Method for determining hemodynamic effects
First Claim
1. A method of assessing changes in stroke volume or cardiac output of a ventilated subject, the method comprising:
- sensing pressure in the ventilated subject'"'"'s airway during at least one breathing cycle comprising an inhalation and an exhalation with an airway sensor;
sensing a blood volume in the ventilated subject during the at least one breathing cycle with a blood volume sensor;
producing a photoplethysmogram spanning the at least one breathing cycle using the blood volume sensed by the blood volume sensor;
determining, with a breathing assistance system, a ratio of the amplitude of the photoplethysmogram during inhalation to the amplitude of the photoplethysmogram during exhalation; and
determining, with the breathing assistance system, a change in cardiac output or stroke volume of the subject using the determined amplitude ratio.
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Accused Products
Abstract
The present disclosure relates, in some embodiments, to devices, systems, and/or methods for collecting, processing, and/or displaying stroke volume and/or cardiac output data. For example, a device for assessing changes in cardiac output and/or stroke volume of a subject receiving airway support may comprise a processor; an airway sensor in communication with the processor, wherein the airway sensor is configured and arranged to sense pressure in the subject'"'"'s airway, lungs, and/or intrapleural space over time; a blood volume sensor in communication with the processor, wherein the blood volume sensor is configured and arranged to sense pulsatile volume of blood in a tissue of the subject over time; and a display configured and arranged to display a representative of an airway pressure, a pulsatile blood volume, a photoplethysmogram, a photoplethysmogram ratio, the determined cardiac output and/or stroke volume, or combinations thereof. A method of assessing changes in cardiac output or stroke volume of a subject receiving airway support from a breathing assistance system may comprise sensing pressure in the subject'"'"'s airway as a function of time, sensing pulsatile volume of blood in a tissue of the subject as a function of time, producing a photoplethysmogram from the sensed pulsatile volume, determining the ratio of the amplitude of the photoplethysmogram during inhalation to the amplitude of the photoplethysmogram during exhalation, and determining the change in cardiac output or stroke volume of the subject using the determined ratio.
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Citations
20 Claims
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1. A method of assessing changes in stroke volume or cardiac output of a ventilated subject, the method comprising:
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sensing pressure in the ventilated subject'"'"'s airway during at least one breathing cycle comprising an inhalation and an exhalation with an airway sensor; sensing a blood volume in the ventilated subject during the at least one breathing cycle with a blood volume sensor; producing a photoplethysmogram spanning the at least one breathing cycle using the blood volume sensed by the blood volume sensor; determining, with a breathing assistance system, a ratio of the amplitude of the photoplethysmogram during inhalation to the amplitude of the photoplethysmogram during exhalation; and determining, with the breathing assistance system, a change in cardiac output or stroke volume of the subject using the determined amplitude ratio. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of assessing a relative strength of an autonomic neural response of a subject connected to a breathing assistance system, the method comprising:
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determining a cardiac output of the subject at a first airway pressure; changing the subject'"'"'s airway pressure to a second airway pressure via the breathing assistance system; monitoring the cardiac output of the subject at the second airway pressure; comparing, with the breathing assistance system, the cardiac output of the subject at the second airway pressure with the cardiac output of the subject at the first airway pressure; measuring a time required for the cardiac output of the subject at the second airway pressure to return to the cardiac output of the subject at a first airway pressure; comparing, with the breathing assistance system, the required time to a reference time; and determining, with the breathing assistance system, the relative strength of an autonomic neural response of the subject using the comparing of the required time to the reference time. - View Dependent Claims (12, 13, 14)
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15. A processor comprising memory and a device, wherein the memory stores logic instructions and the device-executes the logic instructions stored on the memory, the logic instructions comprising:
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instructions to produce a photoplethysmogram spanning at least one breathing cycle using processed sensor input; instructions to determine a ratio of an amplitude of the photoplethysmogram during inhalation to an amplitude of the photoplethysmogram during exhalation; and instructions to determine a change in cardiac output or stroke volume of a subject using the determined ratio. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification