Increased blood pressure following pupillary dilation with 2.5% phenylephrine hydrochloride in preterm infants.

Heart rate and blood pressure changes following 0.5% tropicamide and 2.5% phenylephrine hydrochloride were evaluated in seven ill preterm infants (birth weight, 910 to 2,060 gm; gestational age, 26 to 36 weeks) during the first day of life. Each infant was monitored continuously for 30 minutes before and for 75 minutes after, instillation of the pupillary dilators. There were no significant changes in the heart rate, whereas a significant increase in systolic, diastolic, and mean arterial blood pressure was found. The increase in arterial blood pressure was detected at two minutes, peaked at eight minutes, and remained at significantly higher levels for 30 minutes after instillation. Because of the potential relationship between increased blood pressure and intraventricular hemorrhage, arterial blood pressure must be monitored during instillation of mydriatic drugs in the preterm infant.