| 摘要 |
<p>A method and apparatus for continuously monitoring cardiac output based upon phase shift between an input signal and a temperature signal indicative of change in blood temperature leaving the heart. In a preferred embodiment of a cardiac output monitoring system (10), a catheter (14) is provided with an electrical resistance heater (22). An electrical current having a sinusoidal wave form with a period of from 30 to 60 seconds is applied to the heater, causing power to be dissipated into the blood within a patient's heart (12). A temperature sensor (24) disposed near the catheter produces a signal indicative of the temperature of blood leaving the heart. The temperature signal and the signal corresponding to the electrical power dissipated in the heater are filtered at a frequency φ corresponding to the frequency of the applied electrical current. The amplitude of the input power, the amplitude of the temperature signal, and their phase difference are used in calculating cardiac output.</p> |
