Sensor blood electrolyte

Miniaturized catheter-type ISE sensors, such as the implantable probe shown in Figure 5-20 represent the preferred approach for routine clinical in-vivo monitoring of blood electrolytes. For these intravascular measurements the reference electrode is placed outside die artery (in die external arm of die catheter), tints obviating biocompatability and drift problems associated with its direct contact with the blood. 

FIGURE 5-20 Miniaturized ISE catheter sensor for continuous monitoring of blood electrolytes. (Reproduced with permission from reference 58.)... 

FIGURE 6-21 A silicon-based sensor array for monitoring various blood electrolytes, gases, and metabolites. (Courtesy of i-STAT Co.)... 

The relative simplicity of the sensor setup allows them to be implemented into portable automated devices or bed-side analyzers (Fig. 4.2), which are easily installed at patient beds, eliminating the time-consuming laboratory analyses. On the other hand, modem high throughput clinical analyzers may process more than 1000 samples per hour and simultaneously determine dozens of analytes, using a handful of analytical methods. Blood electrolyte analysis, however, remains one of the most important in... 

The properties of a pH electrode are characterized by parameters like linear response slope, response time, sensitivity, selectivity, reproducibility/accuracy, stability and biocompatibility. Most of these properties are related to each other, and an optimization process of sensor properties often leads to a compromised result. For the development of pH sensors for in-vivo measurements or implantable applications, both reproducibility and biocompatibility are crucial. Recommendations about using ion-selective electrodes for blood electrolyte analysis have been made by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) [37], IUPAC working party on pH has published IUPAC s recommendations on the definition, standards, and procedures... 

Another analytical sensor that is based on the electrolytic reduction of O2 has been commercialized during the past decade. This is a device for the rapid, accurate assay of glucose in human blood and makes use of an immobilized enzyme (glucose oxidase) on a disposable sample probe that includes an O2-electrolysis sensor with electrolyte, buffer, and various inhibitors. When a drop of blood is placed on the sample probe, the glucose oxidase (GO) transformation of the glucose begins via the reduction of the ambient O2 to HOOH. 

Chemical sensors have been developed by companies such as DuPont and Cygus Therapeutic Systems for the measurement of blood electrolytes and gases, and ion selective membranes are common in many clinical analyzer systems. While the use of chemical sensors for such determinations will continue to increase, sensor applications in clinical diagnostics will favor development and application of biosensors due to the high specificity residing in the biological component of these sensors. 

Tusa, keiner, and their colleagues at Roche Diagnostics Corporation produced a commercially successful diagnostic system for blood electrolytes and gases in critical care and point-of-care. situations.Its design platform is PET, with fluorescent sensors for each blood constituent being equipped with an adequately selective receptor. The case for is highlighted here. The Af-(2-methoxy-... 

Clinical chemistry, particularly the determination of the biologically relevant electrolytes in physiological fluids, remains the key area of ISEs application [15], as billions of routine measurements with ISEs are performed each year all over the world [16], The concentration ranges for the most important physiological ions detectable in blood fluids with polymeric ISEs are shown in Table 4.1. Sensors for pH and for ionized calcium, potassium and sodium are approved by the International Federation of Clinical Chemistry (IFCC) and implemented into commercially available clinical analyzers [17], Moreover, magnesium, lithium, and chloride ions are also widely detected by corresponding ISEs in blood liquids, urine, hemodialysis solutions, and elsewhere. Sensors for the determination of physiologically relevant polyions (heparin and protamine), dissolved carbon dioxide, phosphates, and other blood analytes, intensively studied over the years, are on their way to replace less reliable and/or awkward analytical procedures for blood analysis (see below). 

For the detection of cystic fibrosis, which is a quantitative analysis, the situation is different because such an analysis is performed only in the hospital environment. This requires that the conditions to execute such a test with the sensor system can be chosen and controlled in such a way that possible interference is avoided. In addition, for cystic fibrosis detection, the analyst is interested in the electrolyte concentration of the sweat, regardless of how this sweat formation was obtained (high temperature, exercise), with the implication that the sources of interference are much less for cystic fibrosis detection than was the case for the detection of low sugar level in the blood. The complication in this type of analysis is that it is not enough to... 

Clinical analysis of blood gases and electrolytes by ion-selective sensors... 

The main challenge in designing clinically useful sensors is definitely the production of the electroactive element, i.e., the sensor membrane. The membrane is the place where the chemical recognition and discrimination processes occur. The membrane dictates, overwhelmingly, the quality of signal and durability of the sensor. Only a restricted number of membranes can be and are used in routine electrolyte and blood gas measurements ... 

Biotin 629, 808 Biphasic system el45 Bipotentiostat 909 Bis(l-butylpentyl)adipate 60 Bis-pyrene 821 Bismuth electrodes 144 based metal sensor 136 Blood 6 electrolytes 5 gases 5 plasma 6... 

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