Home oxygen therapy involves breathing in air that contains more oxygen than normal from a cylinder or machine in your home.
It may be prescribed if you have a heart or lung condition that causes low oxygen levels in your blood.
You can take oxygen in a number of ways using a:
tube positioned under your nose (nasal cannula)
face mask placed over your nose and mouth
tube placed into your mouth and down your windpipe
The tube or mask is attached to a ventilator machine.
If you have a health condition that causes low levels of oxygen in your blood, you may feel breathless and tired, particularly after walking or coughing. Fluid may also build up around your ankles.
Breathing air with oxygen increases the amount of oxygen in your blood.
This makes it easier to carry out activities that might otherwise be difficult, and helps reduce your symptoms.
Oxygen therapy also helps prevent damage to the heart and brain, which can be caused by low levels of oxygen in the blood.
It can help people with a range of health conditions, such as:
People who have oxygen therapy have different requirements. For example, you may only need oxygen for short periods during the day when you're walking about (ambulatory oxygen), or you may need it for longer periods during the day and night.
Oxygen therapy shouldn't be used to relieve breathlessness if your oxygen levels are normal.
This is because it can decrease your fitness level and cause a delay in finding out what's making you breathless.
If you have a long-term condition and your doctor thinks oxygen therapy might be helpful, you'll be asked to visit your nearest oxygen clinic for an assessment.
The amount of oxygen in your blood will be measured by taking a blood sample from your earlobe or wrist, or by attaching a sensor to your finger (a pulse oximetry test).
You may also be asked to breathe into a device called a spirometer during a lung function test. Regular oxygen treatment may be recommended if your blood oxygen level is low.
If you decide to have oxygen treatment at home, a healthcare professional at the clinic will help you work out how much oxygen you'll need and for how long. They'll also discuss the different ways you can take it.
Once you've agreed this with the clinic, they'll complete a home oxygen order form for you. It's similar to a prescription, and gets sent to the company delivering your oxygen and equipment.
You'll be asked to fill in a consent form, plus a form that asks a number of safety-related questions, such as whether you've had any falls recently. The forms are needed to make sure oxygen is installed in your home in the safest way possible.
The oxygen clinician will need to share some information about your requirements with the NHS and other key organisations, including the home oxygen supplier, your local fire and rescue service, and your electricity provider.
An engineer will visit your home to install the equipment, check that it's working properly, and explain how to use it. They'll also carry out a risk assessment and provide you with other important information, such as how to order oxygen refills.
Oxygen cylinders will probably be prescribed if you only need oxygen for short periods to relieve attacks of breathlessness after an illness.
Oxygen is breathed in through a face mask or soft tube inserted into your nose (nasal cannula). You can talk, eat and drink while using a nasal cannula.
The use of oxygen cylinders should be regularly reviewed, and treatment should be stopped if your blood oxygen levels have returned to normal.
An oxygen concentrator machine is suitable if you'd benefit from having oxygen for many hours a day, including while you're asleep. It ensures you have a source of oxygen that never runs out.
The machine is about 75cm (2.5 feet) high and plugs into an electrical socket. It filters oxygen from the air in the room and delivers it through plastic tubes to a mask or nasal cannula.
Long tubing can be fixed around the floor or skirting board of your house, with two points where you can "plug in" to the oxygen supply. When the machine is installed, the engineer or nurse will discuss the length of tubing needed.
The machine is very quiet and compact. The engineer will explain how to use it and answer any questions you have.
A back-up oxygen cylinder will be provided in case there's a problem with the oxygen machine or there's a power cut. Regular maintenance checks will also be carried out to ensure the concentrator is always working properly.
It may be possible to use a small, portable oxygen cylinder outside your home. This is called portable oxygen or ambulatory oxygen.
You'll need to be assessed to see whether you're able to use portable oxygen and whether it's likely to be beneficial.
Portable cylinders can deliver oxygen at a wide range of flow rates. Your oxygen healthcare professional will be able to advise you about the flow of oxygen you need. Regulators or conserving devices can be fitted to your cylinder so it lasts longer.
When full, portable oxygen cylinders weigh just over 2.3kg (5lbs) and hold just under two hours of oxygen (at a rate of 2 litres a minute).
As long as you're well enough to travel and you plan in advance, you should be able to go on holiday while using oxygen.
Speak to staff at your local oxygen clinic as soon as possible if you're thinking about going on holiday, particularly if you want to go abroad.
They can advise you about what you need to do to stay safe while you're away. For example, you'll need to take your usual medication and a copy of your home oxygen order form.
Before travelling, you should tell the travel company that you use oxygen as they may need to make certain arrangements in advance. Travel insurance is essential.
If you're going on holiday in the UK, talk to your oxygen supplier to see whether it's possible for oxygen to be delivered to your destination. Try to give them as much notice as possible.
The British Lung Foundation website has more information and advice about going on holiday with a lung condition. You can also read more about what you need to consider before you travel.
Oxygen is a fire hazard, so you need to take precautions if you're using oxygen at home.