Neonatal Hypotension, the Role of Hydrocortisone and Other Pharmacological Agents in its Management

Abstract

pressure at which there is loss of auto-regulation of organ blood flow resulting in tissue ischemia [2]. Shead provides yet another working definition by suggesting that a mean blood pressure less than the neonate's gestational age can be considered hypotension [4]. Hence, there is no clear consensus on the definition for neonatal hypotension. Currently, proper diagnosis and management of neonatal hypotension necessitates the use of clinical judgment following a careful review of physiological parameters. Causes of Neonatal HypotensionNeonatal hypotension is most commonly seen in premature neonates and its incidence is inversely related to the gestational age at delivery [5]. The causes of hypotension in both term and preterm neonates are summarized in Table 2.Hypotension in preterm infants is predominantly due to either abnormal peripheral vaso-regulation or myocardial dysfunction. Hypovolemia as a primary cause is observed less frequently [6]. Since the autonomic nervous system that regulates the peripheral systemic resistance is immature in preterm infants [7], these patients are likely to develop peripheral vasodilatation and hypotension [6]. In addition, the immature myocardium of a preterm infant also has less mitochondria than a term infant. This decreases the ability of the myocardium to adapt from pumping against a low resistance circuit (placenta) to pumping against a high resistance circuit (systemic circulation) after delivery, thus leading to hypotension [4,8].Some other etiologies of hypotension in this population include both physiologic/anatomic factors as well as pathologic factors. Physiologic factors include the presence of a patent ductus arteriosus (PDA) and relative adrenal insufficiency secondary to an immature hypothalamic-pituitary axis (HPA) [9]. Pathologic factors include perinatal depression, maternal chorioamnionitis, hypovolemia