Anions and the anaesthetist

Abstract

SummaryAnions are the negative components of most chemical structures and play many important physiological and pharmacological roles that are of interest to the anaesthetist. Their relevance is reviewed with a particular emphasis on the inorganic anions (halides, bicarbonate, phosphate and sulphate) and the significance and limitations of the anion gap. Organic anions (albumin, lactate) are also discussed, albeit briefly. The suitability of anions for their role in neurotransmission and acid2base balance is outlined.

Electrolyte disorders in horses with colic. Part 2: calcium, sodium, chloride and phosphate

“…Chloride ions are important in maintaining acid-base balance, renal tubular function and production of gastric acid (Maloney et al 2002). Chloride is the major anion in the extracellular fluid (de Morais 1993).…”

“…High concentrations of chloride are found in gastric acid and small intestinal secretions and it is normally absorbed from the upper small intestine (de Morais 1993). Large quantities of chloride can be lost via intestinal secretions in patients with diarrhoea (Maloney et al 2002). In the kidney, its reabsorption is heavily influenced by both plasma sodium concentration and acid-base balance.…”

“…The majority of phosphorus in the body is found in bone, with only 1% in blood (Bugg and Jones 1998). Phosphate (inorganic phosphorus) is the most abundant intracellular anion (Maloney et al 2002). Phosphate homeostasis is controlled by parathyroid hormone, calcitonin and vitamin D, involving the intestine, kidneys and bone.…”

“…Phosphate in the body is important as an enzyme cofactor, a buffer and in the production of adenosine triphosphate (ATP) for energy. It is an important part of proteins and lipids, and is also essential for normal functioning of the coagulation cascade and the immune system (Maloney et al 2002).…”

“…The prevalence of hypophosphataemia in post operative colic patients is 44% (Protopapas 2000). It is reported as a poor prognostic indicator in man (Maloney et al 2002). However, as phosphate is primarily intracellular, hypophosphataemia is not necessarily indicative of total body depletion.…”