The Indian subcontinent and parts of Southeast Asia are currently facing a devastating second wave of the COVID-19 pandemic. Oxygen shortage is currently an acute issue in many major cities and towns where infections have spiked. At the time of writing (May 17, 2021), estimates based on WHO data put the current oxygen demand in India at 15.8 million cubic meters or 2.2 million oxygen cylinders per day.1 These numbers, which are based on testing data, are also likely underestimated. Challenges in both production and supply chain management and distribution mean that India is struggling to distribute these life-saving supplies where they are needed the most.2 The problem is only more severe as the disease further spreads in the rural areas, which have two third of India's population but have less infrastructure and are associated with more transportation delays. Worryingly, other countries in the Indian subcontinent, such as Nepal, have also started facing acute oxygen shortages mirroring the situation in India.3
Among symptomatic COVID-19 patients, while most only develop mild (40%) and moderate (40%) disease, around 15% develop severe disease requiring oxygen support, whereas 5% have critical disease with complications requiring intensive care.4 For those patients who require supplemental oxygen, in the course of their clinical management, delivery of oxygen usually starts and stops with nasal cannula at flow rates less than 6 L/min. Oxygen delivered during patient exhalation is mostly vented to the air and wasted, providing an opportunity for oxygen conservation by shutting the flow when the patient is exhaling. Towards this, some completely passive solutions have been developed, such as the Oxymizer device.5,6 However, due to the limited reservoir size and fluid dynamic parameters which these devices are designed for, the effect of oxygen saving decreases significantly as the flow rate is increased (3:1 at 0.5 L/min, 1.7:1 at 2 L/min, 1.4:1 at 4 L/min and 1.3:1 at 5 L/min)11, making these devices useful only in oxygen therapy for COPD. Other more effective oxygen conservation devices have been developed in the 1990's and early 2000's but now have very limited or no availability.
A device which conserves oxygen for oxygen therapy in COVID-19 patients will extend the life of cylinders and will help in this climate of extreme shortages.
In oxygen therapy, when a patient exhales out, the oxygen still leaks away - thus wasting up to approximately 2/3 or more of oxygen in the tank as inhalation only amounts to approximately 1/3 of the respiration cycle. If a sensor can sense inhalation-exhalation cycles, and oxygen flow can be stopped or diverted to a buffer storage during exhalation, then we could save this oxygen and thus increase the life of an oxygen tank by almost three times (and hence tripling the supply).
The goal of the proposed device is to implement a simple yet safe version of a pulse-dose system that can be rapidly manufactured and deployed in the context of the current situation in the Indian subcontinent and Southeast Asia. Our goal is to work with industrial partners to bring this device to the market with quality and scale. The device is envisioned to be used in settings where patients with mild conditions are being treated; it is not intended for severe COVID-19 patients.
The main requirements of the pulse-dose oxygen conservation device are as follows:
Additional requirements for usability are as follows: