SOURCES
Initial design specifications were based on the specifications needed for a ventilator for ADRS-patients, written by Julian Botta, Johns Hopkins Hospital:
Specifications for simple open source mechanical ventilator Public
The current iteration aims to be compliant with the MHRA specifications for a Rapidly Manufactured Ventilator System:
https://www.gov.uk/government/publications/specification-for-ventilators-to-be-used-in-uk-hospitals-during-the-coronavirus-covid-19-outbreak
In consult with doctors from UZ Brussels we have added the requirement for p-, V- and flow-graphs & user-configurable PID-settings to control the shape of the curves.
The machine needs to be durable & reliable enough to operate for 2 weeks continuously.
REQUIRED PERFORMANCE
The ventilator must be able to achieve an RR of 35 at I/E= 1/2
The ventilator must be able to deliver a Vt of 600ml. A Vt of 800ml is preferred.
The ventilator should provide real-time feedback, showing p-, flow- and V-graphs.
REQUIRED SETTINGS
The ventilator must have PC and VC modes.
The ventilator must have settings for RR, Ppeak, I/E
The ventilator should have a ramp-setting.
REQUIRED ACCURACY
•Under steady-state conditions, the indicated airway pressure shall be accurate to within±(2 +(4 % of the actual reading)) cmH2O
.•The accuracy of measurement of expired volumes greater than 50 ml shall be within±(4,0 +(15 % of the actual volume expired through the patient-connection port)) ml.
•Oxygen concentrations will be ± 5 % of the set value.
•Disconnect alarm will sound within 3 seconds of disconnection
COMPONENT SOURCING & AVAILABILITY REQUIREMENTS
-the machine should be designed to be safe to use.
-the machine needs to have the potential to be rapidly manufactured at scale.
-the design is based on a “100 dollar” machine designed for third world use. This is not our current context – and difficult to do with a machine designed to work in an ICU.
The machine needs to be affordable, but we can afford quality parts. The essential criterium for parts is rapid availability in large quantities, not lowest cost.
-components should be sourced from non-medical supply chains as to not strain the supply chains of existing ventilator manufacturers.
