US3874368A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Impedance plethysmograph having blocking system
Assignee: Individual
•
Filing: 1973-04-19
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Granted: 1975-04-01
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Expires: 1993-04-19
Abstract
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.
Inventors
- 👤 Manfred Asrican
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 15:14
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/02; A61B5/026; A61B5/0295; A61B5/72; A61B5/7235; A61B5/7239
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
68 words
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.
Claim 2
Dependent Claim
68 words
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.
Claim 3
Dependent Claim
112 words
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.
Claim 4
Dependent Claim
112 words
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.
References Cited (Backward Citations)
US3171892A
Cited
US3760796A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |