Blood electrolyte determination

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... 

Depressed patients should have a medication review, physical examination, mental status examination, a complete blood count with differential, thyroid function tests, and electrolyte determinations. 

The ICH S7A states that the effects of the NCE on renal parameters should be assessed for example, urinary volume, specific gravity, osmolality, pH value, fluid/electrolyte balance, proteins, cytology, and blood chemistry determinations such as blood urea... 

Today the determination of blood gases (p02, pC02) is performed using electrochemical GSSs, while major blood electrolytes (Na+, K+, Cl as well as Ca2+, Mg2+, Li+ as a therapeutic ion and pH) and main urine electrolytes (Na+, K+) are predominantly determined by electrochemical ISSs or ISEs. Some important metabolites (glucose, lactate, urea, creatinine) are often determined with electrochemical biosensors. 

Blood glucose Electrolyte determinations Urine for hemoglobinuria... 

Reference methods for blood gas and electrolyte determinations have been described in detail by the IFCC. A schematic diagram characteristic of a typical instrument is shown in Figure 27-4. Electrochemical principles and structural features of electrodes are discussed in Chapter 4. Prominent manufacturers of blood gas equipment include Roche Scientific Corp., Bayer Diagnostics, Instrumentation Laboratory, Nova Biomedical, and Radiometer America, Inc. Readers are referred to these manufacturers for details and operational features of specific instruments. 

All depressed patients should have a complete physical examination, mental status examination, and basic laboratory work-up, including a complete blood count with differential, thyroid function tests, and electrolyte determinations to identify any potential medical problems. A complete medication review should be performed because many drugs may precipitate or worsen a depressive episode (see Table 67-1). 

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. 

M3) applied the carbon rod atomizer to the direct atomic absorption determination of lead in 0.5 ixl of packed red cells. A blank correction was required using a synthetic blood electrolyte solution. Two microliters of xylene were added to the carbon rod to prevent samples and standards from soaking into the rod. 

The maintainance of water and electrolyte balance is one of the most important therapeutic activities in the clinic. Normal diet and adequate fluid intake cover one s requirements. Imbalance (see above) has to be verified by electrolyte determination in blood serum as well as in urine and possibly by other diagnostic parameters. Water equilibrium must be attained and compensation of electrolyte deficiency should be performed by oral or parenteral application of medicaments containing the required amount of electrolytes. A very large number of solutions and tablets is available to solve these clinical problems. For further details, see Refs. 27 and 41-44. 

The most common laboratory tests performed to determine acid-base status include an arterial blood-gas determination—pH, Pco, and HCO3 levels, as well as Po because hypoxia can result in lactic acidosis, venous serum CO, electrolytes because electrolyte levels are affected by acid or base states, and urine tests, including urinalysis, urine pH, and litmus dipstick tests. 

Plasma consists of water, electrolytes, metabolites, nutrients, proteins, and hormones. The water and electrolyte composition of plasma is practically the same as that of ail extracellular fluids. Laboratory determinations of levels of Na, K+, Ca, CL, HC03, PaC02, and of blood pH are important in the management of many patients. 

Along with an effective electrolyte and screening program for genetic disease, the laboratory of Neonatology needs to have the capability of analyzing for other components in blood serum, which aid in the diagnosis of disease. These include such determinations as alkaline phosphatase, and various other enzymes, creatinine, uric acid and a host of other components which are normally assayed by the main clinical laboratory. 

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). 

Blood gases (Table 74-1), serum electrolytes, medical history, and clinical condition are the primary tools for determining the cause of acid-base disorders and for designing therapy. 

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