Apparatus for determining cardiovascular parameters
First Claim
1. An apparatus for the continuous determination of a parameter characterizing a patient'"'"'s left ventricular pumping action, comprisinga first input channel for continuous recording of a variable physiological first reading directly dependent on the left ventricular pumping action, andan evaluation unit for calculating said parameter characterizing the left ventricular pumping action,wherein said apparatus also comprises a second input channel for continuous recording of a variable physiological second reading which at least approximately indicates the patient'"'"'s intrathoracic pressure (ITP) or is dependent on same,wherein said evaluation unit is programmed for calculating the parameter characterizing the patient'"'"'s left ventricular pumping action from said first reading, using a corrective function based on said second reading,wherein said corrective function takes into account periodic fluctuations of said second reading.
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Abstract
An apparatus that continuously monitors the arterial pressure measured by a pressure sensor in an artery, which pressure is regarded as the reading Pao that approximately corresponds to the aortal pressure. In principle, the arterial pressure can be measured in the aorta, near the aorta, or in the arterial tree. To provide a second reading, the apparatus, via the input channel, continuously monitors the central venous pressure (CVP), which is regarded as the reading PIT that approximately corresponds to the intrathoracic pressure (ITP). The third reading is provided via the input channel as a reading Z which expresses the thoracic compliance. Via known algorithms of the pulse contour analysis, the apparatus calculates the stroke volume variation, using as the determining pressure the transmural pressure which is calculated according to the formula
Ptransmural=Pao−f(C)*PIT
The cardiac volume responsiveness indicator (CVRI) is calculated for mechanical positive respiration according to the formula
CVRI=k*(SVV/ΔCVP)
or for spontaneous breathing according to the formula
CVRI=l−m*(ΔCVP/SVV).
34 Citations
58 Claims
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1. An apparatus for the continuous determination of a parameter characterizing a patient'"'"'s left ventricular pumping action, comprising
a first input channel for continuous recording of a variable physiological first reading directly dependent on the left ventricular pumping action, and an evaluation unit for calculating said parameter characterizing the left ventricular pumping action, wherein said apparatus also comprises a second input channel for continuous recording of a variable physiological second reading which at least approximately indicates the patient'"'"'s intrathoracic pressure (ITP) or is dependent on same, wherein said evaluation unit is programmed for calculating the parameter characterizing the patient'"'"'s left ventricular pumping action from said first reading, using a corrective function based on said second reading, wherein said corrective function takes into account periodic fluctuations of said second reading.
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11. An apparatus for the continuous determination of the cardiac volume responsiveness indicator, comprising:
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a first input channel for the continuous recording of a variable physiological first reading directly dependent on a patient'"'"'s left ventricular pumping action, a second input channel for continuous recording of a variable physiological second reading at least approximately representing the patient'"'"'s intrathoracic pressure (ITP), a third input channel for continuous recording of a third reading which depends directly on the patient'"'"'s state of respiration, and an evaluation unit for calculating said cardiac volume responsiveness indicator, wherein the evaluation unit is programmed to use said second and third readings to select a function that can be used for the patient'"'"'s current state of respiration and based on this function, to calculate said volume responsiveness indicator from said first and second readings. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29)
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30. A method of continuous determination of a parameter characterizing a patient'"'"'s left ventricular pumping action, comprising the steps of:
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recording a variable physiological first reading directly dependent on the left ventricular pumping action; continuously recording a variable physiological second reading which at least approximately indicates the patient'"'"'s intrathoracic pressure (ITP) or is dependent on same; and calculating said parameter characterizing the left ventricular pumping action from said first reading, using a corrective function based on said second reading; wherein said corrective function takes into account periodic fluctuations of said second reading. - View Dependent Claims (31, 32, 33, 34, 35, 36, 37, 38, 39)
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40. A method of continuous determination of the cardiac volume responsiveness indicator, comprising the steps of
recording a variable physiological first reading directly dependent on the patient'"'"'s left ventricular pumping action, recording a variable physiological second reading at least approximately representing the patient'"'"'s intrathoracic pressure (ITP), recording a third reading which depends directly on the patient'"'"'s state of respiration, using said second and third readings to select a function that can be used for the patient'"'"'s current state of respiration, and, based on this function, calculating said cardiac volume responsiveness indicator from said first and second readings.
Specification