Liquid Oxygen Therapy
Medically Edited and Reviewed by Dr. Erin Zinkhan MD, BSBE
What is Medical Liquid Oxygen?
Liquid oxygen is a form of oxygen therapy that is more recently available for use in the home to treat conditions such as asthma, cystic fibrosis, dysphasia, COPD, heart failure, lung disease, and pneumonia. Medical liquid oxygen offers several key advantages over other methods of oxygen delivery. The primary benefit of liquid oxygen is that continuous flow oxygen can be supplied in a relatively small, lightweight container. The key advantages of liquid oxygen include a light-weight (less than 10 pounds), portable device, continuous flow capability, 100% concentrated oxygen, and long duration (over 18 hours). In comparison, portable oxygen concentrators offer a concentration range of 86 to 97%, weigh 15 to 25 pounds, and last 1.5 to 9.5 hours before the battery needs to be recharged. Currently only five portable oxygen concentrator models offer continuous flow oxygen, making liquid oxygen an additional option for people who live active lives.
To make medical liquid oxygen, the gas form of oxygen is cooled to below -297 degrees Fahrenheit or -183 degrees Celsius. At this low temperature, oxygen remains in a liquid form. In its liquid state, oxygen takes up less space and can be stored at much lower pressures than when in a gaseous state. The properties of liquid oxygen allow for more oxygen to be carried in a portable liquid unit, and the portable container is much lighter in weight and smaller in size than an oxygen gas cylinder. As the temperature of the liquid oxygen rises, the oxygen turns to gas and can be used for medical therapy. One liter of liquid oxygen offers approximately 860 liters of gaseous oxygen. A small amount of liquid oxygen may provide a full day of oxygen therapy away from home. Medical liquid oxygen is stored under low pressure and is therefore safer than oxygen cylinders, which must be stored under high pressure.
Liquid oxygen has moved recently from hospital settings to use in homes. More recently, liquid oxygen has become available in lightweight portable units that can be used almost anywhere. These recent changes have allowed more people to use liquid oxygen as their primary source of oxygen therapy.
What is Liquid Oxygen Therapy?
Doctors prescribing liquid oxygen usually do so for patients who live active lifestyles. The small size, low weight and long duration of liquid oxygen supports active patients better than most other oxygen alternatives.
There are two separate components to a liquid oxygen (LOX) system. The first component is a stationary unit or liquid oxygen reservoir which stores a large volume of liquid oxygen. The second component is the portable, refillable container. Both components consist of insulated containers that are Thermos-like to maintain low temperature.
The Two Major Components of Liquid Oxygen Therapy
- Storage reservoir
- Portable, refillable container
Liquid Oxygen Storage Reservoir
The reservoir for liquid oxygen is a large insulated Thermos-like container. This reservoir tank is filled by an oxygen supplier once or twice a month. The reservoir system requires no electricity and has few moving parts. These factors allow the reservoir tanks to be in operation for many years with little maintenance and few to no repairs. A typical liquid oxygen reservoir weighs 90 to 170 pounds when filled. These reservoirs store 21 to 41 liters, or 49 to 110 pounds, of liquid oxygen. This amount of liquid oxygen, when converted to gas form, becomes 16,750 to 37,916 liters of oxygen. At a flow rate of two liters per minute, 37,916 liters of oxygen would last 316 hours or 13 days.
Because liquid oxygen systems lose oxygen through evaporation even when not in use, the 13 days of oxygen flow referenced above would be shortened. For instance, the HELiOS reservoirs lose around 1.2 pounds of oxygen daily to evaporation. With the addition of modern pulsed delivery or conserving devices, the loss of oxygen through evaporation is somewhat less.
Links to Liquid Oxygen Reservoirs
Portable Liquid Oxygen Unit
The second component of a liquid oxygen system is the portable unit which can be refilled from the reservoir. The portable unit may be carried by the patient in a backpack or shoulder bag and is filled from the reservoir unit. Neither the portable unit nor the reservoir require electricity to operate. This added benefit is a significant advantage not shared by oxygen concentrators. Patients who live in areas with frequent electrical blackouts may benefit more from liquid oxygen than oxygen concentrators.
When at home, patients use the stationary unit as their source of oxygen. When away from home, the portable unit supplies patients with oxygen. Most portable units provide the option for continuous flow or pulse flow oxygen. Patients select the flow level they need for their given situation.
Examples of Liquid Oxygen Portable Units
Liquid Oxygen Maintenance Requirements
Liquid oxygen systems require little maintenance. The stationary reservoir tank should be placed on a level surface and ideally should be secured to a wall. If a drainage bottle is used for collecting excess condensation, it should be emptied and cleaned regularly. Cleaning the outside of the tank with a damp cloth should be done occasionally to remove dust. The reservoir tank should be refilled by a professional service provider. Refilling the portable unit should be accomplished in accordance with manufacturer instructions. Improper filling of the portable unit can lead to freezing in the connection between the portable unit and the reservoir. Procedures for recovering from a freezing incident should also be handled in accordance with manufacturer instructions.
Prescribing Portable LOX Liquid Oxygen
Doctors prescribe liquid oxygen for patients who are mobile and active outside their homes. Liquid oxygen therapy has the advantages of options for continuous or pulsatile flow, lightweight, small size, and high oxygen concentration. Some, but not all, medical studies show improved patient compliance and increased number of outings away from the home compared with patients using other oxygen delivery systems.
Comparing Portable Liquid Oxygen to Portable Oxygen Concentrators
Portable liquid oxygen can be delivered either by continuous flow or pulse flow. On the other hand, most portable oxygen concentrators provide only pulse flow oxygen. Currently only five portable oxygen concentrators provide continuous flow along with pulse flow. These fourconcentrators are listed below with links to more information.
- Oxlife Independence provides 24/7 operation and extraordinary durability.
- Eclipse 5 has the lowest noise output and 24/7 operation.
- SimplyGo offers the smallest profile and lowest weight.
- DeVilbiss iGo has the lowest price and low maintenance requirements.
The two charts below display a comparison between oxygen concentrators and liquid oxygen. The data for the continuous/pulse portable concentrators are the average values for the five portable oxygen concentrators with continuous flow capability. The data for the LOX products are the average values for the Helios and Companion series LOX products.
Comparing Liquid Oxygen to Portable Oxygen Concentrators
LOX portable units are significantly smaller in size and weigh significantly less than continuous flow portable concentrators. Oxygen output is also significantly higher for liquid oxygen units. LOX offers up to 13.7 hours of more run time with pulse therapy than portable oxygen concentrators and takes less than 2 minutes to refill compared to 3.5 hours of battery charging for a concentrator. LOX units produce no sound to operate while concentrators average 44 dBA. However, LOX portable units produce a loud sound when refilling the unit from the reservoir.
Comparing LOX to Pulse Flow Portable Oxygen Concentrators
Pulse flow portable oxygen concentrators are smaller in size by 107 cubic inches and in weight by 0.8 pounds. LOX outperforms concentrators in oxygen output, duration and noise.
Liquid Oxygen Review
Liquid oxygen therapy offers many advantages and few disadvantages. Listed below are the key advantages and disadvantages oxygen patients can expect to experience when using liquid oxygen therapy.
Advantages of LOX
- More flexibility for activities of daily living.
- 100% oxygen concentration levels.
- Higher oxygen output.
- Higher continuous flow volumes up to 15 LPM.
- Long oxygen supply duration.
- More discreet oxygen therapy.
- No electricity use.
- Large oxygen capacity.
- Reservoir doubles as a home oxygen dispenser and as a refill station for the portable unit.
- Continuous flow oxygen for up to 13 days (at 2 LPM)
- Short refill time for portable LOX units of less than 2 minutes.
Disadvantages of LOX
- Limited availability of liquid oxygen service providers in many areas to refill the reservoir tank.
- Limited shelf life due to evaporation loss. (around 1.2 pounds daily)
- Requires regular reservoir refills from a medical oxygen service.
- Produces loud noises while refilling the portable unit. (Less than 2 minutes duration.)
- The connection between the reservoir and the portable unit can become frozen if the filling is not done properly.
Summary of Liquid Oxygen Therapy
Liquid oxygen therapy offers patients many advantages not found in other therapy options. The biggest obstacle to using liquid oxygen therapy is the availability of a local service provider for home delivery of liquid oxygen. Liquid oxygen for patients living in rural areas may not be available due to the lack of liquid oxygen sources. Patients living in large metropolitan areas have greater access to liquid oxygen.
- Liquid Oxygen Use Time Duration Chart for several liquid oxygen devices manufactured in the USA.
- HELiOS and Companion LOX Specifications provided by Chart Industries.
- Cancaster B, Ranking the Top Portable Oxygen Concentrators with Pulse Flow includes concentrator review and comparison.
- Cancaster B, Ranking the Best Portable Oxygen Concentrators with Continuous Flow includes concentrator comparison chart.
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