ABSTRACT
The use of markers to indicate that a spe cific biologic response has occurred is well established in medicine and anesthesiol ogy. For example, eyelash reflex, respira tory rate, heart rate, blood pressure, and electrocardiogram patterns are all common physiologic markers that may be used to in dicate the depth of anesthesia (1). These physiologic-based markers are monitored without removing biologic samples from the patient, and they provide timely and valu able information regarding the physiologic state of the patient.
