Noise rejecting electronic sphygmomanometer and methods for measuring blood pressure
First Claim
1. In a sphygmomanometer having a cuff, a cuff inflating bladder and a bladder pressure measuring element, where the cuff is adapted for positioning around a patient'"'"'s limb, for measuring the patient'"'"'s blood pressure intensity by monitoring Korotkoff sounds as bladder pressure is slowly reduced from above systolic blood pressure, the improvement comprising:
- a first acoustical pickup disposed within the cuff and positioned relative to a patient'"'"'s brachial artery to pick up said Korotkoff sounds;
a second acoustical pickup disposed within the cuff and positioned away from the brachial artery to pick up background sounds;
transducing means associated with said pickups for producing a first electrical signal corresponding to the sounds received by the first pickup and a second electrical signal corresponding to the sounds received by the second pickup; and
electronic logic means connected to receive the first and second signals for providing an output at a first voltage level upon a comparison of said electrical signals when and only when there is a first electrical signal corresponding to Korotkoff sounds and no second electrical signal of comparable magnitude and for providing an output at a second voltage level except when said first output signal is provided.
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Accused Products
Abstract
A noise rejecting electronic sphygmomanometer comprises a conventional cuff-type sphygmomanometer having an inflatable bladder and pressure monitoring manometer connected thereto. A first microphone, having a sound pickup directed inwardly to be toward a patient'"'"'s arm when the cuff is installed thereabout, is provided for picking up Korotkoff sounds as the cuff is deflated and blood flow in a patient'"'"'s arm resumes. To avoid spurious indications caused by background sounds, a second microphone, having a pickup directed to pickup background noises, is also provided within the cuff. The outputs of both microphones are fed into electronic discrimination circuitry.
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Citations
29 Claims
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1. In a sphygmomanometer having a cuff, a cuff inflating bladder and a bladder pressure measuring element, where the cuff is adapted for positioning around a patient'"'"'s limb, for measuring the patient'"'"'s blood pressure intensity by monitoring Korotkoff sounds as bladder pressure is slowly reduced from above systolic blood pressure, the improvement comprising:
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a first acoustical pickup disposed within the cuff and positioned relative to a patient'"'"'s brachial artery to pick up said Korotkoff sounds; a second acoustical pickup disposed within the cuff and positioned away from the brachial artery to pick up background sounds; transducing means associated with said pickups for producing a first electrical signal corresponding to the sounds received by the first pickup and a second electrical signal corresponding to the sounds received by the second pickup; and electronic logic means connected to receive the first and second signals for providing an output at a first voltage level upon a comparison of said electrical signals when and only when there is a first electrical signal corresponding to Korotkoff sounds and no second electrical signal of comparable magnitude and for providing an output at a second voltage level except when said first output signal is provided. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A noise rejecting electronic sphygmamanometer which comprises:
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a. A flexible cuff adapted to be wrapped and fastened around a patient'"'"'s limb, b. an inflatable bladder disposed within a portion of said cuff, c. Means for inflating and deflating said bladder, whereby blood circulation in portions of a limb about which said cuff is wrapped and fastened may be stopped and may be subsequently restored, d. means connected to said bladder for measuring pressure therein, e. first and second microphones disposed in said cuff, said first microphone having a directional pickup portion directed toward a patient'"'"'s limb when said cuff is wrapped and fastened therearound, said first microphone pickup portion being adapted for positioning over a brachial artery, whereby Korotkoff blood sounds in said artery may be picked up thereby, said second microphone having a directional pickup portion directed to pick up background noises, f. electronic discriminating means for receiving electrical signals from said first and second microphones and for discriminating between the electrical means responsive to an output from the discriminating means to provide a detectable indication when and only when a sound is picked up by said first microphone pickup portion and is not picked up by the second microphone pickup portion. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A method of indicating when systolic and diastolic blood pressures are to be read from a pressure monitoring device connected to a cuff-type sphygmomanometer having an inflatable bladder, which comprises the steps of:
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a. installing a first microphone under said bladder and in a position to be over a brachial artery to pick up Korotkoff blood sounds when said sphygmomanometer is positioned about a patient'"'"'s limb, b. installing a second microphone, having a sound pickup positioned to pick up background noises, c. installing said sphygmomanometer on a patient'"'"'s limb and inflating said bladder until blood flow is stopped in the patient'"'"'s limb under and below said sphygmomanometer, d. releasing the pressure in said bladder slowly while monitoring the pressure therein on said pressure monitoring device, e. converting sounds picked up by said first and second microphones into electrical signals, f. comparing said electrical signals from said first and second microphones and causing a detectable indication when and only when said comparison indicates a strong probability that sounds picked up by said first microphone are Korotkoff blood sounds and not background sounds, g. reading a first pressure from said pressure monitoring device at the initial onset of said detectable indication, said first pressure being the systolic blood pressure, and h. reading a second pressure from said pressure monitoring device as pressure is further reduced in said bladder at the first cessation of said detectable indications, said second pressure being the diastolic blood pressure. - View Dependent Claims (25, 26, 27)
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28. A method for measuring systolic and diastolic blood pressures, using a cuff tupe sphygmomanometer having an inflatable bladder, which comprises the steps of:
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a. installing a first, blood-sound microphone, having a pickup under said bladder and in a position to be over a brachial artery to pick up Korotkoff blood sounds when said sphygmomanometer is positioned about a patient'"'"'s limb, b. installing a second noise microphone, under said bladder to pick up background noises, c. connecting a first pressure gauge and a first pressure shutoff valve to said bladder, d. connecting a second pressure gauge and a second pressure shutoff valve to said bladder, e. installing said sphygmomanometer about a patient'"'"'s limb and inflating said bladder until blood flow in the limb under and below said sphygmomanometer is stopped, f. releasing the pressure from said bladder slowly, g. converting sounds picked up by said first and second microphones into electrical signals, h. causing said first valve to close, thereby trapping pressure in said first gauge, the first time an electrical signal received from said first microphone is not coincident with an electrical signal received from said second microphone, i. causing said second valve to momentarily open, thereby admitting pressure to said second gauge, each time an electrical signal received from said first microphone is not coincident with an electrical signal received from said second microphone, and j. reading, when pressure in said bladder is substantially reduced, systolic blood pressure from said first gauge and diastolic blood pressure from said second gauge.
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29. A method for measuring systolic and diastolic blood pressures, using a cuff-type sphygmomanometer having an inflatable bladder, which comprises the steps of:
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a. installing a first blood-sound microphone under said bladder and in a position to be over a brachial artery to pick up Korotkoff blood sounds when said sphygmomanometer is positioned about a patient'"'"'s limb, b. installing a second, noise microphone under said bladder to pick up background noises, c. connecting a first pressure gauge and a first pressure shut-off valve to said bladder, d. connecting a second pressure gauge and a second pressure shut-off valve to said bladder, e. installing said sphygmomanometer about a patient'"'"'s limb and inflating said bladder until blood flow in the limb under and below said sphygmomanometer is stopped, f. releasing the pressure from said bladder slowly, g. converting sounds picked up by said first and second microphones into electrical signals, h. causing said first valve to close, thereby trapping pressure in said first gauge, the first time the ratio between magnitudes of electrical signals received from said first and second microphones exceeds a preselected level, i. causing said second valve to momentarily open, thereby admitting pressure to said second gauge, each time said ratio between magnitudes of electrical signals received from said first and second microphones exceeds said preselected level, and j. reading, when pressure in said bladder is substantially reduced, systolic blood pressure from said first gauge and diastolic blood pressure from said second gauge.
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Specification