Table 15.8 Causes of Systemic Hypertension in Premature Infants Grouped and Listed in Order of Frequency of Presentation Illness Renovascular Cause Thromboembolism related to cardiac catheterization, renal arterial stenosis, renal venous thrombosis, midaortic coarctation, renal arterial compression as caused by severe hydronephrosis, complications of umbilical arterial catheters Polycystic renal disease, multicystic dysplastic renal disease, obstruction at ureteropelvic junction, unilateral renal hypoplasia or agenesis, congenital nephritic syndrome Congenital renal parenchymal disease Acquired renal Acute tubular or cortical necrosis, interstitial nephritis parenchymal disease Drug induced Dexamethasone, α-adrenergic agents such as dopamine, epinephrine, muscular relaxants, theophylline, ophthalmic drops with phenylephrine Neonatal Maternal cocaine or heroin abstinence syndrome Cardiac Thoracic coarctation, iatrogenic fluid overload Endocrine Congenital adrenal hyperplasia, hyperaldosteronism, hyperthyroidism Neurologic Pain, seizures, subdural hematoma Neoplasia Wilms tumor, pheochromocytoma, neuroblastoma Treatment of Systemic Hypertension The urgency of therapeutic intervention with antihypertensive drugs is dependent on illness severity The following general principles should be considered before embarking on specific drug therapy: ▪ Indwelling arterial catheters should be removed if felt to be causal ▪ All current treatments should be reevaluated because they may be contributory ▪ Rapid correction of blood pressure should be avoided, particularly in the early postnatal period, because this may contribute to cerebral ischemia or hemorrhage ▪ It should be the goal of therapy to reduce blood pressure by one-third of the difference between the pretreatment systolic value and the upper limit of normal systolic blood pressure in the first 6 hours Intravenous agents should be used for emergent hypertension Intravenous diuretics and vasodilators are the mainstay of treatment (Fig 15.13) Commonly used oral maintenance treatments include diuretics (such as thiazides), inhibitors of angiotensin-converting enzyme, (except if the neonate exhibits renal impairment), or antagonists of the calcium channel FIG 15.13 Therapeutic approach to the care of premature infants with systemic hypertension >97th percentile Pericardial Effusion Although rare, the differential diagnosis for the acutely unstable preterm neonate should always include acute pericardial effusion because emergent treatment may be lifesaving.263,264 Both peripherally inserted central catheters and umbilical venous catheters have been associated with moderate to large effusions The precise frequency is difficult to estimate; however, an incidence of 1.8 per 1000 catheters with approximately 25% identified at autopsy has been reported.265 Neonates with central venous catheter–associated pericardial effusions have a mortality rate of 30% to 65%.265,266 The mechanism by which central catheters are related to infusions is poorly understood The majority of effusions are associated with malpositioned catheters, the tip of which should ideally be located at the junction of the vena cava and right atrium The precise anatomic location of this site on chest radiography varies.267 There is considerable movement of catheter tips with limb position and direct injury from the catheter tip may be a contributor, making even neonates with well-positioned catheter tips at risk.266 In most cases the clinical decision of repositioning of a catheter whose tip is in the right atrium is a balance of the risk of catheter manipulation and potential infection, versus the risks of effusion and/or perforation Mechanical stress may contribute to myocardial necrosis that when followed by osmotic injury from parenteral nutrition, may result in diffusion of intravenous solution into the pericardial space.268 The presenting features include acute hemodynamic collapse (67%) and unexplained shock (36%), and the majority of significant effusions occur within 3 days of central line placement, although they may occur at any time.268 Clinical signs are nonspecific but may include distant heart sounds and cardiomegaly Echocardiography is diagnostic, and ultrasound-guided drainage is ideal264; however, emergency drainage should not be delayed in an arrest setting if echocardiography is not available Non–central line–associated causes of acute effusion such as malignancy, fungal, or viral infection are rare