Cardiac monitor
First Claim
1. A method of monitoring cardiac activity including directing light at the skin of the individual to be monitored and detecting the reflected light modulated by the pulsatile flow of blood beneath the skin, said method including:
- detecting substantially the peak of the systolic pulse in the cardiac cycle, including automatically coupling a signal indicative of the reflected light into a filtering means, storing a charge level indicative of the peak of said reflected light signal in said filtering means, comparing each signal pulse occurring in said reflected light to said stored charge level, and generating a pulse indicative of each systolic pulse only when a succeeding signal pulse has a peak substantially equal to said charge level;
generating a signal indicative of each detected pulse peak; and
converting the time interval between signals to a signal indicative of the heartbeat rate.
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Accused Products
Abstract
A cardiac monitor generates infrared light which is directed at the skin of an individual to be monitored. The light reflected from the skin is detected and automatically controlled. The pulsatile flow of blood in the underlying vascular network modulates the reflected light which is detected by a photo sensitive sensor which generates a signal indicative of the modulations. The modulated signal is coupled to a pulse detector which filters our spurious signals and generates one pulse for each systole in a cardiac cycle. The systolic pulse is coupled to a pulse interval to heartbeat rate converter which converts the interval between each succeeding systolic pulse into a signal which is preferably continuously and visually displayed to provide a continuous monitor of the heartbeat rate of the monitored individual.
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Citations
14 Claims
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1. A method of monitoring cardiac activity including directing light at the skin of the individual to be monitored and detecting the reflected light modulated by the pulsatile flow of blood beneath the skin, said method including:
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detecting substantially the peak of the systolic pulse in the cardiac cycle, including automatically coupling a signal indicative of the reflected light into a filtering means, storing a charge level indicative of the peak of said reflected light signal in said filtering means, comparing each signal pulse occurring in said reflected light to said stored charge level, and generating a pulse indicative of each systolic pulse only when a succeeding signal pulse has a peak substantially equal to said charge level; generating a signal indicative of each detected pulse peak; and converting the time interval between signals to a signal indicative of the heartbeat rate. - View Dependent Claims (2, 3)
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4. A method of monitoring cardiac activity including directing light at the skin of the individual to be monitored and detecting the reflected light modulated by the pulsatile flow of blood beneath the skin, said method including:
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detecting substantially the peak of the systolic pulse in the cardiac cycle; generating a signal indicative of each detected pulse peak; and converting the time interval between signals to a signal indicative of the heartbeat rate, including discharging a charge storage means in response to each signal, charging said storage means at a predetermined rate between signals, charging a second storage means to a level indicative of the charge on said first storage means when each signal occurs, clamping said second storage means at said indicative level between signals, and generating a rate signal corresponding to the clamped level of said second storage means. - View Dependent Claims (5, 6, 7)
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8. A cardiac monitor for monitoring cardiac activity including means for generating and directing light at the skin of the individual to be monitored and means for detecting the reflected light modulated by the pulsatile flow of blood beneath the skin, said monitor including:
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means for detecting substantially the peak of the systolic pulse in the cardiac cycle, said detecting means including means for generating a signal indicative of the reflected light, means for automatically storing a charge level indicative of the peak of said reflected light signal, means for comparing each signal pulse occurring in said reflected light signal to said stored charge level, and means for generating a pulse indicative of each systolic pulse only when a succeeding signal pulse has a peak substantially equal to said charge level; means for generating a signal indicative of each detected pulse peak; and means for converting the time interval between signals to a signal indicative of the heartbeat rate. - View Dependent Claims (9, 10)
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11. A cardiac monitor for monitoring cardiac activity including means for generating and directing light at the skin of the individual to be monitored and means for detecting the reflected light modulated by the pulsatile flow of blood beneath the skin, said monitor including:
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means for detecting substantially the peak of the systolic pulse in the cardiac cycle; means for generating a signal indicative of each detected pulse peak; and means for converting the time interval between signals to a signal indicative of the heartbeat rate, said converting means including first charge storage means being discharged in response to each signal, means for charging said first storage means at a predetermined rate between signals, second storage means being charged to a level indicative of the charge on said first storage means when each signal occurs, means for clamping said second storage means at said indicative level between signals, and means for generating a rate signal corresponding to the clamped level of said second storage means. - View Dependent Claims (12, 13, 14)
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Specification