Oxygen concentrators are medical devices used for delivering oxygen to patients with breathing-related disorders. Patients with lower than normal oxygen concentrations in their blood may require the use of such an oxygen concentrator to compensate for that oxygen. Normally, your lungs absorb the oxygen in the air and transfer it to your bloodstream. But, if doctors find that you have low levels of blood oxygen, they may recommend short-term or long-term oxygen therapy.

Typically, you cannot buy oxygen concentrators over the counter. A doctor must prescribe it after completing a thorough medical evaluation. The doctor will also show the patient how to use these concentrators while traveling and in their home effectively.

Advantages of oxygen concentrators
Both portable and home oxygen concentrators have many advantages for those patients needing oxygen therapy.

• They are less cumbersome or risky than traditional oxygen cylinders. Oxygen cylinders can rupture or leak, causing or increasing the combustion rate of fire. Oxygen concentrators, on the other hand, present no such danger.
• Home and portable oxygen concentrators that can make their oxygen have become more popular and widely used than old-fashioned oxygen tanks. The main benefit is the ease and increased ability to be mobile with oxygen. Tanks store a specific amount of compressed oxygen that can be used until it runs out.

How does an oxygen concentrator work?
The functioning of oxygen concentrators is like a window air conditioner. They take air in, change it, and deliver it in a different form.

• The oxygen concentrator takes air in and purifies it for use by individuals who require medical oxygen because of low levels of oxygen in their blood.
• They are powered by plugging the device into an electrical outlet or by using a battery. If a battery is used, it will need to be charged by plugging it into an electrical outlet.
• The concentrators also come with adapters so you can use the device while you drive.

So, oxygen concentrators receive air, purify it, and then distribute the newly formed air. Before it goes into the concentrator, the air is made up of 80 percent nitrogen and 20 percent oxygen. After the oxygen concentrator uses that air, it comes out as 90 to 95 percent pure oxygen and 5 to 10 percent nitrogen. The nitrogen is separated to give the patient the highest dose of oxygen possible, as it is difficult to get that percentage of oxygen without the help of a medical device.

An oxygen concentrator works by

• Compressing air, as the cooling mechanism keeps the concentrator from becoming overheated
• Taking air in from its surroundings
• Using an electronic interface to adjust delivery settings
• Removing nitrogen from the air through sieve beds and a filter
• Delivering purified oxygen through a mask or nasal cannula

Understanding the mechanism

Portable oxygen concentrators consist of a compressor and a sieve bed filter, among other main parts.

Compressor : The compressor compresses air that is filtered into the concentrator, and then delivers the air in a continuous stream. The compressed air moves to the sieve bed filters.

Sieve bed filter : This is the device that removes the nitrogen from the air. A material called Zeolite, which is a six-sided microscopic cube with holes on each side, is in the sieve bed, which removes the nitrogen from the air.

• Two sieve beds are placed in the concentrator.
• After the air is first compressed in the concentrator, it is forced into the first sieve bed, and oxygen is sent into the product tank.
• The first sieve bed then gets filled up with nitrogen.
• Next, the gas flow is switched, and the compressed air is moved to the second sieve bed.
• The first sieve bed’s compressor is sent to the outside room, and the air from the product tank goes back into the first sieve bed.
• The drop in pressure from the first sieve bed and the weakening of oxygen makes the Zeolite release nitrogen.
• The oxygen and nitrogen come back together and are released in the room as regular air.
• The air is then compressed and sent to the second sieve, where oxygen is moved to the product tank.
• The whole cycle then starts over again with the first sieve after a few seconds.

Other important parts are the cooling system that keeps the portable oxygen concentrator from overheating, and the nasal cannula that delivers the purified oxygen after the oxygen has been passed through all the sieve bed filters. The cannula helps improve oxygen absorption.

Types of oxygen concentrators
There are two types of oxygen concentrators: stationary oxygen concentrators and a portable oxygen concentrator.

• Stationary oxygen concentrator
  These large machines take up a significant amount of space in a room and limit mobility around your home. Stationary oxygen concentrators typically deliver 1 to 6 liters of oxygen per minute continuously, making them an excellent solution for oxygen-dependent patients who do not want to worry about tank refills.
• Portable oxygen concentrator
  Portable oxygen concentrators operate just like stationary oxygen concentrators but are much smaller. So, they have limited oxygen delivery capabilities. Most portable concentrators available are pulse dose oxygen concentrators. Still, there are a few continuous flow oxygen concentrators available in the market that can deliver up to 3 liters per minute of concentrated oxygen in a continuous flow.

Continuous flow units
They are a more suitable option for most oxygen-dependent patients. They can handle a wider range of oxygen demands than a pulse dose model. As a rule of thumb, if you require 2 to 5 liters per minute of oxygen, a continuous flow portable oxygen concentrator is probably the best choice for you.

These machines are generally bigger and weigh more than other units in the market. The weight of one continuous flow unit is up to 18 pounds, not including additional accessories. As these are heavy, they require the use of a cart to transport your oxygen supply. While a continuous flow machine is indeed portable, it is less portable than many of the pulse dose varieties available in the market today.

Pulse dose portable concentrators
These deliver oxygen intermittently. These types of machines provide oxygen in pulses when the patient inhales, rather than continuously. Most pulse dose units can deliver anywhere from 450 ml per minute to 1250 ml per minute of oxygen in short pulses. Pulse dose portable oxygen concentrators are typically recommended for low oxygen requirement patients who need up to 2 LPM of oxygen.

Pulse dose machines most often run on AC, DC, and battery power. The battery life is often advertised for use at the lowest setting. So, before purchasing, consider how much battery life you will have when the concentrator is used at the oxygen output setting you require.

Though the pulse dose portable oxygen concentrator is less flexible in terms of oxygen delivery than a continuous flow device, it is better in terms of portability. These units are truly portable, with some of the newest ones weighing as little as four pounds. Because of their small physical size and low weight, pulse dose systems are easily wearable and often come with shoulder straps or a backpack for extra ease.

Best oxygen concentrators in 2020
Finding the right device for oxygen therapy can be confusing at times, given the many models and brands in the market. So, here is a list of oxygen concentrators that have made their mark in 2020:

• Invacare Perfecto2 V five-liter oxygen concentrator with SensO2 oxygen sensor
  Invacare Oxygen Concentrator is designed for indoor use and has a patient reset button that can cut down on potentially pricey emergency service calls. It can easily provide concentrated oxygen directly through your nasal cannula. It is small and quiet and very good-looking. It runs smoothly and does not create a lot of noise.
• Devilbiss five-liter compact oxygen concentrator
  It is equipped with turn-down technology to reduce power consumption by 15% or more, which can minimize wear and extend its life. It is reliable and quiet too. It accommodates a nasal cannula, which is up to 50 feet long and has convenient top and side handles for easy portability. It has received five-star reviews from users.
• Devilbiss Ultra Quiet five-liter compact oxygen concentrator
  Devilbliss Ultra Quiet unit is designed to be one of the quietest home oxygen concentrators available, and it is easy to assemble or disassemble for easy transport. This device requires no maintenance for two years. It is easy to use and has a lockable flow meter and a recessed humidifier to minimize damage.
• Respironics EverFlo Q Ultra-quiet stationary oxygen concentrator
  Respironics Oxygen Concentrator is quiet and can provide supplemental oxygen of up to 5 liters per minute with only a sound level of 40 dB, making this one of the quietest home oxygen concentrators. Low on maintenance, it does not need a filter change for two years. This oxygen concentrator, weighing only 31 pounds, can be moved around easily. Users gave this stationary oxygen concentrator a rating of 4 out of 5 stars.
• O2 Concepts Oxlife Independence portable oxygen concentrator
  This oxygen concentrator comes with patented EnergySmart technology that provides the longest battery life while delivering three times the oxygen flow of other portable oxygen concentrators (POC). It can also alert caregivers or loved ones if there is an issue with your supplemental oxygen supply.
• Precision Medical EasyPulse portable oxygen concentrator
  This compact and lightweight POC is designed explicitly for ambulatory patients and can easily be taken with the patient wherever they need to go. The long battery life can provide the user with the proper amount of oxygen when needed and has an on-demand or pulse delivery system that provides 1-5 liter per minute of supplemental oxygen. Users find it quiet and operationally efficient as well.
• Inogen One G4 Portable oxygen concentrator
  Inogen One G4 is one of the smaller portable oxygen concentrators in the market. It is designed for those who need supplemental oxygen and want to maintain their independence and mobility. This oxygen concentrator can be used in the home, an institution, or even in the car, since the single battery provides up to three hours of supplemental oxygen. A double battery can give the user up to six hours of oxygen. Both can be charged via AC/DC power. Designed to meet the clinical needs of over 85% of patients, this can be carried over the shoulder, at the hip/belt, or carried in a backpack, to allow for maximum portability.
• Inogen One G3 Portable oxygen concentrator system
  This POC is for patients who need prescription supplemental oxygen and wish to maintain their ability to get up and about. Used with a nasal cannula, this small but powerful concentrator can deliver the oxygen patients need while maintaining its smaller footprint and portability. No need to carry heavy oxygen tanks or worry about supplemental oxygen running out, with this easy to use, portable POC.
• Precision Medical EasyPulse POC3 Portable oxygen concentrator
  This POC by Precision Medical has the lowest return or repair rates (less than 0.5%) among all available home oxygen concentrators. It has patented controlled minute volume (CMV) that ensures sufficient battery life to all flow settings.
• Respironics Millennium M10 oxygen concentrator
  Respironics oxygen concentrator is all about performance and reliability. It has fewer parts and a flow rate of up to 10 liters per minute. It has tubing that protects electrical wires, and other tubing, and an integrated sieve canister reduces tubing connections to enhance bed life. The twin head compressor allows for more airflow through the sieve beds. It is the Ferrari of oxygen concentrators.

So, now that you know all about oxygen concentrators, you can easily make an informed choice for yourself or a loved one. Do consult your doctor as well, especially if your oxygen need is high or you suffer from multiple health conditions.