Time-segmented pulse oximetry and pulse oximeter performing the same

1. A method of measuring an oxygen saturation in blood of a subject, comprising:

irradiating a living tissue of the subject with a first light beam having a first wavelength and a second light beam having a second wavelength different from the first wavelength;

generating a first electrical signal from the first light beam reflected from or transmitted through the living tissue;

generating a second electrical signal from the second light beam reflected from or transmitted through the living tissue;

dividing the first electrical signal into a plurality of first segments each of which includes a part of the first electrical signal for a predetermined time period;

dividing the second electrical signal into a plurality of second segments each of which includes a part of the second electrical signal for the predetermined time period; and

calculating a gradient of a regression line between every one of the first segments and an associated one of the second segments, thereby obtaining a plurality of gradients.

2. The method as set forth in claim 1 , further comprising:

calculating an arterial oxygen saturation from every one of the gradients, thereby obtaining a plurality of arterial oxygen saturations;

smoothing the arterial oxygen saturations to obtain a smoothed arterial oxygen saturation; and

calculating an oxygen saturation in blood based on the smoothed arterial oxygen saturation.

3. The method as set forth in claim 1 , further comprising:

smoothing the gradients to obtain a smoothed gradient;

calculating an arterial oxygen saturation from the smoothed gradient; and

calculating an oxygen saturation in blood based on the arterial oxygen saturation.

4. A pulse oximeter operable to measure an oxygen saturation in blood of a subject, comprising:

a light emitter, adapted to irradiate a living tissue of the subject with a first light beam having a first wavelength and a second light beam having a second wavelength different from the first wavelength;

a signal generator, operable to generate a first electrical signal from the first light beam reflected from or transmitted through the living tissue, and operable to generate a second electrical signal from the second light beam reflected from or transmitted through the living tissue;

a processor, operable to:

divide the first electrical signal into a plurality of first segments each of which includes a part of the first electrical signal for a predetermined time period;

divide the second electrical signal into a plurality of second segments each of which includes a part of the second electrical signal for the predetermined time period; and

calculate a gradient of a regression line between every one of the first segments and an associated one of the second segments, thereby obtaining a plurality of gradients.

5. The pulse oximeter as set forth in claim 4 , wherein:

the processor is operable to:

calculate an arterial oxygen saturation from every one of the gradients, thereby obtaining a plurality of arterial oxygen saturations;

smooth the arterial oxygen saturations to obtain a smoothed arterial oxygen saturation; and

calculate an oxygen saturation in blood based on the smoothed arterial oxygen saturation.

6. The pulse oximeter as set forth in claim 4 , wherein:

the processor is operable to:

smooth the gradients to obtain a smoothed gradient;

calculate an arterial oxygen saturation from the smoothed gradient; and

calculate an oxygen saturation in blood based on the arterial oxygen saturation.