Cardiovascular support for extremely preterm infants in the first week after birth.
Review evolving blood pressure (BP) parameters occurring immediately after birth.
Review the potential risks and benefits of commonly prescribed antihypotensive therapies.
Provide suggestions for early postnatal blood pressure management in extremely preterm infants.
The intrinsically abnormal condition of extreme prematurity and the associated evolving complex physiology make it difficult to identify an acceptable range of BP values in the immediate postnatal period. Although BP is higher with increasing birth weight and gestational age (GA) at birth and increases spontaneously with advancing postnatal age similar to more mature infants, there is a wide range in observed BP values for extremely preterm infants during this time (Figure 31.1). These factors make it difficult to determine whether the BP for a given infant at a specific postnatal age is too high, too low, rising too quickly or not quickly enough. Multiple disease processes, unpredictable adaptation to extrauterine life, and difficulty assessing organ perfusion also make deciding when to institute therapy for perceived low BP challenging. Consequently, BP management is highly variable.
Systolic (A), diastolic (B), and mean (C) arterial blood pressure curves for 367 extremely preterm infants. (From Batton B. J Perinatol. 2014;34:301-5; reprinted with permission.)
Numerous investigations over the last 25 years suggest preterm infants with perceived hypotension are at an increased risk for adverse outcomes. These observations have led many clinicians to administer therapies in an effort to raise BP and presumably improve an infant’s chances of survival without major morbidity. No such improvement in outcomes has been demonstrated to date. More concerning is the possibility that commonly prescribed antihypotensive therapies such as isotonic fluid boluses, dopamine, dobutamine, epinephrine, and hydrocortisone may be harmful. Although these therapies may increase BP, it remains unclear whether these increases are distinct from the spontaneous rise in BP observed in the first postnatal week (Figure 31.2). Extremely preterm infants who receive antihypotensive therapies have higher mortality and morbidity rates versus untreated infants of a similar GA (Table 31.1). These risks persist even when considering confounding factors such as the frequency of low BP values, severity of illness, inclusion of infants in extremis who are likely to die irrespective of therapeutic interventions, and the underlying cause of perceived low BP (e.g., perinatal asphyxia, sepsis, hemorrhage).
Gestational age specific changes in the systolic (A), diastolic (B), and mean (C) arterial blood pressure 50th percentile curves for 367 extremely preterm infants. (From Batton B. J Perinatol. 2014;34:301-5; reprinted with permission.)
TABLE 31.1.Potential Risks and Benefits ...