Mid-frequency ventilation: A potential strategy for lung protective neonatal mechanical ventilation

Abstract

Mid-frequency ventilation (MFV) is a mode of mechanical ventilation where pressure controlled breaths are delivered at higher than usual respiratory rates with a conventional ventilator. The use of higher than normal frequencies has been used in clinical practice for the last 30 yr. However, MFV is based in the mathematical modeling of a pressure control breath; were as ventilator frequency increases, at a constant inspiratory to expiratory time ratio, alveolar ventilation demonstrates a peak (maximized). This peak is typically found at higher than usual respiratory rates (optimal frequency) and lower tidal volume (V_T). The clinical consequence is that for a given alveolar ventilation target, MFV provides optimal inspiratory pressure and respiratory frequency with the least V_T. MFV is a strategy where peak alveolar ventilation is identified and results in lower V_T at the same ventilation pressures. Current ventilators are able to deliver higher rates and thus can optimize the delivery of mechanical ventilation. Current clinical practice of mechanical ventilation utilizes a low V_T approach as a protective lung strategy to prevent further ventilator induced lung injury and thus potentially reduce mortality. Further, neonatal and pediatric patients who fail a conventional low V_T protective lung strategy are transitioned to either high frequency ventilation, which delivers small V_T at fast respiratory rates, or more invasive and expensive support such as extracorporeal membrane oxygenation. MFV may offer an alternative to deliver a protective lung strategy without the need for advanced equipment.

Keywords

Mechanical ventilation - mid-frequency ventilation - lung injury - pressure control - acute respiratory distress syndrome