British Lung Foundation
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Oxygen and Sats

Can someone explain why people with COPD have to go on Oxygen? My mum has emphysema and was given oxygen cos she was panicky when going from her car to her flat, since she has been on it her lung has collapsed, she had a terrible time in hospital, 3 months later she was unwell again the lung had come away from.the wall, she had the talc procedure and the hospital said her sats are to be between 88-92. She is on Oxygen 15 hours a day and at rest her oxygen is 97 with it on. Without it and walking a short distance it drops to 89-90-91. So what is the need for the oxygen? We keep asking but are getting conflicting answers. So could someone explain the need for it and when? Thanks

21 Replies

This page gives a good, general overview for people new to oxygen/COPD.

It may help you understand better why your mum has been prescribed it and what it does.


Ok thanks I will have a look :)


I received this from a friend

oxygen levels will rob you of your eye sight, short term memory, and your energy. Eventually low oxygen levels will weaken your heart muscle. Read that last sentence again. It is that important.

The world is facing an epidemic of heart failure! This issue is drastically shortening life span and it is just so unnecessary!

Your low oxygen levels may precede a heart failure diagnosis, but if you are experiencing low oxygen levels, you can count on developing heart failure because low blood oxygen saturation levels CAUSE heart failure!

So how low IS too low?

Facts to Remember About Blood Oxygen Saturation Levels

When oxygen saturation levels fall below 92%, the pressure of the oxygen in your blood is too low to penetrate the walls of the red blood cells.

So, oxygen is unable to access transportation to your cells, tissues, and organs.

It is a matter of gas laws.

Every time your oxygen level falls below 92% saturation the cells of your body are oxygen starved!

4. When you fail to meet your oxygen needs, every organ in your body suffers the consequences.

5. Low oxygen levels may be present only at certain times.

when retaining excessive fluid

when airways are reacting to irritants

with respiratory illness

while sleeping (with or without sleep apnea)

about 3:00am when you wake gasping for air

with activity when your heart muscle has become weak (though isn’t technically “congestive heart failure”….. yet)

Recurring low oxygen levels are harmful and should be treated with supplemental oxygen.

If oxygen levels are low, deterioration will occur in every single incidence.

There are no exceptions to this rule.


Low oxygen levels are definitely something to worry about!

If you feel you may be experiencing low oxygen levels be sure to insist that your doctor check your “pulse oximetry reading”.

Hope this helps, I've been on oxygen for a year now and feel much better, I can still get out and go to the shops or do a little bit of gardening which I love, I read that oxygen can extend your life and that's good news!

Best Wishes, huff xxxxxxxx


I understand that if needed oxygen is good for you, but I also know that too much is just as dangerous. My mum's sats today without her oxygen walking just a short distance from the driveway into my living room went from 96 to 91 and within 40 seconds her level went to 94? Now the hospital say her oxygen should be between 88-92 it stayed within that but when at rest with the oxygen on at 2 litres it's 96-98? Surely that is harmful. They have mentioned hypoxia and that's the reason she needs oxygen but at 92 oxygen tissue hypoxia will not occur but at 93 or above it increases the risk of hyperplasia and respiratory acidosis? I'm yet to understand exactly what they are but it's all too confusing and I feel that her oxygen was just given to her because she has emphysema. Thanks for your reply :)


I understand your concerns. It appears the medical people have not explained themselves very well to you. Everything you have said is right, including the fact that long-term oxygen is not usually prescribed for anyone whose saturation levels do not fall below 88. I am assuming that your mum was properly assessed, whilst at rest and whilst ambulatory. You could ask for a copy of the results and check them for yourself. You could also ring the Consultants secretary and say how concerned you are and that you would like more information. Good luck. x


My resp physio who recently assessed me for ambulatory O2 said that if your sats during the 6MWT fell more than 4% below your resting levels, then you are a candidate for O2. Since mine went to 83% there was no question, but i was interested in this 4% thing which id never previously heard of.

Also never heard of below 92% being dangerous (see post above).


No, O2, I have never heard of 92 being dangerous (I am in serious trouble if it is!) and have never heard of the 4% thing either, though that makes some sense I suppose.


Very Informative Huff...You learn something everyday !! I have been told I'm borderline needing ambulatory Oxygen as my levels drop to 90% on a slow walk to shops but heart rate increases threefold !! Cheers Plumbob


Hi huff - see you have got this info from a friend:

"Every time your oxygen level falls below 92% saturation the cells of your body are oxygen starved!"

Do you know where your friend obtained this info, or could you ask please?

I have always understood that 88% is the cut-off point where damage happens. And you'll see many of these posts state this figure too.

Im not aware of levels below 92% being problematic and if this is so, Id like to explore it further as mine frequently are below that point. If its not so, then lots of people here will be unnecessarily alarmed.

Many thanks :)


Hi O2Trees, I had this info quite some time ago from an on line friend of the website called EFFORTS.... and copy and pasted it, but I've just been looking at Wikipedia and it seems levels 90% or less is more likely to be correct depending on sea level? I will look it to it some more and I am really sorry if I've been misinformed, I'll be more carefull in future as I don't want to alarm anyone!

Oxygen[edit]Supplemental oxygen is recommended in those with low oxygen levels at rest (a partial pressure of oxygen of less than 50-55 mmHg or oxygen saturations of less than 88%).[75][91] In this group of people it decreases the risk of heart failure and death if used 15 hours per day[75][91] and may improve people's ability to exercise.[92] In those with normal or mildly low oxygen levels, oxygen supplementation may improve shortness of breath.[93] There is a risk of fires and little benefit when those on oxygen continue to smoke.[94] In this situation some recommend against its use.[95] During acute exacerbations, many require oxygen therapy; the use of high concentrations of oxygen without taking into account a person's oxygen saturations, may lead to increased levels of carbon dioxide and worsened outcomes.[96][97] In those at high risk of high carbon dioxide levels, oxygen saturations of 88-92% are recommended, while for those without this risk recommended levels are 94-98%.[97]

This is from Wikipedia, I can see why people get so confused including me! :)


Thanks huff. You're right, it is confusing with different needs person to person. However its interesting that your friend got that 92% info from Efforts. I used to be on that forum too and noticed that US O2 practice seemed to be very different to ours, seeming to use it earlier and at higher settings, so your friend's info is consistent with that. The difference between between ours and US's practice was confirmed by a very senior respiratory nurse who was involved with the British Thoracic Society (and just happened to have started our BE group!)

Wikipedia's different recommendations for people at different risk of CO2 retention are useful. Being wikipedia of course, anyone can come on and alter what's already been written . . . :D


Hi, How do you measure these levels of oxygen in the blood, is it the pulse oximetry reading, is there a device I can buy to do this.


Hello Markoverton, yes you can buy a finger monitor to take your saturation levels and heart-beat per minute. I bought mine from Amazon for around twenty pounds though they can be a lot more than that! huff x


It helps keep the organs healthy.



Oxygen theraphy is given to maintain other organs by maintaining oxygen levels above 88%

How often do you have a assessment ?, I am on Ambulatory oxygen and I go every six months.

Long term Oxygen Therapy (LTOT) refers to the provision of oxygen therapy for continuous use at home for patients with chronic hypoxaemia (PaO2 at or below 7.3 kPa, (55mHg))

oxygen flow rate must be sufficient to raise the waking oxygen tension above 8 kPa, (60 mmHg)

LTOT is likely to be life long

LTOT is usually given for at least 15 hours daily, to include night time, in view of the presence of worsening arterial hypoxaemia during sleep

indications for LTOT

chronic hypoxaemia

long term oxygen therapy is indicated for the following conditions with chronic hypoxaemia:

chronic obstructive pulmonary disease

severe chronic asthma

interstitial lung disease

cystic fibrosis


pulmonary vascular disease

primary pulmonary hypertension

pulmonary malignancy

chronic heart failure

in patients with chronic hypoxaemia, LTOT should usually be prescribed after appropriate assessment, when the PaO2 is consistently at or below 7.3 kPa (55 mmHg), when breathing air during a period of clinical stability (defined as the absence of exacerbation of chronic lung disease for the previous five weeks)

level of PaCO2 (which may be normal or elevated) does not influence the need for LTOT prescription

also, LTOT can be prescribed in chronic hypoxaemia patients when the clinically stable PaO2 is between 7.3 kPa and 8 kPa, together with the presence of one of the following:

secondary polycythaemia

clinical and or echocardiographic evidence of pulmonary hypertension

LTOT should not be prescribed in patients with chronic hypoxaemia patients with a PaO2 value above 8kPa

nocturnal hypoventilation

obesity Neuromuscular/spinal/chest wall disease*

obstructive sleep apnoea (with CPAP therapy)*

*assessment for LTOT requires referral to a physician with a specialist interest in these disorders. LTOT will normally be used as an adjunct to ventilatory support techniques (noninvasive ventilation (NIV) or continuous positive airway pressure (CPAP)

palliative Use

domiciliary oxygen therapy can be prescribed for palliation of dyspnoea in pulmonary malignancy and other causes of disabling dyspnoea due to terminal disease

assessment for long term oxygen therapy in adults

patient will require referral to a service directed by a consultant physician with an interest in respiratory medicine for measurement of arterial blood gases and assessment for LTOT prescription


smoking and home oxygen

smoking cessation techniques should be continued prior to any home oxygen assessment and prescription. Patients should be made aware of the dangers of continuing to smoke in the presence of home oxygen therapy


British Thoracic Society (January 2006). Report on Clinical Component for the Home Oxygen Service in England and Wales.


My mum was just given oxygen and to be honest we didn't know why? Apart from her getting anxiety attacks at the thought of going from her car to her flat. Since she has been on Oxygen her lung collapsed, the drain they inserted came out, she developed sanctous emphysema, she recovered from that, then they decided to put her oxygen up to 6 overnight, her carbon dioxide levels were through the roof, she had to go on a bipap machine to bring them down. But before she had oxygen she was able to do everything she has always been able to do apart from it taking a bit longer due to slightly being breathless. Now after reading about oxygen being prescribed my mum was never assessed properly. No 6 minute walk test, she's not a co2 retainer and she has only been given a blood gas when she has been in hospital. Apart from a few weeks ago when she was attending pulmonary rehab they tested her and was not concerned with her levels? So surely she doesn't need this oxygen all the time? Thanks for the reply :(


Hello Breatheasy77, I just wanted to say how sorry I am that your Mum has Emph' my Mum was only 70 when she died in '95 of it and I had very little information about the disease at the time, I can't tell you how often I have wished I knew more about it then.

I have severe Emph' too, when I was 49 I was told my lung age was 118 !!!I have recently learnt that my Emphysema is genetic, my son has it also. I am happy to say his is low risk and my lung age this year is only 108! so in ten years I have lost ten years!

Sorry to have rambled, just want to say I admire you wanting to make sure your Mum is getting the best treatment and medicine she can possibly get, and oxygen is just another medicine, a natural one at that.

Both of you take care, huff xxxxx

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Shortness of breath can lead low oxygen levels and excessive carbon dioxide building up, though not all people who are short of breath get this problem. Her Oxygen SAT levels and blood gasses, may have determined the decision to put her on oxygen as high levels of carbon dioxide are very dangerous. My father who had COPD passed away because he had a chest infection which led to him becoming very SOB and his carbon dioxide was extremely high as a result. The Doctor in A & E said In normal people carbon dioxide levels are around 4. COPD patients around 8, but my father's were 16.


We had the respiratory nurses come out today and they done a blood gas as my mum didn't use any oxygen today and by the results it looks like she doesn't need oxygen at rest.

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I am pleased they tested and found she was okay without. The respiratory nurses are the ones I always rely on - they have lots of knowledge and more time than the doctors. Good result. x


well i have copd and i have never i repeat never been on oxygen and i have a oxygen sat of 97 any time day or night . who has told you copd sufferers have to be on oxygen ? on top of that i regulary run up stairs . by the way i am 70 this year .


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