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The electrolytes within AQIX® RS-I are present to provide an ionic and iso-osmotic environment to replace that of the lost fluid(s) during hypovolaemia and to replicate the natural environment for cells, tissue and organs ex-vivo.

Re-polarisation of cell membranes; main cationic contributor to osmotic pressure.
Maintains the resting potential of cell membranes in a polarised state but depolarises if normal interstitial levels [i.e., 5.2 mmoles/L] are exceeded.
Along with potassium and sodium ions preserves Gibbs-Donnan equilibrium and intracellular balance of these ions to prevent oedema within cell components of organs.
Determinate anion in the governance of blood pH, prevention of metabolic acidosis, indispensible in tissue culture media for cell growth and potassium ion permeability in the maintenance of cell membrane excitability.
• The essential ion in many cell actions, e.g. neurotransmitter release
• The essential ion for contraction of skeletal, visceral and cardiac muscle
• Cardiac cell action potentials
• Differentiation and adhesion status in cultured cell lines
• As calcium proteins in 2nd-messenger/'cascade' events
• Determines rate at which cell membrane receptors become desensitized
• The essential ion for relaxation of skeletal, visceral and cardiac muscle
• Co-operative ion with Ca2+ in cell functions
• Co-operative ion with enzymes of major biochemical pathways, e.g. glycolytic

Standard Base Excess

The standard base excess of extracellular fluids is governed by three independent parameters;

  • Partial pressure of carbon dioxide (pCO2)
  • Strong ion difference (SID)
  • Non-volatile weak acid concentration (Atot e.g. albumin, inorganic phosphate and citrate)

Administration of intravenous volume alters two of these three parameters simultaneously through admixture to existing volume, namely the SID and Atot. Reduction of the plasma SID (with a low SID fluid) results in strong ion acidosis (conversely increasing SID result in alkalosis). While solutions devoid of non-volatile acids, dilute the weak acid pool resulting in dilution alkalosis.

It is reported in both predictive models and through experimentation, that the ideal SID for an intravenous solution to have a neutral metabolic acid-base status after volume infusion is 24.00 mEq/L; a level that approximates to the plasma bicarbonate concentration.

The calculated SID for AQIX® RS-I is 24.99 mEq/L.