In order to study the cardiac functional responses on postural changes by tilt table, 6 males were selected, and impedance cardiogram were recorded. An experiment was continuously conducted based on resting in a supine position, changing posture and recovering in supine for each 5 min Postural changes consisted of seven tilting angles ; 0°, ±2°, ±45° and ±90°
1. While the cardiac output was decreased from that of supine resting in head up posture because of decreasing stroke volume and increasing heart rate, cardiac output was increased by increasing stroke volume during head down posture.
2. At ±45° and ±90° postures, measured parameters were significantly changed in 5 sec after postural changes, but at 0° and ±2° postures, measured parameters were no significant difference from that of supine resting state.
The cardiac output is the product of heart rate and stroke volume, but during postural changes stroke volume by fluid shift was main affecter to cardiac output. In conclusion, responses of cardiac function during postural changes are like to start with postural change, and magnitude of cardiac response is like to relate with the tilting angle.