Abstract: The invention relates to a method 10 for determining a beat-to-beat stroke volume 9a and/or a cardiac output 9b based on a measurement 2 of suitable arterial pressure data. At the step 4 a waveform of the arterial pressure pulse is assessed based on data obtained during the measurement of step 2. At step 6 a compliance or impedance in dependence of at least one measurement of arterial pressure data is computed using a non-linear model 7. The non-linear model may comprise an arctangent model. The arctangent model may be differentiated numerically or analytically to obtain the compliance or the impedance of an aortic portions. The thus obtained compliance or impedance may then be substituted into a linear model 8. The linear model 8 may comprise a Windkessel model 8a, or a Waterhammer model 8b or any other suitable linear pulse contour model 8c. As a result, the beat-to-beat stroke volume 9a and/or cardiac output 9b are computed.

Abstract: The invention relates to a method 10 for determining a beat-to-beat stroke volume 9a and/or a cardiac output 9b based on a measurement 2 of suitable arterial pressure data. At the step 4 a waveform of the arterial pressure pulse is assessed based on data obtained during the measurement of step 2. At step 6 a compliance or impedance in dependence of at least one measurement of arterial pressure data is computed using a non-linear model 7. The non-linear model may comprise an arctangent model. The arctangent model may be differentiated numerically or analytically to obtain the compliance or the impedance of an aortic portion. The thus obtained compliance or impedance may then be substituted into a linear model 8. The linear model 8 may comprise a Windkessel model 8a, or a Waterhammer model 8b or any other suitable linear pulse contour model 8c. As a result, the beat-to-beat stroke volume 9a and/or cardiac output 9b are computed.

Abstract: The invention relates to a method 10 for determining a beat-to-beat stroke volume 9a and/or a cardiac output 9b based on a measurement 2 of suitable arterial pressure data. At the step 4 a waveform of the arterial pressure pulse is assessed based on data obtained during the measurement of step 2. At step 6 a compliance or impedance in dependence of at least one measurement of arterial pressure data is computed using a non-linear model 7. The non-linear model may comprise an arctangent model. The arctangent model may be differentiated numerically or analytically to obtain the compliance or the impedance of an aortic portion. The thus obtained compliance or impedance may then be substituted into a linear model 8. The linear model 8 may comprise a Windkessel model 8a, or a Waterhammer model 8b or any other suitable linear pulse contour model 8c. As a result, the beat-to-beat stroke volume 9a and/or cardiac output 9b are computed.

Abstract: Method of determining the stroke volume of the human heart from the pulse-type blood-stream pressure signal derived from the aorta and consisting in each case of a systolic and a diastolic period. The method comprises calculating the flow q(t) from the pressure p(t) and integrating the flow over the systolic period, the aorta being regarded as a transmission line supplemented with a windkessel compliance and the pressure/volume relationship in the aorta as an arctangent relationship. The pressure represented by the pressure signal--for each stroke prior to the calculation of the flow--is linearized by the arctangent relationship, for fixed aorta length, or the aorta pressure/cross section, the values, associated with the final diastolic pressure, of the characteristic impedance of the transmission line and windkessel compliance being adhered to or is used without modification.

Abstract: Arrangement for controlling the cuff pressure in the indirect, non-invasive, continuous measurement of blood pressure in a finger by using a photo-electric plethysmograph in a fluid-filled pressure cuff, an electronic control circuit and an electric pressure valve, the cuff pressure being controlled by the plethysmographic signal in closed-loop operation by means of a servo-reference level, so that the arterial volume is maintained at a pre-adjusted value. For initial adjustment, the cuff pressure or the servo-reference level as initial adjustment quantity is automatically changed continuously in the control range by means of a control waveform supplied to the electronic control circuit, that thereby the peak-through amplitude of the pulsatile plethysmographic signal or cuff pressure signal is detected time and again, and compared with the preceding peak-through amplitude.

Abstract: A bias control circuit for a light-emitting diode having compensation of the light output at changing temperature, in which the light-emitting diode (led) used as temperature sensor is taken up together with a series resistor (R3) in a series circuit to which a fixed supply voltage is applied. A further series circuit of two resistors (R1, R2) having strongly different values is connected parallel across the series resistor (R3) and a differential amplifier (A1) is provided, the one and the other input of which are connected respectively to the junction of the two resistors (R1, R2) and to a setting voltage (Vi), and the output of which is connected to a control means (Tr1) taken up in series with the one series circuit.

Abstract: A method and a device for correcting the cuff pressure in the indirect, non-invasive and continuous measurement of the blood pressure in a part of the body by using a plethysmograph in a fluid-filled pressure cuff, an electronic control circuit, and an electric pressure valve. The cuff pressure is controlled by the plethysmographic signal in closed-loop operation with the aid of a servo-reference level obtained via a memory circuit. The servo-reference level, in operation of the device, is adjusted by opening the closed loop of the control circuit for a short interval, after which, in open-loop operation the cuff pressure is adjusted at an intermediate pressure derived from the pressure last measured and the servo-reference level is adjusted via the memory circuit.

Abstract: A device for the indirect, non-invasive and continuous measurement of blood pressure in a finger by using a photo-electric plethysmograph having a pressure cuff to be placed around the finger and to be filled with fluid, an associated light source and light detector, an electronic circuit, and an electric control valve having at least one fluid flapper-nozzle system, the cuff pressure being controlled by the plethysmographic signal in closed-loop operation such that the arterial volume is maintained on a pre-adjusted value and each deviation thereof due to changes in intra-arterial pressure is compensated immediately, whereby the control valve consists of a double fluid flapper-nozzle system in balance connection, whereby a single flapper member is positioned between the oppositely arranged nozzle openings of two nozzle members and alternately opens and closes these nozzle openings, one flapper-nozzle system being used in opposite sense, and one single chamber surrounding both nozzle openings being connected