Pulse oximeter probe-off detection system

A method of detecting that a pulse oximetry probe may not be properly attached to a tissue site, the method comprising:

• providing a pulse oximetry probe having a light emitter, a light detector configured to detect light from the light emitter when the pulse oximetry probe is properly attached, and at least two contacts configured to make contact to a patient's skin when the pulse oximetry probe is properly attached;
• emitting light from the light emitter;
• checking for continuity across the at least two contacts by measuring a resistance of a coding resistor;
• checking for a valid signal from the light detector;
• and
• determining whether the pulse oximetry probe is properly attached based upon the continuity check and the valid signal check.

A pulse oximetry system comprising:

• a pulse oximeter base unit;
• an optical probe configured to be affixed to a body member of a patient;
• at least two electrical contacts located on the optical probe, the electrical contacts configured to make contact to the body member of the patient when the optical probe is properly affixed to the patient;
• and
• a probe-off detector module configured to check for acceptable continuity across the electrical contacts by measuring a resistance of a coding resistor, thereby determining whether the optical probe is properly affixed to the patient.