US Patent 6899695 Medication security apparatus and method

A security device for a patient-controlled analgesia (PCA) device receives a word or series of words spoken into it as a command by a patient and creates a voice print characteristic of the patient. A subsequent receipt of a voiced command is converted into a test voice print and compared to the patient's voice print. If the system identifies the test voice print as belonging to the patient's voice, it signals the PCA that the patient is requesting a bolus of medication from the PCA. If the device determines that the test voice print does not correspond to that of the patient, the device does not signal the PCA and optionally emits an audible error tone. In this manner, unauthorized people cannot give the patient a bolus dose from the PCA.