A fully mechanical Non-invasive Bi-level pressure support with independently adjustable peep device. This solution consists of the following components:
A blower provides high volume, low pressure air to the regulator. Oxygen is injected into the patient supply hose via a standard wall oxygen flow meter and O2 concentration is dependent on the patient’s tidal volumes and the amount of pressure support and O2 flow dialled in. This will allow use of the device in places without medical air and eliminates the need for costly O2/air blenders, making it suitable for most low-resource environments.
The system, by design, is constrained by the maximum percentage oxygen that can be supplied to the patient. Testing has showed this has a ceiling of 60%O2. This is because of the limitation that we imposed on O2 feed to 15l/min which is what is available from standard wall or bottle flow controllers.
The design of the unique mechanical reciprocal valve that cycles between inspiration and expiration is key to the device and was the most complex part of the system to crack. Traditionally this switching is done with electronic based sensors in the circuit which we wanted to eliminate to produce a fully mechanical system.
The shape of the surfaces, strategically placed airflow ducts and volume symmetry have allowed for a support device that offered what we required.
- With expiration the pressure in the mouth-piece increases pressing the spool backward.
- This shuts off the inlet port and flow and simultaneously opens the outlet port to the PEEP device allowing the patient to exhale against the adjustable PEEP.
- At the start of inspiration, the pressure in the mouthpiece drops, causing the spool to move forward. This movement closes the PEEP outlet and opens the inlet allowing the air/oxygen mixture to be supplied to the patient at a higher pressure.
During expiration, oxygen continues to flow into the patient hose accumulating towards the next inspiration and is not wasted.
Pressure support is provided by an adjustable blow-off valve that allows both pressure and flow to be regulated so that sufficient flow is dialled in to maintain the pressure support during inspiration.
The level of pressure support is conveniently displayed on a simple water manometer which requires no calibration and is cheap and effective to manufacture.
Filters keep inspired air free of dust and debris and filter exhaled air to protect the environment from contamination.
A simpler mask is possible due to the lower volumes being handled by the mask during expiration compared to CPAP. This improves patient comfort and tolerance of the device and the safety of the environment due to reduced leakage of air contaminated with secretions.
Industrialisation of the components are underway and further testing will take place to determine the optimum patient profile and settings for the device.