OxyJet: A Jet Mixing Principle Based Low-cost CPAP

The COVID-19 pandemic has affected more than 20 million people worldwide with a death toll of over 700 thousand. Continuous Positive Airway Pressure (CPAP) therapy is known to reduce the need for mechanical ventilation (MV) in treating hypoxic COVID-19 patients. We present OxyJet CPAP, an electricity-free low-cost noninvasive positive pressure ventilation (NIPPV) system specifically designed for low and middle-income country (LMIC) hospitals. It can provide a 20cm H2O positive end-expiratory pressure (PEEP), peak inspiratory flow-rate up to 65 liters/min (LPM), and a fraction of inspired oxygen (FiO2) of up to 95%. The device utilizes the mechanics of a jet pump driven by high-pressure oxygen to increase the volumetric flow rate by entraining atmospheric air. We use a snorkeling mask (as helmet/hood) to deliver CPAP therapy to reduce aerosolization risk. Although High Flow Nasal Oxygenation (HFNO) is effective in treating severe COVID-19 patients, it is too expensive for public hospitals in LMICs.

CPAP therapy given to A healthy Volunteer using OxyJet CPAP

Challenges in LMIC settings:

  • High-cost of available devices (HFNO up to $5,000,CPAP up to $1200).
  • Scarcity of medical devices in the market.
  • Unreliability of electricity in remote areas.
  • Cylinders being the main source of oxygen supply in rural hospitals.
  • Central oxygen systems not available in most hospitals.
  • Aerosol preventing procedures require expensive negative-pressure rooms or helmet/non-vented masks.

We propose OxyJet CPAP, a low-cost NIPPV system that is easy to use, manufacture, and implement within an LMIC healthcare infrastructure. OxyJet CPAP functions on the basis of jet mixing of oxygen and atmospheric air to deliver a continuous flow of oxygenated air to the patient and maintains a positive pressure inside the patient’s mask.

A schematics showing different components of OxyJet CPAP


Design & Evaluation

The OxyJet device has three inlets for (i) primary oxygen,(ii) air entrainment, and (iii) secondary oxygen. Inside the device, the room air is mixed with high-velocity oxygen as it passes through a venturi nozzle. As a result, a high-flow oxygenated air is channeled through the breathing circuit to the patient. The tightly sealed snorkel mask minimizes aerosolization,and the viral filter decontaminates the expiratory air.The adjustable PEEP valve maintains a fixed positive end expiratory pressure required for patients.

The device is made using 3D printing and a local workshop facility. It is attachable to existing medical oxygen lines and cylinders. The outlet connects to existing 22mm breathing circuits. For ease of use, only the oxygen flow-rate and PEEP valve need to be adjusted. A working prototype is already developed and being tested.

Perfomance Test charts showing Flowrate provided by the device vs. given PEEP.

Pressure curve inside snorkel mask indicating consistant CPAP maintenance.

In the next step, we plan to thoroughly evaluate the system using high-precision measurement instruments to verify the flow-rate, pressure, and FiO2. We are also preparing our application for ethical clearance to perform a pilot clinical study of the CPAP system at Dhaka Medical College and Hospital (DMCH). We already tested our device on a healthy volunteer (at a low PEEP setting) and obtained promising results (Fig 5). We have demonstrated the system to 4 (four)ICU trained physicians and received positive feedback. We are hopeful about a successful pilot clinical study.