Porcine Study #3 was conducted in the same animal facility in the Boston area with and 81 kg porcine. An anesthesiologist, who had never seen MIT E-Vent before, was invited to participate. He was given a simple manual explaining the basic controls and functionalities of MIT E-Vent, this has now been expanded and is provided in Operation.
The anesthesiologist was asked to set specific settings on the control box and collect flow-volume loop data, then to change control box settings to achieve specific pH ranges on arterial blood gases, and to mimic ventilator settings that he would normally provide patients with ARDS.
The anesthesiologist quickly became familiar with the control system and was able to complete the entire experiment and tasks within 3 hours.
Flow-volume loops were again collected using the spirometer with varying tidal volumes between 100 cc and 700 cc in combination with varying PEEPs of 5, 10, 15 cm H2O. Plateau pressure was kept below 30 cm H2O and this limited testing above 700 cc tidal volume. During this protocol, variations in tidal volume actually delivered were noted due to a controls system error. This was promptly corrected the next day.
The anesthesiologist was able to achieve target arterial blood gas pH values with ease. Specific feedback based on testing with this anesthesiologist included:
- Identification of a bug linking tidal volume to breathe per minute – now corrected
- On a fixed I/E the volume delivered as a function of bag compression, measured as a percentage of rotary arm actuation, is approximately linear.
- COVID-19 patients needs a respiratory rate up to 40 BPM – implemented
- We need to implement a “pressure failure” alarm indicating that something is disconnected in the airway
- Breath detection in Assist Control mode requires detecting a drop of 2 – 5 cm H2O with respect to the PEEP pressure, which may be greater than atmospheric
- Alarm need to be accompanied by a light to indicate which unit has failed in a multi-unit scenario.