Do extremely immature preterm infants with blood pressure which is believed to be low have reduced systemic perfusion, reduced cerebral oxygen delivery, increased cerebral injury, an increase in acute complications of prematurity and an increase in long-term disability? If so, below what value of blood pressure do these adverse outcomes increase?

These unanswered questions are of vital importance; extremely preterm infants have high rates of developmental delay and disability, blood pressures are often numerically very low and many preterm infants receive treatments which are potentially toxic with the goal of increasing their blood pressure. Unfortunately, it is not at all clear whether the common treatments for low blood pressure improve systemic flow or cerebral perfusion, or among the available options, which treatments are effective? The reason for this poverty of information is the lack of adequate trials. There are no controlled studies of hypotension therapy in the preterm newborn which include an untreated group, so changes in systemic perfusion or indirect measures of cerebral blood flow cannot necessarily be ascribed to the intervention. In addition, the small number of comparative trials that have been performed have all been vastly underpowered, and have concentrated on short-term physiological end points, usually blood pressure.1 One study which compared the effects of dopamine and epinephrine on indices of cerebral perfusion showed an increase of about 20% in cerebral blood volume after 2 h of treatment, in association with about a 50% increase in mean blood pressure, with no difference between the groups2; there was …