Although dexamethasone (DEX) is used widely in neonates with chronic, and even recently with acute respiratory disease, its potential side-effects on human cerebral and ocular haemodynamics remain unknown. The effects of DEX on cerebral and ocular blood flow velocities were assessed in preterm infants with lung disease and mechanical ventilation. Ten ventilated preterm infants received DEX (0.25 mg/kg/12 h) for ongoing chronic lung disease or extubation failure. Colour Doppler flow imaging studies of the internal carotid, anterior cerebral and ophthalmic arteries were made before and 10, 30, 60, 120 and 240 min after the 1st, 3rd, and 5th doses of DEX. Peak systolic, temporal mean, and end-diastolic flow velocities and the resistance index (RI) of Pourcelot were determined. The brain was examined by ultrasonography before and at the end of each Doppler study. All patients were continuously monitored for transcutaneous blood gases and blood pressure. All flow velocities and the RI of the internal carotid, anterior cerebral and ophthalmic arteries showed a similar trend throughout the study. The means of the values averaged for the 240 min of cerebral and ocular blood flow velocity with each dose were progressively higher and the values of the RI progressively lower up to the 5th dose. The most significant changes occurred in end-diastolic flow velocity and consisted of a percentage increase between the 1st and 5th dose of 72% in the internal carotid artery, 102% in the anterior cerebral artery and 84% in the ophthalmic artery. Changes in arterial blood pressure followed a pattern similar to that of changes in blood flow velocity.
Conclusions: Dexamethasone increments cerebral and ocular blood flow velocity. We speculate that this finding may be relevant to the development of brain and retinal injury.