Sponsored Project: COVID-19 DIY VentilatorActive
This project was created in response to the Columbia University DIY Ventilator Challenge. The goal of this challenge is to design a device based on an Ambu-bag [bag valve mask] that can be used both for invasive ventilation (in hospital setting) and potentially for non-invasive ventilation using a mask. Ambu-bags [bag valve masks] are standard common and low cost CPR devices that are typically used manually to perform resuscitation.
Began: April 2, 2020
Project Summary: As per the challenge description provided by Columbia University:
"In this challenge, we are seeking a design for a makeshift emergency ventilator that will squeeze this bag automatically at a specified amplitude and rate. This will be used to keep patients alive while they wait for a proper ventilator. The device can use something like an Arduino and a RC servo or stepper, and a simple user interface to set rate and amplitude. The device should be easy to fabricate so that many of these can be made quickly.
Scenario A: In-hospital forced periodic ventilation of intubated, sedated (or paralyzed) patients under medical care.
Scenario B: In-or-out of hospital assisted ventilation of alert patients using a face mask. For this scenario, the device must also include a sensor to detect and trigger beginning of air intake."
Project Repository: https://github.com/drfoland/covid-19-ventilator
The key requirements stated as part of this open challenge are as follows:
- The automated device will squeeze a standard ambu-bag by a specified amount (about 1 to 6 inches) and at a specified frequency (10 to 30 squeezes per minute).
- The squeezing mechanism can use an arm, a lever, a piston, a belt, etc.
- Maximum pressure in the bag is typically no more than up to about 30 cmH2O.
- The Ambu-bag has an attached PEEP regulator valve that the physician can use to set the minimum exhalation pressure.
- The attending physician will set the appropriate volume and rate to maintain reasonable lung pressure as determined using a manometer.
- The size of the ambu-bags can vary slightly, so the device should be compatible with (adjustable to) to accommodate a variety of bag sizes (diam 5-7 inches).
- The device should sit firmly on a base (e.g. a plywood base).
- Assume the ambu-bag is disposable. The bag should be easy to replace without dismantling the machine.
- The device should operate reliably and continuously for multiple days at a time.
- Ideally, the device should also detect a drop of pressure in the bag, and sound a loud audible alarm. A drop of pressure indicates a possible leak in the system, or a tube or mask being disconnected. The drop in pressure can be detected in many ways. For example, if the red needle of the manometer is at the lower end of the gauge, a small color sensor can attach to the manometer and detect the position of the needle. Alternatively, a pressure sensor can measure the pressure being applied by the bag to the base. Or a potentiometer can sense the position of the servo arm, or a current detector can measure how much torque is being applied by the servo. Anything inside the tubes that comes in contact with patient air must be either disposable or serializable.
- The units will connect to a power outlet with generator backup. No battery operation is needed.
- No need to worry about contamination. Viral filters, if needed and available, will be connected by the physician to the intake and exhaust tubes.
- No need to worry about oxygenation. If needed and available, oxygen line will be connected by the physician to the bag directly.
- There is no need for the device to be sterile or sterilizable.
- Materials should be standard and minimal. If you need to fabricate specialized components (e.g. using 3D printing or laser cutting), make sure that these parts can be fabricated quickly – avoid large or long prints and cuts.
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