How to Read a Pulse Oximeter: Seniors Guide

Since the COVID-19 pandemic, an unprecedented demand for pulse oximeters has grown. Due to high rates of chronic cardiovascular and respiratory illnesses and the increasing lifespan of older adults, experts project the demand will continue. This article offers everything you need to know about whether a pulse oximeter is necessary for you or a loved one, how to use it, and when to get help for worsening oxygen levels and heart rate.

What is a pulse oximeter?

A pulse oximeter is a small medical device placed on your finger to measure pulse rate and blood oxygen levels. It's a handy tool used in hospitals, clinics, and many households.

The body uses a protein called hemoglobin to transport oxygen within red blood cells (RBCs). Traveling throughout the body, RBCs deliver oxygen to every cell. Without oxygen, cells cannot operate properly.

A pulse oximeter is a simple and helpful way to monitor oxygen delivery, or oxygen saturation, within the body. Knowing your oxygen levels and heart rate can help you decide when to call the doctor or emergency services if a condition worsens.

How does a pulse oximeter work?

How does a pulse oximeter work?

In simple terms, a pulse oximeter shines light through your finger to obtain the two readings on a pulse oximeter.

Here's how it works:

  • Light emission. A typical pulse oximeter has two light-emitting diodes (LEDs), one emitting red light and the other emitting infrared light. When you place the device on your finger or another location, like an earlobe or toe, these lights are transmitted through the body part.
  • Light absorption. The hemoglobin within red blood cells absorbs different amounts of light depending on how much hemoglobin is carrying oxygen.
  • Measurement. The pulse oximeter measures the amount of red and infrared light passing through your fingertip. By comparing the ratio of the absorbed red and infrared light, it measures and calculates blood oxygen levels.
  • Display. The results are displayed on the pulse oximeter's small screen as a percentage indicating how much oxygen the hemoglobin carries in your red blood cells. Most oximeters will also display your pulse — the number of heartbeats per minute — with a moving waveform showing each beat.

A normal blood oxygen level is between 95 and 100% in a healthy individual at any age. Healthcare providers call this oxygen saturation, often abbreviated as SpO2. It's a common vital sign your nurse will take when you visit your provider.

Who should use a pulse oximeter?

Pulse oximeters are most often used in healthcare settings to check and monitor patient vital sign trends. However, as your healthcare provider recommends, they're also beneficial and straightforward to use at home to monitor various situations.

Here are common reasons for using a pulse oximeter:

  • To monitor a lung condition or infection. The doctor may advise people with chronic obstructive pulmonary disease (COPD), heart failure, COVID-19, pneumonia, sleep apnea, lung cancer, or other conditions to monitor blood oxygen levels.
  • To monitor heart rate in certain cardiac conditions. Checking a pulse rate can help patients with various cardiac conditions to assess worsening conditions.
  • To assess your response to a new workout program. Sometimes, healthcare providers and athletes use pulse oximetry to determine how the cardiovascular system adapts to higher activity levels.
  • To adjust home oxygen intake. If you are prescribed home oxygen, your physician may ask you to periodically monitor your oxygen levels and adjust your oxygen intake accordingly.
  • To monitor oxygen levels at a higher altitude. Oxygen levels can decrease at higher altitudes because the air is less dense, causing oxygen molecules to spread out. Older adults and people with cardiovascular conditions who live at or travel to higher elevations may need a pulse oximeter to monitor their SpO2 and heart rate.

How to use a pulse oximeter

Here's a step-by-step guide so that you know pulse oximeter basics.

  1. Prepare the device. Ensure that the pulse oximeter is clean and in good working condition. If it requires batteries, make sure they are installed and sufficiently charged.
  2. Prepare yourself. Position yourself comfortably where you can be still. It's essential to be calm during the measurement to obtain accurate results.
  3. Prepare your finger. When using the fingertip pulse oximeter, remove nail polish from your fingernail and warm your hands if cold. Cold fingers can reduce blood flow to your hand and cause an inaccurate reading.
  4. Insert your finger. Turn on the device and slide your finger into the clip-like opening. Typically, on home devices, the fingernail side of your finger is inserted against the display side of the device. According to one study, the best location for an accurate reading may be the right middle finger or right thumb with your hand below the level of your heart, but other fingers are precise enough to use, too. Aim to use a finger with a shorter fingernail whenever possible.
  5. Wait for the reading. Once the device is positioned, it will measure your oxygen saturation level and pulse rate. An accurate reading typically takes a few seconds.
  6. Read the results. The pulse oximeter will display the results on its screen. The oxygen saturation level appears as a percentage (%), and the pulse rate as beats per minute (BPM). To verify whether a reading is correct, check the pulse waveform. The waveform is the moving wave on the screen that indicates the pulse. If the waveform is consistent and uniform, the reading is likely accurate. If the waveform is erratic, the reading is likely inaccurate and often caused by too much movement.
  7. Record the results. Record the readings with the date and time if you're monitoring your SpO2 and BPM levels over time. Some pulse oximeters have memory functions to store measurements and even transfer the data to your healthcare provider.

What is a normal pulse oximeter reading?

Knowing how to read a pulse oximeter is key to interpreting the results. Most people at sea level have a normal SpO2 reading of 95–100%. A normal heart rate is 60–100 beats per minute (BPM). However, this varies depending on health status, underlying medical conditions, and environmental conditions.

As a result, it's best to consult a healthcare professional for personalized guidance. Ask your provider what oxygen saturation level and heart rate are safe and which are hazardous.

When to worry about pulse oximeter readings

Seeking medical help based on oxygen levels and heart rate depends on several factors. Here are some guidelines for when to seek help based on oxygen levels and symptoms:

Low oxygen saturation levels without symptoms. For healthy individuals at sea level, experts recommend contacting your healthcare provider if your pulse oximeter consistently shows oxygen levels between 88–94%. This may indicate hypoxemia (low blood oxygen levels) caused by a growing health problem. However, the read may be inaccurate if the pulse oximeter is used incorrectly or works poorly.

Low oxygen levels with symptoms. If symptoms like shortness of breath, chest pain, confusion, or bluish discoloration of the lips or nails (cyanosis) accompany lower oxygen levels, call for ambulance assistance urgently.

Sudden or severe symptoms. If an individual experiences severe or sudden symptoms such as difficulty breathing, rapid breathing, confusion, significant heart rate changes, dizziness, or fainting, regardless of the oxygen saturation reading, seek medical evaluation immediately. These symptoms may indicate a medical emergency.

Deteriorating symptoms. When symptoms and pulse oximeter readings worsen over time, despite efforts to manage them at home with prescribed medical treatments, it may indicate a worsening status for patients with conditions like a respiratory infection, heart or lung diseases, allergies, or recent surgery or hospitalization. Monitor closely, adjust oxygen administration and other treatments according to your doctor’s orders, and seek medical advice if there is a significant decline or deterioration.

Low, high, or irregular heart rate. If your heart rate is consistently slightly below 60 BPM (bradycardia) or slightly above 100 BPM (tachycardia) and no associated symptoms are present, contact your healthcare provider for guidance. However, if your heart rate is low, high, or irregular and you have accompanying symptoms like dizziness, light-headedness, weakness, shortness of breath, chest pain, or a pounding, racing, or fluttering heart, call for immediate medical help.

If you have any concerns or questions about pulse oximeter readings, seek medical advice or assistance promptly. Healthcare providers are trained to evaluate, advise, and treat based on individual circumstances and clinical assessment.

Troubleshooting a pulse oximeter

While pulse oximeters are helpful in estimating oxygen saturation levels, they may not always be accurate. Various factors can affect the readings.

Various factors that affect the pulse oximeter

Darker skin pigmentation may also cause inaccurately normal SpO2 levels when hypoxemia is present.

Furthermore, carbon monoxide (CO) poisoning may cause an inaccurately high reading. Carbon monoxide is over 250 times more likely to bind to hemoglobin than oxygen. Unfortunately, a pulse oximeter does not know whether oxygen or carbon monoxide is bound to the hemoglobin. As a result, CO poisoning may cause a pulse oximeter to indicate normal or high SpO2 levels when a poisoned individual has dangerously low oxygen levels.

Tips for using a pulse oximeter with older adults

Older adults may face specific challenges or concerns when using a pulse oximeter due to reduced dexterity, arthritis, vision issues, or cognitive impairment. Among the concerns and tips unique to older adults are:

Reduced dexterity

Vision issues

Reduced skin integrity

Choosing the right pulse oximeter for an older adult

These pulse oximeter features may be particularly beneficial for older adults and caregivers who need to monitor oxygen levels easily and reliably regularly.

  • Built-in memory storage to track oxygen levels and heart rate
  • Extended battery life
  • Easy connectivity options to transfer data to healthcare providers
  • Durability and reliability
  • Comfortable and user-friendly

Understanding how to use a pulse oximeter at home can reduce stress for older adults and their caregivers by helping them know when to seek medical care for heart and lung conditions and infections. Since human biology, medical conditions and environments vary, you must consult your healthcare provider about what to expect from your pulse oximeter results.

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