pheochromocytoma is strongly suspected, obtain this study in tandem with MRI scan of abdomen.
ECG. Quick and easy way to evaluate heart for left ventricular hypertrophy.
Ambulatory BP monitoring. Best way to establish the diagnosis of office hypertension. School nurses are the "poor person's ambulatory BP monitors."
A. Hypertensive Emergency. Hypertension associated with signs of end-organ damage (pulmonary edema, hypertensive encephalopathy, cerebral bleeding, or cerebral infarction) requires immediate IV treatment. Therapeutic goal for first several hours should be ~25% reduction from maximal BP. Final BP goal should be gradually achieved within 48 hours.
1. Nitroprusside. Very powerful drug with predictable and immediate action on BP. Starting dose is 0.3 mcg/kg/min, with maximum of 10 mcg/kg/min. BP changes occur within 1 minute during titration. Infusion set needs to be protected against light. Monitor thiocyanide and cyanide levels after 3 days (earlier, in liver or renal failure).
2. Nicardipine. Rapidly acting calcium channel blocker; used at 0.3-5 mcg/kg/min. Very irritating to tissue.
3. Esmolol. Potent ^-adrenergic receptor antagonist. Load patient with 100-500 mcg/kg quick IV push and maintain BP control with 25-100 mcg/kg/min infusion. Can be carefully titrated up to 500 mcg/kg/min.
4. Labetalol. Combined a- and nonspecific ^-antagonist. Can be given as boluses from 0.1-1 mg/kg; maximum 20 mg per dose. Constant infusion titrated to 0.1-1 mg/kg/min, occasionally to maximum of 3 mg/kg/min.
5. Enalaprilat. Effective in 5-10 mcg/kg doses q8-24h. Because neonates have a more active renin-angiotensin system, they are more sensitive to drug than older children and should be given dose in lower range. Closely monitor renal function and serum potassium level.
6. Hydralazine. Old but trustworthy drug given at 0.1-0.5 mg/kg as a bolus. Maximum dose per bolus is 20 mg. Can be repeated q3-4h. Monitor heart rate and hold doses if significant tachycardia. Watch for resistance to BP-lowering effect.
7. Diazoxide. Extremely effective; can cause precipitous drop in BP and elevate blood glucose concentration. If normal saline infusion is available at bedside to treat acute hypotension, 1-3 mg/kg quick IV push works well. Second bolus can be given within 5-15 minutes if needed, not to exceed 5 mg/kg combined dose. Effective dose can be repeated q4-24h.
B. Hypertensive Urgency. Symptomatic hypertension without evidence of end-organ damage. Oral treatment is acceptable, although IV medications may also be considered. Long-acting oral agents (ie, those recommended in once- or twice-daily doses) should be avoided due to delayed peak concentration.
1. "Sublingual" nifedipine. No excessive side effects reported in pediatric literature; frequently administered, convenient drug of choice for pediatric hypertensive urgencies if administered in appropriate dose. Conventional dose is 0.25-0.5 mg/kg per dose q3-4h, not to exceed 10 mg per dose or 3 mg/kg/day. Although labeled as sublingual, absorption takes place from stomach, so capsule needs to be opened before being swallowing.
2. Oral hydralazine. Doses of 0.75-1 mg/kg q4-6h may work well. Maximum one-time dose is 25 mg, with cumulative daily dose of 5 mg/kg.
3. Minoxidil. More powerful vasodilator than hydralazine, with more side effects. In acute situations, 0.2 mg/kg may work well. Add diuretic if treatment exceeds a few days.
4. Propranolol. Given in doses of 0.12-0.25 mg/kg q6-12h.
5. Chronic hypertension. Not within scope of this discussion, but lifestyle changes, such as low-salt diet, exercise, and weight loss, should be part of any comprehensive treatment plan for patients with chronic hypertension.
VI. Problem Case Diagnosis. The 13-year-old girl had modest BP elevation, which might be attributed to office hypertension, essential hypertension, or metabolic syndrome. Further investigation showed multiple high BP readings had been obtained by school nurse, and patient also had a strong family history of hypertension. Diagnosis of essential hypertension was made, and patient's BP was well controlled on salt restriction and hydrochlorothiazide, 25 mg daily.
VII. Teaching Pearl: Question. What is the only form of hypertension that will never develop into malignant hypertension?
VIII. Teaching Pearl: Answer. Coarctation of the aorta never progresses into malignant hypertension. This is the only form of hypertension in which the kidneys are sheltered from elevated systemic BP. This observation suggests the pivotal role of the kidneys in the pathome-chanism of malignant hypertension.
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