What Is Pulse Oximetry And How Does It Work?

Pulse oximeters are non-invasive monitors that measure blood oxygen content. They measure the ratio of the two main forms of hemoglobin in the blood: saturated arterial hemoglobin (also called oxyhemoglobin) to unsaturated hemoglobin.

Pulse oximeters have gained great popularity, as they are very convenient to use in most clinical situations. Today, pulse oximeters are necessary equipment in situations where it is important to monitor the filling of blood with oxygen.

Application of pulse oximetry

  1. Anesthesiology and resuscitation (for monitoring during sedation with midazolam, for confirming cyanosis, for monitoring during patient transportation);
  2. Vascular and plastic surgery, orthopedics (for monitoring pulse and oxygen saturation);
  3. Neonatology (for non-invasive control in premature infants to determine the risk of damage to the retina, lungs, etc.);
  4. Pediatrics (for non-invasive monitoring of the condition);
  5. Obstetrics (for fetal oximetry);
  6. Therapy (to detect and control respiratory failure, to detect sleep apnea, to control the medical treatment of chronic diseases).

Pulse oximeters have a proven and reliable high accuracy in measuring the blood oxygen content in the range from 70% to 100%, provide a short measurement time and also do not require preparation of the patient before use.

The pulse oximeter is designed to monitor patients of all ages – adults, children and newborn patients. The pulse oximeter is equipped with an internal battery and can also be used during the transportation of the patient by ambulance cars.


  • Long-term anesthesia;
  • Postoperative period (after the restoration of the vascular wall, orthopedic operations, interventions in the distal parts of the body);
  • Respiratory failure;
  • Oxygen therapy;
  • Severe chronic diseases, accompanied by a high risk of hypoxia;
  • Suspicion of obstructive sleep apnea syndrome, central sleep apnea syndrome and chronic nocturnal hypoxemia.

How to use a pulse oximeter?

Wait a few seconds by turning on the pulse oximeter until it completes the self-test. The sensor should be fixed on the finger so that the fixation is reliable and there is no excessive pressure. You have to wait 5 to 20 seconds, and the pulse oximeter will display saturation and pulse data. Yes, a pulse oximeter can be mistaken, like any other electronic medicine, but this is extremely rare. This can be indicated by rapidly varying, over a wide range, indicators of saturation and pulse. For example, 95% suddenly gives way to 86%, which is not physiologically possible. If you doubt the reliability of the data obtained using a pulse oximeter, double-check them with clinical methods. The pulse oximeter is sensitive to bright external light, trembling, movements. All this can artificially create a pulse-shaped curve and saturation indicators. By the way, various dyes contribute to an underestimation of the saturation values, as well as the abnormal methemoglobin that appears in the blood in the case of a dosage of prilocaine. If your nails or fingers are dirty, the pulse oximeter may give false readings. Erroneous indications may also occur if the patient is poisoned by carbon monoxide and carboxyhemoglobin is present in the blood. The device can show 100% saturation but this is not true. By following these simple rules, you will extend the life of your pulse oximeter.

A pulse oximeter is only an addition to other methods of examining a patient and should be used in combination with clinical signs and symptoms.

Category: Health Care

Tags: breathing, lungs, Respiratory, Respiratory diseases, respiratory system