Liquid oxygen is a type of oxygen delivery where oxygen is compressed and cooled to a point that it becomes frozen. Most liquid oxygen systems provide a high concentration oxygen and do not require any electricity to run. They usually consist of a stationary storage unit and a portable container. Liquid oxygen is very cold (-297° F) and can cause frostbite burns to the skin if not handled with care, especially when filling a portable tank.[1]
Liquid Oxygen Supply Systems
The liquid oxygen supply system usually consists of a bulk storage unit or reservoir that’s housed in a permanent place in the home and a refillable, portable unit that you can carry around. The reservoir and portable units have a design similar to that of a thermos bottle, consisting of a container inside a container separated by a vacuum. To remain in liquid form, the oxygen must be stored at very cold temperatures inside the thermos-like container. The medical liquid oxygen (minimum 99.5% purity) must first be vaporized to a compressed gas then warmed at ambient (room) temperature inside the equipment before the patient can receive the oxygen through tubing into the nostrils via a nasal cannula.[2]
Understanding the Bulk Stationary Storage Unit
Oxygen is often stored as a liquid – although it’s used primarily as a gas – because it’s less bulky and less expensive than storing the equivalent capacity of high-pressure gas. One liter of liquid oxygen, when evaporated, expands to approximately 860 liters of gaseous oxygen. A typical bulk storage unit is filled with approximately 40 liters of liquid oxygen. This base equipment provides oxygen for >11 days. When you’re at home, you can use the stationary unit as your primary oxygen source. It is necessary to keep the large liquid oxygen containers filled at home to replenish the smaller, portable tanks frequently. The recurring oxygen deliveries can get quite expensive. Another important point to remember is that the liquid oxygen constantly evaporates and needs to be used and resupplied by a professional service provider at least two to three times a month.[2]
Understanding the Portable Container
Light portable containers are refilled with liquid oxygen from the large stationary reservoir at the patient’s home whenever necessary, giving the patient control over the refilling frequency. The ambulatory oxygen in the portable canisters lasts 8–10 h. Modern liquid oxygen canisters are less cumbersome for the patient to carry than previously reported: 7.7 lbs. (3.5 kg) when full versus 5.5lbs (2.5 kg) when empty for the larger portable canisters, and even lighter for the smaller ones. When compared to gaseous oxygen, patients prefer the liquid oxygen system because the oxygen lasts longer, filling the canister is simpler, and the portable system is easier to carry due to a lighter weight. Small stationary containers may provide a convenient refill supply in a car or van during extended trips from home. If the patient is on high-flow liquid oxygen (up to 15 LPM of continuous flow oxygen), it is important to note that ice may form on the portable’s heat exchange coils due to freezing of ambient humidity. These patients usually possess two portable systems to facilitate continuous usage, allowing for de-icing of one of the units while using the ambulatory oxygen in the other.[2]
Is a Liquid Oxygen Supply System for Me?
Choosing an oxygen supply system is one of the most important decisions you will ever make. If you’re having trouble deciding whether a liquid oxygen system is right for you, it’s a good idea to compare the advantages and disadvantages of different systems. Several factors should inform your decision, such as your oxygen requirements, budget, and lifestyle including how much you travel.
Liquid Oxygen systems use pure oxygen which is compressed and frozen and then placed into metal cylinders. A liquid oxygen system consists of a stationary unit and a portable device. Liquid oxygen is very cold (-297° F) and can cause frostbite or burns if it comes in direct contact with your skin, most likely to occur when filling a portable tank.[1] Liquid oxygen evaporates over time so don’t fill tanks too far ahead of when you need to use them. Liquid oxygen is a good option for people who need high liter flows of oxygen, usually greater than 6 liters per minute.[1] Portable oxygen concentrators vary in range oxygen flow setting and LPM, usually < 2LPM. Stationary or home oxygen concentrators provide an uninterrupted oxygen supply with a flow ranging from 0.5 to 10–15 LPM.[2]
Liquid oxygen tanks are lighter than compressed oxygen tanks but are more expensive. Oxygen concentrators are more expensive upfront, but do not require a lot of future maintenance.[3] Oxygen tanks and liquid oxygen canisters are limited by a finite capacity defined by their size, whereas portable oxygen concentrators have no compressed tanks to exchange or refill. It is necessary to keep the large liquid oxygen containers filled at home to replenish the smaller, portable tanks frequently. The recurring oxygen deliveries can get quite expensive.[2] Another important point to remember is that the liquid oxygen constantly evaporates and needs to be used and resupplied by a professional service provider at least two to three times a month.[2] Therefore, one of the main drawbacks for liquid oxygen therapy is the cost. Compared with oxygen concentrator systems, which do not need to be refilled, long-term liquid oxygen therapy is about four times more expensive.[2]
If you can afford to pay an initial higher price for a concentrator, it may save you money over time, because it eliminates the need for refills and tank replacements. You should consult with your insurance company to see what costs they will cover.[3] Many insurance plans, including Medicare and Medicaid, will cover a portion of the cost for your oxygen therapy equipment, provided that your doctor confirms that you require it.[4] Inogen has direct access to Medicare and can see how long any patient has been on service with a tank. Inogen checks and verifies insurance coverage and patient financial responsibility. To learn more about how Medicare or your insurance may help you pay for an oxygen concentrator, speak to an Inogen Oxygen Specialist by calling 1-800-695-7915, or visit this link: Portable Oxygen Concentrator Medicare.
One of the biggest advantages of using liquid oxygen is that it consumes no electricity. Oxygen concentrators run on electrical power so require internal batteries, automobile adaptors or standard electricity. This need for a continuous power source should be a consideration.[2]
Liquid oxygen takes up less space than oxygen in its gas form, making it easy and light to carry around. Liquid oxygen tanks are safer compared to compressed gas cylinders because they are under lower pressure. Light portable containers are refilled with liquid oxygen from the large stationary reservoir at the patient’s home whenever necessary, giving the patient control over the refilling frequency. However, portable oxygen concentrators are even lighter than liquid oxygen canisters because they do not require a storage reservoir of pressurized oxygen.[2] In addition, the number of patients with impaired lung function wishing to travel by airplane is increasing, but aviation regulations prohibit liquid oxygen on commercial aircraft[2] but may permit portable oxygen concentrators.[5]
The Bottom Line
The right oxygen supply system is one that meets your needs and suits your lifestyle. Before you make that choice, talk to your primary health care provider about each system’s pros and cons.
References
- Lung.org https://www.lung.org/lung-health-diseases/lung-procedures-and-tests/oxygen-therapy/oxygen-delivery-devices and Getting Started with Liquid Oxygen American Lung Association
- Hardavella G, Karampinis I, Frille A, Sreter K, Rousalova I. Oxygen devices and delivery systems. Breathe (Sheff). 2019 Sep;15(3):e108-e116. doi: 10.1183/20734735.0204-2019. PMID: 31777573; PMCID: PMC6876135. Oxygen devices and delivery systems – PMC (nih.gov)
- Supplemental Oxygen: Tanks vs Concentrators | PulmonaryFibrosisNow.org
- Oxygen Equipment Coverage (medicare.gov)
- federalregister.gov-acceptance-criteria-for-portable-oxygen
