The invention comprises devices for noninvasively monitoring physiological characteristics
of a patient's blood. Generally, probes having radiation emitters and detectors
are used to determine absorbance of blood within the patient's tissue to determine
various blood parameters. The device also has either a position sensor for determining
the position of the probe with respect to the patient's heart or a movement generator
for altering the position of the probe with respect to the patient's heart. The
invention also comprises methods for noninvasively monitoring the physiological
characteristics. In one embodiemnt, induced positional changes create differential
hydrostatic pressures to facilitate measurement of blood parameters by absorbance.
In a second embodiment, delays in pulse arrival times in coupled organs or members
on opposite sides of the body are measured to determine cardiac output. The two
methods are such that they can advantageously be used together.
