Home Oxygen Options
Adapted from Home Oxygen Options by Thomas L. Petty, MD.
Previously published on the National Lung Health Education Program Web site.
Types of Home Oxygen Systems
There are three basic home oxygen delivery systems that can be used in various combinations to meet a patient's needs. They are high-pressure cylinders, liquid oxygen units, and oxygen concentrators.
High Pressure Cylinders. Many years ago a cylinder and regulator were the standard for patients who were receiving home O2 therapy. When it is the only source of O2, patients may require 2-3 large cylinders delivered weekly. These units are very heavy and should only be handled by the provider. Today, cylinders of varying sizes are used as backup to concentrators or liquid systems and to provide patient mobility. For mobility outside the home, small aluminum cylinders (M6/M9) with either reservoir cannulas or pulse-dose regulators are currently used as an alternative to portable liquid O2 units (below) when standard line-powered concentrators are the primary residential O2 source.
Liquid Oxygen Units (Stationary Base Unit + Portable). Because one liter of liquid O2 equals 860 gaseous liters, liquid oxygen units are highly efficient means of storing and transporting this gas. Liquid O2 is stored at about -297°F under pressure of 18 to 22 psi. Liquid O2 is delivered to the patient's home in a base unit that can serve as the primary residential O2 source and can be used to fill a smaller portable unit to provide the patient with mobility outside the home. A liquid O2 unit requires no power source to operate, making it an appropriate choice for patients in areas with frequent power outages. In addition, liquid O2 systems are quiet and have no major moving parts. Depending on the patient's liter flow, the liquid O2 base unit typically needs to be refilled about every two weeks.
Portable liquid O2 units enhance patient mobility. Comprised of a small, lightweight refillable vessel that can be carried by the patient, a portable liquid O2 unit is more affordable and convenient for active patients than most other modalities. The duration of flow at a continuous setting of '2' is about 3 hours, with up to 8-9 hours of O2 available if a pulse-dose device is used for delivery.
Oxygen Concentrators. An O2 concentrator separates oxygen from room air. They come in two versions: a standard AC (line-powered) unit and a portable AC/DC/battery model. When used as the sole source for O2, standard line-powered concentrators limit mobility, with the patient 'tethered' to the unit via the O2 delivery tubing. Maximum flow is normally 5 to 6 L/min, delivering at most 40-45% O2. A hidden cost is the electricity that is consumed during concentrator operation, which may cost $30 or more a month and is not normally reimbursable.
Portable AC/DC/battery powered O2 concentrators are smaller and lighter versions of standard concentrators that can run off 110 volt (line) current, 12 volt current (in an automobile) or a battery pack. This essentially allows patients to go wherever they want. Some portable units deliver O2 only via a conserving pulse-dose regulator, while others can operate in either the continuous-flow or conserving mode. Because portable concentrators produce less O2 per minute than standard units, maximum available flows (continuous) are limited to a 3 L/min or less.
Typically, home O2 systems combine two storage/delivery systems, one for regular in-home use and one used either as a back-up or portable supply. In selecting a combination system, it is important to determine the patient's FIO2 needs (low to moderate), mobility activity level, and psychomotor skills as well as caregiver support and availability of third party reimbursement (currently Medicare will not reimburse for a secondary O2 source used solely for back-up nor for a separate portable O2 concentrator). The following table provides a summary of common system selection scenarios.
Scenario 1: Liquid O2 Stationary Base Unit with/without Portable. This traditional Medicare-reimbursed setup requires minimal equipment and psychomotor skills and can provide moderate FIO2s if needed. Patients use the stationary base unit for O2 in the home. For patients active outside the home, a portable refillable liquid unit can easily be added. When used with a pulse-dose delivery system, portable units can provide up to 8-9 hours of O2 at a setting of '2.' The stationary system must be refilled every 1-2 weeks. A combined base unit + portable liquid system precludes the need to store and handle cylinders. These systems also are quiet (occasional venting does occur) and do not involve additional electricity costs.
Scenario 2: Standard O2 Concentrator with Back-up High-Pressure Cylinder(s). For patients with low to moderate FIO2 needs who do not leave the home and can afford the additional coast of electricity, a standard concentrator with high-pressure cylinder(s) (a couple of 'E'-size or a single 'H' or 'K'-size cylinder) as the back-up supply can be used (the back-up supply is usually provided at little to no cost by the DME). Patients are required to store cylinders, know how to change a regulator, and must incur the additional cost of electricity.
Scenario 3: Standard O2 Concentrator with a Small Portable Cylinder. When a concentrator is used in conjunction with smaller, lighter M6 or M9 cylinders (carried in a shoulder bag) and pulse-dose conserving devices, the patient is able to easily leave home for most activities. Patients are still required to store cylinders and must know how to change a regulator. Most pulse-dose systems extend use time by a factor of 2x to 4x as compared to continuous flow, allowing up to 8 hours usage with an M9 cylinder. Patients must incur the additional cost of electricity to run the concentrator.
Scenario 4: Standard Concentrator or Liquid Base Unit + Portable Concentrator. This system is intended for the highly mobile patient with low FIO2 needs who can afford the extra cost of adding a portable concentrator (not reimbursed). The standard concentrator or liquid system provides O2 for use within the home and the portable concentrator provides an essentially unlimited source of O2 outside the home, albeit with limited FIO2/flow capabilities. When battery-powered, the portable concentrator can also serve as the back-up supply in the home setting.