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.