Pulse Oximeter or Saturimeter: some information for the citizen

By Cristiano Antonino Last updated Mar 27, 2023

The pulse oximeter, also known by the term saturation meter, is a kind of clip that is usually placed on a finger (the index finger) to measure the oxygen saturation and heart rate (BPM) in a person

It is used in flowmetry, a non-invasive and indirect technique that gives us information about the percentage of oxygen bound to haemoglobin (blood protein) in arterial blood.

It can also be used in the home environment.

Saturimeter, what does the finger pulse oximeter measure?

As we mentioned earlier, the pulse oximeter measures the oxygen saturation in the blood, and is referred to as SpO2.

In practice, we can know the percentage of haemoglobin saturated with oxygen in relation to the haemoglobin present in the blood.

In a nutshell, we know whether your lungs are taking in enough air.

In most cases, this medical device is worn on the index finger of our hand, but it can also be placed on the earlobe.

Infants are placed on the palm of their hand, wrist or foot.

Why is the pulse oximeter used on a finger?

The pulse oximeter is used on a finger as it is made up of numerous capillaries.

To use this medical instrument in optimal conditions, it is important to have warm fingers.

Before use, therefore, it is a good idea to rub one’s fingers together in order to obtain an optimal measurement.

Furthermore, one should not have nails (real or fake) that are too long or coated with nail polish (even gel), otherwise the percentages will be distorted.

In addition, the finger must be well cleaned.

On which finger is the saturation measured?

Notoriously, the pulse oximeter is worn on the index finger of the hand.

How does the saturation oximeter work?

The operation of the pulse oximeter is more complex than one might think.

In a nutshell, this medical device consists of two parts.

The first is a screen through which the calculation and result of the measurement is displayed.

The second, on the other hand, is the instrumental part itself, i.e. the clamp that attaches to the finger, specifically the fingertip and nail.

The values are estimated using an electronic processor and a pair of light emitters: one is red, while the other is infrared.

What are the optimal pulse oximeter values?

Normal oxygenation (SpO2) reference values should be between 95 and 98 per cent.

This number should not fall below 95 per cent, while optimal values are between 97 and 98 per cent.

In this case, therefore, the person’s saturation and respiratory function are defined as normal.

Depending on the percentage variation, we can run into certain problems:

If the value is 100 per cent, we are dealing with a case of hyperventilation;
In subjects with values between 90 and 95 per cent, we have hypoxia;
Below 90 per cent, we must contact 112 immediately, especially in patients with lung disease, high fever, coughing and ‘air hunger’.

When is saturation low?

In cases where the value is below 95 per cent, saturation is defined as low, and can be differentiated in the following ways

mild (91-94 per cent);
moderate (86-90 per cent);
severe (below 85 per cent).

How high should saturation be in an elderly person?

In the case of an elderly person, the normal saturation value indicated by plussimetry should be 95 per cent.

This percentage indicates a good state of health, which depends very much on age and the presence or absence of pulmonary and respiratory diseases.

When to use the pulse oximeter?

The pulse oximeter is usually used in patients with asthma, pneumonia, chronic obstructive pulmonary disease (COPD), congenital heart defects, heart failure, acute respiratory distress syndrome (ARDS) and sleep apnoea.

This medical tool, therefore, allows monitoring of the patient’s health status and anticipating any deterioration.

Equipment: What Is A Saturation Oximeter (Pulse Oximeter) And What Is It For?

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