Sodium Bicarbonate 8.4%

UK SPC for Sodium Bicarbonate 8.4% w/v solution for infusion (https://www.medicines.org.uk/emc/product/15216/smpc). ALL DOSES ARE IN MILLIMOLES (mmol) OF SODIUM BICARBONATE, NOT MILLIGRAMS. The SPC's own worked example: 'If in a patient of 70 kg body weight the base deficit is 5 mmol/l, then 5 x 70 x 0.2 = 70 mmol of sodium bicarbonate (70 ml of Sodium Bicarbonate 8.4% w/v) are to be given.' The factor 0.2 corresponds to the proportion of the extracellular fluid in relation to total body weight. URINE ALKALINISATION (second indication in §4.2): the dose is adjusted according to the desired pH of the urine, with monitoring of the acid-base balance, the water balance and the electrolyte balance, and care must be taken not to exceed the maximum infusion rate above. 'In haemodynamically stable adults and children urine alkalinisation may be achieved with a bolus of 1-2 mmol sodium bicarbonate per kg body weight, followed by an infusion of 132 mmol sodium bicarbonate in 1 litre of glucose 5% in water, with a flow rate of 1.5-2 times the maintenance fluid rate. Urine pH should not exceed 8.5.' ADMINISTRATION SAFETY (§4.4): it must be made absolutely sure that the solution is infused intravenously — accidental paravenous administration may lead to tissue necrosis and accidental intra-arterial infusion may cause shock or loss of an extremity; if infused undiluted or too rapidly into peripheral veins, the 8.4% solution may cause vein irritation and consequently phlebitis or thrombosis because of its alkalinity and high osmolarity. MONITORING: regular checks of acid-base balance, serum electrolyte concentrations and water balance; correction of acid-base status is always associated with shifts of the electrolyte balance, particularly potassium — alkalinisation promotes potassium influx into cells and may lead to hypokalaemia, and potassium or calcium deficiencies should be corrected BEFORE beginning alkalinising therapy. Administration may lead to sodium and fluid overload. When respiratory acidosis is concomitant with metabolic acidosis, both pulmonary ventilation and perfusion must be adequately supported to ensure adequate elimination of excess CO2. EVIDENCE CAVEAT (§4.4): 'The effects of bicarbonate on organ function, complication rates and survival in diabetic ketoacidosis, cardiac arrest and lactic acidosis have not been investigated sufficiently. Caution is advised when using sodium bicarbonate in these conditions.'

§4.2 paediatric population: 'The dosage has to be adjusted individually. The first dose can be up to 1 mmol/kg body weight, administered by slow intravenous infusion.' STRENGTH: '4.2% w/v (or less concentrated) sodium bicarbonate solutions should be preferred' in newborns and children under 2 years — this entry's product is the 8.4% w/v solution. §4.4 warns that in newborns and children under 2 years, rapid infusion (10 ml/min) of hypertonic sodium bicarbonate solutions may produce hypernatraemia, a decrease in cerebrospinal fluid pressure and, in preterm infants, possible intracranial haemorrhage. The unit is millimoles, not milligrams; the SPC's adult worked example equates 70 mmol with 70 ml of the 8.4% w/v solution. Verify all paediatric dosing against a children's formulary before use.