Method and apparatus for metabolic monitoring
First Claim
1. A metabolic monitor for providing metabolic rate data obtained from inspiration and expiration gases of a patient intubated on a ventilator having an inspiration conduit for providing the inspiration gases from the ventilator to the patient, an expiration conduit for conducting the expiration gases from the patient to the ventilator, said expiration conduit having an exhalation valve in fluid communication with the expiration conduit and an exhaust port of the ventilator in fluid communication with the ambient atmosphere and the exhalation valve for venting the expiration gases to the ambient atmosphere, the monitor comprising:
- a first sample conduit means in fluid communication with the inspiration conduit for collecting a sample of the inspiration gases as provided by the ventilator;
a second sample conduit means in fluid communication with the expiration conduit for collecting an end-tidal sample of expiration gases as exhaled by the patient;
a third sample conduit means in fluid communication with the exhalation valve and the exhaust port for collecting an ambient pressure sample of the expiration gases from a point prior to complete mixing of the gases exhaled in adjacent breaths and such that the pressure is essentially ambient room air pressure;
selector means in fluid communication with the first, second and third sample conduit means for receiving said gas samples, and for selecting one of the gas samples for analysis; and
sensor means in fluid communication with said selector means for receiving a selected one of said gas samples, and operative to provide a signal indicative of a parameter of the selected gas sample related to metabolic rate of the patient.
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Accused Products
Abstract
A method and apparatus for measuring metabolic rates such as oxygen consumption and carbon dioxide elimination rates of a patient intubated on a ventilator utilize an inspiration sample of gases provided by the ventilator and end-tidal and ambient pressure samples of expiration gases exhaled by the patient which are collected and analyzed to determine concentrations of the gases along with flow rate data to calculate the desired metabolic rates on a breath-by-breath flow weighted average basis. The ambient pressure sample is taken from a point prior to complete mixing of the gases exhaled in adjacent breaths and after the exhalation valve such that the pressure is essentially ambient room air pressure to facilitate accurate sychronization of the flow rate and concentration signals.
305 Citations
19 Claims
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1. A metabolic monitor for providing metabolic rate data obtained from inspiration and expiration gases of a patient intubated on a ventilator having an inspiration conduit for providing the inspiration gases from the ventilator to the patient, an expiration conduit for conducting the expiration gases from the patient to the ventilator, said expiration conduit having an exhalation valve in fluid communication with the expiration conduit and an exhaust port of the ventilator in fluid communication with the ambient atmosphere and the exhalation valve for venting the expiration gases to the ambient atmosphere, the monitor comprising:
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a first sample conduit means in fluid communication with the inspiration conduit for collecting a sample of the inspiration gases as provided by the ventilator; a second sample conduit means in fluid communication with the expiration conduit for collecting an end-tidal sample of expiration gases as exhaled by the patient; a third sample conduit means in fluid communication with the exhalation valve and the exhaust port for collecting an ambient pressure sample of the expiration gases from a point prior to complete mixing of the gases exhaled in adjacent breaths and such that the pressure is essentially ambient room air pressure; selector means in fluid communication with the first, second and third sample conduit means for receiving said gas samples, and for selecting one of the gas samples for analysis; and sensor means in fluid communication with said selector means for receiving a selected one of said gas samples, and operative to provide a signal indicative of a parameter of the selected gas sample related to metabolic rate of the patient. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A metabolic monitor for providing metabolic data obtained from inspiration and exhaled gases of a patient intubated on a ventilator of the kind having an inspiration conduit that carries the inspiration gases to the patient, an exhaust port and an expiration conduit that carries the exhaled gases from the patient back through the ventilator to the exhaust port without completely mixing the gases exhaled in one breath with the gases exhaled in an adjacent breath, the expiration conduit having a first extremity adapted to receive the exhaled gases from the patient and a second extremity in fluid communication with the exhaust port, the monitor comprising:
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a first sample conduit means in fluid communication with the inspiration conduit for collecting a sample of the inspiration gases; a second sample conduit means in fluid communication with the expiration conduit adjacent the first extremity for collecting an end-tidal sample of the expired gases; a third sample conduit means in fluid communication with the expiration conduit adjacent the second extremity and operative to an ambient pressure sample of the expired gases; selector means in fluid communication with the first, second and third sample conduit means for receiving and for selecting one of the gas samples for analysis; and sensor means in fluid communication with said selector means for receiving a selected one of said gas samples and operative to provide a signal indicative of a parameter of the selected gas sample related to metabolic rate of the patient. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of providing metabolic data obtained from inspiration and expiration gases of a patient intubated on a ventilator having an expiration conduit for receiving said expiration gases from the patient and an exhalation valve in said expiration conduit for venting said expiration gases to the ambient atmosphere, the method comprising:
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collecting a sample of said inspiration gases as provided by the ventilator; collecting an end-tidal sample of said expiration gases as exhaled by the patient; collecting an ambient pressure sample of the expiration gases from a point in said expiration conduit prior to complete mixing of the gases exhaled in adjacent breaths and after the exhalation valve such that the pressure is essentially ambient room air pressure; selecting one of the gas samples for analysis; and determining a parameter of the selected sample related to metabolic rate of the patient. - View Dependent Claims (16, 17, 18, 19)
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Specification