCO was observed throughout increasing frequencies in both respiratory conditions while maintaining a constant DCO, showing a significant difference between the initial PaCO (at 10 Hz) and the PaCO obtained at 18 and 20 Hz. A new DCO equation (corrected DCO) was calculated in order to better define the correlation between DCO and the observed PaCO.Conclusion: The correlation DCO/PaCO throughout increasing frequencies is not linear, showing a greater CO elimination efficiency at higher frequencies, in spite of maintaining a constant DCO. 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: • The efficacy of COremoval during high-frequency oscillatory ventilation (HFOV), described as the diffusion coefficient of CO(DCO) is related to the square of the high-frequency tidal volume (VThf) and the frequency (f), expressed as DCO= VThf× f.What is New: • The correlation between DCOand PaCOthroughout increasing frequencies is not linear, showing a greater COelimination 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.