BNF for Children 2011-2012

76 2.2 Diuretics BNFC 2011–20122 Cardiovascular systemBreast-feeding manufacturer advises caution—noinformation availableSide-effects ectopic beats, ventricular tachycardia,supraventricular arrhythmias (more likely in childrenwith pre-existing arrhythmias), hypotension; headache;less commonly ventricular fibrillation, chestpain, tremor, hypokalaemia, thrombocytopenia; veryrarely bronchospasm, anaphylaxis, and rashLicensed use not licensed for use in children under18 yearsIndication and doseCongestive heart failure, low cardiac outputfollowing cardiac surgery, shock. By intravenous infusionNeonate initially 50–75 micrograms/kg over 30–60 minutes (reduce or omit initial dose if at risk ofhypotension) then 30–45 micrograms/kg/hour bycontinuous intravenous infusion for 2–3 days(usually for 12 hours after cardiac surgery)Child 1 month–18 years initially 50–75 micrograms/kgover 30–60 minutes (reduce or omitinitial dose if at risk of hypotension) then 30–45 micrograms/kg/hour by continuous intravenousinfusion for 2–3 days (usually for 12 hoursafter cardiac surgery)Administration for intravenous infusion dilute withGlucose 5% or Sodium Chloride 0.9% or SodiumChloride and Glucose intravenous infusion to a concentrationof 200 micrograms/mL (higher concentrationsof 400 micrograms/mL have been used); loadingdose may be given undiluted if fluid-restrictedPrimacor c (Sanofi-Aventis) AInjection, milrinone (as lactate) 1 mg/mL, net price10-mL amp = £16.612.2 DiureticsDiuretics are used for a variety of conditions in childrenincluding pulmonary oedema (caused by conditionssuch as respiratory distress syndrome and bronchopulmonarydysplasia), congestive heart failure, and hypertension.Hypertension in children is often resistant totherapy and may require the use of several drugs incombination (see section 2.5). Maintenance of fluid andelectrolyte balance can be difficult in children on diuretics,particularly neonates whose renal function may beimmature.Loop diuretics (section 2.2.2) are used for pulmonaryoedema, congestive heart failure, and in renal disease.Thiazides (section 2.2.1) are used less commonly thanloop diuretics but are often used in combination withloop diuretics or spironolactone in the management ofpulmonary oedema and, in lower doses, for hypertensionassociated with cardiac disease.Aminophylline infusion has been used with intravenousfurosemide to relieve fluid overload in criticallyill children.Heart failure Heart failure is less common in childrenthan in adults; it can occur as a result of congenital heartdisease (e.g. septal defects), dilated cardiomyopathy,myocarditis, or cardiac surgery. Drug treatment ofheart failure due to left ventricular systolic dysfunctionis covered below; optimal management of heart failurewith preserved left ventricular function has not beenestablished.Acute heart failure can occur after cardiac surgery oras a complication in severe acute infections with orwithout myocarditis. Therapy consists of volume loading,vasodilator or inotropic drugs.Chronic heart failure is initially treated with a loopdiuretic (section 2.2.2), usually furosemide supplementedwith spironolactone, amiloride, or potassium.If diuresis with furosemide is insufficient, the addition ofmetolazone or a thiazide diuretic (section 2.2.1) canbe considered. With metolazone, the resulting diuresiscan be profound and care is needed to avoid potentiallydangerous electrolyte disturbance.If diuretics are insufficient an ACE inhibitor, titrated tothe maximum tolerated dose, can be used. ACE inhibitors(section 2.5.5.1) are used for the treatment of allgrades of heart failure in adults and can also be usefulfor children with heart failure. Addition of digoxin(section 2.1.1) can be considered in children who remainsymptomatic despite treatment with a diuretic and anACE inhibitor.Some beta-blockers improve outcome in adults withheart failure, but data on beta-blockers in children arelimited. Carvedilol (section 2.4) has vasodilatory propertiesand therefore (like ACE inhibitors) also lowersafterload.In children receiving specialist cardiology care, thephosphodiesterase type-3 inhibitor enoximone is sometimesused by mouth for its inotropic and vasodilatoreffects. Spironolactone (section 2.2.3) is usually used asa potassium-sparing drug with a loop diuretic; in adultslow doses of spironolactone are effective in the treatmentof heart failure. Careful monitoring of serumpotassium is necessary if spironolactone is used incombination with an ACE inhibitor.Potassium loss Hypokalaemia can occur with boththiazide and loop diuretics. The risk of hypokalaemiadepends on the duration of action as well as the potencyand is thus greater with thiazides than with an equipotentdose of a loop diuretic.Hypokalaemia is particularly dangerous in childrenbeing treated with cardiac glycosides. In hepatic failurehypokalaemia caused by diuretics can precipitateencephalopathy.The use of potassium-sparing diuretics (section 2.2.3)avoids the need to take potassium supplements.2.2.1 Thiazides and relateddiureticsThiazides and related compounds are moderatelypotent diuretics; they inhibit sodium reabsorption atthe beginning of the distal convoluted tubule. They areusually administered early in the day so that the diuresisdoes not interfere with sleep.In the management of hypertension a low dose of athiazide produces a maximal or near-maximal bloodpressure lowering effect, with very little biochemicaldisturbance. Higher doses cause more marked changesin plasma potassium, sodium, uric acid, glucose, andlipids, with little advantage in blood pressure control.For reference to the use of thiazides in chronic heartfailure see section 2.2.