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Every week we answer some of your urgent questions about coronavirus and how to stay safe. Email your questions to [email protected] with the subject: “Weekly questions on coronaviruses”. This week we are considering questions about pulse oximeters.
As the coronavirus continues to spread, a small medical device called a pulse oximeter has started to steal shelves. In fact, demand has reached such an extraordinary level that you may not be able to purchase one from your local pharmacy or online.
What is the value of the device during this pandemic? Do you need it at home? The first question is relatively easy to answer. The second is a little more complicated.
What is that?
A pulse oximeter is a small electronic device that measures the oxygen saturation of your blood. You want a number between 95% and 100%. If the number drops to 92% or less, this is a concern. This is usually the level where a doctor can put you on extra oxygen and keep you in the hospital for observation.
To reach this percentage, the device attaches to your finger or the lobe of your ear and sends different wavelengths of light through the small capillaries, says Dr. Richard Levitan, New Hampshire emergency physician specializing in management respiratory tract. (For a more detailed scientific explanation, read this.)
The term for low blood oxygen levels is hypoxemia. In this condition, the organs in your body may not function properly. Severe cases can interfere with heart or brain function.
You’ve probably already had your blood oxygen checked by a pulse oximeter. It is used during certain physical examinations and is considered essential during operations and intensive care. The devices also give your heart rate.
Why are these devices suddenly attracting so much attention?
COVID-19 can cause what is called COVID pneumonia – an infection in which the air sacs of the lungs fill with fluid or pus. And it’s possible that someone infected with the new coronavirus is in the early stages of COVID pneumonia – including a drop in blood oxygen levels – without having difficulty breathing.
In such cases, a pulse oximeter can signal that you have problems before you know it. This is what Levitan saw when he spent 10 days working in the emergency room at Bellevue Hospital in New York earlier this month: many COVID patients were already very sick with COVID pneumonia when they arrived. They were breathing fast, their blood oxygen levels were dangerously low. Like the mountaineers, the patients were used to a gradual decrease in oxygen levels and did not realize that they were in distress.
Many of them said that they only started to feel short of breath recently after experiencing symptoms of COVID-19 for days. By the time the patients went to the hospital, Levitan said, the virus had already damaged their lungs and many were in critical condition. He has seen patients with COVID pneumonia with oxygen saturation levels as low as 50 percent.
“These COVID patients have adapted to this slow and insidious drop in their oxygen and they don’t know it,” he told NPR. “Then, when they come out of breath, it’s late in the process. In his opinion, a pulse oximeter could have detected the warning sign of low oxygen in the blood.
The disease “kills by provoking silently [a decrease in] oxygen. When you arrive late in the disease, which is basically everyone we come to now in E.R., there is high mortality, “he says.
Levitan says that earlier treatment in medicine leads to better results – “and this is also true for COVID.”
Should you get one?
Levitan believes that in the midst of a respiratory pandemic, it makes sense to have a pulse oximeter at home – just like you might have a thermometer to track fevers. If you have symptoms of COVID-19, he says, such as weakness, muscle pain or fever, you can use the device to measure oxygen levels in the blood.
This figure of 92% (or less) is a sign that “you should be evaluated because this disease kills silently and you don’t need to be short of breath” to be in danger. (Although people at high altitudes may have levels “in the low 90s and be good,” he adds.)
Dr. Elissa Perkins, a professor of emergency medicine at Boston Medical Center, does not necessarily think that everyone should buy a pulse oximeter. She is concerned that people will depend on reading the device rather than calling a doctor if they feel sick.
“I think it’s a bit of an exaggeration to say that people should have them all at home,” says Perkins, although she understands why people would want them.
“In general, I honestly think that if people start to experience symptoms or even shortness of breath, they should probably contact their doctor, if possible,” she said. “Most places or many places at this point offer telemedicine visits, telehealth visits and that can give a deeper picture of what someone saw than a single number on a pulse oximeter. “
But she is not completely opposed to home pulse oximeters. She says if you have symptoms compatible with the new coronavirus, using a pulse oximeter and consulting a doctor can be a good strategy.
She is concerned about a risk: people may be falsely reassured by good figures that they are not very sick. People with COVID “can get incredibly dehydrated, people can get very weak,” says Perkins. “We have seen people pass out or pass out, who have no particular respiratory symptoms and who are not short of breath. So this is another data, but it is certainly not the only data. “
There are other concerns. Reading may be less accurate if a person wears nail polish or artificial nails, has cold hands or poor circulation.
It is possible to accidentally read the numbers backwards and panic over a number that seems surprising. Or the device itself may be inaccurate.
The American Lung Association medical director Albert Rizzo released a statement on Thursday advising against “buying unnecessary pulse oximeters”.
” [U]Unless you have a chronic lung or heart condition that affects your oxygen saturation level on a regular basis, most people don’t need to have a pulse oximeter in their home, “said Rizzo. Most importantly, if you are interested in purchasing a home pulse oximeter, please discuss the need for and use of the device with your healthcare professional. A health care professional can determine if this would be helpful and also provide guidelines for interpreting the readings in the context of how you are feeling. Your reading of the pulse oximeter should be used with your other symptoms such as shortness of breath, fever, fatigue, as parameters that would encourage calling your doctor. ”
Abraar Karan, a physician in internal medicine at Brigham and Women’s Hospital and Harvard Medical School, is also a proponent of caution when it comes to pulse oximeters for home use. he says it remains to be seen how low predictive oxygen levels can correctly identify patients who will have a severe course of the disease. He reports a recent study of 5,700 patients hospitalized with COVID-19 in New York, which found that only 27.8% needed additional oxygen at triage.
And he shares Perkins’ concern that people may be falsely comforted or unnecessarily alarmed.
“What we don’t want is that people are really distressed but think that because their home pulse oximeter is normal, they are fine,” Karan writes by email. “We also need to make sure that patients use the pulse oximeter correctly and that it reads correctly – otherwise, you may see more people coming to the emergency room who may not need to be there.” “
But Levitan says this kind of pressure on the ER already occurs when people misinterpret blood pressure monitors or home thermometers. According to Levitan, a much bigger concern concerns people who die suddenly from COVID. And he’s not afraid the device will make people more anxious: “You know what? We are scared. We have anxiety. We need to be reassured. “
Where to buy one – and how much should I worry if there is a delay in getting it?
If you think a pulse oximeter would be helpful, Levitan suggests buying one from a medical source like a pharmacy rather than a random internet site – and it’s a good idea to look for one that has been approved by the FDA, if possible. You can go to the FDA 510 (k) pre-market notification page here and search for “oximeter”.
Devices that have not been approved for medical use can be purchased, and these devices may be less accurate.
Just a few months ago, it would have been easy to find consumer models that cost around $ 30, usually on drugstore shelves. They are often used by people with chronic lung disease taking extra oxygen to make sure they’re getting the right amount of oxygen.
With many pharmacies sold out, people are turning to sites like eBay and Amazon, where the devices are in the $ 60 range.
But Levitan says you shouldn’t worry if you have to wait a few weeks to get one: “You know what? We are 12 to 24 months old [coronavirus] “, He predicts.
He says that in the era of respiratory pandemics, there is a very useful health surveillance that people can do at home, along with a phone call to a health care professional.
“We need to change the public perception of what health surveillance means in this era of respiratory pandemics,” he says. “When you combine heart rate measurement, oxygen saturation and temperature, these are the three things you can do at home – and especially if you combine them with a phone call to your doctor or health care provider. local emergency… it’s incredibly instructive. “