BNF for Children 2011-2012

BNFC 2011–2012 9.2.2 Parenteral preparations for fluid & electrolyte imbalance 463Intravenous potassiumPotassium chloride and sodium chloride intravenousinfusion is the initial treatment for the correction ofsevere hypokalaemia and when sufficient potassiumcannot be taken by mouth. Ready-mixed infusion solutionsshould be used when possible (see under SafePractice below); for peripheral intravenous infusion,the concentration of potassium should not usuallyexceed 40 mmol/litre. Potassium infusions should begiven slowly over at least 2–3 hours and at a rate notexceeding 0.2 mmol/kg/hour with specialist advice andECG monitoring in difficult cases. Higher concentrationsof potassium chloride or faster infusion rates maybe given in very severe depletion, but require specialistadvice.Repeated measurements of plasma-potassium concentrationare necessary to determine whether furtherinfusions are required and to avoid the developmentof hyperkalaemia, which is especially likely in renalimpairment.Initial potassium replacement therapy should notinvolve glucose infusions, because glucose may causea further decrease in the plasma-potassium concentration.Safe PracticePotassium overdose can be fatal. Ready-mixed infusionsolutions containing potassium should be used.Exceptionally, if potassium chloride concentrate isused for preparing an infusion, the infusion solutionshould be thoroughly mixed. Local policies onavoiding inadvertent use of potassium chloride concentrateshould be followed.POTASSIUM CHLORIDECautions for peripheral intravenous infusion the concentrationof solution should not usually exceed 3 g(40 mmol)/litre; specialist advice and ECG monitoring(see notes above); interactions: Appendix 1(potassium salts)Contra-indications plasma-potassium concentrationabove 5 mmol/litreRenal impairment close monitoring required—highrisk of hyperkalaemia; avoid in severe impairmentSide-effects rapid infusion toxic to heartIndication and doseElectrolyte imbalance see also oral potassiumsupplements, section 9.2.1.1. By slow intravenous infusionDepending on the deficit or the daily maintenancerequirements, see also notes aboveNeonate 1–2 mmol/kg dailyChild 1 month–18 years 1–2 mmol/kg dailyAdministration see notes abovePotassium Chloride and Glucose (Non-proprietary)AIntravenous infusion, usual strengths potassiumchloride 0.3% (3 g, 40 mmol each of K + and Cl /litre)or 0.15% (1.5 g, 20 mmol each of K + and Cl /litre)with 5% of anhydrous glucoseIn hospitals, 500- and 1000-mL packs, and sometimes other sizes,are availablePotassium Chloride and Sodium Chloride (Non-proprietary)AIntravenous infusion, usual strength potassiumchloride 0.15% (1.5 g/litre) with sodium chloride 0.9%(9 g/litre), containing K + 20 mmol, Na + 150 mmol,and Cl 170 mmol/litreIn hospitals, 500- and 1000-mL packs, and sometimes other sizes,are availablePotassium Chloride, Sodium Chloride, and Glucose(Non-proprietary) AIntravenous infusion, sodium chloride 0.45% (4.5 g,Na + 75 mmol/litre) with 5% of anhydrous glucose andusually sufficient potassium chloride to provide K +10–40 mmol/litre (to be specified by the prescriber)In hospitals, 500- and 1000-mL packs, and sometimes other sizesare availablePotassium Chloride (Non-proprietary) ASterile concentrate, potassium chloride 15%(150 mg, approximately 2 mmol each of K + and Cl /mL). Net price 10-mL amp = 48pSolutions containing 10 and 20% of potassium chloride are alsoavailable in both 5- and 10-mL ampoulesImportant Must be diluted with not less than 50 times itsvolume of Sodium Chloride 0.9% or other suitable diluentand mixed well; see Safe Practice, aboveBicarbonate and trometamolSodium bicarbonate is used to control severe metabolicacidosis (pH < 7.1) particularly that caused by lossof bicarbonate (as in renal tubular acidosis or fromexcessive gastro-intestinal losses). Mild metabolic acidosisassociated with volume depletion should first bemanaged by appropriate fluid replacement because acidosisusually resolves as tissue and renal perfusion arerestored. In more severe metabolic acidosis or when theacidosis remains unresponsive to correction of anoxiaor hypovolaemia, sodium bicarbonate (1.26%) can beinfused over 3–4 hours with plasma-pH and electrolytemonitoring. In severe shock (section 2.7.1), for examplein cardiac arrest, metabolic acidosis can develop withoutsodium depletion; in these circumstances sodiumbicarbonate is best given intravenously as a smallvolume of hypertonic solution, such as 8.4%; plasmapH and electrolytes should be monitored. For chronicacidotic states, sodium bicarbonate can be given bymouth (section 9.2.1.3).Trometamol (tris(hydroxymethyl)aminomethane,THAM), an organic buffer, corrects metabolic acidosisby causing an increase in urinary pH and an osmoticdiuresis. It is indicated when sodium bicarbonate isunsuitable as in carbon dioxide retention, hypernatraemia,or renal impairment. Respiratory support may berequired because trometamol induces respiratorydepression. It is also used during cardiac bypass surgeryand, very rarely, in cardiac arrest.SODIUM BICARBONATEIndication and doseMetabolic acidosis see also notes above. By slow intravenous injection of a strongsolution (up to 8.4%), or by continuous intravenousinfusion of a weaker solution (usually1.26%)An amount appropriate to the body base deficit9 Nutrition and blood