The aim of the project is to experimentally compare the fingers of the hand in terms of measured concentrations of peripheral blood oxygen saturation (SpO2) in healthy humans during gradual desaturation in the range of 60-100% SpO2 and simultaneously during a step change from the hypoxic phase to the recovery phase (return to physiological values).

The finger sensors of pulse oximeters are most often placed on the middle two fingers of the hand. Although there have been many studies looking at the accuracy of different pulse oximeters or comparing fingers in terms of SpO2. There is no study comparing fingers in terms of SpO2 under hypoxic condition with simultaneous randomization of finger probe placement. At the same time, there is no study that compares SpO2 changes between fingers during a step change in blood oxygen saturation. The data obtained could help to improve the reliability of monitoring physiological parameters with pulse oximeters.

Inclusion Criteria:

• Passing the initial examination, which will determine the following data: finger circumference, heart rate, blood pressure and blood oxygen saturation

Exclusion Criteria:

• post-traumatic conditions of the upper limbs affecting the perfusion of the fingers or injuries or skin diseases on the fingers.
• pneumothorax or a condition after cardiovascular surgery.
• anemia, bradycardia, hemoglobinopathy or other diseases of the cardiovascular system, pregnancy, diabetes, hypotension or hypertension.