Do you need a pulse oximeter in your COVID-19 prep bag?

When media reports circulated that some COVID-19 patients were not showing the typical shortness of breath the virus brings – giving them a false sense of security about the severity of their illness - many people started snapping up pulse oximeters. The little devices clip on the end of your finger and are used to measure blood oxygen levels and pulse rate.

But health experts say pulse oximeters don’t need to be part of everyone’s medicine cabinet.

For the average person who doesn’t have chronic respiratory or heart disease, buying a pulse oximeter “is not a rational suggestion,” said Scott A. Slater, MD, pulmonologist and intensivist at Cape Cod Hospital in Hyannis. “It would make more sense to have a relationship with a primary physician,” with whom you can discuss your concerns, he said.

The American Lung Association has weighed in on the issue, releasing a statement saying “silent hypoxia” – low blood oxygen not accompanied by gasping or shortness of breath – is not an early sign of COVID-19, and urging people to contact their doctor if they suspect they have symptoms of infection.

“We don’t know what percent of patients present with silent hypoxia,” said Albert Rizzo, MD, the association’s chief medical officer and a pulmonologist in Wilmington, DE. “We don’t know how many present with that as the only symptom.”

Silent hypoxia in COVID-19 patients was discovered after people sought help for other symptoms, including aches, fatigue, fever and cough, and doctors were surprised at how low oxygen levels were in some patients, Dr. Rizzo said. When COVID-19 patients have silent hypoxia they usually have other symptoms and may be in critical condition. Despite having low oxygen, they do not have shortness of breath or difficulty breathing, a common complaint of COVID-19 patients.

There are theories as to why some COVID-19 patients exhibit silent hypoxia, Dr. Rizzo wrote in the American Lung Association statement. One is that the virus causing the disease disrupts the balance of blood flow and airflow in the lungs without the stiffness or congestion COVID-related pneumonia or acute respiratory distress cause. Another theory supposes that the disease doesn’t prevent the lungs from exhaling carbon dioxide, so the urge to increase breathing may not occur. More research is needed to answer these and other questions about this disease, he said.

Other COVID-19 symptoms can include congestion, runny nose, sore throat, pain or pressure in chest, nausea, vomiting, diarrhea and diminished senses of smell and taste, according to the Centers for Disease Control and Prevention. Conjunctivitis, blood clots, rashes and red, swollen toes have also been reported.

“We do see silent hypoxia in here,” Dr. Slater said. “It’s almost always someone who has chronic lung disease and whose body has acclimated to low oxygen levels. It’s not good – can put pressure on the heart, as well.”

Pulse oximeters can be useful for home monitoring of patients on supplemental oxygen, or people diagnosed with COVID-19 who are well enough to ride out the illness at home, Dr. Rizzo said.

The devices work by measuring light they shine into a finger. They also determine pulse rate, as well. Inexpensive versions can cost $20 to $30, and sturdier professional models used in healthcare facilities run around $100 to $200, he said.

“There was a run on them on Amazon,” he said.

Dr. Slater cautioned that proper use of pulse oximeters does require a little training to prevent inaccurate readings. He said this can happen when:

• The oximeter is loose or incorrectly placed.
• The device’s light is blocked by nail polish.
• Blood flow to fingers is reduced by cold temperature.
• Pulse rate is erratic.

Normal blood oxygen levels are in the 90s, according to the American Lung Association. COVID-19 patients with silent hypoxia have had levels in the mid- to low 80s, according to Dr. Rizzo.

If people using pulse oximeters at home get oxygen readings in the 60s or 70s, the device is probably not working correctly, he said. He also suggested device pulse readings be checked by taking the pulse manually and comparing it to the readout.