Pulsion Medical Systems Ag

Stephan Regh

Ulrich J Pfeiffer

Reinhold Knoll

Determining the transition between systole and diastole is important for pulse contour-analytical determination of hemodynamic, first of all cardiac output. During the temporal progression of arterial pressure P(t) on which pulse contour analysis is based, the transition between systole and diastole appears as a local minimum. This local slump of the pressure curve downward is very short and is often little recognizable in the actually measured curves due to inaccuracies conditioned by measuring techniques. It was also found that the transition between systole and diastole can be more reliably and accurately determined as the site of maximum curvature of function P(t). Consequently, the invention relates to a device having a calculation unit that comprises evaluation means for detecting the site of maximum curvature of function P(t) in a detection area between the maximum and minimum functional value of the pulse cycle as the site of transition between systole and diastole.

Device for determining the transition between systole and diastole

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 SVRis calculated for the current pulse period. The stroke volume SVis numerically determined from the pressure values of a pulse period, according to the following equation: with the compliance C()=(MAP&#x2212;CVP)/[SVR&#xb7;&#x3c;dp/dt&#x3e;]&#xb7;&#x192;(). 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 &#x3c;dp/dt&#x3e;, are re-determined for the current pulse period. The heart/time volume calculated in the current pulse period results from PCCO=SV&#xb7;HR. Therefore, continuous recalibration of the systemic vascular resistance and of the compliance takes place, from the continuously determined pressure measurement data.

Growing community of inventors

Munich, Germany

Stephan Regh