The effect of ophthalmic instillation of 10% phenylephrine on systemic blood pressure in the neonate has not been previously evaluated, despite reports of adverse reactions. The effect of 10% and 2½% phenylephrine eye drops in healthy low birth weight neonates was compared in a double-blind study. Blood pressure showed a rise of 12 to 16 mm Hg in systole and 10 to 14 mm Hg in diastole following administration of 10% phenylephrine. Blood pressure remained stable in infants receiving 2½% phenylephrine.
Consistent, although more variable, increases in blood pressure were noted in eight low birth weight infants given 10% phenylephrine eye drops in a nonblind study. Complete mydriasis was achieved with 2½% phenylephrine as well as with 10%.
Neither concentration had an effect on pulse or respiratory rates. Cutaneous administration of either 10% or 2½% phenylephrine to abdominal skin produced local blanching but no systemic effect.
To avoid potentially dangerous sequelae from iatrogenic hypertension, it is recommended that not more than one drop of 2½% phenylephrine in each eye be administered to neonates for mydriasis.
Early Life Microcirculatory Plasticity and Blood Pressure Changes in Low Birth Weight Infants Born to Normotensive Mothers: A Cohort Study