Method and apparatus for automatically determining pulse rate and diastolic and systolic blood pressure

A device for detecting arterial pulsations for utilization in a system for determining pulse rate and systolic and diastolic blood pressure including an outer, rigid, cylindrical shell to encircle a portion of a subject's body, a first cuff including a substantially flat, flexible, inflatable, bladder, encircled and secured to a first portion of the inside circumference of said shell to engage said body portion and a second cuff including a substantially flat, flexible, inflatable, bladder, encircled and secured to a second portion of the inside circumference of said shell to engage said body portion, a first tubular member having a first and second end, said first end of said first tubular member engaging the interior of said first bladder in a fluid-tight manner, said second end of said first tubular member in fluid communication with a means for increasing and decreasing pressure in said first and second bladders, a second tubular member having a first and second end, said first end of said second tubular member engaging the interior of said second bladder in a fluid-tight manner, said second end of said second tubular member in fluid communication with said means for increasing and decreasing pressure in said first and second bladders, a pressure control means cooperable with said means for increasing and decreasing pressure in said first and second bladders and said interior of said second bladder to control pressure in said second and first bladders, the improvement comprising a first sensor in fluid communication with said first bladder and responsive to arterially-induced pressure pulsations in said first bladder for generating a first electrical signal having an amplitude corresponding to said pulsations in first said bladder, said first sensor comprising a first pressure transducer chamber and a first pressure transducer, said first pressure transducer having an arterial pulsation sensing end in fluid communication with the interior of said first bladder to detect arterially-induced pressure pulsations in said first bladder and to generate a first electrical signal having an amplitude corresponding to said pulsations in first bladder and a non-sensing end of said first pressure transducer in fluid communication with the interior of said first chamber in a fluid-tight manner, a first pressure equalization passageway in said first chamber in fluid communication with the interior of said first bladder and the interior of said first pressure transducer chamber, said first pressure equalization passageway of a sufficient size to allow equalization of pressure between said first bladder and said first chamber sufficiently to substantially reduce inflation pressure from impending upon said first pressure transducer without interfering with detection of said arterially-induced pressure pulsations by said first pressure transducer thereby eliminating any interference of inflation pressure with detection of arterially-induced pressure pulsations in said first bladder by said first pressure transducer, a second sensor in fluid communication with said second bladder and responsive to arterially-induced pressure pulsations in said second bladder for generating a second electrical signal having an amplitude corresponding to said second bladder pulsations, said second sensor comprising a second pressure transducer chamber and a second pressure transducer, said second pressure transducer having an arterial pulsation sensing end in fluid communication with the interior of the second bladder to detect arterially-induced pressure pulsations in said second bladder and generate a second electrical signal having an amplitude corresponding to said second bladder pulsations and a non-sensing end of said second pressure transducer in fluid communication with the interior of said second chamber in a fluid-tight manner, a second pressure equalization passageway through a wall in said second chamber in fluid communication with the interior of said second bladder and the interior of said second pressure transducer chamber, said second pressure equalization passageway of a sufficient size to allow equalization of pressure between said second bladder and said second chamber sufficiently to substantially reduce inflation pressure from impending upon said second pressure transducer without interfering with detection of said arterially-induced pressure pulsations by said second pressure transducer thereby eliminating any interference of inflation pressure with detection of arterially-induced pressure pulsations in said second bladder by said second pressure transducer.

A method for automatically determining pulse rate and systolic and diastolic blood pressure of a subject including a device employing an automatic arterial pulsation monitoring cuff to encircle a portion of said subject's body containing at least a first and second selectively inflatable bladders each containing a sensor reponsive to arterially-induced pressure pulsations in said cuff for generating electrical signals having amplitudes corresponding to the pulsations in said bladders, said second bladder in fluid communication with a sensor responsive to pressure in said second bladder for generating electrical signals corresponding to the pressure in said second bladder, said bladders interconnected with a pressurizing system, all of said sensors connected electrically to a system for automatically processing the electrical signals from said sensors and automatically inflating and deflating the bladders and a means for calculating the pulse rate and the systolic and diastolic pressure of the human subject comprising the steps of:

• (a) positioning said first and second bladders in said cuff in relationship to each other such that said second bladder is an occluding bladder;
• (b) secondly simultaneously inflating at least said first and second bladders to a determined pressure at which inflation ceases and at which said second occluding bladder occludes blood flow resulting in said sensor in said first bladder sensing no arterially induced pressure pulsation amplitudes;
• (c) thirdly deflating said first and second bladders at a predetermined rate;
• (d) during steps (b) and (c) continuously generating electrical signals having an amplitude corresponding to the pulsations in the bladders and the pressure in said second bladder and measuring the time duration between each pulsation;
• (e) during steps (b) through (c) monitoring continuously said signals and said time durations;
• (f) during steps (b) through (c) storing said signals and said time durations;
• (g) fourthly terminating the deflating step (c) at a predetermined pressure and then releasing the pressure from said first and second bladders;
• (h) then processing said stored signals and said time durations to determine the subject's pulse rate, systolic blood pressure and diastolic blood pressure comprising the steps of:
• (1) first determining the systolic pressure of the subject by determining inflation pressure in the second bladder when a first pulsation is detected in said first bladder after deflation begins in step (c);
• (2) secondly, examininig amplitudes of all pulsations detected in said second bladder during step (c) and first determining an increase in amplitudes and then a decrease in amplitudes and then constant amplitudes, and then determining the diastolic pressure of the subject by determining the inflation pressure in said second bladder when a first pulsation at the beginning of the constant amplitudes is detected in said second bladder;
• and
• (3) examining the time duration between all pulsations during step (c) and then caculating the pulse rate of the subject.