As a nurse, you will help provide safe care to clients who have or are at risk for hypoxia, which is when there is not enough oxygen to meet the needs of the body. These clients require pulse oximetry, which is a non-invasive, easy, and pain-free method of measuring the amount of oxygen carried by the hemoglobin in the red blood cells. This is known as arterial blood oxygen saturation, or SaO2 for short. Maintaining a normal SaO2 ensures that the amount of oxygen that travels through the bloodstream to tissues around the body is adequate.
A pulse oximeter consists of a probe, which is attached by a cable to a pulse oximeter. That probe has a light source on one side and a photodetector, or sensor, on the other side. So, when it gets clipped onto a body part, a light shines through the tissues on one side, and on the other side, the sensor detects how much light has been absorbed by the arterial blood in the tissues. The principle is that, when hemoglobin is bound to oxygen, it absorbs more light than when it’s not.
Both earlobe and forehead probes tend to be more accurate than digit probes in cases when blood flow to the extremities is compromised or if the client moves their hands or feet frequently, creating motion artifacts.
All these probes can be either disposable, which are preferred when multiple clients need to be checked using the same oximeter, or reusable when used for a single client. They also come in two types: adhesive and clip sensors. In general, adhesive sensors are better for younger children or if you need to place the sensor on an earlobe, nose bridge, or toe. Clip sensors might not be the best for children because they are very easy to take off.
A pulse oximeter reading, also called SpO2, of 95% or greater is considered normal. Anything below that is considered low for most clients. But, if it falls below 85%, it can get really dangerous for the client. This may occur in clients with various lung conditions that interfere with gas exchange, meaning movement of oxygen and carbon dioxide between the blood, lungs, and tissues.In other cases, though, readings can be falsely low because of poor blood flow to the extremities, which makes it hard for the pulse oximeter to pick up a proper signal. This could be due to:
Readings can also be inaccurate due to motion artifacts, like when the client is shivering or restless, meaning that false signals are generated when they shouldn’t be. Readings may also be inaccurate if the client is wearing nail polish, or if bright light, such as sunlight, is shining on the probe, making it harder to measure the oxygen saturation.
When caring for a client who is monitored with pulse oximetry, there are a few things you should report, such as an SpO2 below a value specific for the client, to the healthcare provider.
Observe the skin integrity, color, moisture, and temperature at the site where the probe is placed. If there’s skin breakdown or irritation or the skin is pale, damp, or cold, choose another site for the probe. Check for any changes in vital signs or in the level of consciousness, unusual respiratory sounds, and bluish discoloration of the skin or mucous membrane.Document:
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