Lithium clinical application

Ion-selective electrodes are available for the electro analysis of most small anions, eg, halides, sulfide, carbonate, nitrate, etc, and cations, eg, lithium, sodium, potassium, hydrogen, magnesium, calcium, etc, but having varying degrees of selectivity. The most successful uses of these electrodes involve process monitoring, eg, for pH, where precision beyond the unstable reference electrode s ability to deliver is not generally required, and for clinical applications, eg, sodium, potassium, chloride, and carbonate in blood, urine, and semm. 

Lithium formate is the most extensively studied new material for ESR-dosimetry [21], It has also been tested for use in clinical applications [53, 54]. Thus, doses in the range 0.2-3.5 Gy due to 6 MeV photons were determined in blind tests shown in Fig. 9.7. A deviation of less than 1.2% from those by ionization chamber measurements was obtained, which is well within the uncertainty of the measurements. It was concluded that no trend could be seen in the ESR dosimeter response, regarding either the dose rate or the beam quality. Each measurement took 15 min, while several hours would be required with the common alanine dosimeter. 

The major clinical application of lithium therapy is in the prevention of the major changes in mood (affect) which are characteristic of the affective disorders [57,58]. In mania the patient... 

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). 

Development of lithium selective electrodes (LiSE) and their application in clinical chemistry have been amply reviewed Several models of lithium ion specific electrodes are commercially available. The central problems in developing such sensing devices are their dynamic range, the accuracy and precision by which the signals are correlated to the concentration of the analyte and the selectivity towards that species, especially in relation to other alkali metal cations. Additional problems of practical importance are the times of response and recovery and the durability of the electrode in the intended service. 

The analysis of clinical samples represents a typical application of flame photometry. Concentrations of sodium, potassium, and lithium in blood and urine are well within instrument working ranges. The specificity of the technique is a distinct advantage. Automated models of flame photometers, available during the past 25 years, are typically designed to serve the needs of the clinical chemist. Instrument calibration protocols are built into instruments to facilitate the timely analysis of sodium, potassium, and lithium in clinical samples. 

Lithium ( Li) (1=1, 312). A review with 117 references was given on the applications of Li NMR spectroscopy and imaging in biology and experimental medicine. The interest derives primarily from the clinical use of Li salts to treat mania and manic-depressive illness. One area of investigation is ionic transport across the cellular membrane and compartmentation, so as to elucidate the mechanisms of therapeutic action and toxicity in clinical practice. The second is the development of a noninvasive, in vivo analytical tool to measure brain Li concentrations in humans, both as an adjunct to treatment and as a mechanistic probe. 

Individual polyethers exhibit varying specificities for cations. Some polyethers have found application as components in ion-selective electrodes for use in clinical medicine or in laboratory studies involving transport studies or measurement of transmembrane electrical potential (4). The methyl ester of monensin [28636-21-7] has been incorporated into a membrane slide assembly used for the assay of semm sodium (see Biosensors) (5). Studies directed toward the design of a lithium selective electrode resulted in the synthesis of a derivative of monensin lactone that is highly specific for lithium (6). 

Flame atomic emission spectrometry Basic information on FAES is presented elsewhere in this encyclopedia. Sodium measurements are performed at 590 nm with the use of a propane flame (1925°C). Physiological samples for sodium determination are highly diluted before measurement. The diluent and the calibrator solution contain the same concentration of lithium ions so as to balance flame instability by a concomitant measurement of lithium in the reference beam (the so-called lithium guideHne). At the same time, lithium ions inhibit the ionization of sodium atoms. This procedure cannot be used in the case of therapy with lithium salts. That is why some authors prefer the concomitant measurement of caesium to that of lithium. Dilution adjusts the viscosity of the sample to that of the calibrator solution to produce identical aspiration rate and drop size on nebulization. As other electrolytes interfere with sodium measurement, their concentration in the caH-brator solution must be similar to their concentration in the sample. For the measurement of sodium in urine, calibrator solutions different from those for serum measurement are needed as the electrolyte concentrations in urine samples are quite different from those in serum and their relations are very variable. As the concentration of the electrolytes in serum is rather constant, calibrator solutions for serum measurements can fulfill their function better than those for urine in other words, urine determinations are usually less accurate. FAES proved to be sufficiently reliable to be used as the basic principle of the sodium reference measurement procedure. In routine use, however, FAES is less accurate. Its application is given up by most clinical laboratories in favor of potentiometric measurements... 

Takeuchi ES, Leising RA, Spillman DM, Rubino R, Gan H, Takeuchi KJ, Marschilok AC (2004) Lithium batteries for medical applications, hi Nazii G-A, Pistoia G (eds) Lithium batteries science and technology. BQuwer, Boston, pp 686-700 Untereker DF, Crespi AM, Rorvick A, Schmidt CL, Skarstad PM (2007) Power systems for implantable pacemakers, cardioverters, and defibrillators. In Ellenbogtai KA, Kay GN, Lau C-P, Wilkoff BL (eds) Clinical cardiac pacing and defibrillation, 3rd edn. Saunders, Philadelphia, pp 235-259... 

In clinical chemistry the determination of sodium, potassium, and calcium is well standardized. In the past decades flame photometry has been reputed to be the mediod of choice in the analysis of biological samples. The advantages of this procedure are a short requirement of time and materials for sample preparation, short duration of the analytical procedure, and the possibility of automation. The procedure became improved due to the application of lithium as internal standard. Excellent precision and accuracy could be obtained in sodium and potassium determination. In calcium determination inaccuracy occurs due to the matrix. It is of disadvantage that only the determination of total calcium and not the differentiation between free and protein bound calcium is possible. Furthermore special equipment (flame photometer) is necessary. 

In a more recent extracorporeal application, a PVC lithium ISE housed in an oxygenator circuit allowed measurement of cardiac output via continuous tracking of post-injection Li+ dilution in the peripheral circulation [69]. The technique has been validated for clinical use and exeplifles the inherent analytical reliability of an ISE [70]. The sensor is disposable, sterihsable and used within a flow-through cell, the active sensor surface here electrolyti-cally connected to the requisite reference electrode using a saline bridge [71]. 

---