Oxygen Concentrators FAQ's
What is Medical Liquid Oxygen?
Liquid oxygen is used to treat respiratory disorders and has been found to be more effective than oxygen concentrators or oxygen cylinders. 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 portable, continuous flow capability, 100% concentrated oxygen, low weight (less than 10 pounds), and long duration (over 18 hours). In comparison, portable oxygen concentrators, offer a concentration range of 86 to 97%, weigh from 15 to 25 pounds, and last for 1.5 to 9.5 hours until the battery needs to be recharged. Currently, there are only five portable oxygen concentrator models that 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 must be cooled to at least -297 degrees Fahrenheit or -183 degrees centigrade. 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. This means more oxygen can 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 for liquid oxygen rises, oxygen gas is produced and used for medical therapy. One liter of liquid oxygen offers approximately 860 liters of gaseous oxygen. A small amount of liquid oxygen may supply an oxygen therapy patient with a full day of service away from home. Medical liquid oxygen is stored under low pressure and is, therefore, safer than oxygen cylinders which are under high pressure.
Liquid oxygen has recently moved 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?
Liquid oxygen therapy is the medical process of providing additional oxygen to a patient who can not get enough oxygen on their own. Conditions such as asthma, cystic fibrosis, dysphasia, COPD, heart failure, lung disease, and pneumonia can be treated by 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 support active patients better than most other oxygen alternatives.
There are two separate components to the liquid oxygen (LOX) system. Both components consist of insulated containers that are Thermos-like to maintain a low temperature. The first component is a stationary unit or liquid oxygen reservoir which stores a large volume of liquid oxygen.
The Two Major Components of Liquid Oxygen Therapy
- Storage reservoir
- Portable, refillable container
Liquid Oxygen Reservoir
The reservoir for liquid oxygen is basically 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 very few moving parts, requiring very little maintenance or repair. These three factors allow the reservoir tanks to be in operation for many years with little maintenance and few to no repairs. Typically a 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 compensated.
Links to Liquid Oxygen Reservoir
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. The reservoir unit is filled every 1-3 weeks by a local medical liquid oxygen provider. Neither component requires electricity to operate. This added benefit is a significant advantage not shared by oxygen concentrators. Oxygen patients who live in areas of frequent electrical blackouts can fare much better with liquid oxygen instead of 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 merely select the flow level they need for their given situation.
Example of Liquid Oxygen Portable Units
Liquid Oxygen Maintenance Requirements
There is very little maintenance for liquid oxygen systems. The stationary reservoir tank should be placed on a level surface. Securing the tank to the wall would also be beneficial. 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. 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. The advantages of low weight, small size, continuous and pulse flow, and high concentration provide a strong argument for liquid oxygen therapy. Patient compliance and outcomes have been shown in medical studies to be improved over patients using other oxygen delivery systems.
Comparing Portable Liquid Oxygen to Portable Oxygen Concentrators
Portable liquid oxygen offers two flow options: continuous flow and pulse flow. On the other hand, most portable oxygen concentrators provide only pulse flow oxygen. Currently, there are five portable oxygen concentrators that provide continuous flow along with pulse flow. These five concentrators are listed below with links to more information.
- SeQual eQuinox offers highest oxygen output, lowest power consumption and 24/7 operation.
- 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 is averaged for the five portable oxygen concentrators with continuous flow capability and the Helios and Companion series of liquid oxygen products.
Comparing Liquid Oxygen to Portable Oxygen Concentrators
As shown in the comparison chart above, LOX does better in every measurement. LOX portable units are significantly smaller in size and weigh significantly less than continuous flow cable portable concentrators. Oxygen output is also significantly higher for liquid oxygen units. LOX offers up to 13.7 hours of more run time than portable oxygen concentrators and takes less than two minutes to refill compared to 3-1/2 hours of battery charging for a concentrator. LOX units produce no sound to operate while concentrators average 44 dBA.
Comparing LOX to Pulse Flow Portable Oxygen Concentrators
As shown in the comparison above, LOX performs better in every category except one—size. Pulse flow portable oxygen concentrators are smaller in size (107 cubic inches) and weight (1 pound). 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
- Better therapy outcomes than alternative methods of oxygen delivery.
- 100% oxygen concentration levels.
- Higher oxygen output.
- Provides higher continuous flow volumes up to 15 LPM.
- Long oxygen supply duration.
- No sound emissions.
- More discreet oxygen therapy with less attention being drawn from others.
- Requires no electricity.
- Large oxygen capacity.
- Reservoir doubles as a home oxygen dispenser and as a refill station for the portable unit.
- Supplies 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 annoying 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. All connections should be airtight.
Summary of Liquid Oxygen Therapy
Liquid oxygen therapy offers oxygen patients many advantages not found in other therapy options. The biggest hurdle 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 a viable option due to the lack of liquid oxygen sources. Patients living in large metropolitan areas have more access to this type of service and can, therefore, take advantage of the better outcomes and the higher oxygen output of liquid oxygen therapy.
- 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.
- Nasilowski J, Przybylowski T, Zielinski T, Chazan R, Comparing supplementary oxygen benefits from a portable oxygen concentrator and a liquid oxygen portable device during a walk test in COPD patients on long-term oxygen therapy. Department of Internal Medicine, Pneumology and Allergology, Medical University of Warsaw, Banacha 1a, 02-097 Warsaw, Poland.
- Croxton TL, Bailey WC. Long-term oxygen treatments in chronic obstructive pulmonary disease: recommendations for future research: an NHLBI workshop report. Am J Resp Crit Care Med. 2006; 174(4): 373-378.
- Doherty DE, Petty TL, Bailey W, et al. Long Term Oxygen Therapy (LTOT): Recommendations of the 6th long-term oxygen therapy consensus conference. Respir Care. 2006; 51(5):519-525.
- Timms RM, Khaja FU, Williams GW. Nocturnal Oxygen TherapyTrial Group. Hemodynamic Response to Oxygen Therapy in Chronic Obstructive Pulmonary Disease. Ann Intern Med. 1985;102:29-36.
- Weitzenblum E, Sautegeau A,Ehrhart M, Mammosser M, Pelletier A. Long Term Oxygen Therapy can Reverse the Progression of Pulmonary Hypertension in Patients with Chronic Obstructive Pulmonary Disease. Am Rev Respir Dis. 1985;131:493-498.
- Morrison DA, Stovall JR. Increased Exercise Capacity in Hypoxemic Patients after Long Term Oxygen Therapy. CHEST. 1992;102:542-550.
- Heaton RK, Grant I, McSweeny AJ, Adams KM, Petty TL. Psychologic Effects of Continuous and Nocturnal Oxygen Therapy in Hypoxemic Chronic Obstructive Pulmonary Disease. Arch Intern Med.1983;143:1941-1947.
- Nocturnal Oxygen Therapy Trial Group. Continuous or Nocturnal Oxygen Therapy in Hypoxemic Chronic Obstructive Lung Disease: A Clinical Trial. Ann Intern Med. 1980;93:391-398.
- Medical Research Council Working Party. Long Term Domiciliary Oxygen Therapy in Chronic Hypoxic Cor Pulmonale Complicating Chronic Bronchitis and Emphysema. Lancet. 1981;1: 681-686.
- Couser JI Jr, Make BJ. Transtracheal Oxygen Decreases Inspired Minute Ventilation. Am Rev Respir Dis. 1989;139:627-631.
- Barker AF, Burgher LW, Plummer AL. Oxygen Conserving Methods for Adults. CHEST. 1994;105:248-252.
- Hida W, Sakurai M, Okabe S, Hajime, Kurosawa, Kikuchi Y, Takishima T. Home oxygen therapy using liquid oxygen system. Nihon Kyobu Shikkan Gakkai Zasshi. 1992 Dec;30 Suppl:164-8.
- O'Donohue WJ Jr, Plummer AL. Magnitude of usage and cost of home oxygen therapy in the United States. Chest 1995;107:301–302.
- Swinburn CR, Mould H, Stone TN, Corris PA, Gibson GJ. Symptomatic benefit of supplemental oxygen in hypoxemic patients with chronic lung disease. Am Rev Respir Dis 1991;143:913–915.
- Dean NC, Brown JK, Himelman RB, Doherty JJ, Gold WM, Stulbarg MS. Oxygen may improve dyspnea and endurance in patients with chronic obstructive pulmonary disease and only mild hypoxemia. Am Rev Respir Dis 1992;146:941–945.
- Neff TA, Petty TL. Long-term continuous oxygen therapy in chronic airway obstruction: mortality in relationship to cor pulmonale, hypoxia, and hypercapnia. Ann Intern Med 1970;72:621–626.
- Gorecka D, Gorzelak K, Sliwinski P, Tobiasz M, Zielinski J. Effect of long-term oxygen therapy on survival in patients with chronic obstructive pulmonary disease with moderate hypoxaemia. Thorax 1997;52:674–679.
- Oswald-Mammosser M, Weitzenblum E, Quoix E, Moser G, Chaouat A, Charpentier C, Kessler R. Prognostic factors in COPD patients receiving long-term oxygen therapy: importance of pulmonary artery pressure. Chest 1995;107:1193–1198.
- Timms RM, Khaja FU, Williams GW. Hemodynamic response to oxygen therapy in chronic obstructive pulmonary disease. Ann Intern Med 1985;102:29–36.
- Aubier M, Murciano D, Milic-Emili J, Touaty E, Daghfous J, Pariente R, Derenne JP. Effects of the administration of O2 on ventilation and blood gases in patients with chronic obstructive pulmonary disease during acute respiratory failure. Am Rev Respir Dis 1980;122:747–754.
Burt Cancaster, Author