Personal Medical Devices
Pure oxygen (>99.95 %) is currently prescribed for patients having COPD in one of two ways: (1) as a compressed gas in cylinders or (2) as liquid oxygen in insulated containers.
Compressed Gas
A normal size compressed gas cylinder operated with continuous flow of oxygen typically lasts a maximum of 2.7 hours and at a higher flow rate could last as little as 45 minutes. All cylinders need to be refilled often, requiring the patients to either bring in the cylinder to a central facility or requiring the suppliers to pick it up, fill it and redeliver it.
Liquid Oxygen
Liquid oxygen (at -183 °C) is distributed in insulated “thermos” bottles and vaporizes to provide the breathing oxygen required. The advantage of liquid oxygen over compressed oxygen is that a significantly larger number of “equivalent cubic feet” of gas can be stored as a liquid in the same volume; however, it still needs to be refilled. The disadvantages are the relatively high cost for equipment and delivery, the occasional “freezing” of the valve at flows of 8 LPM or greater and the continued evaporation of oxygen (~ 0.9 % per day) from the container even when not being actively used.
Concentrators
Lower purity oxygen is provided by what are known as oxygen concentrators which provide “on demand” oxygen ranging from 85-95% purity depending on the flow rate. Oxygen separation is accomplished by adsorption using molecular sieve zeolites; and these devices typically are limited to less than about 10 liters per minute (LPM) flow rate. Due to the way adsorption works, there is an inverse relationship between available oxygen flow rate and purity. That is, at 10 LPM, the purity of oxygen achieved is typically ~85 - 90%, while at lower flow rates (1-5 LPM) it is possible to achieve a maximum of ~ 93% purity. Concentrators also typically are used in conjunction with conservers which pulse the oxygen delivery.
The SeprOx Medical Oxygen System
SeprOx is developing a product that combines the best features of each of these products. Like compressed gas cylinders, it will be capable of supplying pure oxygen (>99.95%) but will never need to be refilled. Like some of the newer concentrators, it will be assembled as a lightweight and portable device that is anticipated to weigh less than 10 pounds but will be able to supply a pure oxygen stream at 5 LPM without the use of a conserver. It will be powered either by an AC adapter in the home or by a battery (not included in the weight estimate) for use outside the home. SeprOx will seek FDA approval for sale and use of the device and will also seek FAA approval for use on airplanes.
Pure oxygen (>99.95 %) is currently prescribed for patients having COPD in one of two ways: (1) as a compressed gas in cylinders or (2) as liquid oxygen in insulated containers.
Compressed Gas
A normal size compressed gas cylinder operated with continuous flow of oxygen typically lasts a maximum of 2.7 hours and at a higher flow rate could last as little as 45 minutes. All cylinders need to be refilled often, requiring the patients to either bring in the cylinder to a central facility or requiring the suppliers to pick it up, fill it and redeliver it.
Liquid Oxygen
Liquid oxygen (at -183 °C) is distributed in insulated “thermos” bottles and vaporizes to provide the breathing oxygen required. The advantage of liquid oxygen over compressed oxygen is that a significantly larger number of “equivalent cubic feet” of gas can be stored as a liquid in the same volume; however, it still needs to be refilled. The disadvantages are the relatively high cost for equipment and delivery, the occasional “freezing” of the valve at flows of 8 LPM or greater and the continued evaporation of oxygen (~ 0.9 % per day) from the container even when not being actively used.
Concentrators
Lower purity oxygen is provided by what are known as oxygen concentrators which provide “on demand” oxygen ranging from 85-95% purity depending on the flow rate. Oxygen separation is accomplished by adsorption using molecular sieve zeolites; and these devices typically are limited to less than about 10 liters per minute (LPM) flow rate. Due to the way adsorption works, there is an inverse relationship between available oxygen flow rate and purity. That is, at 10 LPM, the purity of oxygen achieved is typically ~85 - 90%, while at lower flow rates (1-5 LPM) it is possible to achieve a maximum of ~ 93% purity. Concentrators also typically are used in conjunction with conservers which pulse the oxygen delivery.
The SeprOx Medical Oxygen System
SeprOx is developing a product that combines the best features of each of these products. Like compressed gas cylinders, it will be capable of supplying pure oxygen (>99.95%) but will never need to be refilled. Like some of the newer concentrators, it will be assembled as a lightweight and portable device that is anticipated to weigh less than 10 pounds but will be able to supply a pure oxygen stream at 5 LPM without the use of a conserver. It will be powered either by an AC adapter in the home or by a battery (not included in the weight estimate) for use outside the home. SeprOx will seek FDA approval for sale and use of the device and will also seek FAA approval for use on airplanes.
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