The Science Journal of the American Association for Respiratory Care

2008 OPEN FORUM Abstracts


Brian K. Walsh1, Frantz Teleau2, John Thompson1,2

Introduction: High frequency oscillatory ventilation (HFOV) is no longer considered a mode of ventilation that is outside of conventional. In fact, many consider HFOV a standard mode for respiratory failure of many etiologies. With the growing use of this mode a few issues have surfaced. One issue is the difficulty with the ability to transport the device during off floor procedures. Our institution is a referral center for congenital diaphragmatic hernia patients who occasionally require HFOV for stabilization. Following the stabilization period surgical correction takes place in the operating room. However, removing the patient from HFOV is not ideal and can delay the induction. The Sensormedics 3100A (Cardinal Healthcare) requires a bias flow of 10-30L/min. In addition to the bias flow a 10L/min flow is required for proper temperature control of the driver. The large gas consumption, lack of internal power supply, and bulky stance make the ventilator virtually impossible to utilize during transport. We bench tested the ventilator without using cooling gas, while being powered by an uninterruptable power source(UPS) for the period of one hour with the a goal being able to provide continuous HFOV throughout the corrective surgery process.

Methods: First we tested the Sensormedics 3100A on a flow of 20L/min, FIO2 of 1.0, MAP 18 cmH2O, Power of 10, cooling gas on, and powered by a fully charged Tripp Lite (Chicago, IL) UPS system that was running on internal battery. Following the discharge of the UPS system, we returned the 3100A to normal power and discontinued the cooling gas for an additional hour.

Results: Figure 1 summarizes the results our findings. The Tripp Lite UPS powered the ventilator at maximum power for one hour and ten minutes at which time the five minute power remaining alert sounded. The temperature measured throughout the circuit did rise from baseline. A 4°F increase at the patient wye and a 3°F increase at the connector at the water trap (bottom of membrane). The largest increase was on the metal frame of the driver with an 8°F climb.

Conclusion: The 3100A tolerates the interruption in cooling gas for up to one hour at maximum power. The 329°F internal heat warning did not activate nor did the 347 °F shut-down occur. The circuit did not reach or exceed body temperature. Therefore, the use of a UPS and flexible circuit with cautious discontinuation of the cooling gas appears to favor the continuation of HFOV during off floor procedures.