The Effect of High Frequency Percussive Ventilation on Cerebral Tissue Oxygenation

Hypoxemia is commonly reported in patients admitted to the Intensive Care Unit (ICU) and may result from acute lung injury/acute respiratory distress syndrome (ALI/ARDS), sepsis, trauma and postoperative complications. In an attempt to preserve or increase the oxygenation, conventional mechanical ventilation is initiated in these patients. Unfortunately, patients frequently become refractory to standard ventilatory techniques and as such, gas exchange remains unaltered or becomes worse. High Frequency Percussive Ventilation (HFPV), on the other hand, is an advanced mode of ventilation which can be a salvage option in these patient cohorts as it has already been proven to improve gas exchange with success. The volumetric diffusive respirator (VDR-4; Percussionary, Corp., Sandpoint, ID) is the only commercially available system to deliver HFPV. This ventilator mechanically ventilates the lung by administering small successive subtidal volumes or percussions at unconventional high frequencies to reach an optimal diffusive oxygenation.

Since it has been known that hypoxemia due to a reduced oxygenation results in secondary brain injury, it is conceivable that the cerebral tissue oxygenation might be impaired as well. It has been strongly suggested that a cerebral tissue oxygenation in the optimal range has an ameliorative influence on hypoxic events and in turn leads to a better clinical outcome. Thus far, no studies have been conducted to investigate if an improved oxygenation by means of a switch to HFPV automatically leads to an increment in the cerebral tissue oxygenation. With the use of Near-Infrared Spectroscopy (NIRS) technology, investigators will investigate whether this alternation of ventilation strategy is associated with a (beneficial) change of the cerebral tissue oxygenation.