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Team PANDA, Zurich, Switzerland - [email protected] -
TEAM PANDA TEST PROTOCOL
INLINE PEEP VALVE COMPARISON
Project PANDApeep
Date/Place 4.5.2020 / Winterthur, Switzerland
Authors Dominik Textor, Stefan Stahl
Introduction
This test series shall compare the PANDApeep Inline valve with the commercial PEEP valve Ambu PEEP 20. This is not a medical test.
Components
PEEP valves:
PANDApeep Gen2 inline: https://www.thingiverse.com/thing:4316582 [Configuration: Bike hub spring mounted on retrofit kit / Material: Profill PLA (case)]
o Rubber seal (1 mm thickness) o 3D-printed TPU seal
Ambu PEEP 20 disposable: https://www.ambu.com/emergency-care-and-training/resus-citators/product/peep-valves
Flow restrictor (Tests without PEEP valve only):
PANDAflow: https://www.thingiverse.com/thing:4289425 Test rig:
Compressor: Revell Airbrush Gamma
Check valve SMC AKH
Magnetic fill valve Bürkert 6012
Test lung Dräger MP02400 1000 ml
Manual ball valve RB
Patient Tube: length 400 mm, connectors 22 mm Sensors & Controls:
Pressure Sensor: Bosch BMP280
Control electronics: Arduino Uno with 2x relay bank
24 VDC Power supply
Manual ball valveCheck valve Adjustable PEEP valve
Pressure sensor
Test lung
Compressor Magnetic 3/2 valve
Patient tube 400 mm
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Team PANDA, Zurich, Switzerland - [email protected]
Method Sensitivity testing: Check response to test lung expiration at different PEEP pressure values
Fully open the PEEP valve
Close the PEEP valve to start position
Fill test lung up to 30 cm H2O
Start pressure measurement
Wait 1 s
Open ball valve
Expiration for 5 s
Stop pressure measurement
Close ball valve
Close the PEEP valve to the next position
Iterate until last position is measured
Measure frequency of pressure sensor: 10 Hz Repeatability testing: Check variation of response to test lung expiration
Same procedure as sensitivity testing with a constant PEEP valve position (ca. 15 cm H2O) Overview PEEP valve test positions:
PEEP valve Test series Protocol Pos. 1 Pos. 2 Pos. 3 Pos. 4 Pos. 5
PANDApeep Gen2 inline TPU seal
Series 1 Sensitivity Start +1/4 turn +1/2 turn +3/4 turn +1 turn
Series 2 Repeatability +3/4 turn +3/4 turn +3/4 turn +3/4 turn +3/4 turn
Series 2a Repeatability Same position as Series 2 but top down (minimum PEEP direction)
+3/4 turn +3/4 turn +3/4 turn +3/4 turn +3/4 turn
Series 3 Sensitivity Same positions as Series 1 but starting from 40 cm H2O
Start +1/4 turn +1/2 turn +3/4 turn +1 turn
PANDApeep Gen2 inline Rubber seal
Series 1 Sensitivity Start +1/4 turn +1/2 turn +3/4 turn +1 turn
Series 2 Repeatability +1/2 turn +1/2 turn +1/2 turn +1/2 turn +1/2 turn
Ambu PEEP 20 Series 1 Sensitivity 5 10 15 20 Max
Series 2 Repeatability 15 15 15 15 15
System testing: The test systems expiration curve without PEEP valve was tested qualitatively with a flow restrictor in the same place.
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Team PANDA, Zurich, Switzerland - [email protected]
Results The following results were achieved:
Figure 1: Results PANDApeep Gen2 Inline with TPU seal
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Team PANDA, Zurich, Switzerland - [email protected]
Figure 2: Results PANDApeep Gen2 Inline with Rubber seal
Figure 3: Results Ambu PEEP 20
Figure 4: Results System testing without PEEP valve and restricted flow (PANDAflow)
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Team PANDA, Zurich, Switzerland - [email protected]
Discussion Sensitivity:
All tested valve versions offer enough sensitivity to adjust the PEEP to < 1 cm H2O. The Ambu PEEP 20 has much more revolutions per pressure difference.
All valves need pressure measurement for exact adjustment. Whereas the PANDApeep has no absolute indication, the Ambu PEEP 20 can be adjusted to ±1-2 cm H2O (See Figure 3).
Expiration behavior:
The PANDApeep Gen2 Inline with Rubber seal and the Ambu PEEP 20 have a very similar behavior (Figure 5) The PANDApeep Gen2 Inline with TPU seal shows slower discharge and inferior closing behavior (Figure 6).
Figure 5: Expiration curves PANDApeep Gen2 Inline with rubber seal (Series 1) and Ambu PEEP 20 (Series 1)
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Team PANDA, Zurich, Switzerland - [email protected]
Figure 6: Expiraton curves PANDApeep Gen2 inline with TPU and rubber seal
Repeatability
All valves show excellent repeatability over several expiration cycles (see Figure 1, Figure 2 and Figure 3).
Hysteresis
The PANDApeep Gen2 Inline with TPU seal was tested for dependency on turning direc-tion. A hysteresis of ca. 2 cm H2O can be seen (Figure 7).
Figure 7: Hysteresis in Expiration curves depending on turning direction
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Team PANDA, Zurich, Switzerland - [email protected]
System expiration behavior: As there were ripples in the expiration curves with all valves at low PEEP levels, a qualitative test with a constant flow restriction was conducted. According to this test, the ripples are result-ing of the test system (test lung, connectors and patient tubes) and not caused by the valves (Figure 4). The test setup tries to mimic the setup used in the clinical application. Measuring without the ad-ditional patient tube results in cleaner opening behavior for the commercial as well as for the 3D printed valves. This shows that the valve behavior is dependent on the tube setup.
Conclusion
In our test setup, the PANDApeep Gen2 Inline with Rubber seal and bike hub spring achieves very promising results: Expiration behavior and repeatability are comparable to the commercial Ambu PEEP 20. The version with the 3D-printed TPU seal is working as well, but with much slower discharge and therefore higher dependency on inspiration pressure and frequency.
