Anemia of Prematurity - Portal Neonatal

signify the presence of underlying pathology because renin values are typically quite high in
infancy. In addition, plasma renin may be elevated falsely by medications that are
commonly used in the NICU, such as aminophylline. Keep these factors in mind when
interpreting renin values.
Imaging Studies:
• Chest radiography may be helpful in infants with CHF or in those with a murmur on physical
examination.
• Obtain renal ultrasonography in all hypertensive infants. Accurate renal ultrasonography
may help uncover potentially correctable causes of hypertension (eg, RVT); it may detect
aortic thrombi, renal arterial thrombi, or both; and it can reveal anatomic renal abnormalities
or other congenital renal parenchymal disease. Ultrasonography is fast, noninvasive, and
relatively inexpensive. Ultrasonography has largely replaced intravenous pyelography,
which has little, if any, use in the routine assessment of neonatal hypertension.
• For infants with extremely severe BP elevation, angiography may be necessary. Although
some investigators have used aortography via the umbilical artery catheter, a formal
angiography using the traditional femoral venous approach is much more accurate for
diagnosing renal arterial stenosis, primarily because of the high incidence of intrarenal
branch vessel abnormalities observed in children with FMD.
• Nuclear scanning may demonstrate abnormalities of renal perfusion caused by
thromboembolic phenomenon, although obtaining good studies in infants is difficult
because of their immature renal function.
• Obtain other studies, including echocardiography and voiding cystourethrography, as
indicated.
TREATMENT Section 6 of 10
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 (see Table 1). Nicardipine, which is a dihydropyridine
calcium channel blocker, appears to have some advantages over older drugs, such