Coronavirus patients who suffer even a slight drop in their oxygen levels are at a heightened risk of dying from the disease, a study has warned.
Current NHS guidelines consider someone to be in the healthy range if their blood oxygen levels are between 94 and 98 per cent.
Under the current system, people with the disease are not given oxygen unless their levels drop below the lower threshold.
But researchers looking at 1,000 NHS Covid-19 hospital patients found even small drops of one to two per cent below 96 per cent correlated to an ‘increased mortality risk’.
They have warned the current guidelines may not be sensitive enough and could miss the chance to save people’s lives.
Experts said UK households should keep an oximeter — which reads blood oxygen levels — in their medicine cupboard at home to monitor their condition.
Experts said UK households should keep an oximeter – which reads blood oxygen levels – in their medicine cupboard at home
The mortality rate for Covid-19 patients depending on their blood oxygen levels. It shows that lower oxygen saturation conferred with higher a mortality rate within 30 days. However, even within the ‘normal range’ (94 to 98 per cent, according to the NHS), the mortality rate was higher
Blood oxygen level describes the amount of oxygen circulating in the blood. The body needs oxygen to function, so it’s a concern when it falls.
The study, led by Matt Inada-Kim, a consultant at Hampshire Hospitals NHS Foundation Trust, looked at hundreds of thousands of people who had called an ambulance between March 1 and July 31 this year.
It honed in on 1,080 with a confirmed Covid-19 diagnosis whose oxygen levels and outcome of their disease was available
All patients were taken by ambulance to either Basingstoke & North Hampshire Hospital or the Royal Hampshire County Hospital in Winchester.
NHS ENGLAND TO TRIAL HOME OXYGEN READING FOR COVID-19
NHS England is believed to have purchased around 200,000 pulse oximeters for a scheme of home oxygen saturation reading, according to the British Medical Journal (BMJ).
Patients with Covid-19 who don’t need immediate hospital attention but are at high risk of developing serious symptoms, such as those over 65 years old or with a chronic health condition, are to be given the devices to use at home to help monitor if they are deteriorating.
In most cases of pneumonia, breathlessness is an early symptom of the disease and comes before hypoxia – the state
But with Covid-19, hypoxia often comes first, known as ‘silent hypoxia’; by the time breathlessness occurs, patients may be extremely sick without even knowing.
The pilot study is set to be rolled out across the country over the next six weeks.
It’s being led by Matthew Inada-Kim, national clinical lead for deterioration at NHS England and a consultant in acute and general medicine at Hampshire Hospitals NHS Foundation Trust, whose study recently found that Covid-19 patients with even a slight drop in oxygen levels within the ‘normal range’ are at risk of death.
Wessex Local Medical Committees is expected to be one of the first areas to implement the monitoring at home scheme.
Nigel Watson, chief executive, told The BMJ that the evidence was now fairly strong that if oxygen saturation fell to 93/94 per cent the mortality risk increased to around 13 per cent. If it fell below that level ‘the risk would increase to about 28 per cent’.
The idea is to create ‘virtual covid wards’ of patients at risk and to monitor oxygen saturation through patients taking readings and relating these to their health teams, Mr Watson said.
‘If it starts dropping and particularly goes to 94 per cent, then you’ll potentially take some action, which may include [the patient] being admitted to hospital.’
Rob Barnett, chair of Liverpool Local Medical Committee, confirmed that in his area health officials were working on ‘virtual covid wards’.
He said: ‘As we monitor more patients in the community, we will know what the tipping point is for them to get into hospital, which is likely to be earlier than we might do if we weren’t monitoring them at all.’
But he said even though early treatment is a benefit, it would mean more patients are in the hospital, adding strain to the service.
Their vital signs had been measured by ambulance staff at the first point of contact when they arrived at the home of the patient.
The findings showed ‘even small deflections in oxygen saturations of one to two per cent below 96 per cent confer an increased mortality risk’.
The authors of the paper wrote: ‘Even patients with presenting oxygen saturations of 94-95 per cent, values regarded as within this normal range, had a significantly higher 30-day mortality rate (5.3 per cent) than those presenting with oxygen saturations higher than 95 per cent (2.3 per cent).’
It suggests that patients who are within the ‘normal range’ are in fact at a higher risk of death.
The team added some experts have argued a reading indicative of hospitalisation uses a cut-off of 92 per cent.
But this would miss approximately one third of patients who go onto to suffer adverse outcomes, according to this study.
And the study found that oxygen saturations were the most predictive of death or ICU admission – more than age or pre-existing health problems.
The researchers said a lower threshold for hospital conveyance may be necessary for Covid-19 patients so they are not left at home, where they are at risk of getting sicker.
‘We have demonstrated that even relatively minor derangements in peripheral oxygen saturation are an early warning of potential deterioration,’ they said.
‘Use of oxygen saturation as an indicator of disease severity may therefore underestimate the risk of leaving patients at home after ambulance assessment.’
The study was published online as a pre-print, meaning it has not been critiqued by other scientists to check for flaws before being accepted into a medical journal.
In most cases of pneumonia, breathlessness is an early symptom of the disease and comes before hypoxia – when the body is deprived of oxygen.
But with Covid-19, hypoxia often comes first. By the time breathlessness occurs, patients may be extremely sick without even knowing.
This has been a challenge for treatment because doctors are used to looking for hypoxia when a patient presents with breathlessness first.
Mr Inada-Kim and colleagues said detecting hypoxia early is ‘critical’ for preventing Covid-19 becoming life-threatening.
It has lead for calls of home oxygen saturation readings using a pulse oximeter.
The devices, which cost around £30, cannot detect Covid-19. But it could assist with detecting hypoxia.
The small device clips on to the finger, and beams of light measure the amount of oxygen in the blood, as well as the heart rate.
‘Pulse oximetry is becoming relatively cheap and easily accessible for the public,’ Mr Inada-Kim said.
‘[It] may be a relatively cost-effective tool… perhaps focussed on those with significant co-morbidities who are at higher risk [of severe Covid-19].’
Trisha Greenhalgh, professor of primary care at the University of Oxford, told The Telegraph: ‘Just like you have a thermometer at home, every family should have an oximeter as part and parcel of a first aid kit.
‘It’s the sort of gadget most people could learn to use in two minutes but some practice is important.’
She described the study’s findings as ‘important’, while adding it was not only the absolute level of blood oxygen that was important but ‘its trajectory – how fast it is falling’.
NHS England is believed to have purchased 200,000 pulse oximeters for a scheme, led by Mr Inada-Kim, to assess the benefit of home use in people at risk of severe Covid-19, the British Medical Journal reported last week.
MailOnline contacted NHS England for comment.