2006 OPEN FORUM Abstracts
Extended System Test Performance on the Viasys Avea Ventilator with Heliox Initiation
Daria Donelly RRT, David Heitz
RRT-NPS, Kevin Bullock RRT
Children's
Hospital Boston and
Harvard
Medical
School
,
Boston
,
MA
Background: The
AveaTM ventilator (Viasys Healthcare,
Palm Springs
,
CA
) is manufactured to incorporate safe heliox delivery
utilizing a "smart" fitting technology.
There are two "smart" fittings, one for compressed air and the other for
an 80/20 heliox mixture. The fittings
signal the ventilator which type of gas source is connected and therefore which
gas controls to initiate. Prior to
patient connection an Extended System Test (EST) is recommended by the
manufacturer to simultaneously determine patient circuit compliance and
leak. During the EST test the patient
circuit is pressurized to 60 cmH2O for 10 seconds. When the EST is successful, a circuit
compliance factor is generated. During volume
targeted modes the volume of gas delivered is increased to include the set
volume plus the volume loss as determined by the compressible volume factor. Since the density of helium is less than that
of air and oxygen we hypothesized that the compressible volume determined by an
EST would be altered and should therefore be performed prior to heliox initiation.
Method: We bench tested 3 Avea
ventilators on different occasions utilizing the compressed air and heliox "smart"
fitting technology. For each of the 3
ventilators we performed an EST with the compressed air "smart" fitting and
then repeated the testing with the heliox "smart" fitting connected to an H-size
cylinder of an 80/20 heliox mixture.
Each EST was repeated with the FIO2 set at 1.0, 0.6 and 0.21.
Results: With the ventilator connected to the compressed air "smart" fitting we
found no variation in each of the circuit compliance factors determined with the
FIO2 set at 1.0, 0.6 and 0.21. We did see a difference between the
determined factors for each FIO2 setting with the ventilator connected to an 80/20 heliox mixture using the heliox "smart"
fitting. When comparing the factors determined for each FIO2 setting between the two gas mixtures and fittings a
33% variance was seen with the FIO2 set at 1.0 and a 14% variance with an FIO2 of 0.6. There was no difference between the circuit
compliances determined with the FIO2 set at 0.21(see table).
| EST Circuit Compliance (mL/cmH2O) | |||
| FIO2 | 0.21 | 0.60 | 1.0 |
| Heliox | 2.1 | 2.4 | 2.8 |
| Compressed Air | 2.1 | 2.1 | 2.1 |
Conclusion: From
our results an EST should not be done when transitioning from compressed air to
heliox. If it is necessary that an EST
be performed during heliox utilization we recommend that it be done with the FIO2 set at 0.21.