Blood pressure measurement apparatus
First Claim
1. Blood pressure measurement apparatus using an inflatable cuff which constricts an appendage of a subject whose blood pressure is to be measured, said apparatus comprising means for changing the pressure in the cuff, means for sensing the auscultatory sounds from the appendage while the pressure in the cuff is changing, means for producing a signal having an amplitude which corresponds with the pressure in the cuff, valve means for modulating the pressure in the cuff as the pressure changes during the sensing of said auscultatory sounds, and means for controlling said valve means to linearize the change in pressure in said cuff which comprises means for generating a reference, linear ramp signal, which starts prior to the sensing of said auscultatory sounds, means for comparing said reference signal with said pressure signal to produce a first output corresponding to the difference in amplitude therebetween, means for generating a train of repetitive triangular waves each having a period much less than the duration of said ramp signal, means for comparing such repetitive triangular waves with said first output to produce a train of pulses, the durations of the pulses varying in accordance with the magnitude and sense of deviation of said pressure signal from said linear ramp signal, and means for applying said variable duration pulses to said valve means for opening and closing said valve means in accordance with the duration of the pulses in said pulse train such that the pressure in said cuff changes linearly in amplitude, correspondingly with said ramp signal.
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Accused Products
Abstract
Long-term blood pressure measuring apparatus, particularly adapted for ambulatory blood pressure monitoring where the subject can be engaged in normal activities while blood pressure is being measured and to be worn by the subject whose blood pressure is to be measured uses an inflatable cuff, a pump for inflating the cuff, valves for controlling the pressure in the cuff, sensors for the cuff pressure and for auscultatory (Korotkoff) sounds from the subject, a recorder for recording the sounds and blood pressure measurement cycle control circuits. The control circuits provide for blood pressure measurement cycles to recur repetitively at predetermined time intervals, for example every 30 or 60 minutes over a period of many hours, as well as when the subject manually activates the cycle control circuit to produce a blood pressure measurement cycle, but only when an automatic cycle occurs between successive manual cycles so as to limit the frequency of the blood pressure measurement so as to prevent harm to the subject and to conserve power needed for long-term operation of the apparatus. Circuits which control a valve use a linear ramp generator and triangular wave generator to provide a linear change in cuff pressure while the auscultatory sounds are recorded to enable accuracy of indication of the blood pressure from the recorded sounds.
59 Citations
21 Claims
- 1. Blood pressure measurement apparatus using an inflatable cuff which constricts an appendage of a subject whose blood pressure is to be measured, said apparatus comprising means for changing the pressure in the cuff, means for sensing the auscultatory sounds from the appendage while the pressure in the cuff is changing, means for producing a signal having an amplitude which corresponds with the pressure in the cuff, valve means for modulating the pressure in the cuff as the pressure changes during the sensing of said auscultatory sounds, and means for controlling said valve means to linearize the change in pressure in said cuff which comprises means for generating a reference, linear ramp signal, which starts prior to the sensing of said auscultatory sounds, means for comparing said reference signal with said pressure signal to produce a first output corresponding to the difference in amplitude therebetween, means for generating a train of repetitive triangular waves each having a period much less than the duration of said ramp signal, means for comparing such repetitive triangular waves with said first output to produce a train of pulses, the durations of the pulses varying in accordance with the magnitude and sense of deviation of said pressure signal from said linear ramp signal, and means for applying said variable duration pulses to said valve means for opening and closing said valve means in accordance with the duration of the pulses in said pulse train such that the pressure in said cuff changes linearly in amplitude, correspondingly with said ramp signal.
- 16. Longterm, portable blood pressure monitoring apparatus, for use with an inflatable cuff which is applied to the appendage of the subject whose blood pressure is to be measured, said apparatus comprising means including a pump for inflating said cuff, transducer means for sensing the pressure in said cuff, means for detecting auscultatory sounds from the appendage to which said cuff is applied, means for recording said sounds, means for producing successive first commands at predetermined periods of time for initiating automatically blood pressure measurement cycles at predetermined intervals, means operable manually by the subject for producing upon each operation a second command for initiating manually a blood pressure measurement cycle, means for controlling said blood pressure measurement cycle by operating said pump until the pressure in said cuff reaches a predetermined pressure above the systolic pressure of the subject, said pump being started at the beginning of said cycle and said cuff being deflated below the diastolic pressure of the subject at the end of said cycle, and for operating said recording means during said cycle, means in said cycle control means for producing a measurement cycle upon occurrence of each of said first commands, and means in said cycle control means for producing a measurement cycle upon occurrence of said second command which do not recur with more than a certain frequency.
Specification