Mechanical Ventilator Project by Kiwi

There are many good initiatives that were started to help the overstretched healthcare system to deal with the shortfall of medical ventilators due to COVID-19, such as the Openlung project homebrew ventilator by converting the manual CPR tool – commonly found in ambulances and hospitals, into mechanically driven systems.

The focus for this project is to achieve the following

• A design that is cheap, reliable and easy to be produced by the community
  • makerspaces, schools and homes
• Provide important adjustable parameters such as
  • breathing speed, volume and inhale/exhale ratio. This is to adjust for infants, children and adults with varying breathing condition and capacity
• To provide potential or future feature integration
  • Patient breathing condition feedback control (Will be followed up)
  • Oxygen level feedback when fitted with oxygen concentrator (next project)

What is a Ventilator?

“In its simplest form, a modern positive pressure ventilator consists of a compressible air reservoir or turbine, air and oxygen supplies, a set of valves and tubes, and a disposable or reusable “patient circuit”. The air reservoir is pneumatically compressed several times a minute to deliver room-air, or in most cases, an air/oxygen mixture to the patient. If a turbine is used, the turbine pushes air through the ventilator, with a flow valve adjusting pressure to meet patient-specific parameters. When overpressure is released, the patient will exhale passively due to the lungs‘ elasticity, the exhaled air being released usually through a one-way valve within the patient circuit called the patient manifold.
Ventilators may also be equipped with monitoring and alarm systems for patient-related parameters (e.g. pressure, volume, and flow) and ventilator function (e.g. air leakage, power failure, mechanical failure), backup batteries, oxygen tanks, and remote control. The pneumatic system is nowadays often replaced by a computer-controlled turbopump.Modern ventilators are electronically controlled by a small embedded system to allow exact adaptation of pressure and flow characteristics to an individual patient’s needs. Fine-tuned ventilator settings also serve to make ventilation more tolerable and comfortable for the patient. In Canada and the United States, respiratory therapists are responsible for tuning these settings, while biomedical technologists are responsible for the maintenance. In the United Kingdom and Europe the management of the patient’s interaction with the ventilator is done by critical care nurses.”

The Design

• LeadScrew + Stepper Drive System
• Laser Cut 5mm
• Acrylic/Plywood Structure
• Nano+breakout shield + TB6600 Stepper Drive as the Main Control System
• 3 x 10k Potentiometers as inputs for breathing rate, air volume and exhale/inhale ratio
  

Operations

• Homing on powerup
• Adjustable speed and acceleration knob to adjust breathing rate
• Adjustable compression depth for air volume control
  • The actual settings for proper use on respective type of patients will need medical expert input. For now, the system allows full user control, and the setting combination can be labelled on the knobs later.
• Adjustable exhale speed to provide the control over 1.5 – 3 times slower than inhale speed.

Files