Factors Influencing Pulse Oximeter Accuracy in Seniors

A pulse oximeter is a handy, noninvasive device that can give a quick snapshot of an individual's pulse and oxygen saturation. Using red and infrared light to pass through a body part, it analyzes the pulse rate and the amount of oxygen in the blood. The sensor's accuracy may be affected by physiologic changes caused by normal aging. Understanding these age-related factors can help seniors and caregivers interpret the findings accurately to better care for their health.

The aging process can cause decreased perfusion, temperature changes, and skin thickness. These factors can influence pulse oximetry accuracy in seniors.

  • Decreased perfusion. Normal aging causes blood vessels to become thicker and stiffer, resulting in impaired blood flow to the hands and feet. This makes it difficult for the pulse oximeter to detect a good pulse signal, which may result in false results.
  • Temperature changes. As people age, the body produces less oil and fat below the skin, making it harder for the body to control its temperature. Temperature's role in pulse oximetry accuracy is significant because cold extremities may cause constriction of blood vessels, resulting in poor circulation.
  • Skin thickness. As we age, our skin gradually loses strength and elasticity, often becoming thinner and paler. Because the pulse oximeter uses light to pass through a body part, the thickness and color of the skin may affect its readings.

What are three conditions that can give a false pulse oximetry reading?

Chronic obstructive pulmonary disease (COPD), congestive heart failure (CHF), and atrial fibrillation (Afib) are three medical conditions prevalent in seniors that lead to false pulse oximetry readings. Although there are general acceptable oxygen levels, healthcare providers may provide different ranges that are personalized for people with chronic diseases.

  • COPD. Target oxygen saturation levels for people with COPD are usually lower (88–92%). However, studies have shown that pulse oximeters may overestimate results for COPD patients. If you see an oxygenation level within the target range but are experiencing severe symptoms of COPD, contact a healthcare provider right away.
  • CHF. People with CHF often have peripheral arterial disease, which may cause decreased blood flow to the hands and feet. Severe cases of CHF may also cause low blood pressure, resulting in cold extremities.
  • Afib. This is a condition that causes the heart to beat irregularly, often resulting in a very fast heart rate. A rapid, irregular pulse may result in an inadequate waveform, which also leads to a poor signal. When using a pulse oximeter at home, take note of the pulse signal bar which signifies how well the sensor is working.

What are the steps to ensure accurate pulse oximeter readings for seniors?

Choose a reliable pulse oximeter that the FDA has cleared for accuracy and medical use. Review the manufacturer’s guidelines, then choose a warm site with intact skin to place the sensor. Be mindful of the impact of nail polish on pulse oximeter readings. The colors of the fingernail polish, especially darker ones, may cause the oxygenation readings to be falsely low.

How to properly use a pulse oximeter

Make sure your hands are dry and clean before proceeding with the following steps:

  1. Attach the glowing red sensor to the fingernail. It should feel snug, not too tight, around the finger. If you need to attach the sensor to another location, such as the earlobe, use a different type of pulse oximeter designed explicitly for that site.
  2. Keep the site that has the probe still. Do not move the body part until the numbers stop fluctuating or the red light keeps blinking. If the oximeter has a pulse signal bar, the signal should be high, not low. If it takes more than a minute to get a steady number, try another site.
  3. Record the two distinct numbers. The one marked as 'SpO2' with a percentage sign is the oxygen saturation. The one labeled as 'Pr' or has a heart sign is the pulse rate. Record the results, date, and time so you can keep track of changes.
  4. Compare the findings with your symptoms. Do the numbers correspond with how you are feeling? Remember, multiple factors can lead to a false pulse oximetry reading.
  5. Store the device in a safe place. Place the pulse oximeter in a place that is safe and easily accessible.

How do you interpret pulse oximetry results in elderly patients?

The normal values for pulse and oxygen saturation may vary for different age groups and conditions. Aging, activity levels, and medications are factors that need to be taken into consideration when interpreting pulse oximeter results in elderly patients.

For pulse

At rest, a normal pulse rate range in oximeters is generally 60–100 beats per minute. For elderly patients, this range may be slower — even up to 50 beats per minute. Sometimes, it’s better to double-check pulse oximeter heart rate accuracy manually. To do this, put two fingers over a pulse site and count the number of beats for 60 seconds. If the number is below 50 or over 100 and you feel chest pains, palpitations, and shortness of breath, you should seek medical attention immediately.

For oxygen saturation

At sea level, oxygen saturations between 96% and 100% are considered normal. Most pulse oximeters are made to sense readings from 70% to 100% with an accuracy between 2% and 4%. This means two things. First, if the oxygen level is below 70%, the pulse oximeter may not be able to detect it. Second, if the true oxygen saturation is 86%, the device may display a result between 88% and 90%. So, if your device shows an acceptable range but you are wheezing, lightheaded, and feel like you just can’t get enough air, you need to speak to a healthcare provider.

What are some safety precautions for seniors who use pulse oximetry at home?

Here are several safety precautions to keep in mind when evaluating pulse oximeter reliability in home care settings:

  • Inspect the integrity of the device. Remember that the elderly may experience temperature and sensory age-related changes, so check for missing or broken parts. Damaged or missing parts of the sensor may cause overheating or electrochemical burns to the skin.
  • Ensure proper device hygiene. Clean the pulse oximeter before and after use to reduce contamination and bacterial growth.
  • Monitor for signs of discomfort or skin irritation. The device should fit well and not be painful, too tight, or cause irritation. Single-use pulse oximeters may leave residue from the adhesive. When removing the adhesive, do it gently so you do not tear fragile skin, then properly clean the device.
  • Avoid prolonged use in one site. Sometimes the healthcare provider may advise using the pulse oximeter over an extended period. Older adults are more prone to pressure injuries because of thinning skin. Monitor the site of the probe at least every two hours to make sure that there is no redness, irritation, or pain.

Pulse oximeters can play an essential role in monitoring the health of seniors aging in place. Seniors and caregivers can make better-informed health decisions by understanding age-related changes and conditions, carefully interpreting results, and correctly using the devices.

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