SAN FRANCISCO (KPIX) – When it comes to COVID-19, a tiny over-the-counter device may potentially save your life. The new go-to gadget is called the pulse oximeter. Some health experts believe during this pandemic you should have one by your side.

COVID-19 can result in severe illness, organ failure, and death. The sickest of patients develop acute respiratory distress syndrome – a type of respiratory failure characterized by widespread inflammation in the lungs.

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But with this virus the syndrome is strange.

“Patients can have very, very low oxygen amounts and they yet they kind of still look comfortable,” said Stanford Pulmonary and Critical Care Dr. Angela Rogers.

Emergency room doctors are reporting how some patients are apparently walking around with pneumonia for days, getting sicker and sicker, without developing any symptoms.

The really peculiar thing about this infectious disease is that people don’t appreciate how short of breath they are until they are dangerously short of breath.

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“People would be sick for days and then they would come in with shortness of breath on the day they presented,” says emergency room doctor Richard Levitan. “And they would have oxygen levels that are basically incredible to us, almost unimaginable how people could be awake and alert and have oxygen levels that are half normal. Shortness of death is a late sign. ”

That’s why the pulse oximeter may help. Clip it on your finger and it measures the oxygen in your blood.

“You know normally we are 94 to 100 percent on these devices pulse oximeters that measure how much oxygen we have in our blood and people were showing up with oxygen levels of 50 percent,” said Levitan.

Dr. John Swartzberg of University of California at Berkeley is an infectious disease expert. He says with this device, doctors may get a patient hospitalized earlier and that could potentially save lives.

“(Patients) Look at the numbers and say, ‘wow I should call my doctor,’” said Swartzberg. “Early identification of people who are going to be in trouble means we can grab them before they fall off the cliff.”

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The devices have become hard to find and the prices have jumped. Also, the home devices are not as accurate as those found in the hospital. There can be operator error if it is not clipped on correctly and fingernail polish can skew the results.