CO Technology
Cardiac Output (CO) refers to the amount of blood pumped by the heart to the surrounding circulation per minute, which reflects the function of the entire circulatory system and is an extremely important parameter indicator reflecting the cardiac function of patients, and can monitor the pumping function of the heart. It is one of the most important basic indicators to understand circulatory function in clinical practice, and it is an important indicator to reflect the cardiac function of patients, and the cardiac displacement of adults is generally 4 to 7 L/min. Through cardiac displacement and related parameters, a full set of hemodynamic indexes can be calculated to guide a variety of clinical treatment, including drugs, infusion, fluid, etc. In particular, it is of great value in the monitoring of cardiac function in various critical patients, major surgery, cardiac patients and hemodynamic unstable patients.
Basic principle of thermal dilution method: This system adopts the thermal dilution method, where a floating catheter is inserted into the heart from the superior vena cava, passes through the atrium and enters the pulmonary artery through the ventricle. The position of the catheter is shown in the figure. The thermal dilution method for measuring cardiac output is the instantaneous injection of a certain amount of physiological saline or glucose solution at a certain temperature into the heart (usually a solution at 0 ℃ or room temperature) at the injection end of the floating catheter. Due to the significant difference in injection temperature and blood temperature, the internal energy of the heart can change rapidly. However, under the influence of blood circulation, the blood temperature will quickly return to normal blood temperature, The high sensitivity thermistor located at the end of the floating catheter at the pulmonary artery can accurately record changes in bleeding temperature. This change in blood temperature can be described as a curve, known as the time thermal dilution curve. By analyzing this curve through relevant formulas and algorithms, cardiac output can be accurately calculated.
CO Technology一Advantage
Powerful System Security Design
1）Safety Design of Energy Release Control Module: Thermodilution monitoring of cardiac displacement requires a heat release device that controls a floating catheter that is in direct contact with the person and releases heat into the patient. Therefore, in order to ensure the safety of patients in clinical application, multiple control methods are used to control the energy release when controlling the heat release device: energy release control circuit, energy release timeout control circuit, and timeout hardware control circuit. Only when the triple control circuit meets the heating requirements, the total control circuit starts the heating circuit and begins to release heat. If there is a request to close the heat release, the system will immediately stop the work of the heat release device.
2）Design of Status Monitoring for Floating Tube Heat Release Device: If the catheter is placed outside and the blood is stationary without flow, the system cannot adjust the work of the heat release device through Tb feedback. In order to ensure the safety of patients, reliable control of the system and accurate measurement, the system must monitor the state of the heat release device of the floating catheter in continuous monitoring mode. It mainly includes monitoring the voltage and current flowing through the heat release at both ends of the floating conduit under the measurement condition, so that the changes in the working temperature of the heat release can be analyzed, and the changes in the released power and released energy can be obtained, and the energy release during the monitoring process can be accurately controlled.
Rich parameter calculation functions
With powerful and rich parameter calculation function, in the full set of hemodynamic parameters, in addition to the directly measured parameter indicators, more and more detailed hemodynamic parameter indicators can be obtained through the comprehensive calculation of patient information and direct measured parameters. The calculation method of the parameter indicators is based on the second edition of Edwards Critical Care Education published by Edwards Company and relevant literature on hemodynamic monitoring. The indicators of direct measurement are shown in the table. Through the indicators of direct measurement, a full set of hemodynamic parameters and oxygenation parameters can be calculated according to the corresponding formula.
Precision and accuracy assurance
This system is validated through a large number of clinical trials to ensure the accuracy of system measurements at the frontline level. In clinical validation experiments, a well-known company's online product is used as a reference device, and the selection requirement for the reference device is to support intermittent measurement of cardiac displacement using the standard thermal dilution method. Due to the particularity of measuring cardiac displacement, the two devices cannot be fully synchronized for measurement. Therefore, using this system and reference equipment to alternately measure the test subjects, record the data, and record all the states and data of this system.
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