Pulse oximetry is a simple, inexpensive, and non-invasive diagnostic procedure that is used to measure the level of oxygen (or oxygen saturation) in the blood. Oxygen saturation should always be above 95%, but may be lower in the presence of respiratory disease or congenital heart disease. You can measure the percentage of oxygen saturation in your blood using a pulse oximeter, a device with a clip-like sensor that is placed on a thin part of the body, such as a lobe or nose.
Steps
Part 1 of 2: Preparing to Use the Pulse Oximeter
Step 1. Understand the relationship between oxygen and blood
Oxygen is inhaled through the lungs and then passes into the blood, where it mostly binds to hemoglobin. Hemoglobin is a protein found inside red blood cells that, through the blood, carries oxygen to the rest of the body and tissues. In this way, the body receives the oxygen and nutrients it needs to function.
Step 2. Understand the reasons for the measurement
Pulse oximetry is done to assess blood oxygen saturation for a variety of reasons. It is often used in surgery and other procedures involving sedation (such as a bronchoscopy). The pulse oximeter can also be used to assess whether the dose of oxygen administered needs to be changed, whether pulmonary medications are effective, and to determine the patient's tolerance to increased physical activity.
Your doctor may also advise you to have this measurement if you use a mechanical ventilation system to support your breathing, if you have sleep apnea, or if you have (or have had) a serious medical condition, such as a heart attack, congestive heart failure., chronic obstructive pulmonary disease (COPD), anemia, lung cancer, asthma or pneumonia
Step 3. Learn how the pulse oximeter works
The oximeter takes advantage of hemoglobin's ability to absorb light and the natural pulsation of blood flow in the arteries to measure the level of oxygen in the body.
- A device called a probe is equipped with a light source and detector and a microprocessor, which compares and calculates the differences between an oxygen-rich versus a deficient hemoglobin.
- A light source with two different types of light is mounted on one side of the probe: infrared and red. These two beams of light are sent through the body tissues to the light detector on the other side of the probe. Hemoglobin that is more saturated with oxygen absorbs more infrared light, while hemoglobin that is poor in oxygen absorbs more red light.
- The microprocessor inside the probe calculates the differences and converts the information into a digital value. It is this resulting value that is then evaluated to determine the amount of oxygen carried in the blood.
- Relative light absorption measurements are performed multiple times every second and are then processed by the instrument to give a new reading every 0.5-1 second. At the end, the average of the measurements of the last three seconds is shown.
Step 4. Know the risks of the procedure
Know that the risks associated with using the pulse oximeter are usually very minimal.
- If you use the oximeter for a long time, tissue collapse can occur at the site where the probe is applied (for example, the finger or ear); in addition, the skin can sometimes also become slightly irritated when adhesive probes are used.
- There may be other risks, based on your general health and any specific medical conditions you may have. Consult your doctor before starting the procedure if you are concerned.
Step 5. Choose a pulse oximeter that suits your needs
Several types and models are commercially available. The most popular are portable, handheld and finger ones.
- Portable pulse oximeters can be purchased in many stores, including drugstores and drugstores, orthopedics stores, and even online.
- Most of these devices have a clip-on probe that looks a bit like a clothespin. You can also find on the market those stickers that can be applied on the finger or on the forehead.
- For children and infants you should use appropriate sized probes.
Step 6. Make sure the oximeter is charging
Plug it into a grounded wall outlet if your device is not portable. If it is, make sure it has enough charge to turn it on before putting it into operation.
Part 2 of 2: Using a Pulse Oximeter
Step 1. Evaluate if you need to take a single reading or if you need to do continuous monitoring
Unless you need to undergo continuous monitoring, the probe should be removed after detection.
Step 2. Remove anything on the application site that can absorb light
For example, if you plan to apply the oximeter to your finger, it is important to remove anything that absorbs light (such as dried blood or nail polish) to avoid erroneously low readings.
Step 3. Heat the area where the probe is to be applied
Cold can cause poor perfusion or slow blood flow, which in turn can cause erroneously low readings. Make sure your finger, ear, or forehead is at room temperature or slightly warm before starting the procedure.
Step 4. Eliminate any sources of environmental interference
High levels of ambient light, such as ceiling lights, phototherapy lights, and hot infrared lights, can "blind" the device's light sensor and give an inaccurate reading. Solve the problem by reapplying the sensor or shielding it with a cloth or blanket.
Step 5. Wash your hands
This allows to reduce the transmission of microorganisms and body secretions.
Step 6. Connect the probe
It is usually placed on a finger; then turn on the pulse oximeter to "on".
- The probes can also be placed on the lobe and forehead, although studies have found that the lobe is often not a reliable site for measuring oxygen saturation.
- If you use the finger pulse oximeter, your hand should be placed on your chest at heart level, rather than raised in the air (as patients very often do); this helps to minimize any movement that could interfere with detection.
- Minimize any movement. The most common cause of inaccurate readings is excessive movement. One way to prevent movement from affecting the reading is to verify that the displayed heart rate matches the manually controlled heart rate. The beat numbers should not deviate from each other by more than 5 beats per minute.
Step 7. Read the measurement
The oxygen saturation level and heart rate are shown in a few seconds on the bright display. A result of 95% - 100% is generally considered normal. However, if your oxygen level drops below 85%, you need to see a doctor.
Step 8. Record your readings
You can print them or download them to a computer, if your pulse oximeter has this feature.
Step 9. Troubleshoot if the oximeter makes a mistake
If you think your device is getting an inaccurate or inaccurate reading, try these steps:
- Verify that there is no interference (environmental or directly on the probe site).
- Warm and scrub the skin.
- Apply a topical vasodilator to help open blood vessels (for example, a nitroglycerin cream).
- Try applying the probe to a different place on your body.
- Try a different probe and / or pulse oximeter.
- If you are still unsure whether the tool is working properly, consult your doctor.
Advice
Don't worry if your oxygen level isn't 100%. In reality, very few people have this level of oxygen
Warnings
- Do not apply the pulse oximeter to a finger on the arm where you have the automatic blood pressure monitor attached, as blood flow to the finger is interrupted every time the cuff inflates.
- If you are a smoker it is not useful to use the pulse oximeter, as the device would not be able to distinguish between the normal oxygen saturation in hemoglobin and the carboxyhemoglobin saturation that occurs when smoke is inhaled.
