|Aspirin or Salicylates toxicity
|Ethylene glycol toxicity
|Renal Tubular Acidosis
- Urinary excretion of weak acids and bases is affected by urinary pH
- Highly ionised molecules pass poorly through lipid membranes and therefore little tubular reabsorption occurs and urinary excretion is increased.
- The evidence for a clinical benefit in lactic acidosis is unclear. It can worsen intracellular acidosis. In most cases reserved for when pH < 7.0
Indications and dose
- Metabolic acidosis: Sodium Bicarbonate e.g. 1.5 L of 1.26% Sodium Bicarbonate over 2hrs. Also, Need to replace K due to losses. Aim urine pH >7.5. Weak acids are highly ionised with enhanced urinary excretion. Used for salicylate and methotrexate toxicity.
- Drug TCA toxicity: patients with arrhythmias, significant QRS > 0.16 sec or QT prolongation or acidosis, IV Sodium Bicarbonate (50 mL of 8.4% solution) should be administered and repeated to correct serum pH. Aim for alkalinisation of the serum to a pH level of 7.45-7.55 which increases protein binding, decreases the QRS interval, stabilises arrhythmias, and increase blood pressure in patients with TCA poisoning.
- Severe metabolic acidosis pH < 7.0: Take expert advice, Some may give 500 ml Sodium Bicarbonate 1.26% over 4 hrs. May be considered in DKA
- Alkalaemia, Hypokalaemia, Tetany
- Hypocalcaemia is rare, Volume overload