NEONATAL HYPERTENSION MEDICAL CARE

Medical Care:
Numerous medications are available that may be used in the treatment of neonatal hypertension. Assess the clinical status of the infant and correct any easily correctable iatrogenic causes of hypertension (eg, infusions of inotropic agents, volume overload, pain) prior to instituting drug therapy. Next, choose an antihypertensive agent that is most appropriate for the specific clinical situation.

• Intravenous antihypertensive infusions
ο Usually, continuous intravenous infusions are the most appropriate initial therapy, especially in acutely ill infants with severe hypertension. The advantages of intravenous infusions are numerous, most importantly including the ability to quickly increase or decrease the rate of infusion to achieve the desired BP. As in patients of any age with malignant hypertension, take care to avoid too rapid a reduction in BP in order to avoid cerebral ischemia and hemorrhage; premature infants in particular are already at an increased risk because of the immaturity of their periventricular circulation. Because of the paucity of available data regarding the use of these agents in newborns, the choice of agent depends on the individual clinician's experience.

ο Currently available drugs for continuous infusion include nitroprusside, labetalol, esmolol, and nicardipine. Nicardipine, which is a dihydropyridine calcium channel blocker, appears to have some advantages over older drugs, such as nitroprusside, that may make it the drug of choice in this population. Regardless of the drug chosen, monitor BP continuously via an indwelling arterial catheter or by frequently repeated (q10-15min) cuff readings so that the rate of infusion can be titrated to achieve the desired degree of BP control.

• Intermittently administered intravenous antihypertensive agents: For some infants, intermittently administered intravenous agents have a role in therapy. Hydralazine and labetalol, in particular, may be useful in infants with mild-to-moderate hypertension who are not yet candidates for oral therapy because of GI dysfunction. Enalaprilat, the intravenous ACE inhibitor, has also been reported to be useful in the treatment of neonatal renovascular hypertension, but it should be used with great caution. Even doses at the lower end of published ranges may lead to significant prolonged hypotension and oliguric acute renal failure.

• Oral antihypertensive agents
ο Oral antihypertensive agents are best reserved for infants with less severe hypertension or infants whose acute hypertension has been controlled with intravenous drugs and who are ready to be converted to long-term therapy. Captopril, in particular, is a useful agent for many causes of neonatal hypertension and is considered by many authorities to be the oral drug of choice for neonatal hypertension. The initial dose of captopril recommended for premature infants is lower than that used in older infants because it may produce a rapid exaggerated fall in BP in preterm infants. For BP that cannot be controlled by captopril alone, a diuretic should be used as the second agent.

ο Beta-blockers may need to be avoided in long-term antihypertensive therapy in infants with BPD. In such infants, diuretics may have a beneficial effect not only in controlling BP but also in improving pulmonary function. Other drugs, which may be useful in some infants, include vasodilators, such as hydralazine and minoxidil (because it can be compounded into a stable suspension) and the calcium channel blocker isradipine, which may be superior to the older agents. Nifedipine is a poor choice for long-term therapy because of the difficulty in administering small doses and because of the rapid, profound, and short-lived drops in BP that are typically produced by this agent.

Surgical Care:
Surgery is rarely indicated for treatment of neonatal hypertension, except for specific diagnoses, such as ureteral obstruction, aortic coarctation, or certain tumors. Unilateral RVT is commonly treated with nephrectomy to avoid the need for long-term drug therapy. For infants with renal arterial stenosis, managing the infant medically may be necessary until growth is sufficient to undergo definitive repair of the vascular abnormalities. Infants with malignant hypertension secondary to PKD may require bilateral nephrectomy. Fortunately, such severely affected infants are quite rare.

Consultations:
Consultation with a cardiologist may be indicated for performance of echocardiography or evaluation of CHF or both. Consultation with an interventional radiologist may also be needed in some cases for performance of renal angiography.

Diet: A low-sodium diet may assist in treatment of infants with persistent hypertension; however, because most infant formula is relatively low in sodium content, no special dietary modifications are usually necessary in the neonatal period.

Drug Category: Vasodilators -- Relax blood vessels; thus, they decrease peripheral vascular resistance.

Drug Category: Calcium channel blockers -- Blockade of calcium channels in vascular smooth muscle, which leads to vasodilatation.

Drug Category: Beta-adrenergic blockers -- Decrease heart rate and cardiac output.

Drug Category: Angiotensin-converting enzyme (ACE) inhibitors -- Inhibit conversion of I to II.

Drug Category: Diuretic agents -- Decrease plasma volume. Promote excretion of water and electrolytes by the kidneys. May be used as monotherapy or combination therapy to treat hypertension.

Drug Category: Central agonists -- Decrease central adrenergic output