Impedance plethysmograph having blocking system
First Claim
1. In a plethysmograph of the type including means for measuring an impedance in a mammalian subject, means providing a first output corresponding to impedance changes of said measured impedance and means providing a second output corresponding to a time differential of said measured impedance, the improvement comprising a means responsive to said first output connected to inhibit said second output when said first output exceeds a determined magnitude.
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Abstract
An impedance plethysmograph has an oscillator for applying constant current to the thorax of a patient. A detector circuit connected to the patient provides an output corresponding to thoracic impedance. Circuits responsive to detected impedance provide signals corresponding to change of impedance and the first time differential of impedance. Means are provided to block the differential signal when it is meaningless, for example, due to respiration.
108 Citations
2 Claims
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1. In a plethysmograph of the type including means for measuring an impedance in a mammalian subject, means providing a first output corresponding to impedance changes of said measured impedance and means providing a second output corresponding to a time differential of said measured impedance, the improvement comprising a means responsive to said first output connected to inhibit said second output when said first output exceeds a determined magnitude.
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2. In a plethysmograph for measuring cardiac output including a source of alternating constant current, electrode means for applying said constant current to a mammalian subject, amplifier and detector means, further electrode means for connecting said amplifier and detector means to the thorax region of said subject for producing an impedance signal corresponding to thoracic impedance, means responsive to said impedance signal for producing a first signal corresponding to the change of said thoracic impedance, and means responsive to said impedance signal for producing a second signal corresponding to the first time differential of said impedance;
- the improvement comprising means responsive to the amplitude of said first signal for blocking said second signal.
Specification
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- Resources
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Current AssigneeManfred Asrican
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Original AssigneeManfred Asrican
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InventorsAsrican, Manfred
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Primary Examiner(s)Kamm, William E.
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Application NumberUS05/352,426Time in Patent Office712 DaysField of Search128/2.6A,2.6B,2.6G,2.6R,2.1RB,2.1Z,2.5RUS Class Current600/526CPC Class CodesA61B 5/0535 Impedance plethysmography f...A61B 5/7239 using differentiation inclu...
