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 (VT). The clinical consequence is that for a given alveolar ventilation target, MFV provides optimal inspiratory pressure and respiratory frequency with the least VT. MFV is a strategy where peak alveolar ventilation is identified and results in lower VT 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 VT 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 VT protective lung strategy are transitioned to either high frequency ventilation, which delivers small VT 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.