Oxygen Systems

 As reimbursement decreases, HME suppliers face the challenge of providing home oxygen therapy appropriately and cost-effectively.

The use of long-term oxygen therapy (LTOT) in the home has been increasing over the past several years due to an increase in the number of patients with chronic obstructive pulmonary disease (COPD) who require oxygen, as well as to a better understanding of the value of early COPD diagnosis and treatment. With this increase in the number of patients receiving oxygen therapy has come an increase in the overall cost associated with LTOT. The Medicare program, being the largest payor for LTOT, has been evaluating the cost increase and attempting to control it using a decrease in payment. As reimbursement decreases, home medical equipment (HME) suppliers face the challenge of providing home oxygen therapy appropriately and cost-effectively.

One option for controlling costs associated with LTOT is the use of oxygen-conserving devices. These devices, used with liquid oxygen and compressed gases, can reduce the number of systems required for service or can reduce the cost associated with refilling these systems as often as previously necessary.

Another option that has become available to the market is a system that allows gas from an oxygen concentrator to fill a high-pressure cylinder. This system includes a concentrator that is equipped to supply oxygen to a compressor unit. The compressor unit fills the cylinders from the concentrator’s supply of oxygen. The specially designed cylinders connect to an oxygen-conserving device to extend the operating time of the small cylinders.

The purpose of this investigation was to determine whether a cylinder filled (from a concentrator) with approximately 93% oxygen, coupled with an oxygen-conserving device, could maintain the same level of oxygenation as a cylinder using 99.6% USP oxygen in a patient performing activities of daily living.

Case Study
A patient was selected who was active and using four to six M6 (180-L) oxygen cylinders per week. This 68-year-old white female had been using supplemental oxygen at a flow rate of 2 L/min for more than 4 years. She had a history of smoking for more than 30 years. The patient was interviewed to determine her interest in participating in the investigation, her activity level, and her ability to work with the equipment and maintain a diary of activity. The patient was found capable, and she agreed to participate.

The study monitored the patient using her existing oxygen system for 72 hours, then using the new system for the next 72 hours. The patient’s existing oxygen system consisted of an oxygen concentrator, an oxygen-conserving device, and M6 cylinders. The evaluation unit comprised an oxygen concentrator and compressor unit, a conserving unit, and home-fillable M6 cylinders. An oximeter was worn for the entire period of the study, and data were downloaded after each segment of the evaluation. A diary was used by the patient to record daily activity and any unique episodes that might have had an impact on oxygenation. A patient-activity log was created to record significant activity hourly (during waking hours).

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The patient’s activity log indicated that there was no limit or change to activity with the use of either system. The patient had a daily routine that was similar using both systems; it included household chores and outside trips. One episode of desaturation was recorded in the activity log during use of the existing system when the patient returned from a shopping trip and became short of breath while entering the house. The pulse-oximetry value (Spo2) dropped to 85% and the heart rate was 107 beats per minute.

More activity related to the new system was recorded due to the closer observation of a different system. Details related to the connection of the portable cylinders to the compressor were noted, along with the connection of the supply tubing to the oxygen-conserving device. There was one episode of desaturation on the new system related to walking approximately 12 m inside her house. Her Spo2 dropped to 87% and her heart rate was 104. The oxygen-conserving device sounded its alarm once when the tubing from the cylinder to the oxygen-conserving device became disconnected. The patient appreciated this alarm, since the older system does not have this feature.

The patient was very compliant with use of the oximeter. The total hours recorded on the baseline test of the existing system were 71, and 72 hours were recorded for the newer system. The patient was encouraged to do activities of daily living and there were no set times or logged hours for when she was on her portable or stationary device. A desaturation event was defined, for purposes of analysis, as a reduction in Spo2 of at least 6% lasting a minimum of 8 seconds. A pulse event was defined as a change in rate of at least 6 beats per minute lasting for 8 or more seconds. Oximetry data indicated that there were fewer desaturation events during use of the existing system, but the total time spent in desaturation events was the same for both systems. The average duration of an event was similar for both tests. Average pulse rates and lowest pulse rates were similar between the tests (see table).

New technology is entering the HME market due to reimbursement changes and the development of innovative means of delivering therapy. Understanding the principles of operating these new devices is necessary, and the clinical implications of their use must be understood before a clinician can appreciate the impact that a device might have on a patient. Oxygen-conserving devices are a recent addition to the LTOT market, and research1 has documented the variability of individual products.

Oxygen concentrators have been clinically accepted, and oxygen levels of 85% or more are therapeutically equivalent to 100% oxygen, according to the findings2 of the first consensus conference on home oxygen therapy. The combination of lower oxygen concentrations and the use of an oxygen-conserving device by an active patient may require the clinician to assess the patient for proper oxygen levels (via oximeter) and make adjustments if necessary. This study, therefore, was intended to determine whether desaturation would occur when an active patient used a system incorporating cylinders filled at home from an oxygen concentrator. These findings indicate that the patient did not experience any adverse effects attributable to use of the new system.

This evaluation involved only one patient during a 3-day period. Numerous variables could have been monitored that might have affected oxygenation and findings; these include activity level, activity time, and the number of cylinders used. This study, however, was intended to provide initial information on the compounding of several variables related to patient oxygenation. There was no indication that the patient had any additional desaturation using the system being evaluated, compared with the system already being used.

In this single-patient study, the data showed no adverse effects of using the new system while performing activities of daily living. More studies involving larger patient groups are recommended for determining the value and applications of the new oxygen system.

Robert McCoy, RRT, is managing director of Valley Inspired Products, Burnsville, Minn. Peter Bliss is technical director of Valley Inspired Products, Burnsville, Minn.

1. McCoy R. Oxygen conserving techniques and devices. Respir Care. 2000;45:95-103.
2. Problems in prescribing and supplying oxygen for Medicare patients. Summary of a conference on home oxygen therapy held in Denver, February 28 and March 1, 1986. Am Rev Respir Dis. 1986;134:340-341.