Defibrillator with means for determining patient impedance and delivered energy
First Claim
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1. Patient defibrillator apparatus comprising:
- means for storing high voltage patient defibrillation energy;
patient electrode means coupled to said energy storage means for applying a defibrillation shock pulse to a patient;
first means coupled to said energy storage means for determining the magnitude of stored defibrillation energy to be applied to said patient electrode means;
second means coupled to said electrode means for sensing and holding the magnitude of the peak current applied to a patient during a defibrillation shock pulse;
third means coupled to said first means and said second means for determining the actual transthoracic resistance of a patient being defibrillated, in response to the magnitudes of stored defibrillation energy and peak current; and
fourth means coupled to said first means and said third means for determining the proportion of said stored defibrillation energy actually delivered to a patient during defibrillation.
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Abstract
A defibrillator apparatus applies defibrillation a shock pulse to a patient at a selected energy level. The peak current magnitude of the pulse is sensed and processed to produce an indication of the value of transthoracic load resistance presented by the patient during the pulse. Also produced is an indication of the energy actually delivered to the patient by the defibrillation pulse. An alarm is activated when patient transthoracic resistance exceeds a predetermined value, thereby to warn the operator to take corrective action before again attempting defibrillation.
71 Citations
14 Claims
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1. Patient defibrillator apparatus comprising:
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means for storing high voltage patient defibrillation energy; patient electrode means coupled to said energy storage means for applying a defibrillation shock pulse to a patient; first means coupled to said energy storage means for determining the magnitude of stored defibrillation energy to be applied to said patient electrode means; second means coupled to said electrode means for sensing and holding the magnitude of the peak current applied to a patient during a defibrillation shock pulse; third means coupled to said first means and said second means for determining the actual transthoracic resistance of a patient being defibrillated, in response to the magnitudes of stored defibrillation energy and peak current; and fourth means coupled to said first means and said third means for determining the proportion of said stored defibrillation energy actually delivered to a patient during defibrillation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. Apparatus for applying a preset quantity of stored defibrillation energy through a pair of electrodes to a patient comprising:
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means for sensing the magnitude of peak current applied to a patient through said electrodes during a defibrillation shock pulse; means responsive to said sensing means for normalizing said peak current magnitude to the square root of said preset quantity of stored defibrillation energy; means responsive to said normalizing means for correlating the normalized peak current magnitude to a specific value of patient transthoracic resistance based on predetermined valuations; means responsive to said correlating means for detecting when transthoracic resistance of a patient exceeds a predetermined threshold; and means responsive to said threshold detecting means for indicating poor contact between said electrodes and the patient. - View Dependent Claims (10, 11, 12, 13, 14)
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Specification