How to use Pulse Oximetry

 How to use Pulse Oximetry

Pulse oximetry is a method used to estimate the percentage of oxygen bound to hemoglobin in the blood. This approximation to SpO2 is designated SpO2 (peripheral oxygen saturation).

The pulse oximeter consists of a small device that clips to the body (typically a finger, an earlobe or an infant’s foot) and transfers its readings to a reading meter by wire or wirelessly.

The device uses light-emitting diodes of different colours in conjunction with a light-sensitive sensor to measure the absorption of red and infrared light in the extremity. The difference in absorption between oxygenated and deoxygenated hemoglobin makes the calculation possible.[6]

How it works

During a pulse oximetry reading, a small clamp-like device is placed on a finger, earlobe, or toe. Small beams of light pass through the blood in the finger, measuring the amount of oxygen.

It does this by measuring changes of light absorption in oxygenated or deoxygenated blood. This is a painless process.

The pulse oximeter will thus be able to tell you your oxygen saturation levels along with your heart rate.


  • Diagnose symptoms like shortness of breath
  • Track your blood oxygen level during surgery
  • Test oxygen levels when you use supplemental oxygen
  • Show if you need extra oxygen when you exercise

Factor that affect blood oxygen levels to become low

Blood oxygen levels can get low due to any of the problems that include:

Low air oxygen levels: Atmospheric oxygen becomes extremely low at high altitudes such as mountainous regions.

Decreased capacity of the body to take in oxygen: This can be caused by lung conditions that include:

  1. Asthma
  2. Emphysema (damage of the air sacs in the lung)
  3. Bronchitis
  4. Pneumonia
  5. Pneumothorax (leaking of air in the space between the lung and chest wall)
  6. Acute respiratory distress syndrome (ARDS)
  7. Pulmonary edema (the lung swells due to build-up of fluid)
  8. Pulmonary fibrosis (scarring of the lungs)

Common sites

The pulse oximeter is a small, clip-like device that attaches to a body part, like toes or an earlobe. It is commonly put on a finger.

Procedure steps

Pulse oximetry may be used in both inpatient and outpatient settings. In some cases, your doctor may recommend that you have a pulse oximeter for home use.

The pulse oximetry process is as follows:

Most commonly, a clip-like device will be placed on your finger, earlobe, or toe. You may feel a small amount of pressure, but there is no pain or pinching.

In some cases, a small probe may be placed on your finger or forehead with a sticky adhesive. You may be asked to remove your fingernail polish if it’s being attached to a finger.

You’ll keep the probe on for as long as needed to monitor your pulse and oxygen saturation. When monitoring physical activity capabilities, this will be during the extent of the exercise and during the recovery period.

During surgery, the probe will be attached beforehand and removed once you’re awake and no longer under supervision.

Sometimes, it will only be used to take a single reading very quickly.

Once the test is over, the clip or probe will be removed.

Radhika Basnet

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