Information and tips about oxygen saturation

What is a pulse oximeter?

The optimal oxygen saturation of the blood lies between 95 and 98 percent. This value corresponds to the percentage of haemoglobin molecules which transport oxygen in proportion to the total number of haemoglobin molecules.

On one side, the clip contains a strong light source, which shines through the finger. On the other side, a sensor measures what proportion of the light penetrated through the finger and what was absorbed. Different proportions of light penetrate the finger according to the level of saturation of the blood. From this, the oxygen saturation figure is calculated.

The pulse rate can likewise be measured and displayed.

Application of the pulse oximeter

The pulse oximeter is a simple, portable monitor for measuring oxygen saturation and pulse rate and is suitable for use indoors and outdoors.

In hospitals, in the rescue service and during patient transfer, e.g. in aircraft, helicopters or ambulances.

The pulse oximeter ensures safe, non-invasive monitoring of the cardiorespiratory condition of patients in need of care.

The monitoring of COPD patients is another important field of application.
COPD is the abbreviation for chronic obstructive pulmonary disease.

Pulse oximetry is used in leisure aviation during flights at high altitudes in order to be able to prevent hypoxia through self-monitoring.

And pulse oximeters are also used in the field of high-altitude mountaineering to recognise early signs of impending altitude sickness.


  • patients who need to monitor oxygen saturation
  • patients with pulmonary disease, e.g. COPD or fibrosis
  • pilots, in whom hypoxia can occur at high altitudes
  • mountaineers and others spending time at high altitudes
  • emergency medicine
  • hospitals
  • pulmonary function diagnosis

Measurement errors

The following factors may impair the SpO2 measurements and/or lead to inaccurate readings:

  • High levels of ambient light (shield the sensor area if necessary)
  • Excessive patient movement
  • Placement of a sensor on an extremity with a blood pressure cuff, arterial catheter, or intravascular line
  • The patient has hypotension, severe vasoconstriction, severe anaemia, or hypothermia
  • The patient is in cardiac arrest or is in shock
  • Fingernail polish or artificial fingernails
  • Cold or dirty fingernails
  • Significant levels of dysfunctional haemoglobins (such as carboxy-haemoglobin or methaemoglobin)
  • Intravascular dyes such as indocyanine green or methylene blue
  • Venous pulsations

Evaluation of pulse oximetry

In healthy patients, oxygen saturation levels lie between 96 and 98 %. Values below 95 % can indicate a health disorder and make it necessary to supply the patient with additional oxygen. If your oxygen saturation value is below 95 %, please consult your physician.

Normal pulse values depend on the age and fitness level of the individual.

Here are a few reference values indicating normal pulse rates:

  • Infants under 1 year: 100 – 160 bpm
  • Children between 1 and 10 years: 70 – 120 bpm
  • People over 10 years: 60 – 100 bpm
  • Highly trained individuals/athletes: 40 – 60 bpm