Hemodynamic monitor and method of hemodynamic monitoring
First Claim
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1. An apparatus for determining stroke volume comprising:
- an input for receiving an arterial pressure waveform;
means arranged to define a start point within the arterial pressure waveform at a beginning of a systolic arterial pressure increase due to a ventricular contraction phase of a heart beat;
means arranged to determine an end point of the heart beat for the purpose of calculating stroke volume bydetermining whether there is a part or point of the arterial pressure waveform that has substantially the same arterial pressure value as said starting point,responsive to said arterial pressure value at said starting point being regained, setting the end point to be the part or point of the arterial pressure waveform that has substantially the same arterial pressure value as said starting point, andresponsive to said arterial pressure value at said starting point not being regained, extrapolating the end point of the heart beat to a point where the arterial pressure waveform has substantially the same arterial pressure value as said starting point to define the end point;
means arranged to calculate a stroke volume from a part of the arterial pressure waveform or of the extrapolated arterial pressure waveform between the start point and the end point; and
an output means and configured to output, via the output means, an indication of at least one of a current stroke volume, a current heart rate, a number of previous stroke volumes and a number of previous heart rates.
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Abstract
An apparatus and method for determining stroke volume. The apparatus receives an arterial pressure waveform and is arranged to correct a part of the pressure waveform that relates to a heart beat for an influence of an ectopic heart beat, of atrial fibrillation on the pressure waveform or of changes in the pressure waveform'"'"'s baseline. The apparatus also comprising means arranged to calculate the stroke volume from the corrected waveform.
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12 Claims
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1. An apparatus for determining stroke volume comprising:
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an input for receiving an arterial pressure waveform; means arranged to define a start point within the arterial pressure waveform at a beginning of a systolic arterial pressure increase due to a ventricular contraction phase of a heart beat; means arranged to determine an end point of the heart beat for the purpose of calculating stroke volume by determining whether there is a part or point of the arterial pressure waveform that has substantially the same arterial pressure value as said starting point, responsive to said arterial pressure value at said starting point being regained, setting the end point to be the part or point of the arterial pressure waveform that has substantially the same arterial pressure value as said starting point, and responsive to said arterial pressure value at said starting point not being regained, extrapolating the end point of the heart beat to a point where the arterial pressure waveform has substantially the same arterial pressure value as said starting point to define the end point; means arranged to calculate a stroke volume from a part of the arterial pressure waveform or of the extrapolated arterial pressure waveform between the start point and the end point; and an output means and configured to output, via the output means, an indication of at least one of a current stroke volume, a current heart rate, a number of previous stroke volumes and a number of previous heart rates. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification