Oxygen Concentrators: A Buying and Renting Guide

First, a doctor decides whether oxygen is needed

Oxygen is a medicine. Too little leaves the body short of oxygen, and in some people too much can be harmful, particularly those with long-term lung disease who retain carbon dioxide. A home oxygen prescription normally follows an assessment that includes oxygen levels measured in the blood, symptoms and sometimes a walking or sleep test. The prescription states how many litres per minute, for how many hours a day and whether it is needed at rest, on exertion or during sleep. See oxygen flow rates and prescriptions: what families should know.

Do not buy or rent a concentrator because a pulse oximeter showed a number you did not like, or because a relative "had one". If your parent is breathless or the reading is low, see when oxygen saturation is low: what to do and call a doctor, or 112 in an emergency.

How a concentrator works

Inside the machine a compressor pushes room air through a sieve bed of a mineral that traps nitrogen. What comes out is oxygen-enriched air, usually in the range of 87 to 96 per cent oxygen at the flow rates a home user needs. A flow control knob lets the user set the litres per minute that the doctor has prescribed. The oxygen then passes through a small humidifier bottle if one is used, along the tube and to the face.

A concentrator makes a steady hum and gets warm. It must have clear space for air to enter and leave. It works only while there is power, and its output is lower at the highest flow settings. Most home models are designed for flows up to 5 litres per minute, and some go up to 10. Few older adults need more than 5, and anyone who does is usually under close specialist care.

Types of concentrator

Stationary (home) concentrators. Larger machines on wheels, plugged into mains power, delivering continuous flow. They are the usual choice for night-time and daily use at home.

Portable concentrators. Smaller, battery-powered machines that can be carried or wheeled for outings and travel. Many deliver oxygen in pulses that are triggered by the user's breath, which is not the same as a continuous flow. See portable oxygen concentrators: travel and daily use. They usually cost more than a similar stationary machine, and a household often needs a stationary unit as well.

Single- or dual-outlet models. A few machines can feed two people. Do not use one unit for two patients unless the maker and the doctor say it is safe.

Choosing flow capacity

Ask the doctor for the prescribed flow and then choose a machine whose continuous flow range covers it comfortably, with some headroom. A 5 litre machine is the common choice. Check that the machine maintains its stated oxygen percentage at the prescribed flow, not only at a lower setting. If the prescription may change, for example after illness or at night, ask the doctor whether a higher-capacity machine is wise. Do not choose a machine for the maximum number on the box alone.

Buying or renting

Renting suits short-term needs such as recovery after pneumonia, or while the family waits to see how long oxygen will be needed. A rental should include delivery, set-up, servicing, replacement if the machine fails and pick-up. It avoids a large upfront outlay and the problem of owning a machine after it is no longer needed. Costs vary by city and supplier. See renting breathing equipment: costs, checks and return and equipment to rent vs buy checklist.

Buying suits long-term, continuous use. A new machine with a warranty and a local service centre can be economical over years, but think about maintenance, replacement parts and what happens when the machine ages. A second-hand machine can carry hidden wear; the sieve beds degrade over time, and a secondhand unit may deliver a lower oxygen concentration than it claims. If you consider one, insist on an oxygen purity test, the service history and the running hours, and be wary of sellers who cannot show them.

Either way, keep a backup: a power cut or a breakdown can be dangerous. See oxygen at home and power cuts: a backup plan.

Features that matter

• Oxygen concentration indicator or alarm. Many machines have a sensor and an alarm that sounds if purity falls below a set level. This is a major safety feature.
• Low-flow, high-pressure and power-failure alarms. Check that these exist and are audible in the next room.
• Noise. Machines range from a low hum to a loud drone. Hear it running before you decide, particularly if it will sit in a bedroom.
• Power use. Home concentrators draw a few hundred watts. Ask for the figure and check that the home wiring and any inverter or generator can supply it.
• Wheels and weight. Heavy machines are hard to move on carpets and thresholds. A handle and smooth castors help the caregiver.
• Filters. Easy access to the intake filter for weekly cleaning is more important than it sounds.
• Humidifier bottle compatibility. If the doctor advises humidification, ensure the machine takes a standard bottle.
• Running hours counter. Helps with service schedules.
• Tubing length. Longer tubing allows movement, but each maker sets a maximum length. Do not extend beyond the limit, and keep tubing off the floor where people walk.
• Service network. A machine is only as good as the support nearby. Ask where the nearest service centre is and how fast they respond.

What to check on delivery

Insist on an in-person demonstration and ask the technician to:

• Set the prescribed flow and show how to read the flow meter.
• Show where the filters are and how to clean them.
• Explain each alarm and what to do.
• Place the machine correctly, with space around it.
• Check the plug, socket and earthing.
• Leave a written guide, the warranty or rental terms and service numbers.
• Test the oxygen purity, if a tester is available.

Check the humidifier bottle, spare cannulas and masks, and the emergency number of the supplier. Ask for a backup cylinder plan. Do not sign for delivery of a machine with obvious damage. See equipment delivery, installation and aftercare and medical device licences and safe buying.

Where to place the machine

• In a well-ventilated room, with at least 30 cm of space around the intake and vents, and away from curtains and walls that block air.
• Away from dust, smoke, kitchens and damp. Do not place it near a gas stove, an incense stick or a cooking area.
• Away from heat and flames, including heaters, geysers, lamps with open flames, diyas and candles.
• On a hard, level floor. Avoid a bed or a soft surface.
• Where the tube can reach the person without stretching, and without crossing a walkway.
• Plugged directly into a wall socket with earthing, not via a loose extension board, and not shared with high-power appliances.

Safety rules that apply to every machine

Oxygen makes fire burn faster and hotter. These rules are not optional:

• No smoking by anyone in the room or near the equipment, and no cigarettes, bidis or hookahs in the home while oxygen is in use.
• No open flames, including candles, diyas, agarbatti, matches, lighters, gas stoves and tandoors, near the machine, tubing or the person. Keep at least two metres away from heat sources, or the distance the maker states.
• No oil, grease, petroleum jelly or alcohol-based products on the face or tubing connections. Use water-based lip care only if the doctor agrees.
• No sparks: avoid faulty sockets, frayed cables and overloaded plugs.
• Avoid synthetic, static-prone blankets near the face where possible, and keep electric heaters well away.
• Tell family, visitors and household helpers about these rules and display a sign.
• Never change the flow setting from the prescribed rate, and never lend the machine to someone else.

See safe use of oxygen and electrical equipment and smoke and gas safety for older adults, and read using an oxygen concentrator safely at home before the first night.

Running costs and upkeep

A concentrator uses electricity continuously while on. Ask the supplier for the running wattage and estimate the extra cost. Routine upkeep includes weekly cleaning of the intake filter, wiping the exterior, replacing cannulas and tubing at the intervals recommended, replacing humidifier water daily if used, and servicing as the maker advises. See a cleaning schedule for breathing equipment.

When to ask a professional

Ask your parent's chest physician or doctor for the oxygen prescription, the target oxygen level and when to call. Ask the supplier's technician to demonstrate the machine and alarms. Ask a pharmacist or nurse to show you how to use the oximeter alongside it; see pulse oximeters: how they work and how to use one. Call the doctor if breathlessness worsens, if your parent is drowsy or has morning headaches while on oxygen, or if the machine alarms and cannot be fixed. Call 112 if your parent is struggling to breathe, has blue lips, chest pain or confusion, and switch to the backup oxygen supply while waiting.