Portable oxygen concentrator

A Philips Respironics Oxygen Concentrator (humidifier attached)

An Invacare Perfecto 2 oxygen concentrator

Portable oxygen concentrator (or POC) is a portable device used to provide oxygen therapy to patients at substantially higher oxygen concentrations than the levels of ambient air. It is very similar to a home oxygen concentrator, but is smaller in size and more mobile. The portable oxygen concentrator makes it easy for patients to travel freely; they are small enough to fit in a car and many concentrators are now FAA-approved.

Development

Portable oxygen concentrators have been around for decades, but the older versions were bulky, unreliable, and were not permitted on airplanes. Since 2000, manufacturers have improved their reliability and they now produce anywhere between one and six liters per minute (LPM) of oxygen. The portable concentrators plug directly into a regular house outlet for charging at home or hotel, but they came with a power adapter that can usually be plugged into a vehicle DC adapter. They have the ability to operate from the battery power as well for either ambulatory use, or away from a power source, or on an airplane.

How does it work?

Portable oxygen concentrators operate on the same principle as a home domestic concentrator, operating through a series of cycles. Air at barometric pressure contains 21% oxygen combined with nitrogen and a mixture of other gases. A miniaturised air compressor inside the machine will pressurise this air through a system of chemical filters known as a molecular sieve. This filter is made up of silicate granules called Zeolite which sieves the nitrogen out of the air, concentrating the oxygen. Part of the oxygen produced is delivered to the patient; part is fed back into the sieves to clear them of the accumulated nitrogen, preparing them for the next cycle. Through this process, the system is capable of producing medical grade oxygen of up to 90% consistently. The latest models can be powered from mains electricity supply, 12v DC (car/boat etc.), and battery packs making the patient free from relying on using cylinders and other current solutions that put a restriction on time, weight, and size.

Most of the current portable oxygen concentrator systems provide oxygen on a pulse (on-demand) delivery in order to maximise the purity of the oxygen. The system supplies a high concentration of oxygen and is used with a nasal cannula to channel oxygen from the concentrator to the patient.

Benefits

Portable oxygen therapy allows oxygen therapy patients to maintain their mobility and independence throughout their day-to-day activities. Here are some benefits of using portable oxygen concentrators:^[1]

Allows patients to utilize oxygen therapy 24/7, which helps increase survival.

Portable oxygen concentrators help improve exercise tolerance, as supplemental oxygen during exercise helps you exercise longer.

Helps increase stamina throughout day-to-day activities.

Freedom to travel lightly and easily. No need to carry around heavy oxygen tanks which are difficult, heavy, and dangerous (explosive properties).

In addition to this, portable oxygen has a variety of uses commercially;^[2] for example, for use in the glass-blowing industry, health clubs, beauty spas as well as airports.^[3]

The difference between on-demand & continuous flow

On-demand (also called intermittent-flow or pulse-dose) POCs are the smallest, often no bigger than a briefcase or picnic cooler and weighing about 5 pounds or less. These deliver oxygen only when patients inhale, avoiding the waste of oxygen during exhalation. Their ability to conserve oxygen is key to keeping the units so compact without sacrificing the duration of oxygen supply.^[4] Sleek, slim exterior cases, some with form-fitted carrying bags, optimize the flexibility to take these units almost anywhere—even to altitudes of 10,000 feet—as long as there's sufficient battery run time until the next opportunity to recharge.

Another type of POC combines on-demand and continuous-flow capabilities to meet a wider range of patient needs. These dual-supply concentrators can provide a larger volume of oxygen than smaller on-demand units, but there's a trade-off: they need bigger, heavier battery supplies (or battery run time is reduced) and they weigh almost twice as much, between 10 and 20 pounds. These dual-system converters often come with built-in wheels or a cart to offset the extra weight without compromising mobility.^[5]

Although each category includes multiple brands with varied characteristics, the most important consideration for any POC is its ability to supply adequate supplementary oxygen to relieve hypoxia (oxygen deficiency) during normal activities of daily living.^[6] With continuous-flow, oxygen delivery is measured in LPM (litres per minute). With on-demand or pulse-flow, delivery is measured by the size (in millilitres) of the "bolus" of oxygen per breath, referring to a burst of oxygen released at the instant of inhalation. Other important variables include maximum oxygen purity (oxygen percentage), the number and increment of settings for adjusting oxygen flow, and battery capacity (or number of add-on batteries) and power cord options for recharging.

Although portable concentrators are an appealing option for active patients, it is not simple to match any patient's unique physiology and varying oxygen needs with the right oxygen equipment. Instead, it is a job for a specialist with extended training, such as a pulmonologist, to prescribe the correct oxygen flow and, with the help of a respiratory therapist, begin the trial and error process of choosing a POC that best suits a patient's needs.

A great deal of controversy has surrounded the suitability of portable concentrators during sleep. On-demand units are typically not advised for patients with sleep apnea, who usually require a CPAP (Continuous Positive Airway Pressure) mask. For patients without apnea, the use of portable concentrators during sleep is on the rise, especially with the advent of alarms and technology that detects a patient's slower breathing during sleep and adjusts the flow or bolus size accordingly. ^{[7] [4]}

FAA approval

On May 13, 2009, The Department of Transportation (DOT) ruled that air carriers conducting passenger capacity of more than 19 seats, must allow travelers with a disability to use an FAA approved Portable Oxygen Concentrator (POC) on all flights, unless the POC does not abide by valid FAA requirements.^[8] POC labeling by the FAA was expected to be complete by May 13, 2009. The DOT rules regarding Oxygen Concentrators have been adopted by many international airlines around the world, but airline customers need to check with their carrier to find out the rules for their particular airline of choice. A list of Portable Oxygen Concentrators approved for air travel is provided on the FAA website.^[9]

Future of Portable Oxygen Concentrators

The market for portable oxygen concentrators was at $242.5 million in 2012 and is expected to rise to $1.9 billion by year 2019. The growth is attributable to new competitors coming into the market, demand for the lighter technology by consumers, and the need of greater mobility support for the elderly. The competition is expected to drive innovation, resulting in lighter units and lower prices.^[10]

Comparison of POCs

Intermittent flow (IF)-only products weighed in the range of from 2.8 to 9.9 pounds (1.3 to 4.5 kg). The continuous flow (CF) units were between 10 and 20 pounds (4.5 to 9.0 kg).^[11]

Due to limitations in sensing inhalation during sleep, some patients need continuous flow while sleeping, as indicated above. Patients who are ambulatory often encounter difficulty moving without catching the tubes from stationary oxygen concentrators on everyday objects like furniture and doors.

See also

• Hyperbaric Oxygen Therapy
• Oxygen Bar
• Oxygen concentrator

References