An oxygen concentrator (OC) is a medical device that provides supplementary oxygen therapy. The apparatus takes in ambient air and increases the oxygen concentration of the delivered air. This supplies oxygen-enriched gas to individuals whose medical condition impairs their ability to take in sufficient oxygen from the atmosphere. Unlike pressurized oxygen tanks, which store a finite amount of compressed gas, the concentrator continuously manufactures its own supply.
The Core Mechanism
The technology used to filter and enrich the air is called Pressure Swing Adsorption (PSA). This process relies on a physical principle to separate gases based on their molecular characteristics. Ambient air (approximately 78% nitrogen and 21% oxygen) is drawn into the machine, compressed, and then forced into specialized cylinders known as sieve beds.
These sieve beds are packed with a material called zeolite, a crystalline aluminosilicate that acts as a molecular sieve. Zeolite is engineered to selectively adsorb, or trap, nitrogen molecules onto its surface under high pressure. Oxygen molecules, being slightly smaller and having a different electrical charge distribution, pass through the zeolite material unhindered. This physical separation process effectively removes the majority of nitrogen from the air stream.
The PSA system uses at least two sieve beds that alternate between adsorption and regeneration phases to ensure a continuous flow of high-purity oxygen. While one bed traps nitrogen under high pressure, allowing oxygen to pass to the patient, the other bed is depressurized. This “swing” in pressure causes the trapped nitrogen to be released, or desorbed, and vented back into the atmosphere as waste gas. This cyclical process allows the concentrator to consistently produce gas that is up to 95% pure oxygen.
Applications in Health Care
Oxygen concentrators are a standard therapeutic tool for managing chronic respiratory diseases that cause low blood oxygen levels (hypoxemia). The most frequent use is in patients diagnosed with Chronic Obstructive Pulmonary Disease (COPD), which includes chronic bronchitis and emphysema. These conditions reduce the lungs’ efficiency in transferring oxygen into the bloodstream, making supplemental oxygen necessary.
Another significant application is in the treatment of pulmonary fibrosis, a progressive disease where scar tissue builds up in the lungs, stiffening them and severely hindering gas exchange. Patients with advanced heart failure may also require oxygen therapy, as their weakened hearts struggle to circulate enough oxygenated blood throughout the body. The goal of using a concentrator is to maintain the patient’s blood oxygen saturation level above 90% during all activities, including rest and sleep.
Providing a continuous supply of oxygen helps alleviate symptoms such as shortness of breath and fatigue, improving the patient’s quality of life and endurance. Oxygen therapy is often prescribed for use during sleep, as breathing rate and depth naturally decrease, which can lead to low oxygen saturation. The therapy mitigates the strain on the heart and other organs that results from prolonged hypoxemia.
Comparing Concentrator Types
Oxygen concentrators are broadly categorized into two main types based on their size and intended use: stationary and portable. Stationary concentrators are larger units, typically placed in the home, that plug into an electrical outlet and are designed to run for many hours a day. These devices generally offer higher flow rates and are used when a patient requires a consistent, high volume of oxygen, often for rest or overnight use.
Portable Oxygen Concentrators (POCs) are smaller, lighter, and operate on rechargeable batteries, providing patients with mobility. These units allow users to maintain an active lifestyle, travel, and complete daily errands without being tethered to a wall unit. The functionality of both stationary and portable units is further defined by their oxygen delivery method.
The two primary delivery methods are continuous flow and pulse dose. Continuous flow delivers oxygen at a constant, steady rate, measured in liters per minute (LPM), regardless of the user’s breathing pattern. This method provides the most consistent oxygen supply and is often necessary for nighttime use or for patients with very advanced disease. Pulse dose delivery, in contrast, is a more efficient method that senses when the user begins to inhale and delivers a quick burst, or bolus, of oxygen only at that moment.
Pulse dose technology conserves the oxygen supply, allowing the internal battery of a portable unit to last significantly longer, making it the preferred method for most portable concentrators. The choice between continuous flow and pulse dose depends on the patient’s specific medical prescription and their lifestyle needs, as determined by a healthcare provider.