Apparatus and method for measuring cardiac output
First Claim
1. An apparatus for measuring cardiac output by a thermal dilution method, comprising:
- injection means for injecting an indicator into a blood vessel;
data setting means for manually inputting indicator data on the indicator prior to injection into the blood vessel;
measuring means for measuring injectate data on the indicator prior to injection into the blood vessel;
fault detection means for detecting that said measuring means is inoperative;
blood data detection means for detecting blood data on blood diluted by the indicator injected into the blood vessel;
integration means for integrating the blood data obtained by said blood data detection means to produce an integral value;
selection means for selecting the indicator data set by said setting means when said fault detection means detects that said measuring means is inoperative and otherwise selecting the injectate data, as selected data; and
cardiac output indication means for indicating cardiac output from the selected data and the integral value.
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Accused Products
Abstract
Disclosed is an apparatus for measuring a cardiac output on the basis of a dilution method. The measuring apparatus includes a switch for inputting a parameter or the like of an outer diameter or the like of a catheter, a probe for detecting the temperature of an injectate into the blood vessel by the dilution method, a switch for manually inputting the injectate temperature, a circuit for detecting non-connection of the probe, a circuit for selectively switching over the manually input injectate temperature data and the detected injectate temperature data, a catheter having an opening through which the indicator is injected, a first thermistor for measuring the temperature of the blood diluted by the indicator, and a second thermistor for detecting its heat balanced temperature obtained by being cooled by the blood, a circuit for detecting a variation in the blood temperature detected by the first thermistor and starting the integration of the area of a dilution curve in accordance with the theory of the dilution method, a circuit for continuously operating a cardiac output from the heat balanced temperature detected by the second thermistor, and a recording device for recording the continuously obtained cardiac outputs in the order in which they are operated.
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Citations
21 Claims
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1. An apparatus for measuring cardiac output by a thermal dilution method, comprising:
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injection means for injecting an indicator into a blood vessel; data setting means for manually inputting indicator data on the indicator prior to injection into the blood vessel; measuring means for measuring injectate data on the indicator prior to injection into the blood vessel; fault detection means for detecting that said measuring means is inoperative; blood data detection means for detecting blood data on blood diluted by the indicator injected into the blood vessel; integration means for integrating the blood data obtained by said blood data detection means to produce an integral value; selection means for selecting the indicator data set by said setting means when said fault detection means detects that said measuring means is inoperative and otherwise selecting the injectate data, as selected data; and cardiac output indication means for indicating cardiac output from the selected data and the integral value. - View Dependent Claims (2, 3, 4)
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5. An apparatus for measuring cardiac output by a thermal dilution method, having an automatic measurement starting function, comprising:
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blood data detecting means for outputting blood data on blood diluted by an indicator injected into a blood vessel; variation detection means for detecting variation in the blood data; comparison means for comparing the variation in the blood data with a predetermined value to determine whether the variation is at least as large as the predetermined value; integration means for performing integration of the blood data starting at a time subsequent to said comparison determining that the variation is at least as large as the predetermined value; integration period determination means for determining an integration period of the integration performed by said integration means in dependence upon the predetermined value and a peak value of the variation in the blood data detected by said variation detection means; integration stopping means for stopping the integration of the blood data at the end of the integration period; and cardiac output operating means for indicating a cardiac output from the integral value of the integration performed by said integration means. - View Dependent Claims (6, 7, 8, 9, 10)
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11. A cardiac output measuring apparatus, comprising:
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initial cardiac output measuring means for performing measurement of an initial cardiac output using a dilution method in a blood vessel at least once to obtain an initial cardiac output indication; blood flow velocity measuring means for measuring initial blood flow velocity data and subsequent blood flow velocity data nearby a portion of the blood vessel used by said initial cardiac output measuring means; means for independently generating a first memory pointer and a second memory pointer; memory means for storing the initial blood flow velocity data and the subsequent blood flow velocity data measured by said blood flow velocity measuring means, at a location indicated by said first memory pointer; data retrieving means for retrieving the initial blood flow velocity data and the subsequent blood flow velocity data using said second memory pointer; function operation means for generating a function representing a relation between the initial cardiac output indication obtained in dependence upon the dilution method and the initial blood flow velocity data obtained when the initial cardiac output is measured; cardiac output operation means for continuously indicating cardiac output repeatedly updated in dependence upon the function and the subsequent blood flow velocity data retrieved by said data retrieving means; and recording means for visually and retroactively recording the cardiac output indicated by said cardiac output operation means. - View Dependent Claims (12, 13, 14)
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15. An apparatus for continuously measuring relative changes in a cardiac output, comprising:
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blood flow velocity measuring means for measuring a blood flow velocity in a blood vessel; input means for inputting;
a cross-sectional area of the blood vessel where the blood flow velocity is measured; andcardiac output operation means for continuously indicating relative changes in the cardiac output which occur over time in dependence upon the cross-sectional area of the blood vessel and the blood flow velocity measured by said blood flow velocity measuring means.
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16. A measuring method for measuring cardiac output using a thermal dilution method, comprising the steps of:
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(a) storing, into a memory table prior to measuring the cardiac output, correction data on heat capacity of an indicator; (b) injecting the indicator into a blood vessel; (c) detecting blood data on blood diluted by the indicator injected in step (b); (d) retrieving the correction data from the memory table in dependence upon heat capacity data for the indicator; (e) calculating a time integration value using the blood data; and (f) indicating a cardiac output in dependence upon the time integration value and the correction data, in accordance with the thermal dilution method. - View Dependent Claims (17, 18, 19, 20, 21)
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Specification