Updated 1 May 2020
Clinical Guidance
We have interviewed clinicians and reviewed existing ventilator standards to determine the most important alarms needed, the appropriate action to take when an alert condition is detected, and the expected behavior for silencing alarms.
Silencing
- The alarm silence button should silence only the alarm tone, the visual notification should remain
- All alarms should be silenced for two minutes, even if a new alarm is triggered, the alarm silence should be maintained
- Pressing the alarm silence button again, before two minutes have elapsed should unsilence the alarms
- If multiple alarms are active, they should be visually displayed with LED’s. On the screen, the messages should cycle through.
The following table describes in detail the most important alarms identified. You are welcome to add more alarms as needed.
| Alarm Name | Detection | Clearing Condition | Tone | Response | Display Message |
| Exceeded PIP Pressure | P > Pmax = 40cmH20 This ensures the unit can never deliver air at a pressure higher than 40 cmH20 to mitigate the risk of barotrauma (lung damage). | One complete breathing cycle with no over pressure | Emergency Tone | Immediately stop compression, open completely, resume normal operation at start of breathing cycle | “HIGH PRESURE” |
| Under Pressure | Pplateau < Pplat_min = 5cmH20 This alarm detects any disconnections or leaks and notifies the clinician to check the breathing tube. | Measured plateau pressure normal | Emergency Tone | Continue normal operation | “LOW PRES DISCONNECT?” |
| High Resist Pressure | Ppip –Pplateau>Presist_max = 10cmH20 This alarm notifies the clinician that there is unusual resistance in the breathing tube or airway. | One resistance pressure measurement in normal range | Notify Chirp | Continue normal operation | “HIGH RESIST PRES” |
| Over Current Fault | I ≥ Imax = 4.5A This alarm detects the motor being pushed too hard. It indicates something may be stuck in the mechanism, or there may be a blockage in the breathing tube. | One complete breathing cycle without an overcurrent event | Emergency Tone | Immediately stop compression, open completely, resume normal operation at start of breathing cycle | “OVER CURRENT FAULT” |
| Tidal Volume not Delivered | Vfinal<Vset – Vthres = 50mL | Delivered tidal volume in the correct range | Emergency Tone | Continue normal operation | “UNMET TIDAL VOLUME” |
| Tidal Pressure Not Detected | Ppeak – Ppeep < Ptidal-min = 5cmH20 (2 cycles) This alarm detects situations where the pressure does not reflect inspiration but there may not be a leak. For example, if the bag is removed from the machine. | One complete breathing cycle without a tidal pressure failure | Emergency Tone | Continue normal operation | “NO TIDAL PRESSURE” |
hello
How can I detect Tidal Volume not Delivered ?
Encoder indicates failure to reach desired rotational position – sorry this was missing
sir please update arduino code
In the event of an AMBU replacement? Will the e-vent be place in a stand by mode by clinician?
I assume a spare AMBU need to be readily available for quick exchange.
How fast will this exchange need be during e-vent prolong usage? How fast clinician need to respond?
Thanks for the feedback on these concerns. Just to provide sufficient information and warns to clinicians operating the e-vent.
Best Regards
LR
This system is designed to be a short-term solution for critical ventilation in patients where a full feature ventilator may not be available. One advantage of this system is that, if the machine were to have a problem, the Ambu bag can also be used manually. When switching out the Ambu bag in the E-Vent device, the old bag can be removed from the device while still connected to the patient. The patient could then be manually ventilated with the old bag, while a new bag is secured in the ventilator. Once the new bag is ready, the tubing can just be swapped over to the new bag, which will minimize the amount of time that ventilatory support is not provided. If the old Ambu bag develops a significant defect that requires immediate replacement, the tubing can quickly be switched to a new Ambu bag, so that manual ventilatory support can be provided until the defective bag in the E-Vent is replaced.
Regarding response by clinicians, the patients will still be monitored for oxygenation status, CO2 levels, inspiratory pressures, and other critical signs. If the bag is not properly working, the patient is not receiving adequate oxygenation or another issue arises, the clinician can make adjustments to the ventilator settings or manually use the Ambu bag until a mechanical ventilator can be provided to the patient. These actions are similar to those that would be done for a patient with new-onset respiratory distress until a ventilator was made available.
We are in the process of adding a flow sensor to the design (for a non for profit to send them to Africa). Unfortunately we are not able to find an available flow sensor (all are with 0 stock), but a one from Drager (Spirolog).. but we are not able to find the data sheet which shows the electrical interference and the specification .. can anybody share these?
https://www.draeger.com/en-us_us/Hospital/Products/Accessories-and-Consumables/Sensors/Flow-Sensor-Accurate-and-intelligent-flow-measurement
Hi Team, welldone on a supper product. We can manufacture the product in Durban, South Africa. We are a technology electricity metering manufacturer, who has capacity to manufacture the device. Please place me in contact who I can speak to with this regards.
Viven Perumal
Marketing Executive
viven.perumal@conlog.com
Goord morning everybody, I have developed the calculation accroding the gears set used by MIT. At this stage I wonder if the max and min speeds found:
BPM = 10 (1.12 rpm for insp phase and 5.11 rpm for exp stage)
BPM = 20 ( 11.9 rpm for insp phase and 2.24 rpm for exp stage)
BPM = 30 ( 21.5 rpm for insp phase and 3.36 rpm for exp stage)
BPM = 40 ( 35.8 rpm for insp phase and 4.48 rpm for exp stage)
I/E rate 1:4 and Thold = 0.15
Could anyone provide me some help if those data are matching because the motor and drive specs dependi directly on this.
My best wishes
Eduardo
+55-11-942712038 (whatzapp)
Good evening,
Currently I am developing a e-vent and using the driver mentioned by MIT:
https://www.basicmicro.com/Roboclaw-Solo-30A-34VDC-Motor-Controller_p_44.html
Could anyone share me the source code for the driver parameterization?
Regards!
Eduardo Viana
Hi all, we have made the source code available at https://github.com/mit-drl/e-vent
Currently working to setup motor and driver units per MIT reference information for the e-vent project.
Would like to request for the driver parameters regarding BASICMICRO GUI to setup the driver/motor.
Using motor PG188 1/2 Hex Gearmotor P/N: am-3656 with motor driver P/N:IMC408 for the Robo Claw Solo 30A.
Thanks for your feedback and support.
Best Regards
LR
I am working in ethiopia, no online payment method for online order.so only chance is buying the available component in local stores.anyways I am working with a nema 23 stepper motor and with driver tb6600.and more the display part I2C LCD.i am modifying the code to make it work with I2C LCD.But the tb6600 motor driver seems specific to simple motor control compared to Rorboclaw 30A motor controller.So am working on modifying the motor control.any help with pseudo code or algorithm? many thanks for the MIT team and everyone trying to tackle this pandemic.
Hello Mesay!
I’m working in Colombia in a similar project, based on E-Vent. Coincidentially, we’re using a NEMA 23 18 Kgcm stepper motor and the same kind of driver. By testing, we realized, this motor doesn’t have enought torque to accomplish the insufflation using the mechanic proposed here (As you, we didn’t have acces to a bigger motor) So, we decide to use a mechanic based on endless screw.
Another aspect, is this driver is not too fast (200KHz) so you have to find a way out to get the required breath frequence.
If you would like to talk more about things we have found w.ariza@misena.edu.co
Thanks Mr. Williams.I will send u my email.
hey, can anyone tell me? if I can do any flow analysis on Ambu Bag or any other Ansys simulation. if yes, then please share the information regarding this.