A pulse oximeter is a small, non-invasive device commonly used to monitor a person’s general health status. It clips onto a body part, typically a fingertip, to provide insights into two important physiological measurements: how well the body is delivering oxygen and how frequently the heart is beating.
Oxygen Saturation Explained
Oxygen saturation, often displayed as SpO2, represents the percentage of hemoglobin in red blood cells that is carrying oxygen. Hemoglobin is a protein within red blood cells responsible for transporting oxygen from the lungs to the body’s tissues. A pulse oximeter measures this percentage by shining light through the skin and detecting how much light is absorbed by oxygenated versus deoxygenated hemoglobin.
For most healthy individuals, a normal SpO2 reading typically ranges between 95% and 100%. Readings within this range suggest that the blood is well-saturated with oxygen, supporting normal bodily functions. All cells and tissues require a constant supply of oxygen to function properly and produce energy.
A reading below 95% may indicate that the body is not receiving enough oxygen, a condition known as hypoxemia. While a single low reading might be temporary due to factors like shallow breathing, consistently low SpO2 levels could signal an underlying issue. Very low readings, such as below 90%, are generally considered a medical emergency requiring immediate attention.
Pulse Rate Explained
The second reading displayed on a pulse oximeter is the pulse rate, often labeled as PRbpm or BPM, indicating beats per minute. This measurement reflects the number of times the heart contracts and pumps blood throughout the body within one minute. The pulse oximeter determines this by detecting the pulsatile flow of blood through the capillary bed in the finger, providing an immediate indication of heart activity.
For most healthy adults at rest, a normal pulse rate typically falls between 60 and 100 beats per minute. Factors such as age, fitness level, activity, and certain medications can influence an individual’s resting heart rate. A pulse rate consistently above 100 beats per minute is referred to as tachycardia, while a rate consistently below 60 beats per minute is known as bradycardia. These deviations from the typical range can sometimes indicate that the heart is working harder than it should or not efficiently enough.
Interpreting Readings and Seeking Care
Several factors can influence the accuracy of pulse oximeter readings. Nail polish, especially dark colors, or artificial nails can interfere with the light signals, leading to inaccurate results. Cold fingers or poor circulation in the extremity being measured can also affect the device’s ability to detect blood flow accurately. Movement during measurement, such as wiggling a finger, can also disrupt the reading, so it is important to remain still. Skin pigmentation can also impact accuracy, with some studies suggesting a higher risk of underestimating low oxygen levels in individuals with darker skin tones.
To ensure the most accurate measurement, place the device on a clean, warm finger and remain still for a few moments, ensuring the battery is adequately charged. While pulse oximeters provide valuable information, they are not diagnostic tools.
If readings are consistently outside the normal ranges, or if you experience symptoms like shortness of breath, dizziness, or chest pain, it is advisable to seek medical attention. A healthcare professional can interpret the readings in the context of your overall health and symptoms, providing a proper diagnosis and treatment plan if necessary.