Apparatus for measuring the area between a fluctuating signal and an inclined baseline

Claim 2

Cardiac monitoring apparatus comprising a blood pressure detector for deriving a signal representative of blood pressure at each instant in time and an arrangement for providing a measurement of the area bounded, on a plot of the signal, by the straight line joining adjacent diastoles and the signal curve extending between said diastoles, said arrangement including, first means responsive to said detector for detecting the occurrence of diastoles of the blood-pressure-representative signal and for determining the magnitude of the signal at each diastole relative to a fixed datum, second means responsive to said first means for providing an output representative of the elapsed time between successive occurrences of diastoles, third means responsive to said first means for providing an output representative of the difference in magnitude of the signal at successive diastoles, fourth means for multiplying the outputs from the second and third means and providing an output representative of one half thereof with a polarity dependent upon the output of the third means, an integrator responsive to said detector to integrate said blood-pressure-representative signal with respect to time, said integrator being reset by said first means on the occurrence of each diastole, fifth means for repetitively summing the outputs of said fourth means and said integrator immediately prior to resetting of said integrator, and means for displaying each said summation which is representative of cardiac stroke volume.

Claim 3

Apparatus as claimed in claim 1, including sixth means responsive to said detector for detecting the occurrence of systoles of the blood-pressure-representative signal and seventh means responsive to said sixth means for proviDing an output of predetermined duration and being representative of heart rate.

Claim 4

Apparatus as claimed in claim 1, including a further summation means responsive to said fifth means and arrangement to sum over a predetermined time interval consecutive outputs of said fifth means to provide an output which is representative of cardiac output.

Claim 5

Cardiac monitoring apparatus comprising a blood pressure detector for deriving a signal representative of blood pressure at each instant in time and an arrangement for providing a measurement of the area bounded, on a plot of the signal, by the straight line joining adjacent diastoles and the signal curve extending between said diastoles, said arrangement including, first means responsive to said detector for detecting the occurrence of diastoles of the blood-pressure-representative signal and for determining the magnitude of the signal at each diastole relative to a fixed datum, second means responsive to said first means for providing an output representative of the elapsed time between successive occurrences of diastoles, third means responsive to said first means for providing an output representative of the difference in magnitude of the signal at successive diastoles, fourth means for multiplying the outputs from the second and third means and providing an output representative of one half thereof with a polarity dependent upon the output of the third means, an integrator responsive to said detector to integrate said blood-pressure-representative signal with respect to time, said integrator being reset by said first means on the occurrence of said diastole, fifth means for repetitively summing the outputs of said fourth means and said integrator immediately prior to resetting of said integrator, to provide an output which is representative of cardiac stroke volume, further summation means responsive to said fifth means and arranged to sum over a predetermined time interval consecutive outputs of said fifth means to provide an output which is representative of cardiac output, sixth means responsive to said detector for detecting the occurrence of systoles of the blood-pressure-representative signal, seventh means responsive to said sixth means for providing an output of predetermined duration and being representative of heart rate, display means including a visual display device and a function selector connected to permit display of a selected one of the outputs from said fifth means, said further summation means, and said seventh means.

Claim 6

Cardiac monitoring apparatus comprising a blood pressure detector for deriving a signal representative of blood pressure at each instant in time and an arrangement for providing a measurement of the area bounded, on a plot of the signal, by the straight line joining adjacent diastoles and the signal curve extending between said diastoles, said arrangement including, first means responsive to said detector for detecting the occurrence of diastoles of the blood-pressure-representative signal and for determining the magnitude of the signal at each diastole relative to a fixed datum, second means responsive to said first means for providing an output representative of the elapsed time between successive occurrences of diastoles, third means responsive to said first means for providing an output representative of the difference in magnitude of the signal at successive diastoles, fourth means for multiplying the outputs from the second and third means and providing an output representative of one half thereof with a polarity dependent upon the output of the third means, an integrator responsive to said detector to integrate said blood-pressure-representative signal with respect to time, said integrator being reset by said first means on the occurrence of said diastole, fifth means for repetitively summing the outputs of said fourth means and said integrator immediately prior to resetting of said integrator, to provide an output which is representative of cardiac stroke volume, further summation means responsive to said fifth means and arranged to sum over a predetermined time interval consecutive outputs of said fifth means to provide an output which is representative of cardiac output, sixth means responsive to said detector for detecting the occurrence of systoles of the blood-pressure-representative signal, seventh means responsive to said sixth means for providing an output of predetermined duration and being representative of heart rate, display means including a visual display device and a function selector connected to permit display of a selected one of the outputs from said fifth means, said further summation means, and said seventh means.

Claim 7

Apparatus as claimed in claim 4, wherein said display means includes a timer coupled to impose a maximum duration on the display of a selected function.

Claim 8

Apparatus as claimed in claim 5, wherein said function selector includes a further timer coupled to cause automatic display of a predetermined function at predetermined intervals of time.