The Clinical Utility of In-line Blood Monitoring Systems (CDI 500) during Cardiopulmonary Bypass
It is crucial to monitor certain physiological parameters such as pH, pCO2, K+, oxygen saturation, hematocrit, hemoglobin, and temperature. Blood gas monitoring is currently based upon traditional laboratory analyzers, which are known as the œgold standard for accuracy. These laboratory analyzers use sensor technology, which provide intermittent blood gas samples. The field of perfusion has made significant strides by developing innovative technology to improve methods. New technology, which uses continuous in-line blood gas management, allows obtaining results in real-time. The CDI 500 is an in-line blood gas monitoring system, which uses optical fluorescence technology, which continuously monitors and displays results. Fluorescence is a characteristic seen when molecules from an excited state fall to a lower state of energy. When this happens, light particles are emitted and the difference of the frequencies of light emission is how they are calculated. Dyes are placed within the shunt sensor of the CDI 500, which contains four micro sensors. These micro sensors allow readings for pH, pCO2, pO2, and K+. The cable head of the CDI 500 has LED lights, which allow the excitation of the dyes in the shunt sensor and the value is appropriately measured. The ABL800 Flex is a laboratory analyzer, which uses sensor technology: electrochemical and optical. This machine is capable of measuring the pH, blood gases, electrolytes, metabolites, and oximetry. The electrochemical sensor technology depends upon the potentiometric measuring principle, which is used for calculation of pH, pCO2, and electrolytes. The amperometric measuring principle pO2, glucose, and lactate values. The optical measuring principles depend upon a 128-wavelength spectrophotometer, which allows the calculated values of hemoglobin.
The purpose of this thesis is to validate the accuracy of the CDI 500 in-line blood monitoring system during cardiopulmonary bypass by comparing it to values derived from the hospital’s laboratory, which uses the ABL800 Flex. This study will compare pH, pCO2, pO2, HCO3, BE, SaO2, HCT, Hb, SVO2, and K+. The research will also compare a cost analysis between the CDI 500 and ABL800 Flex. It is important to analyze the accuracy of results obtained from the CDI 500 and compare it to the traditional gold standard because critical information such as blood gas samples are important to the patient’s health and can not be compromised.
If the hypothesis is significantly supported, this will positively impact perfusion parameters. The CDI 500 is highly beneficial during CPB because it provides the perfusionist with real time blood gas values. With the ABL800 Flex, the perfusionist may not be aware of the blood gas values when they are not in the proper physiological range, thereby causing a delay to respond to the patient’s needs. Since the CDI 500 displays the current blood gas values, it may decrease chances of damage to the patient by determining the appropriate mechanism of action based upon the current physiological variations. The CDI 500 is also more convenient since the perfusionist is able to monitor blood gas values during CPB without having to step away. It is also more cost efficient compared to the ABL800 Flex.
As mentioned above, it is crucial to have accurate blood gas values during CPB. The current method of analysis for blood gas monitoring uses the laboratory analyzers. However, there is controversy over the accuracy of the CDI 500. The statement of problem is that CDI 500 has always been suspect in terms of accuracy in clinical uses. Most clinical perfusionists do not have confidence in the accuracy of the in-line blood gas monitoring system compared to the traditional laboratory analyzer.
The CDI 500 blood gas values will be accurate when compared with the values derived from the ABL800 Flex. There will be no significant difference between the two values, which will validate the importance of the CDI 500.
MATERIALS AND METHODS
The values of the CDI 500 and ABL800 Flex will be compared and measured as follows. Blood gas samples will be obtained during CPB. One set of blood gas (arterial and venous) value readings will be taken from the ABL800 Flex and compared with the CDI 500 values. One limitation exercised in this experiment is that only values, which fall within a five-minute duration of the reading taken from the ABL800 Flex and CDI 500 will be used. This will assure the accuracy of the CDI 500 based upon the laboratory analyzer. By keeping a five-minute or less range, it will assure the blood gas values will not fluctuate significantly. The CDI 500 shunt sensor is calibrated once before each case. CDI 500 blood gas values are stored and calibrated to hospital laboratory values every hour during CPB. There will be a total of 40 blood gas samples taken. The following values on the CDI500 correlate to arterial blood gases: pH, PCO2, PO2, HCO3, BE, and SaO2. Therefore, will be compared to arterial blood gases from the ABL800 Flex/ Hospital Laboratory. The following values on the CDI500 correlate to venous blood gases: Hct, Hg, and SvO2. Therefore, will be compared to venous blood gases from the ABL800 Flex/ Hospital Laboratory. From the results obtained, calculations will be made. The following statistical analysis will be done: the mean differences, standard deviations, pearson correlation, t-test, absolute differences between values. The absolute difference between the two values will be found according to:
Example for pH:
Absolute Difference = |Lab [pH] “ CDI 500 [pH]|
The [pH] percentage error was then calculated according to:
Percent Error = Absolute Difference
In order to support the hypothesis, two landmark papers with common data points for a meta-analysis has been made (The Effects of Continuous Blood Gas Monitoring During Cardiopulmonary Bypass: A Prospective, Randomized Study-Part I and CDI Blood Parameter Monitoring System 500-A New Tool for the Clinical Perfusionist). It compares the K+ values obtained from the CDI 500 and the traditional lab analyzers of both studies, which is one of the parameters, which will be measured to gage the accuracy of the CDI 500 in this study. This study will use the retrospective data as well as prospective data to be collected from the CDI 500 and ABL800 Flex. Reference articles will be taken from LIU Medical Library, JECT database, and various search engines such as Google.
In conclusion, the CDI 500 is a valuable tool for perfusionists. This study will help determine the accuracy of the in line blood gas monitoring system compared to the ABL800 Flex system. By comparing the two technologies based upon accuracy and cost, it will allow perfusionists to rely upon the CDI 500, which will allow delivery of a quicker response time towards patients.