BNF for Children 2011-2012

460 9.2.2 Parenteral preparations for fluid & electrolyte imbalance BNFC 2011–20129.2.1.3 Oral bicarbonateSodium bicarbonate is given by mouth for chronicacidotic states such as uraemic acidosis or renal tubularacidosis. The dose for correction of metabolic acidosis isnot predictable and the response must be assessed. Forsevere metabolic acidosis, sodium bicarbonate can begiven intravenously (section 9.2.2).Sodium supplements may increase blood pressure orcause fluid retention and pulmonary oedema in those atrisk; hypokalaemia may be exacerbated.Sodium bicarbonate may affect the stability or absorptionof other drugs if administered at the same time. Ifpossible, allow 1–2 hours before administering otherdrugs orally.Where hyperchloraemic acidosis is associated withpotassium deficiency, as in some renal tubular andgastro-intestinal disorders it may be appropriate togive oral potassium bicarbonate, although acute orsevere deficiency should be managed by intravenoustherapy.Potassium Tablets, Effervescent (Non-proprietary)Effervescent tablets, potassium bicarbonate 500 mg,potassium acid tartrate 300 mg, each tablet providing6.5 mmol of K + . To be dissolved in water beforeadministration. Net price 56 = £33.38. Label: 13, 21Note These tablets do not contain chloride; for effervescenttablets containing potassium and chloride, see under PotassiumChloride, section 9.2.1.19.2.2 Parenteral preparationsfor fluid and electrolyteimbalance9.2.2.1 Electrolytes and water9.2.2.2 Plasma and plasma substitutes9 Nutrition and bloodSODIUM BICARBONATECautions see notes above; avoid in respiratory acidosis;interactions: Appendix 1 (antacids)Indication and doseRenal acidosis (see also notes above). By mouthNeonate initially 1–2 mmol/kg daily in divideddoses, adjusted according to responseChild 1 month–18 years initially 1–2 mmol/kgdaily in divided doses, adjusted according toresponseMetabolic acidosis section 9.2.2.1Renal hyperkalaemia section 9.2.2.1Sodium Bicarbonate (Non-proprietary)Capsules, sodium bicarbonate 500 mg (approx.6 mmol each of Na + and HCO –3 ), net price 56-cappack = £5.16Tablets, sodium bicarbonate 600 mg, net price 100-tab pack = £2.48Important Oral solutions of sodium bicarbonate are requiredoccasionally; these need to be obtained from ‘special-order’manufacturers or specialist importing companies, see p. 809,and the strength of sodium bicarbonate should be stated onthe prescriptionPOTASSIUM BICARBONATECautions cardiac disease, interactions: Appendix 1(potassium salts)Contra-indications hypochloraemia; plasma-potassiumconcentration above 5 mmol/litreRenal impairment close monitoring required—highrisk of hyperkalaemia; avoid in severe impairmentSide-effects nausea, vomiting, abdominal pain, diarrhoea,and flatulence9.2.2.1 Electrolytes and waterSolutions of electrolytes are given intravenously, to meetnormal fluid and electrolyte requirements or to replenishsubstantial deficits or continuing losses when it is notpossible or desirable to use the oral route. When intravenousadministration is not possible, fluid (as sodiumchloride 0.9% or glucose 5%) can also be given subcutaneouslyby hypodermoclysis.In an individual patient the nature and severity of theelectrolyte imbalance must be assessed from the historyand clinical and biochemical examination. Sodium,potassium, chloride, magnesium, phosphate, and waterdepletion can occur singly and in combination with orwithout disturbances of acid-base balance; for referenceto the use of magnesium and phosphates, see section9.5.Isotonic solutions may be infused safely into a peripheralvein. Solutions more concentrated than plasma, forexample 15% glucose, are best given through an indwellingcatheter positioned in a large vein.Maintenance fluid requirements in children are usuallyderived from the relationship that exists betweenbody-weight and metabolic rate; the figures in thetable below may be used as a guide outside the neonatalperiod. The glucose requirement is that needed tominimise gluconeogenesis from amino acids obtainedas substrate from muscle breakdown. Maintenancefluids are intended only to provide hydration for ashort period until enteral or parenteral nutrition canbe established.It is usual to meet these requirements by using astandard solution of sodium chloride and glucose. Solutionscontaining 20 mmol/litre of potassium chloridemeet usual potassium requirements when given in thesuggested volumes; adjustments may be needed if thereis an inability to excrete fluids or electrolytes, excessiverenal loss or continuing extra-renal losses. The exactrequirements depend upon the nature of the clinicalsituation and types of losses incurred; see Caution ondilutional hyponatraemia below.