A pulse oximeter is a device used to indirectly measure the amount of oxygen present in the blood by measuring the oxygen saturation or SpO2. It is important to note that the SpO2 is a measurement of the percentage of hemoglobin molecules bound to oxygen.
Hemoglobin which is the main oxygen-carrying protein in the blood changes color once it is bound to oxygen. With the help of the sensors that detect color changes in the blood due to movement of the oxygen-bound hemoglobin, a pulse oximeter can determine the amount of oxygen in the blood which is beneficial in measuring the respiratory function of an individual.
Reading a pulse oximeter
Locating the SpO2 reading
The reading is usually found on the digital screen of the pulse oximeter and given as percentage, often between 90-100%. The exact location tends to vary depending on the type of device used.
There are some pulse oximeters that have a bar that indicates the signal strength which is the measurement of the signal’s intensity that the sensor is generating. A high signal is less prone to any errors.
Generally, individuals have SpO2 levels between 96-99%. Levels that are below 90% usually indicate acute respiratory failure. Nevertheless, the standard range can differ from one individual to another. Those who have chronic respiratory diseases might have an SpO2 level lower than 90% without the presence of any acute respiratory problem.
Identifying the pulse rate
The pulse oximeter measures the pulse rate of the individual aside from the oxygen saturation. The pulse is displayed as a 2-3-digit number which is normally between 60-100 among adults and higher among children and infants. It is often displayed with a heart-shaped icon or the letters BPM which means beats-per-minute.
Check for other measures on the display screen
There are some pulse oximeters that display the ECG and plethysmogram of the individual. The ECG measures the electrical activity that the heart produces while beating that can be used to monitor the cardiac function and identify arrhythmias.
A plethysmogram displays any changes in the amount of oxygen in the blood that occur with every pulse. These types of pulse oximeters are not available for home use though.