The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

COMPARISON OF OXYGEN DELIVERY DURING OSCILLATORY AND JET VENTILATION

Andora L. Bass, MD; Michael A. Gentile, RRT FAARC; Damian M. Craig, MS;

Ira M. Cheifetz, MD FAARC

Division of Pediatric Critical Care Medicine

Duke Children's Hospital

Duke University Medical Center , Durham , NC

Background: High frequency ventilation (HFV) can be delivered using different technologies: oscillatory ventilation (HFOV) and jet ventilation (HFJV). HFOV is typically used at elevated mean airway pressures (mPaw) to augment oxygenation; while HFJV is used at lower mPaw to optimize cardiac output. The overall goal for both approaches is an improvement in oxygen delivery (DO2).  However, it is unknown if matching the mPaw during HFJV (by increasing the positive end expiratory pressure) and HFOV will result in similar DO2. We hypothesized that oxygen delivery would be similar during HFOV and HFJV at matched mPaw settings of 10, 15, and 20 cm H2O.

Methods: A lung injury model of acute respiratory distress syndrome (ARDS) was created in 11 juvenile swine (5.4 ± 0.6 kg) by surfactant depletion using bronchoalveolar lavage. A Life Port jet adapter was placed in-line during HFOV and conventional ventilation (CV) to obtain measurements of mPaw and peak inspiratory pressure (PIP) during the following interventions. The animals were randomized to high-frequency ventilation with a mPaw of 10, 15, or 20 cm H2O. The sequence of HFOV (SensorMedics 3100A; Viasys Healthcare; Yorba Linda , CA ) or HFJV (Life Pulse; Bunnell, Inc.; Salt Lake City , UT ) was also randomized. HFOV settings included: frequency 7 Hz, % inspiratory time 0.33, and FiO2 0.70. The power was set to maintain a delivered PIP of 30 cm H2O as measured by the in-line jet ventilator. During HFJV, settings included: rate 420 bpm, inspiratory time 0.2 sec, FiO2 0.70, and PIP 30 cm H2O. Subsequently, the alternate HFV mode (HFJV or HFOV) was initiated at the mPaw set during the first sequence of HFV. The process was repeated for a total of three mPaw settings on each device. For each combination of HFV device and mPaw, gas exchange, ventilator, hemodynamic, and respiratory mechanics data were obtained after 15 minutes of stabilization. DO2 was calculated for each set of data.

Results: At mPaw of 10 and 15 cm H2O, there was no statistically significant difference in DO2 between the two HFV modes. At a mPaw of 20 cm H2O, DO2 was significantly higher during HFJV than during HFOV (539.3 vs. 389.0 ml O2/min; p < 0.006).

Conclusions: In an animal model of ARDS, oxygen delivery is similar between jet and oscillatory ventilation and is based on the mean airway pressure used. Thus, the selection between high frequency ventilation devices should be determined primarily by the unique gas delivery properties of each machine and the individual patient's pathophysiology.  

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