An oxygen conserving device (OCD) is a specialized component used in supplemental oxygen therapy to manage and extend the duration of the oxygen supply from a tank or cylinder. These devices maximize the efficiency of stored oxygen, which is particularly relevant for individuals using portable systems. By controlling oxygen delivery, an OCD allows a user to carry a smaller, lighter tank or significantly increase the time a larger tank lasts between refills.
Defining Oxygen Conserving Devices
Oxygen conserving devices act as regulators or attachments for compressed gas cylinders or liquid oxygen reservoirs. They solve the inefficiency of continuous flow oxygen delivery systems, where oxygen streams constantly regardless of the user’s breathing cycle. Much of this oxygen is wasted because it flows out during exhalation or is lost to the environment.
OCDs minimize this waste by ensuring oxygen is only delivered when needed. They are typically used with portable oxygen tanks, which have limited storage capacity. This function is accomplished by turning the continuous stream into a series of precisely timed bursts, allowing patients greater mobility and independence away from a stationary source.
The Mechanics of Oxygen Conservation
The operational principle of an oxygen conserving device centers on pulse dose delivery. This mechanism functions by delivering a precise, measured burst, or “bolus,” of oxygen only at the beginning of the inhalation phase. This precise timing is possible because the device is equipped with a sensitive sensor that detects the slight negative pressure created when the user begins to draw a breath.
The sensor triggers the release of a specific volume of oxygen, timed to enter the lungs at the start of inspiration. This timing ensures the majority of the gas is inhaled deep into the lungs during the most productive period for gas exchange. This approach avoids the waste that occurs when oxygen is supplied during the entire breath cycle, including exhalation. The conservation achieved can often extend the lifespan of a tank by a factor of three to five times compared to a continuous flow regulator.
Key Types of Conserving Devices
Oxygen conserving devices are available in several forms, each utilizing a different technology.
Electronic Pulse-Dose Regulators
Electronic pulse-dose regulators are a common type, often integrated into portable oxygen concentrators. These battery-powered units use sophisticated electronic sensors and valves to detect the inspiratory phase. They deliver a highly controlled dose of oxygen, and the output is measured in milliliters per breath rather than the traditional liters per minute.
Passive Reservoir Cannulas
Another category includes passive, non-electronic devices like reservoir cannulas, which can be mustache or pendant style. These devices feature a small reservoir where oxygen accumulates during the exhalation phase. When the user inhales, they draw this stored bolus of oxygen before the main flow from the tank is initiated. This simple, mechanical storage system allows for conservation without the need for batteries or electronic components.
Demand-Flow Systems
A third type is often referred to as demand-flow systems. These operate similarly to electronic pulse-dose devices by only releasing oxygen when a breath is detected. The term can also be used more broadly to describe any system that delivers oxygen based on the user’s demand. The choice among these types depends on the patient’s prescribed flow rate and their ability to consistently trigger the device.
Advantages and Practical Considerations
The use of an oxygen conserving device provides several practical benefits for therapy. The most immediate advantage is the enhanced portability and independence gained from extending the tank duration. A smaller, lighter portable cylinder can last for several hours, making it easier for the user to maintain an active lifestyle outside the home. This efficiency also translates directly into cost savings by reducing the frequency of cylinder refills and home deliveries.
Users often report a better experience because the intermittent pulse delivery can reduce the nasal dryness commonly associated with a high, continuous stream of oxygen. However, practical considerations exist, particularly with electronic models. These devices rely on battery power, and users must manage battery life to ensure continuous operation. Furthermore, the user must maintain a consistent breathing pattern to reliably trigger the device and receive the correct dose. A healthcare professional must test and calibrate the device settings to ensure the user maintains adequate oxygen saturation levels both at rest and during activity.