Clinical Factors Influencing Blood Pressure in the Neonate

After completing this article, readers should be able to: 1. Describe the association between gestational age, birthweight, and postnatal age and blood pressure in the neonate. 2. Delineate the primary clinical consideration in an infant who has hypotension. 3. Describe the controversy surrounding the relationship between antenatal steroid therapy and neonatal blood pressure. 4. Delineate the aspects of management of respiratory illnesses in the neonate that may be associated with altered blood pressure. 5. List factors that may cause altered blood pressure in the neonate. Few aspects of neonatal care have generated as much controversy as the assessment of blood pressure (BP) and need for treatment of perceived abnormalities of this physiologic variable. Familiarity with clinical situations in which BP may be low should allow anticipation of this common clinical problem and timely intervention when such treatment is necessary (Tables 1 and 2). In this article, we review factors that have been shown to have the greatest effect on BP. View this table: Table 1. Some Risk Factors for Shock in the Newborn View this table: Table 2. Some Causes of Cardiogenic Shock in the Newborn A direct reading from an indwelling arterial catheter represents the “gold standard” for measuring BP in the neonate, and this method should be used whenever possible. Obviously, arterial access may not always be available, and the ability to monitor BP noninvasively using an oscillometric technique represents a major advancement in neonatal care. The correlation between direct and indirect methods generally has been good. Disparities in results have been related to various factors, including inappropriate cuff width-to-arm ratio or problems with the arterial catheter-transducer system, such as air bubbles or clots. In general, indirect determinations are higher than those obtained directly, often by 3 to 5 mm Hg. The individual contributions of birthweight and gestational age to BP are difficult to delineate. Several groups of investigators have shown that BP …