EFFECT OF DEXAMETHASONE THERAPY ON CEREBRAL AND OCULAR BLOOD-FLOW VELOCITY IN PREMATURE-INFANTS STUDIED BY COLOR DOPPLER FLOW IMAGING

Although dexamethasone (DEX) is used widely in neonates with chronic, and even recently with acute respiratory disease, its potential side-e ffects on human cerebral and ocular haemodynamics remain unknown. The effects of DEX on cerebral and ocular blood flow velocities were asses sed in preterm infants with lung disease and mechanical ventilation. T en ventilated preterm infants received DEX (0.25 mg/kg/12 h) for ongoi ng chronic lung disease or extubation failure. Colour Doppler flow ima ging studies of the internal carotid, anterior cerebral and ophthalmic arteries were made before and 10, 30, 60, 120 and 240 min after the 1 st, 3rd, and 5th doses of DEX. Peak systolic, temporal mean, and end-d iastolic flow velocities and the resistence index (RI) of Pourcelot we re determined. The brain was examined by ultrasonography before and at the end of each Doppler study. All patients were continuously monitor ed for transcutaneous blood gases and blood pressure. All flow velocit ies and the RI of the internal carotid, anterior cerebral and ophthalm ic 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 th e RI progressively lower up to the 5th dose. The most significant chan ges occurred in end-diastolic flow velocity and consisted of a percent age increase between the Ist and 5th dose of 72% in the internal carot id artery, 102% in the anterior cerebral artery and 84% in the ophthal mic artery. Changes in arterial blood pressure followed a pattern simi lar to that of changes in blood flow velocity. Conclusions Dexamethaso ne increments cerebral and ocular blood flow velocity. We speculate th at this finding may be relevant to the development of brain and retina l injury.