Rebreathing methods including oscillating, substantially equal rebreathing and nonrebreathing periods
First Claim
Patent Images
1. A differential Fick technique, comprising:
- inducing a change in effective ventilation of a subject for a first duration of time of approximately eighteen seconds to approximately forty-two seconds;
removing the change in effective ventilation for a second duration of time of approximately eighteen seconds to approximately forty-two seconds immediately following the first duration of time, wherein a transition between inducing the change and removing the change is gradual; and
obtaining measurements of at least one respiratory gas and of respiratory flow during both the first duration of time and the second duration of time.
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Abstract
A differential Fick technique including a first phase in which baseline breathing parameters may be established and a second phase in which a change in the effective ventilation of a patient is induced. The durations of the first and second phases may be substantially the same and may be abbreviated relative to the durations of comparable phases of previously known differential Fick techniques. The disclosed differential Fick technique also lacks a recovery period in which the respiratory parameters of a patient are permitted to return to “normal” levels.
48 Citations
81 Claims
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1. A differential Fick technique, comprising:
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inducing a change in effective ventilation of a subject for a first duration of time of approximately eighteen seconds to approximately forty-two seconds; removing the change in effective ventilation for a second duration of time of approximately eighteen seconds to approximately forty-two seconds immediately following the first duration of time, wherein a transition between inducing the change and removing the change is gradual; and obtaining measurements of at least one respiratory gas and of respiratory flow during both the first duration of time and the second duration of time. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A method for noninvasively determining at least one of a pulmonary capillary blood flow and a cardiac output of a subject, comprising:
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inducing a change in effective ventilation of the subject for a first period of time; removing the change in effective ventilation of the subject for a second period of time, which is substantially the same as the first period of time, immediately following inducing; and repeating inducing immediately following the second period of time. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method for noninvasively determining at least one of a pulmonary capillary blood flow and a cardiac output of a subject, comprising:
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evaluating respiration of the subject during a first phase in which a change in effective ventilation of the subject is induced for a first period of time; and evaluating respiration of the subject following removal of the change in effective ventilation of the subject;
the removal being effected for a second period of time immediately following the first period of time, the first and second periods of time each lasting for approximately eighteen seconds to approximately forty-two seconds;repeating the first phase immediately following the second period of time and evaluating respiration of the subject during repeating. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method for noninvasively estimating at least one of a pulmonary capillary blood flow and a cardiac output of a subject, comprising:
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evaluating respiration of the subject during a first ventilation state having a duration of approximately eighteen seconds to approximately forty-two seconds; evaluating respiration of the subject during a second ventilation state having a duration of approximately eighteen seconds to approximately forty-two seconds; and optimizing a duration of at least one of the first ventilation state and the second ventilation state. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52)
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53. A method for noninvasively estimating at least one of a pulmonary capillary blood flow and a cardiac output of a subject, comprising:
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evaluating respiration of the subject during a first ventilation state comprising rebreathing; evaluating respiration of the subject during a second ventilation state immediately following the first ventilation state; and evaluating respiration of the subject during another first ventilation state immediately following the second ventilation state, each of the first ventilation state, the second ventilation state, and the another first ventilation state having a duration of approximately eighteen seconds to approximately forty-two seconds. - View Dependent Claims (54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69)
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70. A differential Fick technique, consisting essentially of:
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a first phase in which a change in the effective ventilation of a subject is induced; and a second phase following the first phase and during which a change in the effective ventilation of the subject is not present, the first phase and the second phase having substantially the same duration, wherein the first and second phases are repeated in immediate sequence with one another. - View Dependent Claims (71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81)
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Specification