What is Non Invasive Pulse Oximetry?


With the rising  COVID – 19 cases and deaths in the world one of the things a person might ask is ” Am I breathing the right amount of oxygen” ? Sad to say we do not know only when you start having difficulty of breathing then you become alarmed and head straight to the ER or call 911. It is sad to say that people on assisted ventilation in the ICU with COVID-19 either make it or they don’t. But folks there is good news with the use of an oxygen saturation pulse oximeter we can be sure if we are breathing the proper concentration of oxygen to bring oxygen to our red blood cells. So what is non invasive pulse oximetry?

In this article I would like give you a short education on the uses of this little cute device and yes you got it right they are affordable ! Below this article I have recommended four pulse oximeters that you may want to purchase. I have a pulse oximeter image on the first one on the left below that I personally use for the last 3 years and it is still kicking. Have an open mind and heart. Read on as we go on this journey. I promise you will not get bored !

What is a pulse oximeter and its medical uses?

A pulse oximeter is a small electronic device to measure the percentage of oxygen in arterial blood carried in your red blood cells and the pulse (heart rate) normally 60 -100 per minute. The pulse oximeter can be attached to your fingers, forehead, nose, earlobe and toes. One of the good things about this cute device is you can carry it with you specially the fingertip pulse oximeters. A pulse oximeter will indicate if you will need supplemental oxygen. They are commonly use in operating rooms, ICU and in outpatient clinics. But anyone can use this if they are mountain climbers, athletes or aviators. I would recommend one that I use in my profession as an RN for the last 3 years and it has proven the test of time later in this blog. Right now what are the indications for the use of a pulse oximeter?

    • COVID-19  (Difficulty of breathing, cough and fever)
    • Lung problems –  Emphysema and Chronic Bronchitis (COPD), Pneumonia, Asthma, Sleep Apnea, Lung Cancer
    • Heart problems –  Heart Attack, Congestive Heart Failure, Congenital Heart Defects
    • Anemia

Physiology of Oxygen Saturation

Our circulatory system carries blood through all of our major organ systems – brain, heart, lung, kidneys. Hemoglobin is a protein in the blood that binds and transports oxygen to carry it through the bloodstream to the organs, tissues, and cells of your body. Without oxygen our organs will not function to do its work just like the heart muscle needs oxygen otherwise it will die resulting in a heart attack or myocardial infarction. In COVID-19 the surface tension in our lungs increases resulting in difficulty in breathing, low oxygen saturation below 90% and the need for assisted ventilation called a ventilator seen in the ICU.

How does an Oxygen  Saturation Pulse Oximeter work?

If you have gone this far this is how this little cute device works. I am talking here of the fingertip pulse oximeter where the nurse or doctor clips on this device into your fingers preferably the middle finger which gives the best reading. Inside the clip is a light source and a light detector with a computer to determine your body’s oxygen saturation. The light source emits a red light and infrared light and the light detector senses how much of each light is absorbed and how much is allowed to pass through the finger (or toe or ear lobe). As it turns out, oxygenated hemoglobin absorbs more infrared light and allows more red light to pass through.

On the other hand, deoxygenated blood allows more red light and allows more infrared light to pass through. The ratio of red light to infrared light that is absorbed by the body on its way from the light source to the light sensor is your oxygen saturation.

The pulse is measured by the constant stream of light. It measures the changing absorbance in your finger. It is the light absorbance that happens with every heartbeat. That is why a pulse oximeter measures the oxygen saturation and pulse rate.

Pulse Oximetry Readings – Normal and Abnormal

The normal oxygen saturation is typically measured as an O2 saturation at room air. In the medical world you will hear such words as Pulse Ox, O2 Sat or SpO2. No matter what wording is used it refers to the percentage of oxygen saturation. Normal range is from 95%-100%. If you get a reading of 100% that means a hemoglobin molecule can bind up to 4 oxygen molecules for transport in the blood.

Abnormal readings below 90% requires attention or the need for supplemental oxygen as the organs are not being perfused well. Medical professionals should be consulted if a patient with suspected or confirmed COVID19 has SpO2 ≤90%. Now the next question you may ask is “Is it accurate” Yes it is as most pulse oximeters give a reading of 2% above or 2% below as comparable with a standup monitor. I have seen this in my practice assessing patients.

Barriers to a Low or Inaccurate Oxygen Saturation Readings

If you ever work in the emergency room which I used to work in my initial nursing career there is so much in and out of patients with all the chaos and ambulances bringing in trauma patients from the outside. There are times we forget the basics and I would like to give you the barriers to a correct oxygen saturation reading. Here is the list:

  • Artificial nails
  • Nail polish
  • Cold hands
  • Poor circulation
  • Increase blood fats
  • Lighting in the environment
  • Shivering
  • Incorrect sensor application


Benefits of Pulse Oximetry

Pulse oximeters can help people with breathing problems and medical professionals monitor oxygen saturation by:

  • Monitoring oxygen saturation over time
  • Offering the peace of mind for people with chronic pulmonary problems specially people with exposure to COVID-19 whether to go the ER or not and people with cardiovascular conditions
  • The need for supplemental oxygen
  • Monitoring patients in surgery under anesthesia and post operatively in the recovery room
  • People taking drugs that affect breathing
  • Determine the effectiveness of interventions such as supplemental oxygen and ventilators
  • Helping with anxiety


Since COVID-19 started there has been a rush to get oxygen saturation pulse oximeters. And they are as I said earlier inexpensive and portable. Having one to carry maybe a lifesaver as it measures blood oxygen saturation levels whether you need to go the ER or not if you suspect you may have COVID-19 symptoms of difficulty of breathing. Other than this is used to monitor heart and lung problems. Oxygen is vital for life as every cell and tissue needs to carry out its individual function. Pulse oximeters should be used the proper way otherwise it will give false inaccurate readings.

If you want to take action now and get this inexpensive device for your everyday use or medical reasons you have, please click here 0r the link below. As I have said earlier I have used this device for the past 3 years, I love it and best of all it comes with a belt pouch, lanyard, user manual and batteries included. It has six display modes.What I am talking about is the Santemedical Generation 2 Fingertip Pulse Oximeter. It is very accurate. It is the first image below. Take action now and who knows you might save your life!

Disclosure: “As an Amazon Associate, I earn from qualifying purchases.”

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