Improvements in Oxygen Delivery Systems Lead to More Efficient, Easier-to-Use Devices

Key Point

Oxygen delivery technologies continue to improve with respect to efficiency and ease of use.

CHICAGO—Significant technological advancements have occurred in the area of supplemental oxygen delivery, said Joseph S. Lewarski, RRT, at the American College of Chest Physicians’ 2007 Annual International Scientific Assembly. Mr. Lewarski, Vice President of the Respiratory Products Group at Invacare Corp in Elyria, Ohio, highlighted oxygen concentrators and portable liquid oxygen devices as delivery systems that have become more efficient and easier to use.

PORTABLE DEVICES AND CONCENTRATORS

“The real advancements in the modern liquid oxygen systems are in the portables,” said Mr. Lewarski. Portable oxygen delivery devices usually weigh less than 7 lb, compared to 120 lb (or as heavy as 175 lb when full) for the typical stationary liquid oxygen tank designed for home use. Furthermore, the portable devices now permit two to eight hours of continuous supplemental oxygen delivery.

Noteworthy progress has also been made in the area of oxygen concentrators. “There was always concern that the oxygen in concentrators was not as good or as pure as it should be,” said Mr. Lewarski. Earlier oxygen concentrator models were invariably large, noisy, and inefficient, producing only about 40% oxygen at 2 L/min—less than half the expected output. The newest oxygen concentrators, however, can deliver a 93% oxygen output at 5 L/min.

Ranging from 25 to 35 lb, they are also much lighter than their older counterparts, and they consume much less electricity—less than 300 watts at 2 L/min versus as much as 1,000 watts with earlier models. The newer models’ noise level has been described as merely white noise in the background.

Oxygen concentrators with transfilling capability have been available for about five years. These devices have slightly different features according to each model, but they all include a small oxygen tank that can be attached to a larger main tank and, depending on the small tank’s size, can be filled with oxygen in an hour or two. The small tank can then be used as a portable oxygen therapy system. This procedure led to the development of the stand-alone portable oxygen concentrator (POC).

Manufacturing POCs involves trade-offs in size, weight, battery life, and oxygen output in order to create a final product that reasonably meets patient needs. For example, some POCs were designed to weigh no more than 10 lb so that they could be easily carried over the patient’s shoulder. The newest POC is a continuous oxygen flow device that has been on the market for slightly more than a year; it can provide 3 L/min of oxygen, versus about 1 L/min with the earlier models. The tradeoffs for this 3-L/min capability, however, were greater size (20 lb when full of oxygen) and more noise.

KEY FACTORS OF OXYGEN DELIVERY

“What’s important to know is that all of these systems contain oxygen-conserving devices (OCDs),” Mr. Lewarski stressed. OCDs are electric or pneumatic pulse-dose systems that save oxygen by providing the appropriate amount of oxygen to the patient on demand during the inspiratory phase, and also by allowing the patient to exhale passively. OCD may not be the most appropriate term for these devices, because it may lead people to believe that they are meant to conserve oxygen, whereas their primary function is to deliver as much oxygen as possible efficiently.

With respect to factors such as trigger sensitivity and oxygen bolus size, it is important for clinicians to be aware of the variability in performance between different oxygen delivery devices. Mr. Lewarski explained that a setting of 2 L/min on one device is not the same as a setting of 2 L/min on another device and that “each device should be titrated to the individual patient.” In most cases, 2 L/min of oxygen is a good starting point, but there are data showing that 50% of patients receiving supplemental oxygen desaturate nocturnally, and a significant number of patients desaturate during exercise at a dose of
2 L/min.

Mr. Lewarski remarked that it is regrettable that the federal government plans to cut annual reimbursement for supplemental oxygen therapy by $1.8 billion in the near future. Although the annual cost of oxygen therapy in the United States is roughly $3 billion, that sum is relatively small considering that the therapy has been proved to extend patient life, and at an expense of only several dollars a day per patient, it is also one of the most cost-efficient treatments available.

He cautioned that minimal federal reimbursement for oxygen delivery devices will reduce manufacturer incentive to continue the technological progress made so far, which could result in patients being faced with fewer and less effective choices than those available now.           

—Timothy Begany

Suggested Reading
Chatburn RL, Lewarski JS, McCoy RW. Nocturnal oxygenation using a pulsed-dose oxygen-conserving device compared to continuous flow. Respir Care. 2006;51(3):252-256.
Gallegos LC, Shigeoka JW. Novel oxygen-concentrator-based equipment: take a test drive first! Respir Care. 2006;51(1):25-28.
Lewarski JS, Gay PC. Current issues in home mechanical ventilation. Chest. 2007;132(2):671-676.

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