BRAIN BLOOD-FLOW RESPONSES TO INDOMETHACIN DURING HEMORRHAGIC HYPOTENSION IN NEWBORN PIGLETS

Indomethacin has been shown to reduce cerebral blood flow and cerebral blood flow velocities in newborn infants and animals of various speci es. To answer the question of whether there may be a compromise of cer ebral perfusion in hypotensive infants who have been treated with indo methacin, cerebral blood flow and cerebral vascular resistance were de termined in 10 control and 16 indomethacin-treated 1-day-old piglets d uring (1) steady state conditions; (2) 10 min after the administration of saline or a 0.2-mg/kg dose of indomethacin; (3) 1 h after saline o r indomethacin administration, and (4) 10 min after induction of moder ate hemorrhagic hypotension. Mean arterial blood pressures increased i mmediately after the infusion of indomethacin in the experimental grou p. Cerebral blood flows did not change throughout the study despite he morrhagic hypotension in controls; cerebral blood flows were significa ntly decreased 10 min after indomethacin infusion in the experimental animals. However, total and regional cerebral blood flows were not fur ther decreased in the presence of moderate hypotension. Cerebral vascu lar resistance increased 10 min after indomethacin infusion but return ed to steady state 1 h following the indomethacin dose. These results suggest that indomethacin lowers baseline cerebral blood flow, but doe s not impair cerebrovascular regulatory responses during acute, modera te hemorrhagic hypotension in the newborn piglet.