Method for noninvasive continuous determination of physiologic characteristics

A method for noninvasively determining the concentration of a blood constituent comprising the steps of:

• providing a tissue probe, said tissue probe including a first radiation emitter adapted to emit radiation having a first wavelength and a first radiation detector adapted to receive said radiation after absorbance through a radiation path length of a patient's blood;
• measuring absorbance of said patient's blood by transmitting said radiation at said first wavelength through said patient's blood and detecting said radiation after passage through said patient's blood;
• varying the volume of said patient's blood through gravitational force to change said path length of said tissue probe to provide multiples of said path length;
• measuring absorbance of said patient's blood at each multiple of said path length;
• and
• determining the concentration of the blood constituent based on said measured absorbance.