Pulse oximeter normal reading

Pulse oximeters measure blood oxygen saturation noninvasively and continuously.

Pulse oximeter oxygen levels – pulse oximeter normal reading:

The body’s need for oxygen is certain. Its availability at a tissue level is sometimes in doubt. Blood gas measurements provide critical information regarding oxygenation, ventilation, and acid-base status.

However, these measurements only provide a snapshot of the patient’s condition taken at the time that the blood sample was drawn. It is well known that oxygenation can change very quickly. In the absence of continuous oxygenation monitoring, these changes may go undetected until it is too late.

What is spo2 pulse oximeter?

What is SpO2?

A blood-oxygen saturation reading indicates the percentage of hemoglobin molecules in the arterial blood which are saturated with oxygen.

• The reading may be referred to as SaO2.
• Readings vary from 0 to 100%.
• Normal readings in a healthy adult, however, range from 94% to 100%.

The term SpO2 means the SaO2 measurement determined by pulse oximetry.

How does pulse oximetry work?

Within the Sp02 sensor, light-emitting diodes shine red and infrared light through the tissue. Most sensors work on extremities such as a finger, toe, or ear.

The blood, tissue, and bone at the application site absorb much of the light. However, some light passes through the extremity. A light-sensitive detector opposite the light source receives it.

Spo2 sensor how does it work?

SpO2 Sensors

Most sensors work on extremities such as a finger, toe, or ear. The sensor measures the amount of red and infrared light received by the detector and calculates the amount absorbed. Much of it is absorbed by tissue, bone, and venous blood, but these amounts do not change dramatically over short periods of time.

The amount of arterial blood does change over short periods of time due to pulsation (although there is some constant level of arterial blood). Because the arterial blood is usually the only light-absorbing component which is changing over short periods of time, it can be isolated from the other components.

How to calculate spo2 from heart rate?

The amount of light received by the detector indicates the amount of oxygen bound to the hemoglobin in the blood. Oxygenated hemoglobin (oxyhemoglobin or HbO2) absorbs more infrared light than red light. Deoxygenated hemoglobin (Hb) absorbs more red light than infrared light. By comparing the amounts of red and infrared light received, the instrument can calculate the SpO2 reading.

How is spo2 detected by pulse oximeter?

Using pulse oximetry is fairly simple. Many questions may be answered by referring to your instrument’s Instructions for Use.

Choosing a Sensor

There are some general guidelines for choosing the right sensor. The ideal application site has good perfusion, does not generate movement artifact, is comfortable for the patient, and allows easy application.

The size of the application site determines what size sensor to use. The age of the patient is not a factor.

How Do I Use SpO2?

If a sensor is too big or too small, the light-emitting diode and the light detector may not line up. This could cause a false reading or an alarm.

If a finger sensor is too large, it may slip partway off so that the light source partly covers the finger. This condition, called an optical bypass, causes incorrect readings.

If a finger is inserted too far into the sensor it may be squeezed by the sensor, which causes venous pulsation. The pulse oximeter recognizes arterial blood only by its pulsing motion, so in this case, it also measures venous blood. This causes readings that are falsely low.

Since motion between the sensor and the application site may cause movement artifacts, adhesive sensors may be better than non-adhesive sensors.

Neonates tend to have movement artifacts in their fingers, so choose a toe or foot sensor.

Do not apply the sensor too tightly in an attempt to reduce movement artifacts.

Not only does this not reduce movement artifacts, but it may also lead to venous pulsation and necrosis

Check all sensors regularly and move them if necessary. Refer to the sensor documentation for recommended times for checking and replacing the sensor.

If the patient’s skin cannot breathe or is subjected to sustained pressure, he or she may suffer from skin necrosis, particularly if the patient has poor microcirculation.

Pulse oximeter spo2 uses

Using SpO2

Because pulse oximetry provides continuous monitoring and is noninvasive, it may be useful in several clinical situations.

Surgery and Post Anesthetic Care Units

Since pulse oximetry provides a means of continuously assessing the oxygenation of the patient, many require it. If ventilation fails, an alarm sounds.

Additionally, SpO2 is noninvasive so it is safer and more pleasant for the patient than invasive methods of oxygen analysis.

Neonatal Care and NICU

Blood-oxygen saturation levels taken immediately after birth, preferably on the right hand, (within five minutes) are a good guide to the neonate’s general state of health. Levels below 75% may indicate abnormalities. Together with Apgar scores, blood-oxygen saturation readings are very useful. Both too little or too much oxygen is dangerous for the neonate, particularly for the premature neonate.

Oxygen partial pressure (PaO2) is most critical for the neonate. Although blood-oxygen saturation and PaO2 are related, there are too many other factors involved to convert easily between the two measurements.

Emergency Care

In emergent care situations, both in and out of the hospital, patients may need ECG monitoring, SpO2 monitoring, pacing, and defibrillation at a moment’s notice.

Noninvasive Transcutaneous Pacing

Pulse oximetry, as integrated into Philips’ defibrillator/monitors, provides a tool to help determine whether pacing is effective. You can use the SpO2 measurements in addition to the patient’s ECG signal as shown on the monitor to verify that mechanical capture has been achieved.

When the patient is being successfully paced, the pulse rate derived from the pulse oximeter, the ECG heart rate derived from the ECG monitor and the pacing rate should all be about the same. In addition, there should be signs of improved cardiac output.

Recorded strips provide a printed record of SpO2 measurements and SpO2 alarm violations during pacing.

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

Pulse oximetry is a very useful technology, but there are situations where you must be careful in applying it. Keep the following in mind when you use a pulse oximeter.

Considerations When Using Pulse Oximetry

Blood oxygen saturation is a measure of the amount of oxygen carried by the hemoglobin in the bloodstream. It is usually expressed as a percentage rather than an absolute reading. Pulse oximeters define this percentage in a different way than other instruments. These subtle, but important differences, are described in the following section.

how does hemoglobin affect oxygen saturation?

Effects of Non-functional Hemoglobin on Oxygen Saturation Measurements

In order to judge a patient’s condition, ideally, you would like to have blood oxygen saturation expressed as a percentage of the total hemoglobin that is saturated with oxygen. Under many circumstances, that is the reading you get from pulse oximeters. However, if the patient has a large amount of nonfunctional hemoglobin, the reading is not accurate.

Can a pulse oximeter detect anemia?

Damage to red blood cells may cause anemia, a lack of red blood cells, and thus hemoglobin in the blood. An anemic patient may not have enough functioning hemoglobin in the blood to oxygenate the tissues. The small amount of functioning hemoglobin in the blood may be well saturated with oxygen, so the patient may have a normal SpO2 reading, but the patient may not have enough oxygen going to the tissues.

More on this story

Pulse Oximeters: Answering Your Frequently Asked Questions