Cardiac flow monitor
First Claim
1. The method of deriving blood flow information from a single color signal produced by a fiberoptic cardiac catheter, comprising the steps of:
- (a) filtering said signal to obtain its AC and DC components;
(b) determining the RMS value of said AC component; and
(c) dividing said RMS value by the value of said DC component.
3 Assignments
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Accused Products
Abstract
Previously undesired artifacts in a color signal used in fiberoptic cardiac catheters to measure blood oxygenation levels are used to produce indications of blood flow and true pulse. For this purpose, the color signal is band-pass filtered to derive a DC mean signal level μ and an AC signal containing only those frequencies at which the signal is affected by blood flow variations. The RMS value of that band-pass-filtered AC signal (which corresponds to the standard deviation σ of the AC signal) is divided by the DC value μ to produce a σ/μ signal representative of flood flow. By clipping the AC signal and using the resulting square wave to drive a one-shot multivibrator, an indication of the patient'"'"'s true pulse can be obtained.
26 Citations
15 Claims
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1. The method of deriving blood flow information from a single color signal produced by a fiberoptic cardiac catheter, comprising the steps of:
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(a) filtering said signal to obtain its AC and DC components; (b) determining the RMS value of said AC component; and (c) dividing said RMS value by the value of said DC component. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. Apparatus for determining blood flow from a single color signal in a fiberoptic cardiac catheter, comprising:
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(a) means adapted to provide a color signal input; (b) filter means adapted to receive said input to produce AC and DC signals representing, respectively, the AC and DC components of said color signal; (c) RMS-determining means connected to said filter means for determining the RMS value of said AC signal; and (d) divider means connected to said filter means and said RMS-determining means for producing an output representative of the RMS value of said AC signal divided by the value of said DC signal. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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Specification