| 摘要 |
An arterially measured pressure signal is continuously read in and temporarily stored in the working memory (RAM). The function p(t) is processed by the central processing unit (CPU), to calculate the heart/time volume PCCO and other hemodynamic parameters. The calculation comprises the following steps: The systemic vascular resistance SVR<SUB>k </SUB>is calculated for the current pulse period. The stroke volume SV<SUB>k </SUB>is numerically determined from the pressure values of a pulse period, according to the following equation: <maths id="MATH-US-00001" num="1"> <MATH OVERFLOW="SCROLL"> <MROW> <MSUB> <MI>SV</MI> <MI>k</MI> </MSUB> <MO>∝</MO> <MROW> <MO>∑</MO> <MROW> <MO>(</MO> <MROW> <MFRAC> <MROW> <MSUB> <MI>p</MI> <MI>i</MI> </MSUB> <MO></MO> <MROW> <MO>(</MO> <MI>t</MI> <MO>)</MO> </MROW> </MROW> <MSUB> <MI>SVR</MI> <MI>k</MI> </MSUB> </MFRAC> <MO>+</MO> <MROW> <MROW> <MSUB> <MI>C</MI> <MI>k</MI> </MSUB> <MO></MO> <MROW> <MO>(</MO> <MSUB> <MI>p</MI> <MI>i</MI> </MSUB> <MO>)</MO> </MROW> </MROW> <MO></MO> <MFRAC> <MROW> <MO>ⅆ</MO> <MSUB> <MI>p</MI> <MI>i</MI> </MSUB> </MROW> <MROW> <MO>ⅆ</MO> <MI>t</MI> </MROW> </MFRAC> </MROW> </MROW> <MO>)</MO> </MROW> </MROW> </MROW> </MATH> </MATHS> with the compliance C(p)=(MAP-CVP)<SUB>k</SUB>/[SVR.<DP/DT><SUB>k</SUB>].f(p). The difference between the mean arterial pressure MAP and the central venous pressure CVP, and the mean incline of the pressure curve in the diastole <dp/dt>, are re-determined for the current pulse period. The heart/time volume calculated in the current pulse period results from PCCO<SUB>k</SUB>=SV<SUB>k</SUB>.HR. Therefore, continuous recalibration of the systemic vascular resistance and of the compliance takes place, from the continuously determined pressure measurement data.
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