2004 OPEN FORUM Abstracts
TIDAL VOLUME EVALUATION IN TWO HIGH-FREQUENCY OSCILLATORS FOR ADULT PATIENTS USING A MODEL LUNG WITH A POSITION SENSOR
Naoya
Iguchi MD1, Yuji Fujino MD1, Osamu Hirao
MD1, Takashi Mashimo MD1, Masaji Nishimura MD2 1Intensive
Care Unit, Osaka University Hospital; 2Emergency and
Critical Care Medicine, University of Tokushima Graduate School
INTRODUCTION:
Until the recent introduction of the R100® (Metran,
Saitama, Japan), the 3100B® (SensorMedics, Yorba
Linda, CA) was the only high-frequency oscillator available for adult
patients. Both of these oscillators create airway pressure swings by
driving a diaphragm to and fro. It has been difficult to compare
delivered tidal volume (VT) at a specific setting during
HFOV although it is a very important aspect of oscillator
performance.
METHODS:
A model lung (TTL, Michigan Instruments, MI) was oscillated using the
3100B or R100. Settings for both oscillators were: frequency 5, 7, 9
Hz; mean airway pressure, 15 cmH2O; oxygen inspiratory
fraction, 0.21; and inspiration:expiration (I:E) ratio, 1:1. At each
setting, the oscillator pressure swing was set at maximum. Model lung
compliance was set at 50 mL/cmH2O and an endotracheal tube
of 8.0 mm internal diameter was used to provide resistance. During
the trials, attached to the upper surface of the model lung and
converting lung movement to analog electrical signals, a position
sensor evaluated VT. Pressure and volume signals were
recorded at a sampling rate of 667 Hz, digitized using an
analog-to-digital converter, and recorded in a computer. At each
setting, three waveforms were analyzed and the average value was
used.
RESULTS:
At 5 Hz, the R100 delivered more VT than the 3100B. As
frequency increased the difference of delivered VT
decreased (Figure).
CONCLUSION:
Using a model lung with a position sensor, oscillator performance can
be evaluated by measuring VTs.