Method for determining flush interference in measurement of chemical and physical parameters with indwelling probe
First Claim
1. A method for detecting an interference during an in vivo measurement of at least one parameter sensed by an indwelling probe, where the interference is caused by introducing a flush fluid proximate said probe, comprising the steps of:
- (a) periodically measuring at least one parameter using the indwelling probe, an accuracy with which said parameter is measured being affected by the flush fluid, wherein the step of measuring at least one parameter comprises measurement of at least a pH and a pCO2 ;
(b) determining a time rate of change of the measured parameter, wherein the step of determining a time rate of change comprises the step of determining a time rate of change of a base excess value calculated using the measured pH and the measured pCO2 ;
(c) comparing the time rate of change of the measured parameter with a predefined threshold time rate of change; and
(d) activating a warning device if the time rate of change of the measured parameter exceeds the predefined threshold time rate of change to indicate that the flush fluid has substantially affected the accuracy with which the parameter has been measured.
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Accused Products
Abstract
A system (10) for in vivo measuring chemical and physical parameters of a patient'"'"'s blood includes a probe (12), a sensing system (14), and flush interference warning devices (20). The system measures pH, pCO2, and temperature values, and determines a base excess value using the measured pH and pCO2. The time rate of change of the base excess value is also determined, as is the time rate of change of temperature. The warning devices are activated, indicating that the measured parameters are likely affected by the presence of flush solution flowing past the probe, when either: (a) the base excess value is less than a predefined threshold base excess; (b) the absolute value of the time rate of change of the base excess value is greater than a predefined threshold time rate of change of base excess; or, (c) the absolute value of the time rate of change of temperature is greater than a predefined threshold time rate of change of temperature.
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Citations
16 Claims
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1. A method for detecting an interference during an in vivo measurement of at least one parameter sensed by an indwelling probe, where the interference is caused by introducing a flush fluid proximate said probe, comprising the steps of:
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(a) periodically measuring at least one parameter using the indwelling probe, an accuracy with which said parameter is measured being affected by the flush fluid, wherein the step of measuring at least one parameter comprises measurement of at least a pH and a pCO2 ; (b) determining a time rate of change of the measured parameter, wherein the step of determining a time rate of change comprises the step of determining a time rate of change of a base excess value calculated using the measured pH and the measured pCO2 ; (c) comparing the time rate of change of the measured parameter with a predefined threshold time rate of change; and (d) activating a warning device if the time rate of change of the measured parameter exceeds the predefined threshold time rate of change to indicate that the flush fluid has substantially affected the accuracy with which the parameter has been measured. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for detecting an interference during the in vivo measurement of a parameter using an indwelling probe, where said interference is caused by introducing a flush fluid proximate said probe, comprising the steps of:
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(a) periodically measuring a pH and a pCO2 using said probe; (b) determining a base excess value using the measured pH and measured pCO2 ; (c) comparing the base excess value to a predefined threshold base excess; and (d) activating a warning device if the base excess value is less than the predefined threshold base excess. - View Dependent Claims (9, 10)
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11. A method for detecting an interference during an in vivo measurement of a parameter using an indwelling probe, where said interference is caused by introducing a flush fluid proximate said probe, comprising the steps of:
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(a) periodically measuring a temperature with the probe; (b) determining an absolute value of the time rate of change of the measured temperature; (c) comparing the absolute value of the time rate of change of the measured temperature with a predefined threshold time rate of change of temperature; and (d) activating a warning device if the absolute value of the time rate of change of measured temperature is greater than the predefined threshold time rate of change of temperature.
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12. In a system for in vivo monitoring a plurality of parameters of a patient'"'"'s blood, apparatus for providing a warning when a flush fluid interferes with the accuracy with which said plurality of parameters are monitored, comprising:
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(a) a probe for sensing a pH and a pCO2 in the blood, producing a pH signal and a pCO2 signal that are respectively indicative thereof; (b) means coupled to the probe to receive the pH and pCO2 signals, for determining a measured pH and measured pCO2 in response to said signals, and for determining a base excess value using the measured pH and measured pCO2 ; (c) means for comparing the base excess value to a predefined threshold base excess; (d) a warning device; and (e) means for activating the warning device if the base excess value is less than the predefined threshold base excess. - View Dependent Claims (13, 14, 15)
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16. A method for detecting an interference during an in vivo measurement of at least one parameter sensed by an indwelling probe, where the interference is caused by introducing a flush fluid proximate said probe, comprising the steps of:
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(a) periodically measuring at least one parameter using the indwelling probe, an accuracy with which said parameter is measured being affected by the flush fluid, wherein the step of measuring at least one parameter comprises measurement of a pH; (b) determining a time rate of change of the measured parameter, wherein the step of determining a time rate of change comprises determining the time rate of change of the measured pH; (c) comparing the time rate of change of the measured parameter with a predefined threshold time rate of change; and (d) activating a warning device if the time rate of change of the measured parameter exceeds the predefined threshold time rate of change to indicate that the flush fluid has substantially affected the accuracy with which the parameter has been measured.
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Specification