Methods of and apparatus for the measurement of blood pressure
First Claim
1. The method of measuring blood pressure by the use of the arterial pressure pulses which accompany the temporary constriction of an artery by means of a compression cuff or the like, said method comprising the steps ofselecting, and storing signals corresponding to, a plurality of pulses which consist of the highest pulses in a group of said pressure pulses regardless of the order of their occurrence during said temporary constriction,detecting from said highest pulses a reference level, andthen providing outputs corresponding to the pressure exerted by the blood in said artery upon occurrence of first and second pulses in said group, respectively preceding and following at least one of said highest pulses, which first and second pulses bear certain amplitude relationships to first and second levels which are in predetermined proportional relationship with said reference level, the one of said outputs provided upon occurrence of said first pulse corresponding to the systolic blood pressure and the other of said outputs provided upon occurrence of said second pulse corresponding to the diastolic blood pressure.
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Abstract
Blood pressure is measured with the aid of a programmed data processor such as a microcomputer. Electrical signals are provided in response to the pressure in a blood pressure cuff as the pressure therein is changed to vary the constriction of an artery. The signals are processed to provide a train of pulses corresponding to successive blood pressure pulses and digital signals representing the amplitude of each pulse and the cuff pressure which accompanies each pulse are stored in the memories of the data processor. The processor has means by which the pulses are first selected in accordance with their relative amplitudes and location in the train so as to satisfy criteria for the rejection of artifacts. The processor provides outputs from its memories in which digital signals representing cuff pressures which were acquired at the same time as the pulses which are identified as occurring at the times of the systolic and diastolic events. These outputs may be displayed as on a digital readout device or processed for remote transmission so as to indicate the blood pressure. Information as to the pulse rate may be obtained from the time intervals between a group of pulses in the train by converting that time interval into a digital signal which represents the pulse rate. This signal may also be outputted to a display or for remote transmission.
142 Citations
65 Claims
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1. The method of measuring blood pressure by the use of the arterial pressure pulses which accompany the temporary constriction of an artery by means of a compression cuff or the like, said method comprising the steps of
selecting, and storing signals corresponding to, a plurality of pulses which consist of the highest pulses in a group of said pressure pulses regardless of the order of their occurrence during said temporary constriction, detecting from said highest pulses a reference level, and then providing outputs corresponding to the pressure exerted by the blood in said artery upon occurrence of first and second pulses in said group, respectively preceding and following at least one of said highest pulses, which first and second pulses bear certain amplitude relationships to first and second levels which are in predetermined proportional relationship with said reference level, the one of said outputs provided upon occurrence of said first pulse corresponding to the systolic blood pressure and the other of said outputs provided upon occurrence of said second pulse corresponding to the diastolic blood pressure.
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9. The method of obtaining information as to the vascular condition of a body comprising the steps of
producing a change in circulation through a blood vessel and generating electrical signals corresponding thereto, translating said signals into a train of pulses which correspond to the pressure pulsations in said blood vessel as said circulation changes, deriving from a plurality of pulses in said train which are of the highest amplitude pulses in said train and certain of which have predetermined amplitude relationship with respect to the pulse of highest amplitude in said plurality of pulses, a reference level corresponding to the average peak level thereof, detecting those of said pulses in said train having amplitudes which are approximately of amplitudes which are certain percentages of said reference level, and providing outputs representing said information from those of said electrical signals which are substantially coincidental with said pulses.
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19. The method of obtaining information as to blood pressure comprising the steps of
providing electrical signals corresponding to the constriction pressure exerted on a blood vessel as the constriction thereof is changed, translating said electrical signals into a train of successive pulses each corresponding to a successive pulsation of said vessel and having an amplitude which is a function of the pulsatile component of the blood pressure, translating said electrical signals into first digital signals each corresponding to a different one of said pulses in said train and representing the amplitude of said electrical signals when each of said pulses in said train occur, which first digital signals represent the constriction pressure on said vessel, storing all said first digital signals, storing all second digital signals representing the amplitudes of said pulses in said train, developing from said pulses in said train a reference level corresponding to the average of the amplitudes of a set of those of said pulses in said train which are of highest amplitude level regardless of where they occur in said train, identifying from said stored second digital signals first and second pulses in said train respectively having amplitudes at least equal to a systolic threshold level and a diastolic threshold level each of which are different percentages of said reference level, and displaying as systolic blood pressure and as diastolic blood pressure the values of said first digital signals respectively corresponding to said first pulse and to said second pulse.
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32. Apparatus for obtaining physiological information from the pressure exerted by a blood vessel which comprises
(a) means for producing a pair of electrical signals a first of which is a function of the pressure exerted by said blood vessel as a changing constricting pressure is applied thereto and a second of which is a function of the pulsatile component of said pressure and is in the form of a train of pulses each for a successive blood pressure pulse, (b) means for converting said first and second signals into first and second digital signals, (c) a programmed data processor responsive to said first and second digital signals having means for (1) acquiring and storing said first and second digital signals upon occurrence of each of said pulses and a group of said second digital signals of highest amplitudes, (2) locating one of said second digital signals the value of which has a certain relationship to the average of the peak value of a plurality of the second digital signals in said group, and was acquired after a member of said second digital signals in said group when said constricting pressure changes in a decreasing sense and before said member of second digital signals in said group when said constricting pressure changes in an increasing sense, (3) producing an output corresponding to the value of said first digital signal which is acquired for the same one of said pulses in said train as said one of said second digital signals to represent the diastolic blood pressure.
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40. Apparatus for obtaining information as to the vascular condition of a body comprising
means for producing a change in circulation through a blood vessel and generating electrical signals corresponding thereto, means for translating said signals into a train of pulses which correspond to the pressure pulsations in said blood vessel as said circulation changes, means for deriving from a plurality of pulses in said train which are of the highest amplitude and certain of which have predetermined amplitude relationships with the pulse of highest amplitude in said plurality of pulses a reference level corresponding to the average peak level thereof, means for detecting those of said pulses in said train having amplitudes which are approximately of amplitudes which are certain percentages of said reference level, and means for providing outputs representing said information from those of said electrical signals which are substantially coincidental with said pulses.
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50. Apparatus for obtaining information as to the vascular condition of a body comprising
means for producing a change in circulation through a blood vessel and generating electrical signals corresponding thereto, means for translating said signals into a train of pulses which correspond to the pressure pulsations in said blood vessel as said circulation changes, means for selecting certain pulses in said train which comprises an envelope detector for providing an output signal which follows the peaks of the pulses in said train, a peak detector which provides an output signal having an amplitude corresponding to the peak amplitude of that envelope detector output signal, multiplier means for providing a systolic threshold level which is a certain percentage of said peak detector signal level and a diastolic threshold level which is another percentage of said peak detector output level, comparators for outputting trigger signals when said envelope reaches said systolic reference level and said diastolic threshold level, respectively, and means for providing outputs representing said information includes means operated by said trigger signals for producing as said outputs, signals corresponding to the amplitude of said electrical signals which correspond to the circulation through said blood vessel upon occurrence of said systolic trigger signal and upon occurrence of said diastolic trigger signal, the amplitude of said electrical signals produced upon occurrence of said systolic trigger signal being a measure of the systolic blood pressure in said vessel and the amplitude of said electrical signal produced upon occurrence of said diastolic trigger being a measure of the diastolic blood pressure in said blood vessel.
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51. Apparatus for obtaining information as to blood pressure comprising
means for providing electrical signals corresponding to the constriction pressure exerted on a blood vessel as the constriction thereof is changed, means for translating said electrical signals into a train of successive pulses each corresponding to a successive pulsation of said vessel and having an amplitude which is a function of the pulsatile component of the blood pressure, means for translating said electrical signals into first digital signals each corresponding to a different one of said pulses in said train and representing the amplitude of said electrical signals when each of said pulses in said train occur, which first digital signals represent the constriction pressure on said vessel, means for storing all said first digital signals, means for storing all second digital signals representing the amplitudes of said pulses in said train, means for developing from said pulses in said train a reference level corresponding to the average of the amplitudes of a set of those of said pulses in said train which are of highest amplitude level regardless of where they occur in said train, means for identifying from said stored second digital signals first and second pulses in said train respectively having amplitudes at least equal to a systolic threshold level and a diastolic threshold level each of which are different percentages of said reference level, and means for displaying as said systolic blood pressure and as said diastolic blood pressure the values of said first digital signals respectively corresponding to said first pulse and to said second pulse.
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64. The method of measuring blood pressure by the use of the arterial pressure pulses of varying amplitude which accompany the temporary constriction of an artery by means of a compression cuff or the like, said method comprising translating said pulses into corresponding electrical signals, storing digital signals corresponding to the amplitudes of said electrical signals, deriving from said stored digital signals a reference level related to at least one of said digital signals which corresponds to a pressure pulse of highest amplitude and a predetermined threshold level which is less than said reference level, selecting a plurality of said stored signals corresponding to a plurality of successive ones of said pulses the amplitudes of which and said threshold bear a predetermined relationship with each other, and then providing an output corresponding to the pressure exerted by the blood in said artery upon occurrence of a selected one of said plurality of successive ones of said pulses.
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65. A system for measuring blood pressure by the use of the arterial pressure pulses of varying amplitude which accompany the temporary constriction of an artery by means of a compression cuff or the like, said system comprising means for translating said pulses into corresponding electrical signals, means for storing digital signals corresponding to the amplitudes of said electrical signals, means for deriving from said stored digital signals a reference level related to at least one of said digital signals corresponding to a pressure pulse of highest amplitude and the predetermined threshold level which is less than said reference level, means for selecting a plurality of said stored signals corresponding to a plurality of successive ones of said pulses, the amplitudes of which and said threshold level bear a predetermined relationship, and means for providing an output corresponding to the pressure exerted by the blood in said artery upon occurrence of a selected one of said successive ones of said plurality of pulses.
Specification