Noise-immune blood pressure measurement technique and system
First Claim
1. A method for the non-invasive sensing of the diastolic and systolic blood pressures of a patient, said method comprising the steps of:
- installing a proximal occlusion bladder and a distal sensing bladder on a limb of the patient;
inflating said occlusion and sensing bladders;
allowing said occlusion bladder to deflate controllably over time;
monitoring a pressure in the sensing bladder;
filtering out blood pulses from the monitored pressure to obtain a filtered pressure;
determining when the filtered pressure in the sensing bladder reaches a minimum, and identifying the pressure in the occlusion bladder at that time as the systolic pressure;
determining when the filtered pressure in the sensing bladder passes through an inflection point, and identifying the pressure in the occlusion bladder at that time as the mean arterial pressure; and
calculating the diastolic pressure from said systolic and means arterial pressures.
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Accused Products
Abstract
An apparatus and method for non-invasive, noise insensitive blood pressure determination which is useful in a battlefield or emergency vehicle environment. The system features an occlusion bladder and a sensing bladder both adapted to fit over the limb of a patient. The pressure in the occlusion bladder is raised to a value which prevents flow and is then gradually decreased. The pressure in both bladders is monitored. When the pressure in the sensing bladder reaches a minimum value, the pressure in the occlusion bladder is equal to the systolic pressure. The first, second, and third time derivatives of the pressure in the sensing bladder are monitored. The first derivative is useful in identifying the minimum in the pressure in the sensing bladder. When the third time derivative of the pressure in the sensing bladder passes through zero, the pressure in the occlusion bladder is equivalent to the mean arterial pressure. The diastolic pressure can be calculated from the values of the systolic and mean arterial pressures.
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Citations
28 Claims
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1. A method for the non-invasive sensing of the diastolic and systolic blood pressures of a patient, said method comprising the steps of:
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installing a proximal occlusion bladder and a distal sensing bladder on a limb of the patient; inflating said occlusion and sensing bladders; allowing said occlusion bladder to deflate controllably over time; monitoring a pressure in the sensing bladder; filtering out blood pulses from the monitored pressure to obtain a filtered pressure; determining when the filtered pressure in the sensing bladder reaches a minimum, and identifying the pressure in the occlusion bladder at that time as the systolic pressure; determining when the filtered pressure in the sensing bladder passes through an inflection point, and identifying the pressure in the occlusion bladder at that time as the mean arterial pressure; and calculating the diastolic pressure from said systolic and means arterial pressures. - View Dependent Claims (2, 3, 4, 5)
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6. A system for non-invasive, substantially noise-immune measurement of the blood pressure of a patient, comprising:
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first cuff means for occluding blood flow in a limb of the patient; second cuff means for sensing pressure in the limb and disposed between said first cuff means and the distal end of the limb; means for monitoring the pressure in said first cuff means; means for monitoring the pressure in said second cuff means; means for reducing the pressure in said first cuff means at a predetermined rate; means for filtering out blood pulses from the monitored pressure in the second cuff means to obtain a filtered pressure; means for monitoring the time rate of change of the filtered pressure in said second cuff means, and for determining when said filtered pressure in said second cuff means passes through a minimum value and when said filtered pressure in said second cuff means exhibits an inflection point; and means for associating element values of the pressure in said first cuff means at the time at which the filtered pressure in said second cuff means passes through said minimum value and said inflection point which the systolic and mean arterial blood pressures of the patient, respectively. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A non-invasive method of measuring blood pressure without detecting a pulse, comprising the steps of:
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occluding a limb of a patient by applying pressure thereto; releasing the pressure to the limb; filtering out blood pulses from and measuring a filtered blood volume in the limb as the pressure in the limb is released; and determining blood pressure from the filtered blood volume. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20)
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21. A non-invasive, noise immune method of measuring the blood pressure of a patient not requiring detection of pulses in the blood flow comprising the steps of:
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occluding the limb of a patient by applying occlusion pressure thereto; gradually releasing the pressure applied to the limb; monitoring the occlusion pressure as a function of time; monitoring the pressure sensed in a bladder about the limb; filtering out blood pulses from said monitored sensed pressure; and determining the patient'"'"'s systolic, diastolic and mean arterial pressures from said filtered pressure. - View Dependent Claims (22, 23, 24, 25)
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26. A method of detecting the mean arterial pressure of a patient, comprising the steps of:
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occluding a limb of the patient by applying pressure thereto; gradually releasing pressure to said limb; monitoring pressure in said limb downstream of the point at which said pressure is applied; filtering out blood pulses from the monitored pressure to obtain a filtered pressure; monitoring the sensed filtered pressure as a function of time to locate an inflection point therein; and determining the mean arterial pressure based upon location of said inflection point. - View Dependent Claims (27, 28)
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Specification