METHOD AND APPARATUS FOR THE NON-INVASIVE DETECTION OF MEDICAL CONDITIONS BY MONITORING PERIPHERAL ARTERIAL TONE

摘要

A novel method and apparatus for non-invasive detection of a physiological state or medical condition is disclosed. The method provides an indication of such state or condition such as myocardial ischemia or sleep apnea, by detecting the peripheral arterial tone's response to such state or condition. A static pressure field is applied around the distal part of a digit of the subject, which field is sufficient to (a) substantially prevent venous pooling, (b) substantially prevent uncontrolled venous backflow, and (c) partially unload the wall tension of, but not to occlude, the arteries, in each case in such distal end. Changes in peripheral arterial tone and related volume changes in the distal part of the digit are detected to thereby detect or monitor a physiological state or medical condition. The apparatus comprises a finger probe, in the form of a tube accommodating the patient's finger, which is designed to apply pressure according to constraints (a)-(c) above, and a contiguous pressure cuff which extends the boundary of said pressure field. The finger probe either includes or is associated with a signal sensor/transducer for monitoring changes in the arterial tone. The inventive method and device are particularly suitable for detecting myocardial ischemia and sleep apnea, and for monitoring sleep stages and continuously measuring blood pressure. A novel method for calibrating the compliance characteristics of measured vascular beds wherein intra vascular pressure is modulated is also disclosed, this being useful in effecting the measurements of blood pressure.