24-hour Blood Pressure Measurements and Ischemic Conditioning

Unlike casual blood pressure measurements, 24-hour ambulatory blood pressure monitoring provides an insight into blood pressure changes in everyday life and an estimate of the overall blood pressure load exerted on the cardiovascular system over 24 hours. Blood pressure recordings over a 24-hour period of normal daily activity will be made using a noninvasive ambulatory monitor (Spacelabs, Redlands, WA). The ambulatory system will be calibrated against a mercury sphygmomanometer, and the cuff will be programmed to inflate automatically every 15 min from 6 AM to 11 PM and every 20 min between 11 PM and 6 AM. For each individual subject, the nighttime period will be defined as the time when the subject goes to bed at night until rising in the morning. Daytime will be defined as the remainder of the 24-hour period. Daytime and nighttime states will be monitored by an Actiwatch (Mini-MItter, Bend, OR), a watch-like device placed on the wrist that measures gross motor activity.