Calcium, electrolyte/acid-base

The third principle of anesthesia is the maintenance of the internal environment of the body. For example, the regulation of electrolytes (sodium, potassium, chloride, magnesium, calcium, etc.), acid-base balance, and a host of supporting functions on which cellular function and organ system communications rest. 

Sodium, potassium and chloride are the primary dietary ions that influence the electrolytic balance and acid-base status, and the proper dietary balance of sodium, potassium and chloride is necessary for growth, bone development, eggshell quality and AA utilization. Potassium is the third most abundant mineral in the body after calcium and phosphorus, and is the most abundant mineral in muscle tissue. It is involved in electrolyte balance and neuromuscular function. The content of potassium in poultry diets is usually adequate. Chloride is present in gastric juice and chlorine is part of the HC1 molecule which assists in the breakdown of feed in the proventriculus. Sodium is essential for nerve membrane stimulation and ionic transport across cell membranes. Signs of sodium, potassium or chloride deficiency include reduced appetite, poor growth, dehydration and increased mortality. 

In assessment of acid-base disorders, commonly measured electrolytes are serum Na, K" ", H+ (as pH), Cl , and HCOI- Other anions (e.g., sulfates, phosphates, proteins) and cations (e.g., calcium, magnesium, proteins) are not measured routinely but can be estimated indirectly, since (to maintain electrical neutrality) the sum of the cations must equal that of the anions. Serum Na" " and K" " content accounts for 95% of cations, and Cl and HCOJ for about 85% of anions. The concentration of phosphate, sulfate, and proteins can be calculated from the formula ... 

Maintenance of fluid volume, osmolarity, electrolyte balance, and acid-base status are aU regulated in large part by the kidney. Homeostasis of sodium, potassium, chloride, calcium, magnesium, and phosphorus is altered due to changes in urinary excretion that occur in patients with impaired kidney function. A comprehensive discussion... 

While alcohol abuse may be associated with a variety of electrolyte and acid-base disorders, the role of the kidneys in this process has only recently been fully defined [164]. Renal functional abnormalities have now been related to chronic alcoholism in patients without liver disease and these defects have reverted to normal with abstinence from alcohol abuse. These abnor-mahties include decreases in the maximal reabsorptive abihty and threshold for glucose, a decrease in the threshold for phosphate excretion, and increases in the fractional excretion of P2-microglobulin, uric acid, calcium, magnesium, and amino acids. Defective tubular acidification and impaired renal concentrating ability... 

Acute hepatic failure is a major medical emergency, since the f ailure of the complex metabolic functions of the liver cannot be compensated for by any other organ. In severe ca.ses, much of the biochemical picture is disnipied. Electrolyte imbalance occurs, sodium and calcium concentrations may both fall. There may be severe metabolic acid-base ilisuirbances and hypoglycaemia. 

Chloride is mostly described in relation to hydrogen, sodium, potassium, and calcium, except when deviations are well described specifically for Cl in biological systems as a result of deficiency or excess availability. In addition, dysfunctions of CD transport or CD channels are of clinical relevance and have indeed been the subject of intensive research. One principle of CD-mediated effects is a change in osmotic condition, cell volume, and excitability and in acid-base balance in biological systems. In this way, CD is essentially linked to water distribution and electrolyte turnover. 

The electrolytes—both anions and cations—perform a number of vital roles in maintaining fluid balance and acid-base balance, membrane potentials, muscular functions, and nervous conduction. They act as cofactors in many enzyme-mediated reactions. In addition, calcium and phosphate are the main mineral constituents of the skeleton. 

The drug of choice in malignant hyperthermia is dantrolene, which prevents release of calcium from the sarcoplasmic reticulum of skeletal muscle cells. Appropriate measures must be taken to lower body temperature, control hypertension, and restore acid-base and electrolyte balance. The answer is (C). 

Chapter 4 focuses on fluid volume imbalances (i.e., hypervolemia and hypovolemia) and related symptoms and treatments. Chapters 5 through 9 present the major electrolytes and concepts related to excessive or insufficient blood levels of sodium, potassium, calcium, magnesium, and phosphate. Chapter 10 focuses on acid-base imbalances and discusses the procedures needed to determine the underlying source of the imbalance and the appropriate treatments and patient care needed to address the imbalance. Chapters 11 and 12 contain presentations of developmental conditions and disease conditions that involve imbalances in fluids, electrolytes, and acid-base, with the aim of enabling the reader to apply the concepts learned in earlier chapters of the book. 

Electrolyte balance Aminoglycosides cause fluid, electrolyte, and acid-base disorders by altering renal tubular function in several ways, leading to hypokalemia and acidosis or alkalosis. Stimulation of the calcium-sensing receptor has been reported to cause a Bartter-like syndrome (hypokalemic metabolic alkalosis, hypomagnesemia, hypocalcemia, and normal serum creatinine concentrations). More rarely, a proximal renal tubular acidosis (Fanconi syndrome non-anion gap metabolic acidosis) can develop. The mechanisms have been summarized [4 ]. 

Sodium ar chloride comprise the bulk of the electrolytes in plasma and interstitial fluid. Sodium constitutes 90 % of the total base of the plasma, the normal concentration being 140 meq. per liter. The normal concentration of chloride is 104 meq. per liter. The sodium ion plays an important role in the maintenance of acid-base equilibrium and in the maintenance of osmotic pressure, which depends largely on total base. Cations in blood, other than sodium, are calcium, potassium, and magnesium anions, other than chloride, are bicarbonate, protein, and small amounts of organic acid. The pH is usually regulated by the relative amounts of chloride and bicarbonate. Acidosis and alkalosis are encountered in many diseases of man, but these problems belong in the fleld of clinical medicine rather than nutrition and will not be discussed here. 

The kidneys are two fist-sized organs whose primary function is to generate urine for excretion of water and metabolic waste products. The kidneys not only remove accumulated nitrogen products (urea, creatinine, uric acid, and others) but also maintain homeostasis of water and electrolytes (sodium, potassium, chloride, calcium, phosphate, magnesium) and regulate acid-base balance. In addition, human kidneys perform a few endocrine and metabolic functions, such as production of the hormone erythropoietin (a hormone that stimulates blood cell production) and conversion of vitamin D to its active form. Because of the tremendous overcapacity of normal kidney function, a person can live with only a fraction of normal kidney capacity, and the 0.1% of the population who are bom with a single kidney often are not even aware of the missing kidney. 

The apparent acid strength of boric acid is increased both by strong electrolytes that modify the stmcture and activity of the solvent water and by reagents that form complexes with B(OH) 4 and/or polyborate anions. More than one mechanism may be operative when salts of metal ions are involved. In the presence of excess calcium chloride the strength of boric acid becomes comparable to that of carboxyUc acids, and such solutions maybe titrated using strong base to a sharp phenolphthalein end point. Normally titrations of boric acid are carried out following addition of mannitol or sorbitol, which form stable chelate complexes with B(OH) 4 in a manner typical of polyhydroxy compounds. EquiUbria of the type ... 

In a modified process, potassium substitutes for calcium to form BiTMgeCag which liquates to the top of the bath and is removed from the molten lead. The Betts process is based on electrolytic refining using a solution of lead flu-orosilicate and fluorosilicic acid. While lead is deposited on the cathode, bismuth goes to the anode where it is collected with other impurity metals. It is then filtered, dried, smelted, and further refined, depending on the purity desired. Impurities are removed by adding molten caustic and zinc, and finally by chlorination. 

Ordinary anion and cation ion-exchange resins are of limited use for the analytical concentration of trace elements from water, because of their lack of selectivity. This is especially so with strong electrolytes such as seawater. In this case the major ions sodium, magnesium, calcium and strontium, are retained preferentially. However, the recent advent of commercial chelating resins based mainly on iminodiacetic acid-substituted cross-linked polystyrene, makes it possible to concentrate trace elements from waters. In consequence, a number of researchers have used chelating resins for trace-metal preconcentration from seawater and natural waters. 

Capillary electrophoresis Capillary electrophoresis (CE) is used to analyze sodium, potassium, calcium, and magnesium in water samples. The detection is conducted by reverse absorbance measurements. Sufficient separation of the four cations is established with an electrolyte solution of 5 mM imidazole/6.5 mM a-hydroxyisobutyric acid/2 mM 18-crown-6 ether of pEI 4.1 [42]. CE with a contactless conductometric detector is used to determine small anions and cations in water samples from different sources. 2-(N-Morpholino)ethanesulfonic acid/histidine-based (Mes/Elis) electrolytes are used for direct conductivity detection of anions and cations, while ammonium acetate is used for indirect conductivity determination of alkylammonium salts. Eor the simultaneous separation procedure, involving dual-opposite end injection, an electrolyte consisting of 20 mM Mes/EIis, 1.5 mM 18-crown-6 and 20 mM cetyltri-methylammonium bromide provides baseline separation of 13 anions and cations in less than 6 min [43]. Also CE with a capacitively coupled... 

Practically all soluble salts, acids (such as sulfuric, nitric, and hydrochloric acids), and bases (such as sodium, potassium, calcium, and barium hydroxides) are strong electrolytes. Weak electrolytes include numerous other acids and bases such as acetic acid, nitrous acid, carbonic acid, and ammonia. The terms strong acid, strong base, weak acid, and weak base refer to whether an acid or a base is a strong or weak electrolyte. A brief list of strong and weak electrolytes is given in Table 15.3. 

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