- Dual Adult model of Michigan Instruments TTL® or PneuView® System
- Michigan Instruments Head Simulation Module-Adult (HSM-A)
- CPAP delivery system
- BSM or other ventilator for lifting (left) lung
- TTL Lung Coupling Clip
For this application, the TTL Test Lung or PneuView System may be used. Use of the PneuView System will provide the user with digital data and waveforms that are unavailable on the TTL alone. Still, the TTL can provide accurate mechanical indications of volume and pressure seen during ventilation.
This setup and application may be used to assess:
- The sensitivity / responsiveness of the CPAP system to patient effort
- The effects of airway resistance on performance of the CPAP system
- Level of residual volume in the lungs resulting from varying CPAP set levels
- Any augmentation of inspired tidal volume as affected by CPAP level
- The effects of varying levels of bias flow on sensitivity and responsiveness of the CPAP system
Response of CPAP Systems to Change in Patient Effort
- Connect the Head Simulation Module-Adult accessory to the right lung of the TTL, select an appropriate Pneuflo® resistor for resistance. For adult patients, MII recommends initial use of an Rp5 or Rp20 resistor.
- Set nominal compliance setting(s) on the TTL. We suggest a starting setting of .05 L/cmH2O.
- Set up for spontaneous lung simulation using the MII Breath Simulation Module (BSM) and the Lung Coupling Clip. (Other ventilation devices may be used on the lifting (left) lung).
Note: Set the compliance for the left lung at highest level. This lung is simply being used as the “diaphragm” to lift the right lung and a realistic lung compliance setting is not needed. Similarly, no additional simulated resistance is required in this lifting lung.
- If using the PneuView System, start the PneuView Software and make appropriate selections in the Conditions screen. Select “Right Lung” as you will be looking at the response of the CPAP system to the breathing right lung. Set the Compliance to actual conditions in the data display screen.If not using PneuView, proceed to step 5.
- Set initial CPAP setting on the CPAP system and connect the CPAP system to the Head Simulation Module-Adult.
- Begin ventilation of the lifting (left) lung using the BSM or another ventilator. Note the pressure and volume response on the breathing (right) lung.
- Note the resulting pressure and values and waveforms. Also note the volume values on the TTL.
Note: Volumes indicated on the TTL volume scale will be accurate, however, because pressure changes in the lung are used to measure and calculate flow and volume values in PneuView software, some spontaneous breathing simulations will result in inaccurate flow and volume readings. If you have questions, please contact Michigan Instruments.
- Vary settings on the CPAP system and note changes in your resulting pressures and volumes.
- Vary spontaneous breath rates and volumes at the BSM and again note the results.
- The user may also vary TTL settings of lung compliance and/or airway resistance in the right lung, and again note changes in the behavior of the CPAP system and results at the TTL.
Michigan Instruments’ “Application & Use Case” documents are intended to provide some guidance and suggestions for use of the Test Lung Simulators. They do not encompass the range of applications for which the TTL and PneuView Systems are appropriate.
We welcome your suggestions for future Application & Use Case topics, and encourage you to share your own experiences and applications with us via email at firstname.lastname@example.org or contact us today.