| Hemodynamics refers to dynamics inside the blood circulation. According to the arterial mechanical environment, we can analyze the corresponding relationship between blood volume and blood pressure and blood flow velocity, as well as find the explanation of illness and evaluate the hemodynamic function. The study of hemodynamics help us to explain the regulation of blood flow and material interchange and the energy transfer. More importantly than all of that, it provide us a new way to safeguard human health.By detecting hemodynamic parameters, many cardiovascular diseases can be analyzed and judged. From a pathophysiological point of view, cardiovascular diseases exhibit sustained lesions, with the dangerous hemodynamic characteristics and hemodynamics is the key factor in vascular remodeling. From a treatment point of view, hemodynamic characteristics always changed by the vascular surgery, which will influence the long-term safety and effectiveness of cardiovascular surgery. Therefore, analysis of the patient’s hemodynamic characteristics guarantees the surgical planning and the postoperative effect.Hemodynamics involves many parameters, and the measuring method of them are also various. The traditional methods on clinic exist the problems of invasiveness and discontinuity. Although many hospitals have introduced some real-time hemodynamic monitoring equipment relied on import, the high price is difficult to accept by most of patients. In order to solve these problems, an indicator densitometry analysis method has been proposed based on the indicator-dilution method and near-infrared spectroscopy(NIRS), which realized the hemodynamic parameters measured noninvasively and continuously.The traditional indicator-dilution method is depend on injecting the indocyanine green(ICG). By regular blood sampling, ICG concentration curve in the blood system can be drawn. This article used near-infrared probe to emit near-infrared light at 660 nm, 735 nm, 805 nm and 940 nm wavelengths through the patient’s fingertip and capture the pulse wave signals of transmission light synchronously. By uploading the measured data, the upper computer would calculate pulse rate(PR) and oxygen saturation(Sp O2) of the patient, as well as ICG concentration. According to establish the ICG continuous concentration curve, cardiac output(CO) and circulating blood volume(CBV) could be calculated.The implement system is consisted of the pulse optical density sampling platform and the dynamic parameter monitoring software. When the system running, the finger-clip-pattern photoelectric sensor emit three wavelength light through a finger which is time-division driven by the sampling platform. By sampling and uploading the measuring signal, computer will realize the system control. The dynamic parameter monitoring software is designed by C# language. At the same time, it invoked the data processing function interface designed by MATLAB, and access the My SQL database to manage the patients’ information.The system function test and clinical comparison test have been taken to validate the function and measurement accuracy after the completion of system development. The system function test shows that the system can stalely realize the upper-lower computer communication and the pulse characteristic components extraction. Then the hemodynamic parameter will be continuous calculated. Finally, measurement results will be dynamically exit on the system window and save into the patient database. Comparing with the clinical instruments and methods, the clinical comparison test shows that the system can realize the accurate parameter measurement on Sp O2, PR, CO and CBV. |
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