A portable oxygen concentrator (POC) comprises the following components:

• Compressor: This is the pump, motor, and cooling system. The compressor typically consumes greater than 80% of the power of the system and generates the majority of the noise and all of the vibration in the system.
• Sieve beds: A sieve bed is a kind of filter or molecular separation device that removes the nitrogen and leaves the oxygen from air. Concentrators normally produce between 87% and 95% oxygen.
• Electronics: These are the printed circuit boards, sensors, and user interface.
• Oxygen-conserving device (OCD): An oxygen-conserving device allows oxygen to be provided to the patient through a nasal cannula on demand rather than by continuous flow. OCDs are key components of current POCs. With limited oxygen production and the need for energy efficiency, OCDs maximize effective oxygen delivery while concurrently minimizing energy consumption. The result is highly portable and lightweight oxygen technology.
• Power supply: All POCs require a power source. The method of powering the unit is usually:
  • AC power for use in the home;
  • DC power for use in cars, airplanes, boats, or trains;
  • internal and/or external rechargeable battery for use during remote ambulation and activity, in lieu of using a portable cylinder or liquid oxygen device.
• Cooling system: a blower or fan designed to remove heat from the compressor.

DESIGN TRADE-OFFS

In the design of a POC, some technical and performance trade-offs have to be made. These trade-offs typically revolve around size, weight, noise, energy consumption, and oxygen production. Limits of current battery and compressor technologies typically force a compromise between size, weight, and oxygen production. Current technology does not allow the "ideal or perfect POC" to be manufactured (less than 4 pounds, with a battery life of more than 8 hours, and capable of producing 5 L/min of continuous flow).

As you compare units, you will constantly review them relative to the performance criteria below. Some of these criteria will be important to you as an HME provider, while others will be important to patients.

• Size, shape, and appearance: Is the device flat or boxy? Does it have a carrying handle? Is the weight evenly distributed to make it easy to carry? Does it look like a medical device? Does the unit come with a carrying bag? Is the unit available in multiple colors?
• Ease of use: Are the device and its accessories easy or difficult for patients to set up and use? Can patients misuse the device in normal daily use by inadvertently blocking the air inlet filter? One important question is "can your POC be operational on all six faces (such as lying flat under an airline seat)?".
• Weight: Is the device considered lightweight? (The 5th Long Term Oxygen Therapy Consensus Conference defined a lightweight, ambulatory oxygen device as one that is less than 10 pounds and can be easily carried by the patient. In late 2006, CMS raised this weight limit to 20 pounds, thus allowing heavier units to be defined as portable.) Can patients carry the device? How easy is it to move the device? All POCs have to be lifted into and out of an automobile or carried on an airplane. If the weight distribution is not balanced, then it may be more difficult for patients to lift and move the device.
• Noise: What is the noise level of the device while operational and is it irritating? Can patients sleep when the device is operating, or are they bothered by the noise of the unit and/or the OCD? Can patients take the unit and go out to eat or to a movie? Will the device's noise level be noticeable or irritating to others? Some units are quieter than others even when delivering pulsed flow. If a POC delivers continuous flow, it will be noisier than when used with pulsed flow. Remember, the decibel scale is logarithmic, not linear; a device only 3 decibels louder will emit nearly twice as much noise.
• OCD method of operation and subsequent oxygen production number of milliliters per breath: How does the unit function with a typical COPD or restrictive patient? What happens if the patient's respiratory rate increases? Does the unit adjust to patients, or do patients need to adjust their settings to a higher level? Can the unit ever max out and not deliver the amount of oxygen the patient needs per breath and per minute? If this happens, does the oxygen percent drop (increased minute ventilation forces a significant drop in the oxygen purity)?

POCs differ in the way in which the OCD functions. Typical differences are in bolus volume delivered (pulse size), fixed versus variable oxygen minute volume production, trigger sensitivity, trigger delay time, and pulse delivery time. The efficiency of OCD performance is based on the majority of the pulse volume being delivered in the first two thirds of the inspiration. More oxygen delivered in this period will likely produce a higher FiO₂ per breath.

• Battery duration: How long does the battery last? Does the patient know the amount of battery charge left? Is it easy to remove and replace the battery? Battery run time, the amount of battery charge left, and ease of battery replacement are important to patients.
• Power supply: Can the unit be operated from AC, DC, and/or battery? POCs allow patients to live on electrical/battery power, rather than stored oxygen. They have oxygen as long as they have access to electrical/battery power. Patients want flexibility so they can use these devices at home, during activities of daily living, and while traveling by car, airplane, train, boat, or bus.
• Durability: Durability is a major concern for this new class of technology. POCs will be subject to use not common to traditional concentrators. Is the device durable? Patients will inevitably drop these devices. Can it function after it has been inadvertently dropped from 2 or 3 feet? What happens if it has been inadvertently banged against a car door getting into or out of an automobile?
• Patient's method of movement: How easy is the device carried and transported? Is it easy to carry with a handle or via a shoulder strap, or is it draggable? Different patients will demand different movement options.
• Maintenance requirements: What are the manufacturers' requirements? Can this maintenance be done by the patient, or must it be done by trained professionals? What are the costs? Routine or periodic required maintenance affects both patients and providers. It affects patients if the unit is purchased outright, or if the transfer of the asset comes after 36 months. It affects HME providers because they have a postpurchase cost of operation. Since all patients can do is change the air-intake filter, any other required maintenance is the obligation of the HME provider during the rental period.

OXYGEN CLASSIFICATIONS AND PAYMENTS

The Centers for Medicare and Medicaid Services (CMS) has approved a few POCs as both stationary and portable concentrators. When the POC meets these criteria, HME providers can bill for:

• E1390: Oxygen concentrator, single delivery port, capable of delivering 85% or greater oxygen at the prescribed flow rate. This code is to be used for the stationary application of a POC that has been approved by the Statistical Analysis Durable Medical Equipment Regional Carrier (SADMERC).
• E1392: POC rental. Use this code for the portable application of a POC that has been approved by the SADMERC. This code describes a POC system and is used only when billing Medicare for the portable equipment add-on fee for patients using lightweight oxygen concentrators that can function as both the patient's stationary and portable oxygen equipment.

Not all POC devices are listed on the SADMERC product Web site for coding verification. Manufacturers are not required to seek coding verifications. However, HME providers are held accountable for ensuring accurate billing with HCPCS codes. HME providers should check with each manufacturer for billing guidance for items not listed on the SADMERC Web site.

USE AT NIGHT

For more information on oxygen and respiratory issues, including additional articles by Thomas J. Williams, MBA, RRT, go to the free online archives section.

The conventional wisdom is that POCs cannot be used with oxygen-dependent patients at night because POCs rely on an OCD to deliver the oxygen with each breath. Data suggests this belief may be based more on conjecture than clinical fact. A number of published clinical studies demonstrate the effective use of oxygen-conserving devices in a variety of patient care situations, including use during sleep. In fact, there are more total patients in clinical studies validating the use of OCDs during sleep than the number of patients studied in the two landmark studies establishing the use of long-term oxygen in hypoxemic patients (Nocturnal Oxygen Therapy Trial, NOTT, and British Medical Research Council, BMRC, studies). In the meantime, HME providers who are concerned that their patients may desaturate during nighttime use of a POC should test their blood oxygen saturation levels by oximetry before placing them on the specific device.

Ultimately, appropriate oxygen-dependent patients can enjoy an unprecedented level of freedom and independence with POCs. This technology is mutually beneficial for both HME providers and patients.

Thomas J. Williams, MBA, RRT, is managing director of Strategic Dynamics, Scottsdale, Ariz. Williams assists clients in strategy formulation, market research, sales training, and clinical and benchmark studies. Williams can be reached through his Web site: www.strategicdynamicsfirm.com. Robert Chatburn, RRT-NPS, FAARC, is clinical research manager, Section of Respiratory Therapy, Cleveland Clinic; associate professor of medicine at Lerner College of Medicine, Case Western Reserve University, Cleveland; and vice president of Research and Clinical Services for Strategic Dynamics Inc.