What is a Pulse Oximeter Used For?

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what is a pulse oximeter used for

Even if you’ve never heard the name before, you’ve likely seen pulse oximeters during an emergency room or hospital visit. They’re the small devices used to monitor respiratory health conditions. Anyone with a sick and bedridden loved one might be familiar with the home variety.

But exactly what is a pulse oximeter used for?

The short answer is that a pulse oximeter tests oxygen concentration in the blood, but it’s more complicated than that. Let’s examine this device from the ground up.

What Does the Device Look Like?

Pulse oximeters are small, plastic devices that look like oversized paper clips. The top has a digital readout to deliver results on pulse and oxygen levels. Traditionally, a cord connects the finger clip to a computer, but these days there are many wireless varieties, including ones that use Bluetooth technology.

The greatest strengths in pulse oximeters’ designs are their immediate results and noninvasive nature. Before their invention, doctors had to draw blood with a needle and do external tests.

A Beam of Light Through Your Bloodstream

The enduring popularity of pulse oximetry comes from its simplicity. Once the device clips to your finger, it emits a broad spectrum of light that travels through the skin and blood. All blood absorbs light. However, there is variation in the wavelength of light absorbed by oxygenated and deoxygenated blood.

From here, the light absorption patterns transmit to a receiver. This device can distinguish wavelengths and determine the level of oxygen in your blood. A few more calculations are done by the oximeter to counterbalance alternate light sources like the sun or overhead lighting in a hospital room.

What Conditions are Tested For by Oximeters?

Blood oxygenation is an essential indicator of several health conditions. Generally, it tests any conditions related to the heart and lungs. Heart failure, chronic obstructive pulmonary disease (COPD), anemia, pneumonia, and lung cancer are common issues that oximeters assist in testing.

However, pulse oximeters also test for more than just the presence of an illness or disorder. You can also use them to indicate whether or not a patient is capable of strenuous physical exercise, how sedation affects a patient during all parts of an invasive procedure, and whether or not a specific lung medication or treatment is working or having adverse effects.

Basically, pulse oximeters can help us understand any aspect of someone’s respiratory health.

Is Your Reading Healthy?

Now that you know the purpose of pulse oximeters, how can you know if your reading is healthy? What use is a number you can’t interpret?

The primary data gathered by these devices is called oxygen saturation level. This is the percentage of your blood that is oxygenated. To keep your body healthy, 89 percent of your blood should be saturated. Should you dip below this temporarily, it will not necessarily cause permanent damage. Repeated drops, however, can lead to trouble.

Despite this minimum, a reading from an oximeter of an average, healthy person is anything at 95 percent or above. A rating below 92 percent can indicate hypoxemia, an oxygen deficiency in body tissues.

What are the Risks of Hypoxemia and Hypoxia?

Let’s briefly define our terms. Hypoxemia refers to a deficiency of oxygen in the blood. Hypoxia is a condition in which your body tissues are not oxygenized. These two often overlap, as hypoxemia can lead to hypoxia, but the two concepts are distinct.

Both are dangerous, but hypoxia can lead to severe issues if left untreated. Depression, fatigue, hypertension, heart failure, and respiratory failure are all risks.

Symptoms for hypoxemia are similar. They include shortness of breath, headache, disorientation, and discoloration of extremities.

Though pulse oximeters test specifically for hypoxemia, they can be useful indicators of both issues. If undetected, oxygen deprivation can lead to carbon monoxide poisoning and brain damage.

Is it Accurate?

Arterial blood gas tests are the most accurate way to measure oxygen saturation, but they require blood to be drawn and tested. The good news is that pulse oximeters aren’t far off. The American Thoracic Society concludes that oximeters are sometimes two percent higher or lower than results from an arterial blood gas test would show.

Results can also vary due to cold hands, poor circulation, or artificial nails. Regardless, the practice of taking any test results of 92 percent or under help offset this inaccuracy. The system may not be perfect, but the practicality outweighs its shortcomings. You can always take multiple readings from other body parts like toes for greater accuracy.

Are Home Oximeters Useful in Detecting or Preventing COVID-19?

Now, we’ve reached the big question. Home versions of these devices have exploded in popularity throughout 2020. Since COVID-19 can wreak havoc on your respiratory system, pulse oximeters can be helpful tools in managing or identifying the disease.

We’ve learned throughout the year that COVID-19 has a broad spectrum of symptom severity. If you’re feeling sick, a home pulse oximeter can act as a first indicator that something is wrong beyond common cold symptoms.

Home oximeters are also very useful for detecting the common condition of happy hypoxia, a recent development of the novel disease. Patients with this condition can have dangerously low levels of blood oxygenation but display no outward symptoms.

Someone who feels no different than usual is unlikely to seek out medical attention or tests. However, if you were to have a home oximeter, it would be easy to find thirty seconds per day to test yourself. Potentially, this could save lives.

Though pulse oximeters cannot prevent COVID-19, they can help patients detect it early enough to quickly and efficiently seek out medical attention. It is important to note, though, that a healthy reading from your home pulse oximeter is not a guarantee that you are free of the disease. For completely asymptomatic carriers, it will not be helpful.

Is Early Detection Important?

Recent research from The Lancet tells us that in over 30 percent of COVID-19 related hospitalizations, pneumonia induced by the disease leads to acute respiratory distress syndrome. Many patients need ventilators to keep breathing. Should you use one of these devices at home, you may be able to detect drops in your oxygen levels before severe damage occurs.

What if You Already Have COVID-19?

If you have a mild case of COVID-19, a home pulse oximeter can allow you to monitor your own symptoms while still socially isolating at home.

A home pulse oximeter is no substitute for an actual doctor, however, so it’s crucial for patients to only use it as a tool in tandem with doctor’s orders. However, it is an incredibly useful way to look after your condition without needing to return to a hospital or doctor’s office.

If you’re considering getting a pulse oximeter for home or other use, check out our list of the best finger pulse oximeters.

Final Thoughts

In short, pulse oximeters detect blood oxygen concentration, which allows us to understand aspects of our respiratory health that may otherwise go unobserved. Though they do not give definitive answers as to what causes their readings, they are a critical first tool in the medical process.

It should come as no surprise that pulse oximeters are one of the most common and useful medical tools, but some people have no idea what doctors are testing for when they clip these devices onto your finger. Fewer still know that they can have uses at home too.

Though useful for certain patients in any era, they’ve taken on new usefulness in 2020. In the age of a pandemic, anything that can empower us against disease is a force for good.

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Written By

Stephanie Corrales

Stephanie Corrales is the Founder and Managing Editor here at HeyScrubs. As a former director of a career college for entry-level medical professionals, she offers valuable insights to aspiring healthcare professionals. In her free time she loves spending time with her husband and two children.