Andersons pediatric cardiology 1622

maximum 4 hourly 0.025–0.05 mg/kg/h IV to maximum of 3 mg/kg in 24 h 0.25–0.5 mg/kg PO Nifedipine (capsules) 20–30 Calcium channel blocker Minoxidil 5–10 min 0.1–0.2 mg/kg/dose PO Furosemide 5–10 min 2–5 mg/kg IV as a bolus Loop diuretic injection or as an infusion if required Direct vasodilator Initial dose may cause marked hypotension Adverse events include flushing and tachycardia Effect is less controllable than with antihypertensive medications given as intravenous infusion; may cause tachycardia Child must bite and swallow capsule, or liquid contents should be removed via a needle and syringe and then swallowed Effect is less controllable than with antihypertensive medications given as intravenous infusion May cause fluid retention For severe intravascular volume expansion states Rapid administration of large doses may be ototoxic Hypokalemia A selection of drugs for use in hypertensive emergencies is shown in Table 60.8 Labetalol is an effective first choice If it proves insufficient, then sodium nitroprusside may be added The latter is especially useful because of its very short duration of action Constant monitoring of the rate of infusion and blood pressure is required during its use Thiocyanate toxicity can occur with longterm therapy or with renal insufficiency Although nitroprusside has been used without ill effects for up to 10 days,412 levels of thiocyanate should be monitored in the blood after 48 hours, and treatment discontinued if the concentration exceeds 100 µg/mL The solution must be protected from light by shielding the syringe and infusion lines Other intravenous drugs are now available, including nicardipine, esmolol, and glyceryl trinitrate, but their use in children is limited by their availability, clinical experience, and reported use in children and young people In volume expanded states, loop diuretic furosemide is indicated Less severe hypertensive crises are often managed successfully with oral nifedipine in rapid-acting capsule form Children should be instructed to bite the capsule, as most absorption occurs after swallowing the contained liquid In young children, a liquid preparation is available, or the contents of a capsule may be aspirated by syringe and fine needle and then administered orally Intravenous hydralazine may also be used as a rapid-acting vasodilator These agents, however, give less precise control over the rate of fall of blood pressure, and intravenous infusion treatment is preferred where there is symptomatic severe hypertension Once severe hypertension is controlled using an intravenous antihypertensive medication, oral antihypertensive drugs should be commenced to allow ongoing control of hypertension The underlying cause of severe hypertension, age, and associated comorbidities often dictate the choice of antihypertensive therapy Long-acting oral drugs such as amlodipine are an effective first choice for most cases of severe hypertension Patients with renovascular disease often require two or more medications to control hypertension optimally while more specific interventions are planned Patients with acute kidney injury, glomerulonephritis, and fluid overload have marked improvement of their severe hypertension following management with dialysis and adequate fluid removal, and often normal BP control following complete recovery of renal function References Beevers G, Lip GYH, O'Brien E ABC of Hypertension 4th ed BMJ Books: London; 2001 Gomez O, Prineas RJ, Rastam L Cuff bladder width and blood pressure measurement in children and adolescents J Hypertens 1992;10:1235–1241 O'Brien E A century of confusion: which bladder for accurate blood pressure measurement? J Hum Hypertens 1996;10:565– 572 Stenfield L, Dimich L, Reder R, et al Sphygmomanometry in the pediatric patient J Pediatr 1978;92:934–938 Perloff D, Grim C, Flack J, et al Human blood pressure determination by sphygmomanometry AHA Medical/scientific statement Circulation 1993;88:2460–2470 Whincup PH, Cook DG, Shaper AG Blood pressure measurement in children: the importance of cuff bladder size J Hypertens 1989;7:845–850 Lum LG, Jones JMD The effect of cuff width on systolic blood pressure measurements in ... measurement? J Hum Hypertens 1996;10:565– 572 Stenfield L, Dimich L, Reder R, et al Sphygmomanometry in the pediatric patient J Pediatr 1978;92:934–938 Perloff D, Grim C, Flack J, et al Human blood pressure determination by sphygmomanometry