High Frequency Positive Pressure Ventilation via the IMV Bird—Two Cases

Abstract

Conventional low frequency ventilatory techniques using large tidal volumes and slow rates may be accompanied by such undesirable cardiopulmonary side-effects as impeded venous return, decreased cardiac output, and barotrauma. Therefore, we supported two patients admitted with severe blunt chest trauma, with high frequency positive pressure ventilation (HFPPV) via the Bird IMV ventilator at rates of 60 breaths/min and tidal volumes of 150-200 ml. The IMV Bird meets the basic criteria for an HFPPV ventilator, which are low internal compliance, high initial flowrates, and patient tubing with minimal compressible volume. This device can also attain respiratory rates up to 72 breaths/min without modification. HFPPV was able to support ventilation and ensure good gas exchange in both patients while apparently avoiding the undesirable side-effects of conventional low frequency ventilation. Minute ventilation was adequate, while peak pressures were minimized, even with the use of PEEP.